U.S. patent application number 09/803664 was filed with the patent office on 2001-11-08 for versatile transmitter and receiver for position measurement.
Invention is credited to Corey, Nathan A., Denney, James E., Detweiler, Philip L., Douglas, Frank B., Hart, Edward E., Jackson, Jonatha A., Leyshon, Frank A., Pfiffi, Horst, Sayer, David A..
Application Number | 20010038447 09/803664 |
Document ID | / |
Family ID | 22692836 |
Filed Date | 2001-11-08 |
United States Patent
Application |
20010038447 |
Kind Code |
A1 |
Detweiler, Philip L. ; et
al. |
November 8, 2001 |
Versatile transmitter and receiver for position measurement
Abstract
Improved versatility, reliability and performance for
field-deployable spatial positioning or measurement systems that
use rotating laser fans or beams. Teachings include [1] A system
integrated field-deployable length standard uses a reelable tape
with positional indents; [2] the use of labyrinth seals at
interface volumes between rotating laser heads and transmitter
assemblies to prevent ingress of contaminants and allow for
elimination of the use of rotary seals; [3] new dynamic leveling
techniques to plumb positional laser transmitter systems; [4]
strobe beam configurations for improved near/far performance; and
[5] a vertical mode sensing scheme that allows switching to
measuring tall structures when needed.
Inventors: |
Detweiler, Philip L.; (Tipp
City, OH) ; Denney, James E.; (Springfield, OH)
; Sayer, David A.; (Waynesville, OH) ; Corey,
Nathan A.; (Fairborn, OH) ; Jackson, Jonatha A.;
(Centerville, OH) ; Douglas, Frank B.; (Tipp City,
OH) ; Pfiffi, Horst; (Kaiserslautern, DE) ;
Hart, Edward E.; (Springfield, OH) ; Leyshon, Frank
A.; (Cambridge, OH) |
Correspondence
Address: |
ALLEN BLOOM
C/O DECHERT
PRINCETON PIKE CORPORATION CENTER
P.O. BOX 5218
PRINCETON
NJ
08543-5218
US
|
Family ID: |
22692836 |
Appl. No.: |
09/803664 |
Filed: |
March 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60188367 |
Mar 10, 2000 |
|
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|
Current U.S.
Class: |
356/141.4 |
Current CPC
Class: |
G01C 15/002 20130101;
G01S 3/789 20130101; G01S 5/16 20130101; G01C 15/00 20130101 |
Class at
Publication: |
356/141.4 |
International
Class: |
G01C 001/00; G01B
011/26 |
Claims
What is claimed:
1. A transmitter and spatial positioning receiver for a spatial
positioning system, comprising: [a] a stationary portion and a
rotating laser head in proximity to said stationary portion, said
rotating laser head further comprising a first light emitting
device emitting a divergent rotating light fan onto a field of
measurement; [b] a synchronization strobe providing a
synchronization strobe beam for communicating with said spatial
positioning receiver operating in said field of measurement; [c] a
detector in said spatial positioning receiver to detect said
divergent rotating light fan and also said synchronization strobe
beam; [d] a processor to determine at least one spatial coordinate
of said detector in said spatial positioning receiver based on a
time of receipt of said divergent rotating light fan and said
synchronization strobe beam; said transmitter and spatial
positioning receiver also comprising: [e] a field-deployable length
standard for use with said spatial positioning receiver for spatial
position-marking, setting, calibrating or referencing in said
spatial positioning system, said field-deployable length standard
comprising: a reelable tape comprising at least one markable
position; said reelable tape and said markable position each so
positioned and oriented with respect to said spatial positioning
receiver such that when said spatial positioning receiver is posed
to a second location upon unreeling said reelable tape and using
said markable position, a detector in said spatial positioning
receiver is a known distance from a first location of said detector
in said spatial positioning receiver prior to unreeling said
reelable tape; said transmitter so constructed that said stationary
portion and said rotating laser head are each individually
positioned, shaped, and oriented such that there is defined an
interface volume therebetween, said transmitter further comprising:
[f] labyrinth seal, so sized, positioned and oriented so as to
restrict the motion of contaminants through the interface volume
between the rotating laser head and the stationary portion of said
transmitter; [g] a strobe set to provide a spatial positioning
transmitter synchronization strobe beam to improve energy
distribution and operating range when communicating with said
spatial positioning receiver operating in said field of
measurement, said strobe set comprising: [h] a first strobe having
an output distribution of a first value for half power beam angular
width, oriented to provide output onto the field of measurement;
[i] a second strobe having an output distribution of a second value
for half power beam width higher than said first value for half
power beam angular width, oriented to provide output onto the field
of measurement; said first and second strobes further positioned
and oriented such that said operating range of said spatial
positioning receiver is increased with respect to said first and
second strobes both having either said first value or said second
value for half power beam angular width; [j] said transmitter
comprising a sensor to sense when said transmitter is oriented so
as to sweep said divergent rotating light fan in a substantially
vertical plane, said sensor communicating said sense to said
processor for a vertical coordinate determination.
2. A field-deployable length standard for use with a spatial
positioning receiver for spatial position-marking, setting,
calibrating or referencing in a spatial positioning system, said
field-deployable length standard comprising: a reelable tape
comprising at least one markable position; said reelable tape and
said markable position each so positioned and oriented with respect
to said spatial positioning receiver such that when said spatial
positioning receiver is posed to a second location upon unreeling
said reelable tape and using said markable position, a detector in
said spatial positioning receiver is a known distance from a first
location of said detector in said spatial positioning receiver
prior to unreeling said reelable tape.
3. The field-deployable length standard of claim 2, wherein said
markable position comprises a detent operative upon said reelable
tape.
4. The field deployable length standard of claim 2, wherein said
reelable tape is reeled upon a reel assembly in mechanical
communication with a housing.
5. The field-deployable length standard of claim 4, wherein said
reel assembly is under a spring bias with respect to said housing
so as to allow movement of said reel assembly with respect to said
housing.
6. The field-deployable length standard of claim 5, wherein said
spring bias allows for a desired force loading along said reelable
tape.
7. The field-deployable length standard of claim 6, wherein said
housing comprises an aperture so shaped, sized, positioned, and
oriented so as to allow a viewing of said movement of said reel
assembly, said viewing operative to allow a calibration of said
force loading along said reelable tape.
8. The field-deployable length standard of claim 7, wherein said
aperture comprises a lens so shaped, sized, positioned and oriented
so as to allow said viewing of said movement of said reel assembly,
said viewing operative to allow a calibration of said force loading
along said reelable tape.
9. A field-deployable length standard for use with a spatial
positioning receiver for spatial position-marking, setting,
calibrating or referencing in a spatial positioning system, said
field-deployable length standard comprising: a reelable tape in
mechanical communication with said spatial positioning receiver;
said reelable tape comprising a first markable position, and a
second markable position a known path length along said reelable
tape from said first markable position when said reelable tape is
unreeled; said first and second markable positions so positioned
and oriented with respect to said spatial positioning receiver when
said reelable tape is unreeled such that when said spatial
positioning receiver is posed to a first location upon unreeling
said reelable tape and using said first markable position, a
detector in said spatial positioning receiver is a known distance
with respect to the detector when said spatial positioning receiver
is posed to a second location upon unreeling said reelable tape and
using said second markable position of said reelable tape.
10. The field-deployable length standard of claim 9, wherein any of
said first and second markable positions comprise a detent
operative upon said reelable tape.
11. The field deployable length standard of claim 9, wherein said
reelable tape is reeled upon a reel assembly in mechanical
communication with a housing.
12. The field-deployable length standard of claim 11, wherein said
reel assembly is under a spring bias with respect to said housing
so as to allow movement of said reel assembly with respect to said
housing.
13. The field-deployable length standard of claim 12, wherein said
spring bias allows for a desired force loading along said reelable
tape.
14. The field-deployable length standard of claim 13, wherein said
housing comprises an aperture so shaped, sized, positioned, and
oriented so as to allow a viewing of said movement of said reel
assembly, said viewing operative to allow a calibration of said
force loading along said reelable tape.
15. The field-deployable length standard of claim 14, wherein said
aperture comprises a lens so shaped, sized, positioned and oriented
so as to allow said viewing of said movement of said reel assembly,
said viewing operative to allow a calibration of said force loading
along said reelable tape.
16. A transmitter for a spatial positioning system, said
transmitter having a stationary portion and a rotating laser head
in proximity to said stationary portion, said stationary portion
and said rotating laser head each individually positioned, shaped,
and oriented such that there is defined an interface volume
therebetween, said transmitter comprising: a labyrinth seal, so
sized, positioned and oriented so as to restrict the motion of
contaminants through the interface volume between the rotating
laser head and the stationary portion of said transmitter.
17. The transmitter of claim 16, wherein said labyrinth seal is so
formed that a necessary path for said contaminants is
serpentine.
18. The transmitter of claim 16, wherein said labyrinth seal is so
formed that a necessary path for said contaminants is substantially
straight.
19. The transmitter of claim 16, wherein said stationary portion
and said rotating laser head are each individually positioned,
shaped, and oriented such that said labryrinth seal is formed by at
least a portion of said stationary portion and said rotating laser
head, said labyrinth seal operative in said interface volume.
20. The transmitter of claim 16, wherein said stationary portion
and said rotating laser head comprise a rotary transformer
positioned proximate said interface volume and positioned, shaped,
and oriented such that said labryrinth seal is formed by at least a
portion of said rotary transformer, said labyrinth seal operative
in said interface volume.
21. A method for dynamic leveling of a rotating body to bring a
rotational axis of said rotating body into better alignment with a
desired axis, said method comprising: [a] aligning an operating
axis of an autocollimator to said desired axis, said autocollimator
designed to output a light ray along said operating axis, and said
desired axis as a result of said aligning, and to monitor any
reflected light rays from said light ray with respect to said
desired axis; [b] affixing a mirror to said rotating body; [c]
orienting the rotating body to within the field of view of said
autocollimator; [d] noting the position of said reflected light
rays monitored by said autocollimator, whereby a circular arc is
formed by said reflected light rays; [e] determining the direction
and magnitude of a deviation of a geometric center of said circular
arc from the operating axis of said autocollimator; [f] changing
the orientation of said rotating body in such a manner so as to
bring said rotational axis into better alignment with said
operating axis of said autocollimator, whereby said rotational axis
will be put into better alignment with said desired axis.
22. The method of claim 21, wherein said desired axis is a downward
gravitational vector.
23. The method of claim 21, wherein said rotating body is a
rotating laser head in a spatial positioning system.
24. The method of claim 23, wherein said mirror is affixed to said
rotating laser head in such a manner that a normal axis of said
mirror is substantially parallel with said desired axis.
25. The method of claim 23, wherein said mirror is affixed to said
rotating laser head in such a manner that a normal axis of said
mirror is within 90 degrees of said desired axis.
26. A method for forming a spatial positioning transmitter
synchronization strobe beam to improve energy distribution and
operating range when communicating with a spatial positioning
receiver operating in a field of measurement, said method
comprising: [a] arraying a first strobe having an output
distribution of a first value for half power beam angular width
onto the field of measurement; [b] arraying a second strobe having
an output distribution of a second value for half power beam width
higher than said first value for half power beam angular width,
onto the field of measurement; [c] said first and second strobes
further positioned and oriented such that said operating range of
said spatial positioning receiver is increased with respect to said
first and second strobes both having either said first value or
said second value for half power beam angular width.
27. The method of claim 26, wherein said first value for half power
angular beam width is less than 15 degrees.
28. The method of claim 26, wherein said second value for half
power angular beam width is more than 20 degrees.
29. The method of claim 26, wherein a plurality of first strobes
are arrayed about a single second strobe, for output of said beam
onto the field of measurement.
30. The method of claim 29, wherein said plurality is numerically
three.
31. The method of claim 29, wherein said plurality of first strobes
and a plurality of second strobes are arrayed in such a manner and
orientation that each strobe of such first and second strobes is
aimed at a distinct direction onto the field of measurement.
32. A strobe set to provide a spatial positioning transmitter
synchronization strobe beam to improve energy distribution and
operating range when communicating with a spatial positioning
receiver operating in a field of measurement, said strobe set
comprising: [a] a first strobe having an output distribution of a
first value for half power beam angular width, oriented to provide
output onto the field of measurement; [b] a second strobe having an
output distribution of a second value for half power beam width
higher than said first value for half power beam angular width,
oriented to provide output onto the field of measurement; [c] said
first and second strobes further positioned and oriented such that
said operating range of said spatial positioning receiver is
increased with respect to said first and second strobes both having
either said first value or said second value for half power beam
angular width.
33. The strobe set of claim 32, wherein said first value for half
power angular beam width is less than 15 degrees.
34. The strobe set of claim 32, wherein said second value for half
power angular beam width is more than 20 degrees.
35. The strobe set of claim 32, wherein a plurality of first
strobes are arrayed about a single second strobe, for output of
said beam onto the field of measurement.
36. The strobe set of claim 35, wherein said plurality is
numerically three.
37. The strobe set of claim 35, wherein said plurality of first
strobes and a plurality of second strobes are arrayed in such a
manner and orientation that each strobe of such first and second
strobes is aimed at a distinct direction onto the field of
measurement.
38. A transmitter and spatial positioning receiver for a spatial
positioning system, said system capable of switching to a vertical
mode, said system comprising: [a] a stationary portion and a
rotating laser head in proximity to said stationary portion, said
rotating laser head further comprising a first light emitting
device emitting a divergent rotating light fan onto a field of
measurement; [b] a synchronization strobe providing a
synchronization strobe beam for communicating with said spatial
positioning receiver operating in said field of measurement; [c] a
detector in said spatial positioning receiver to detect said
divergent rotating light fan and also said synchronization strobe
beam; [d] a processor to determine at least one spatial coordinate
of said detector in said spatial positioning receiver based on a
time of receipt of said divergent rotating light fan and said
synchronization strobe beam; said transmitter and spatial
positioning receiver also comprising: [e] said transmitter
comprising a sensor to sense when said transmitter is oriented so
as to sweep said divergent rotating light fan in a substantially
vertical plane, said sensor communicating said sense to said
processor for a vertical coordinate determination.
39. A field-deployable spatial positioning transmitter and receiver
for spatial position-marking, setting, calibrating or referencing,
the field-deployable spatial positioning transmitter and receiver
comprising: a transmitter kit comprising a rotating laser head
emitting an angled fan of light, where angled means that the fan is
neither orthogonal nor parallel to the plane through which the head
rotates, and a strobe emitter that emits a light pulse in
predetermined or programmed relation to the position of the laser
head; a processor in data communication with a receiver; and the
receiver adapted to be moved about a field of measurement and
determine, in conjunction with the processor, distance and
orientation, the receiver comprising a light detector, the receiver
determining distance and orientation to the transmitter based on
the timing of detections of light from the fan of light and from
the strobe, the receiver further comprising a field-deployable
length standard comprising: a reelable tape comprising at least one
markable position and a reel attached to or incorporated within a
housing for the receiver, the reelable tape and the markable
position each so positioned and oriented with respect to the
receiver such that when the receiver is posed at a first location
and then, upon unreeling the reelable tape and using the markable
position, a second location, the processor makes its calculations
using light detections at the first location and second location,
and a known distance provided by the reelable tape.
40. The field-deployable spatial positioning transmitter and
receiver of claim 39, wherein the processor is attached to or
incorporated within the receiver housing.
41. The field-deployable spatial positioning transmitter and
receiver of claim 39, wherein the rotating laser head and strobe
emitter are incorporated into or attached to a common transmitter
housing.
42. A transmitter for a spatial positioning system comprising: the
transmitter having a portion adapted to be stationary during
operation and a rotating laser head mounted on the stationary
portion; and a labyrinth seal between the rotating laser head and
the stationary portion effective to restrict the motion of
contaminants between the rotating laser head and the stationary
portion.
43. A method for dynamic leveling of a rotating body to bring a
rotational axis of the rotating body into better alignment with a
desired axis, the method comprising: aligning an operating axis of
an autocollimator to the desired axis by outputting a light ray
along the operating axis, and monitoring any reflected light rays
from the light ray to identify any deflection from the desired
axis; orienting the rotating body, said rotating body having an
affixed mirror, to within the operating axis of the autocollimator;
noting the position of the reflected light rays monitored by the
autocollimator, whereby a point or circular arc is formed by the
reflected light rays; determining the direction and magnitude of a
deviation of a geometric center of the point or circular arc from
the operating axis of the autocollimator; and changing the
orientation of the rotating body to bring its rotational axis into
better alignment with the operating axis of the autocollimator,
whereby the rotational axis is put into better alignment with the
desired axis.
44. A method for forming a spatial positioning transmitter
synchronization strobe beam to improve energy distribution and
operating range when communicating with a spatial positioning
receiver operating in a field of measurement, the method
comprising: operating a rotating a laser head emitting an angled
fan of light periodically operating, in connection with defined
rotations of the laser head, a first strobe having an output
distribution of a first value for half power beam angular width
onto the field of measurement; and periodically operating, in
connection with defined rotations of the laser head, a second
strobe having an output distribution of a second value for half
power beam width higher than the first value for half power beam
angular width, onto the field of measurement.
45. A spatial positioning system, the system capable of switching
between a horizontal and a vertical mode, the system comprising: a
transmitter kit comprising a rotating laser head emitting an angled
fan of light, a transmitter processor and a strobe emitter that
emits a light pulse in predetermined or programmed relation to the
position of the laser head, and a sensor to sense when a housing
containing the rotating laser head is oriented so as to sweep in a
substantially vertical plane and communicate this information to
the transmitter processor; a receiver kit comprising a receiver
processor, which can be the same as the transmitter processor, in
data communication with a receiver, and the receiver adapted to be
moved about a field of operation and determine, in conjunction with
the receiver processor, distance and orientation, the receiver
comprising a light detector, the receiver determining distance and
orientation to the transmitter based on the timing of detections of
light from the fan of light and from the strobe, wherein the
transmitter processor signals the receiver processor of the
orientation or modulates the transmitter kit light emissions or
rotation in a manner detectable by the receiver kit.
Description
[0001] This application claims the priority of U.S. Provisional
Application Serial No. 60/188,367, filed Mar. 10, 2000.
[0002] This invention relates to field-deployable spatial
positioning or measurement systems. Specifically, this invention
uses novel system hardware, calibration methods, and
transmission/detection modes to provide increased ease-of-use,
better reliability and system longevity, easier calibration
methods, wider usable range and versatility for spatial positioning
systems to provide high resolution, reproducible and accurate
spatial or position measurements in two or three dimensions. This
allows enhanced accuracy and utility for use in surveying,
construction and manufacturing layout, and spatial data generation
for design or vehicular systems, or vector and tensor mapping such
as accumulating data relating to temperature, wind shear, electric
fields, radiation flux, etc.
[0003] Present uses for field-deployable spatial positioning
systems include construction layout, where is setting reference
points or setting control lines, asymptotes and similar geometric
boundaries or guide lines; or laying out parallel or perpendicular
lines; measuring linear distances between points; and navigating to
specific points entered by a user; or establishing working planes.
This would include generation of level or sloped plane references
for earthwork and site preparation; generation of vertical (plumb)
plane references for tilt-up wall placement; and XY (2-D) or XYZ
(3-D) coordinate measurement for positioning concrete forms,
footers, and anchor bolts.
[0004] Additional uses for field-deployable spatial positioning
systems include machine control or robotic applications, and
transfer of measurement or spatial positioning data to and from CAD
systems or databases.
[0005] Prior art field-deployable spatial positioning and
measurement systems include those described in U.S. Pat. Nos.
4,874,238; 5,100,229; 5,110,202; 5,579,102; 5,461,473; 5,294,970;
and 5,247,487, all of which are hereby incorporated by reference in
their entirety. Spatial positioning systems described in these
patent references usually comprise a single "laser transmitter" and
a single "laser receiver". The transmitter is placed at a fixed
location, and serves as a measurement reference or beacon for the
receiver. The handheld receiver is carried by the user, and
displays in real-time the location of the receiver relative to the
transmitter. Because of mathematical constraints, such a
single-transmitter system is only capable of measuring the
horizontal (azimuth) and vertical (elevation) angular location of
the receiver; that is, no direct measurement of the range from the
transmitter to receiver is possible. A more advanced system
consists of two or more transmitters and a single receiver. The
transmitters are again placed at fixed locations, and serve the
same purpose as before. The receiver calculates its azimuth and
elevation location relative to each transmitter. If the
transmitters are at known locations, the receiver can then
calculate its position in 3-D space using known methods and
algorithms, e.g., see U.S. Pat. No. 5,100,229 as cited above. In
either the single or multi-transmitter systems, multiple receivers
may be used simultaneously with the same transmitter(s). This is
possible since the transmitters only serve as a reference or
beacon, in the same way that GPS satellites serve as a reference
for many users. Calculations to determine the location of a given
receiver take place in that receiver, not the transmitter(s).
[0006] As will be described more fully below, the primary
components of a transmitter can include the following: a rotary
laser head containing two laser assemblies; a spindle assembly,
including a motor and encoder, for spinning the rotary laser head;
an optical strobe assembly, which functions as an azimuth reference
to establish a "zero" angle for the azimuth angle; a gimbal
assembly, including level sensors and motors, for leveling the
rotary laser head; and control electronics needed to perform
various functions, including sensing, balancing, monitoring,
position determination, user interfacing, and data output. The
rotary laser head contains two laser assemblies that produce two
fanned infrared laser beams perpendicular to the spin axis of the
head, as described in the above-reference U.S. patents. The radial
axes of the fan beams can be chosen to be separated by
approximately 90 degrees (or other angle) around the head. The fan
beams are rotated approximately 30 degrees in opposite directions
about their respective radial axes.
[0007] The rotating laser head is attached to the top end of a
shaft through the spindle assembly. The lower end of the shaft is
attached to a motor and rotary encoder. The motor spins the shaft,
and thus the head, at a known constant speed. The rotary encoder is
used to sense the rotation speed of the shaft, and provides
feedback to the motor drive circuit in the control electronics.
[0008] As is described in the above-reference U.S. patents, an
optical strobe assembly can be used to synchronize, or set a
rotation datum for, the azimuthal angle swept by the fanned beams.
This can be implemented as a ring of outward-facing IREDs (infrared
emitting diodes) located just below the rotating laser head. The
strobe is stationary, and mounted to the outside of the spindle
assembly. Using feedback from the rotary encoder on the shaft, the
control electronics causes the strobe to emit a very short flash of
infrared light once per revolution of the head, or any other set
interval. This flash is detected by the mobile receiver, and used
as a zero azimuth angle reference.
[0009] The gimbal assembly is attached to the outside of the
spindle assembly, and connects it to the outer housing of the
transmitter. The purpose of the gimbal assembly is to allow a tilt
(in two axes) in a known manner of the rotary head spin axis
relative to the outer housing. In most applications it is
desirable, for reasons to be explained below, to plumb the spin
axis of the head with respect to gravity (or to some other desired
axis). If this is done, the radial axes of the fan lasers, which
are perpendicular to the spin axis, will sweep through a plane that
is level with respect to gravity. In order to plumb the spin axis,
the control electronics reads the output of the level sensors,
which are attached to the outside of the spindle assembly, and
drives the motors of the gimbal assembly until the sensor outputs
indicate that the spin axis is plumb. Well known electrolytic vials
can be used as monitors in assisting this feedback function.
[0010] Control electronics govern the overall operation of the
laser transmitter. As mentioned above, it controls the rotation
speed of the head by using the rotary encoder output as feedback,
triggers the optical strobe once per revolution of the head, and
plumbs the spin axis by moving the gimbal assembly based on
feedback from the level sensors.
[0011] The primary components of the receiver generally include the
following: a detector such as a (photodiode) assembly for sensing
the optical strobe and fan lasers from the transmitter(s); timing
electronics for measuring the time between received pulses; and
some processor, such as a microprocessor, for calculating the
location of the receiver; a user interface, such as a display and
keypad. The detector or photodiode assembly produces an electrical
output in response to the optical strobe signal from the
transmitter(s). It also produces an output pulse whenever it is
crossed by one of the rotating fan beams from a transmitter. For
example, when the detector is in the vicinity of a single
transmitter, the output for one complete rotation of the
transmitter head can include times T1, T2, and Trev measured by
timing electronics, where T1 is the time between a (received)
strobe light pulse and a first fanned laser beam; T2 is the time
between a strobe light pulse and a second fanned laser beam; and
Trev is the time between strobe pulses. The microprocessor
calculates the angular location of the receiver relative to the
transmitter by using the output of the timing electronics. Since
the strobe is omnidirectional, the absolute time at which the
strobe pulse is received is independent of the position of the
receiver. The two fan beams projected from the transmitter are
tipped 30 degrees in opposite directions about their radial axes,
which are separated by 90 degrees about the rotating laser head.
Therefore the elevation (vertical) angle of the receiver relative
to the transmitter will be a function of the time between the
received laser pulses, and the azimuth (horizontal) angle will be a
function of the average time from the strobe to the two laser
pulses, as given, for example, in U.S. Pat. No. 5,110,202 cited
above. If the speed of rotation of the transmitter head is very
steady, the angular position of the receiver may be calculated as:
1 azimuth angle = 360 * ( T1 + T2 ) / ( 2 * Trev ) Eqn1 elevation
angle = 360 * ( T2 - T1 ) / Trev - 90 2 * cot ( 30 ) Eqn2
[0012] The result of these calculations is output in various
formats on the display, depending on the particular application.
The keypad allows the user to control the operating mode.
[0013] One aspect of such a spatial positioning system is the use
of a length standard to set a scale for the spatial positioning
system, because the above scheme often measures the azimuthal and
elevation angles only, depending on the number of transmitters and
the system functions selected. With a single detector and
transmitter, for example, the distance between the two is unknown.
One method of estimating the distance is to perform a "stadia
measurement", which is a common technique in surveying. This
measurement can be performed with two detectors (such as
photodiodes) mounted to a straight rod a known distance apart
(e.g., 2 meters). Both detectors would be connected to the same
receiver, which would then simultaneously calculate the angular
position of each detector relative to the transmitter. Since the
distance between the detectors is known, the receiver can make a
relatively crude estimate of the distance from the rod to the
transmitter. This method is suitable if highly accurate
measurements are not required, but suffers from parallax type
error, especially over long ranges in the field of measurement.
[0014] If more accuracy is required, a multi-transmitter system may
be used. This system is capable of calculating accurate
2-dimensional or 3-dimensional positions of a single-detector
receiver. The basic measurement is the same as in the
single-transmitter system; that is, the receiver calculates its
angular location relative to each transmitter. Mathematically, the
location of the receiver relative to a given transmitter is
somewhere along a vector that starts at the transmitter and passes
through the receiver. If the transmitters are at known locations,
then solving for the intersection of the vectors extending from
each transmitter to the receiver will give coordinates of the
receiver. More precisely, the coordinates found are at the center
of the detector or photodiode.
[0015] However, for systems using only one transmitter, or for
systems using multiple transmitters where increased accuracy and
resolution is desired, a scaling reference is needed. One usually
introduces a linear scale or distance reference into a known setup
procedure for this purpose. Since the basic measurements made are
all angular, and the transmitters and setup points are at arbitrary
locations, inherent scale in the system can be obtained by several
means. For example, a scale bar or tape measure can be used. When,
for example, the user measures a point at each end of an object
that is exactly one meter long, and the receiver is told that the
distance between these points is one meter; then the receiver can
adjust the scale of the relative coordinate system to give
measurements in meaningful units such as meters, inches, feet, etc.
The measurement of this scale reference object must be done very
accurately, since the operating distance multiplies any error in
the scale reference. That is, if a 1 mm error is made in measuring
a 1 m scale reference, then the absolute position error at a
distance of 50 m is 50 mm. Therefore it is desirable to use long
scale references, such as a 10 meter scale reference.
[0016] A second aspect for such a spatial positioning system,
particularly if it is to be field-deployable, is that contaminants
are kept out of certain critical areas containing vital components
like the spindle shaft and required shaft bearings.
[0017] A third aspect for the spatial positioning system is the
desirability of a leveled transmitter, to enhance the accuracy of
the measurements that are made. With the automatic leveling
described above, there is still a need for frequent and continued
calibration of such leveling in the transmitter units. This
calibration is vital for accuracy and usability. From the outset,
initial manufacturing tolerances must be set before new
transmitters are sold. Transmitters that are dropped, or subject to
excessive mechanical vibration should preferably be re-calibrated,
and six month periodic calibration are usually recommended and
expected. Calibrations are also often required after removal and
replacement of mechanical components such as the rotating laser
head or spindle assembly. Finally, preparation and certification of
a used transmitter for sale would require close calibration of the
auto-leveling system.
[0018] A fourth aspect of such a spatial positioning system is that
the output light or energy from the strobes used to synchronize the
azimuthal fan sweep should preferably cover the field of
measurement and be of sufficient strength to be detected without
ambiguity and with a high enough signal to noise ratio in the
control or sensing electronics.
[0019] A fifth aspect of such a spatial positioning system is that
fiduciary volume over which the transmitter-receiver combination
can function should preferably cover the desired field of
measurement, such as when doing spatial positioning of tall or high
structures.
[0020] In the prior art, there are problems associated with each of
these requirements.
[0021] The first aspect of setting a scale is made difficult by
having to measure a ruler, tape, or other reference in the field.
Accuracy can suffer, as noted above, due to measurement errors.
Reproducibility can suffer from using different length standards,
or using the same standard, but with slightly different deployment,
such as when a tape measure is not pulled to the same tightness
from measurement to measurement.
[0022] The second aspect for keeping contaminants out of selected
areas or away from critical components in the transmitter has not
been adequately addressed. Typically one uses rotary seals, which
introduce friction associated with spinning the rotating laser
head. This added friction can reduce battery life in the
transmitter. Rotary seals also introduce vibrations and shaft
wobble, that, while subtle, can affect accuracy and reproducibility
for coordinate measurements, especially over a large field of
measurement. Degradation of such rotary seals can reduce system
longevity and can send bits of elastomer or other debris into the
protected areas, and can release trapped dirt as well.
[0023] The third aspect for a calibration of the automatic leveling
in a transmitter is quite onerous, and requires use of known
elaborate procedures using measurement stands, sensors, and the
like. Such present calibrations are very time consuming, and
require the laser output to be painstakingly and manually compared
to benchmarks and references in a setup stand. This can take hours
per unit, and drives up costs. Careful work is required, and setup
errors are not well tolerated, resulting in overall calibration
errors.
[0024] The fourth aspect for strobe or synchronization distribution
suffers from severe tradeoffs in usable range and signal strength.
Light emitting devices that have narrow solid-angle output
distributions that are suitable for long distance "reaching" of the
strobe beam to far locations in the field of measurement are
inadequate for measurements close to the transmitter, especially
down low or up high. Conversely, light emitting devices that have
wide solid-angle output distributions that are suitable for good
wide coverage of measurement very close to the transmitter are
inadequate for measurements far from the transmitter, because their
output intensity drops rapidly as a function of distance from the
strobe.
[0025] The fifth aspect of keeping a large usable range for
vertical types of measurements cannot be addressed with present
fanned beam transmitters because the divergence or extent of the
fan beams used are not sufficient to cover the entire field of
measurement, and can suffer from "fringe" effects where the
crispness or quality of the beam fans degrades at large divergence
angles. When the usable range of measurement over the field of
measurement suffers because the working space or fiduciary volume
subtended by the capabilities of spatial positioning system
operation is limited, such as when working in the vertically
extended environments, the system cannot be used. Such conditions
come up often, such as when tilting pre-fabricated walls to a
vertical position. Conventional spatial positioning systems cannot
span the necessary vertical fiduciary volume over which accurate
measurements must be made, unless a transmitter dedicated to laser
sweeps in a vertical plane is used.
[0026] It is therefore an object of this invention to provide a
field-deployable length standard that is built into the spatial
positioning system receiver, with capability to reproduce
faithfully the force loading of the standard for greater accuracy.
It is also an object to provide protection against contaminant
entry without the use of rotary seals or other conventional means
used in the spatial positioning system field that have not met with
great success without the drawbacks mentioned. It is a further
object of this invention to provide a method of calibration the
leveling of a transmitter which is easy to implement, accurate, and
tolerant of setup errors. It is yet a further object of this
invention to provide a scheme for synchronization strobe beam
distribution which maximizes usable range for both near and far
measurements with respect to the transmitter. It is another object
of this invention to provide a way to use the same transmitter for
vertical types of measurements, while allowing use of the same
control electronics and calibration procedures as cited in the
third requirement above. Other objects will become apparent upon
reading of the specification.
SUMMARY OF THE INVENTION
[0027] One general embodiment disclosed includes a transmitter and
spatial positioning receiver for a spatial positioning system. The
system comprises a stationary portion and a rotating laser head in
proximity to the stationary portion, the rotating laser head
further comprising a first light emitting device emitting a
divergent rotating light fan onto a field of measurement. The
system also comprises a synchronization strobe providing a
synchronization strobe beam for communicating with the spatial
positioning receiver operating in the field of measurement, and a
detector in the spatial positioning receiver to detect the
divergent rotating light fan and also the synchronization strobe
beam. Additionally, there is also a processor to determine at least
one spatial coordinate of the detector in the spatial positioning
receiver based on a time of receipt of the divergent rotating light
fan and the synchronization strobe beam. The transmitter and
spatial positioning receiver also comprise a field-deployable
length standard for use with the spatial positioning receiver for
spatial position-marking, setting, calibrating or referencing in
the spatial positioning system. This field-deployable length
standard comprises a reelable tape comprising at least one markable
position. The reelable tape and the markable position are each so
positioned and oriented with respect to the spatial positioning
receiver such that when the spatial positioning receiver is posed
to a second location upon unreeling the reelable tape and using the
markable position, a detector in the spatial positioning receiver
is a known distance from a first location of the detector in the
spatial positioning receiver prior to unreeling the reelable tape.
Additionally, the transmitter is so constructed so that the
stationary portion and the rotating laser head are each
individually positioned, shaped, and oriented such that there is
defined an interface volume therebetween. The transmitter then
further comprises a labyrinth seal, so sized, positioned and
oriented so as to restrict the motion of contaminants through the
interface volume between the rotating laser head and the stationary
portion of the transmitter. Additionally, there is found a strobe
set to provide a spatial positioning transmitter synchronization
strobe beam to improve energy distribution and operating range when
communicating with the spatial positioning receiver operating in
the field of measurement. The strobe set further comprises a first
strobe having an output distribution of a first value for half
power beam angular width, oriented to provide output onto the field
of measurement. A second strobe is provided having an output
distribution of a second value for half power beam width higher
than the first value for half power beam angular width, oriented to
provide output onto the field of measurement. The first and second
strobes are further positioned and oriented such that the operating
range of the spatial positioning receiver is increased with respect
to the first and second strobes both having either the first value
or the second value for half power beam angular width. The
transmitter can also comprise a sensor to sense when the
transmitter is oriented so as to sweep the divergent rotating light
fan in a substantially vertical plane, with the sensor
communicating the sense to the processor for a vertical coordinate
determination.
[0028] Other embodiments of the inventions described herein will be
described below, and individually, some embodiments have only some
of the elements thus far cited. For example, we disclose a
field-deployable length standard for use with a spatial positioning
receiver for spatial position-marking, setting, calibrating or
referencing in a spatial positioning system, the field-deployable
length standard comprising a reelable tape comprising at least one
markable position. The reelable tape and the markable position are
each so positioned and oriented with respect to the spatial
positioning receiver such that when the spatial positioning
receiver is posed to a second location upon unreeling the reelable
tape and using the markable position, a detector in the spatial
positioning receiver is a known distance from a first location of
the detector in the spatial positioning receiver prior to unreeling
the reelable tape. Additionally, the markable position can comprise
a detent operative upon the reelable tape. Alternatively, the field
deployable length standard can comprise a reelable tape reeled upon
a reel assembly in mechanical communication with a housing. This
reel assembly can optionally be under a spring bias with respect to
the housing so as to allow movement of the reel assembly with
respect to the housing. The spring bias can optionally allow for a
desired force loading along the reelable tape. The housing can also
comprise an aperture so shaped, sized, positioned, and oriented so
as to allow a viewing of the movement of the reel assembly, with
the viewing operative to allow a calibration of the force loading
along the reelable tape. Alternatively, the aperture can comprise a
lens so shaped, sized, positioned and oriented so as to allow
viewing of the movement of the reel assembly, with the viewing
through the lens operative to allow a similar calibration of the
force loading along said reelable tape.
[0029] Another embodiment can comprise a field-deployable length
standard for use with a spatial positioning receiver for spatial
position-marking, setting, calibrating or referencing in a spatial
positioning system, with the field-deployable length standard
comprising a reelable tape in mechanical communication with the
spatial positioning receiver. The reelable tape comprises a first
markable position, and a second markable position a known path
length along the reelable tape from the first markable position
when the reelable tape is unreeled. The first and second markable
positions can be so positioned and oriented with respect to the
spatial positioning receiver when the reelable tape is unreeled
such that when the spatial positioning receiver is posed to a first
location upon unreeling the reelable tape and using the first
markable position, a detector in the spatial positioning receiver
is a known distance with respect to the detector when the spatial
positioning receiver is posed to a second location upon unreeling
the reelable tape and using the second markable position of the
reelable tape. In turn, any of the first and second markable
positions can comprise a detent operative upon the reelable tape.
Optionally, the reelable tape for this embodiment can be reeled
upon a reel assembly in mechanical communication with a housing.
Additionally, the reel assembly can be under an optional spring
bias with respect to the housing so as to allow movement of the
reel assembly with respect to the housing. Optionally, this spring
bias can allow for a desired force loading along the reelable tape.
And, as before, the housing can comprise an aperture so shaped,
sized, positioned, and oriented so as to allow a viewing of the
movement of the reel assembly, with the viewing operative to allow
a calibration of the force loading along the reelable tape. Again,
the aperture can optionally comprise a lens so shaped, sized,
positioned and oriented so as to allow the viewing of the movement
of the reel assembly, with the viewing again operative to allow a
calibration of the force loading along the reelable tape.
[0030] Further embodiments include a transmitter for a spatial
positioning system, with the transmitter having a stationary
portion and a rotating laser head in proximity to the stationary
portion, the stationary portion and the rotating laser head each
individually positioned, shaped, and oriented such that there is
defined an interface volume therebetween. The transmitter further
comprises a labyrinth seal, so sized, positioned and oriented so as
to restrict the motion of contaminants through the interface volume
between the rotating laser head and the stationary portion of the
transmitter. The labyrinth seal can optionally be so formed that a
necessary path for any contaminants is serpentine, or, in the
alternative, substantially straight. Optionally, the stationary
portion and the rotating laser head can each be individually
positioned, shaped, and oriented such that the labryrinth seal is
formed by at least a portion of either or both of the stationary
portion and the rotating laser head, with the labyrinth seal
operative in the interface volume. Alternatively, the stationary
portion and the rotating laser head can comprise a rotary
transformer positioned proximate the interface volume where the
rotary transformer is positioned, shaped, and oriented such that
the labryrinth seal is formed by at least a portion of the rotary
transformer, with the labyrinth seal again operative in the
interface volume.
[0031] Also disclosed is a method for dynamic leveling of a
rotating body to bring a rotational axis of the rotating body into
better alignment with a desired axis. This is useful for
maintaining functionality and accuracy of the rotating elements
used in the systems described. The method comprises:
[0032] [a] Aligning an operating axis of an autocollimator to the
desired axis, with the autocollimator designed to output a light
ray along the operating axis, and the desired axis as a result of
the aligning, and to monitor any reflected light rays from the
light ray with respect to the desired axis;
[0033] [b] affixing a mirror to the rotating body;
[0034] [c] orienting the rotating body to within the field of view
of the autocollimator;
[0035] [d] noting the position of the reflected light rays
monitored by the autocollimator, whereby a circular arc is formed
by the reflected light rays;
[0036] [e] determining the direction and magnitude of a deviation
of a geometric center of the circular arc from the operating axis
of the autocollimator;
[0037] [f] changing the orientation of the rotating body in such a
manner so as to bring the rotational axis into better alignment
with the operating axis of the autocollimator, whereby the
rotational axis will be put into better alignment with the desired
axis.
[0038] If desired, the desired axis can be a downward gravitational
vector. As comtemplated here, one can certainly make the rotating
body be a rotating laser head in a spatial positioning system.
Optionally, too, the mirror can be affixed to the rotating laser
head in such a manner that a normal axis of the mirror is
substantially parallel with the desired axis. Alternatively, the
mirror can be affixed to the rotating laser head in such a manner
that a normal axis of the mirror is within 90 degrees of the
desired axis.
[0039] There is also disclosed a method for forming a spatial
positioning transmitter synchronization strobe beam to improve
energy distribution and operating range when communicating with a
spatial positioning receiver operating in a field of measurement,
the method comprising:
[0040] [a] arraying a first strobe having an output distribution of
a first value for half power beam angular width onto the field of
measurement;
[0041] [b] arraying a second strobe having an output distribution
of a second value for half power beam width higher than the first
value for half power beam angular width, onto the field of
measurement;
[0042] [c] the first and second strobes further positioned and
oriented such that the operating range of the spatial positioning
receiver is increased with respect to the first and second strobes
both having either the first value or the second value for half
power beam angular width.
[0043] Optionally, the first value for half power angular beam
width can be less than 15 degrees, and/or the second value for half
power angular beam width can be more than 20 degrees. Also, a
plurality of first strobes can be arrayed about a single second
strobe, for output of the beam onto the field of measurement. Such
a plurality can also be numerically three, as opposed to two or
four. In another embodiment, the plurality of first strobes and a
plurality of second strobes can be optionally arrayed in such a
manner and orientation that each strobe of such first and second
strobes is aimed at a distinct direction onto the field of
measurement.
[0044] In the same vein, one can also optionally select a strobe
set to provide a spatial positioning transmitter synchronization
strobe beam to improve energy distribution and operating range when
communicating with a spatial positioning receiver operating in a
field of measurement, with the strobe set comprising a first strobe
having an output distribution of a first value for half power beam
angular width, oriented to provide output onto the field of
measurement; a second strobe having an output distribution of a
second value for half power beam width higher than the first value
for half power beam angular width, oriented to provide output onto
the field of measurement; with the first and second strobes further
positioned and oriented such that the operating range of the
spatial positioning receiver is increased with respect to the first
and second strobes both having either the first value or the second
value for half power beam angular width, which achieves one of many
objectives sought in the instant teachings. Using this
prescription, the first value for half power angular beam width can
again be less than 15 degrees, and the second value for half power
angular beam width can also be more than 20 degrees. Another
embodiment allows that a plurality of first strobes are arrayed
about a single second strobe, for output of the beam onto the field
of measurement; optionally the plurality can be numerically three.
Optionally, the plurality of first strobes and a plurality of
second strobes are arrayed in such a manner and orientation that
each strobe of such first and second strobes is aimed at a distinct
direction onto the field of measurement.
[0045] Another embodiment of the instant teachings yields a
transmitter and spatial positioning receiver for a spatial
positioning system, with the system capable of switching to a
vertical mode. That system comprises a stationary portion and a
rotating laser head in proximity to the stationary portion, with
the rotating laser head further comprising a first light emitting
device emitting a divergent rotating light fan onto a field of
measurement; a synchronization strobe providing a synchronization
strobe beam for communicating with the spatial positioning receiver
operating in the field of measurement; a detector in the spatial
positioning receiver to detect the divergent rotating light fan and
also the synchronization strobe beam; and a processor to determine
at least one spatial coordinate of the detector in the spatial
positioning receiver based on a time of receipt of the divergent
rotating light fan and the synchronization strobe beam. The
transmitter and spatial positioning receiver also comprise a sensor
to sense when the transmitter is oriented so as to sweep the
divergent rotating light fan in a substantially vertical plane, the
sensor communicating this directionality or sense to the processor
for a vertical coordinate determination.
[0046] Another embodiment includes various elements, such as a
field-deployable spatial positioning transmitter and receiver for
spatial position-marking, setting, calibrating or referencing,
where the field-deployable spatial positioning transmitter and
receiver comprise a transmitter kit comprising a rotating laser
head emitting an angled fan of light, where angled can mean that
the fan is neither orthogonal nor parallel to the plane through
which the head rotates, and a strobe emitter that emits a light
pulse in predetermined or programmed relation to the position of
the laser head; a processor in data communication with a receiver;
with the receiver adapted to be moved about a field of measurement
and determine, in conjunction with the processor, distance and
orientation. The receiver comprises a light detector, and the
receiver determines distance and orientation to the transmitter
based on the timing of detections of light from the fan of light
and from the strobe. The receiver can optionally further comprise a
field-deployable length standard. Such a standard can comprise a
reelable tape that in turn comprises at least one markable position
and a reel attached to or incorporated within a housing for the
receiver, the reelable tape and the markable position each so
positioned and oriented with respect to the receiver such that when
the receiver is posed at a first location and then, upon unreeling
the reelable tape and using the markable position, a second
location, the processor makes its calculations using light
detections at the first location and second location, and a known
distance provided by the reelable tape. The processor can
optionally be attached to or incorporated within the receiver
housing. Alternatively, the rotating laser head and strobe emitter
can be incorporated into or attached to a common transmitter
housing.
[0047] General embodiments include a transmitter for a spatial
positioning system comprising a transmitter having a portion
adapted to be stationary during operation and a rotating laser head
mounted on the stationary portion; and a labyrinth seal between the
rotating laser head and the stationary portion effective to
restrict the motion of contaminants between the rotating laser head
and the stationary portion.
[0048] The dynamic leveling teachings also include a method for
dynamic leveling of a rotating body to bring a rotational axis of
the rotating body into better alignment with a desired axis, the
method comprising:
[0049] aligning an operating axis of an autocollimator to the
desired axis by outputting a light ray along the operating axis,
and monitoring any reflected light rays from the light ray to
identify any deflection from the desired axis;
[0050] orienting the rotating body, the rotating body having an
affixed mirror, to within the operating axis of the
autocollimator;
[0051] noting the position of the reflected light rays monitored by
the autocollimator, whereby a point or circular arc is formed by
the reflected light rays;
[0052] determining the direction and magnitude of a deviation of a
geometric center of the point or circular arc from the operating
axis of the autocollimator; and
[0053] changing the orientation of the rotating body to bring its
rotational axis into better alignment with the operating axis of
the autocollimator, whereby the rotational axis is put into better
alignment with the desired axis.
[0054] Another embodiment includes method for forming a spatial
positioning transmitter synchronization strobe beam to improve
energy distribution and operating range when communicating with a
spatial positioning receiver operating in a field of measurement,
the method comprising:
[0055] operating a rotating a laser head emitting an angled fan of
light
[0056] periodically operating, in connection with defined rotations
of the laser head, a first strobe having an output distribution of
a first value for half power beam angular width onto the field of
measurement; and
[0057] periodically operating, in connection with defined rotations
of the laser head, a second strobe having an output distribution of
a second value for half power beam width higher than the first
value for half power beam angular width, onto the field of
measurement.
[0058] In kit form, another possible embodiment includes a spatial
positioning system, with the system capable of switching between a
horizontal and a vertical mode. This system comprises a transmitter
kit that further comprises a rotating laser head emitting an angled
fan of light; a transmitter processor and a strobe emitter that
emits a light pulse in predetermined or programmed relation to the
position of the laser head; and a sensor to sense when a housing
containing the rotating laser head is oriented so as to sweep in a
substantially vertical plane and communicate this information to
the transmitter processor; a receiver kit that in turn further
comprises a receiver processor, which can be the same as the
transmitter processor, in data communication with a receiver, and
the receiver adapted to be moved about a field of operation and
determine, in conjunction with the receiver processor, distance and
orientation, the receiver comprising a light detector, the receiver
determining distance and orientation to the transmitter based on
the timing of detections of light from the fan of light and from
the strobe, wherein the transmitter processor signals the receiver
processor of the orientation or modulates the transmitter kit light
emissions or rotation in a manner detectable by the receiver
kit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0059] FIG. 1 shows a cross sectional schematic view of a
transmitter according to the invention.
[0060] FIG. 2 shows a cross sectional schematic view of a receiver
according to the invention.
[0061] FIG. 3 shows a schematic block diagram of possible controls
for the receiver according to the invention.
[0062] FIG. 4 shows a schematic block diagram of possible controls
for the transmitter according to the invention.
[0063] FIG. 5 shows an oblique exploded view of a possible stadia
mount assembly which is part of a field-deployable length standard
for the receiver according to the invention.
[0064] FIG. 6 shows an oblique exploded view of a possible spring
assembly which is part of a field-deployable length standard for
the receiver according to the invention.
[0065] FIG. 7 shows a portion of the cross-sectional view of FIG.
1, showing use of a labyrinth seal.
[0066] FIG. 8 shows a closer cross-sectional view of FIG. 7,
showing use of a labyrinth seal.
[0067] FIG. 9 shows the left side portion of the cross-sectional
view of FIG. 8, showing use of a labyrinth seal and a rotary
transformer.
[0068] FIG. 10 shows a close view of the left side portion of the
cross-sectional view of FIG. 9, but with non-serpentine labyrinth
seals.
[0069] FIG. 11 shows an end-on surface view of the labyrinth seal
shown in FIG. 7, in a plane perpendicular to spindle shaft SFT.
[0070] FIG. 12 shows conventional leveling of the operating axis of
an autocollimator.
[0071] FIG. 13 shows a transmitter calibration technique for the
present invention using a mirror affixed to the rotating laser head
RH.
[0072] FIG. 14 shows a reticle inside the autocollimator of FIG.
12, illustrating the calibration technique of the present
invention.
[0073] FIG. 15 shows a transmitter calibration technique similar to
that shown in FIG. 13, but for a transmitter in vertical mode.
[0074] FIG. 16 shows a prior art configuration of strobe light
emitting devices for azimuth synchronization.
[0075] FIG. 17 shows a longer range prior art configuration of
strobe light emitting devices for azimuth synchronization.
[0076] FIG. 18 shows a configuration of strobe light emitting
devices for azimuth synchronization according to the present
invention.
[0077] FIG. 19 shows a unfolded 360 degree view of the strobe light
emitting devices arrayed about a transmitter according to the
present invention.
[0078] FIG. 20 shows the detector end of a receiver according to
the present invention.
[0079] FIG. 21 shows the detector end of a receiver according to
the present invention, when used with a transmitter in a vertical
mode.
DEFINITIONS
[0080] The following definitions shall be employed throughout:
[0081] Autocollimator shall include any optical instrument or
technique that provides equivalent information to that given by a
conventional autocollimator as known in the field of metrology,
such as where a device uses a single lens to collimate diverging
light from a slit, and then focuses the light on a exit slit after
it has passed through a prism to a mirror and been reflected back
through the prism. For this definition, any other device or thing,
such as the interior of a 55 gallon drum, could be used as a
projection surface for a light ray emitted by a plumbed device,
such as an autocollimator. The term autocollimator automatically
includes any and all such supplementary devices.
[0082] Azimuthal angle or azimuth shall be consistent with its
definition in the field of surveying and shall refer to what is
known mathematically as the polar angle .theta. in spherical polar
coordinates (r, .theta., .phi.). The azimuthal angle shall be the
angle formed in the horizontal plane between the horizontal
projection (or component of) a spatial vector to a spatial
position, and an azimuthal reference vector. Corresponding
rotations representing changes in the azimuthal angle shall occur
through rotations about a vertical axis. (See elevation angle).
[0083] Circular arc(s) shall include complete circles as well as
subset segments or arcs of any angular extent.
[0084] Contaminant shall include any material, material body,
particle, gas, fluid, or compound deemed undesirable and for which
restriction of movement is sought to prevent deleterious effect(s)
on selected components.
[0085] Coordinate(s) shall not be limited to whatever spatial
coordinate system(s) is/are 3used herein (e.g., spherical polar (r,
.theta., .phi.)), and shall be equivalent to and convertable to
other coordinate systems, such as circular cylindrical (r, .theta.,
z), rectangular cartesian (x, y, z), elliptic cylindrical,
parabolic cylindrical, bipolar, prolate spheroidal, oblate
sphereoidal, parabolic, toroidal, bispherical or other accepted
coordinate systems, with or without added scaling factors or
metrics used to tailor output information to a user's needs, e.g.,
aerodynamic studies over specific air foils, etc.
[0086] Detector shall include any device or devices that receive
spatial position-specific information from a transmitter, whether
from a light emitting device inside a rotating laser head, or a
synchronization (strobe) pulse.
[0087] Elevation angle or elevation shall be consistent with its
definition in the field of surveying and shall refer to what is
known mathematically as the azimuthal angle .phi. in spherical
polar coordinates (r, .theta., .phi.), and not to be confused with
the azimuthal angle from the field of surveying in the definition
above. The elevation angle shall be the angle formed in the
vertical plane between the vertical projection (or component of) a
spatial vector to a spatial position, and a zero degree elevation
reference vector determined by gravity. Corresponding rotations
representing changes in the elevation angle shall occur through
rotations about a horizontal axis. (See azimuthal angle).
[0088] Fan shall include divergent light or laser beams such as
those described in U.S. Pat. Nos. 4,874,238 and 5,100,229.
[0089] Half power beam angular width (HPBW) shall be used here,
including in the appended claims, as a mere illustration of one of
many ways to characterize energy distribution as a function of
solid angle (or other spatial parameters) from a strobe or light
emitting device, and shall not be taken to be limiting as to other
characterizations and distribution functions that can be used.
[0090] Labyrinth seal(s) shall include non-contact seals that serve
to restrict motion of fluids and/or contaminants such as
particulates by the use of surfaces in close proximity; such
non-contact seals shall include--but not be restricted
to--conventional labyrinth seals where motion through an interface
volume takes a serpentine, curved, or labyrinthine path.
[0091] Laser shall include any active device that uses charged
species to convert input energy into a narrow intense beam of
phase-coherent light using stimulated emission, such as
conventional laser diodes and VCSEL's (vertical cavity surface
emitting lasers), and shall also be broadened in meaning to also
include any light emitting device--regardless of any physical,
chemical, or electronic light generating mechanisms used therein
(such as conventional light emitting diodes or LED's)--that
possesses the requisite coherence, divergence, isotropic
uniformity, electromagnetic frequency distribution and capability
of modulation to serve the purposes of this invention.
[0092] Light shall include electromagnetic radiation of any
frequency, such as radio waves; microwave emissions; infrared,
visible, and ultraviolet light; and modulated soft and hard x-rays,
and gamma emission, such as might be used for space applications
where a light emitting device that does not require input power may
be required.
[0093] Light emitting device shall include a strobe as defined
below, and any other device that emits electromagnetic waves of any
frequency in any manner. This shall include, for example,
photoflash units, laser emitting diodes and lamps, with or without
mechanical or other means, such as shutters or switchable optical
filters, for modulating a time profile of emission.
[0094] Markable position shall refer to any means by which a
location on a tape can be used to position a detector for position
marking or setting, or spatial data accumulation, including the use
of physical detents, indexing, alignment marks or tabs, bosses,
holes, hubs, or the use of magnetic or other distinguishing
materials on or about the tape surface.
[0095] Necessary path shall denote the path that a contaminant must
take in traversing a route, path or interface volume.
[0096] Pose shall refer to spatial translations, rotations,
orientations and manipulations (e.g., unfolding or unreeling) to
effect a desired result.
[0097] Positioning shall include position measurement in a field of
measurement; data acquisition of position information, including
map generation, establishing lines, curves, and planes; setting
points; and determining or tracking the position of any moveable
object, whether by explicit determination of position as a function
of time or other parameter, or by providing simple increments or
differentials to provide a similar result.
[0098] Processor shall include not only all processors, such as
CPU's (Central Processing Units), but also any intelligent device
that performs the functions given, such as analog electrical
circuits that perform the same functions. In the appended claims,
the word processor can include any processor in the receiver and/or
any processor in the transmitter.
[0099] Receiver shall include any device that receives and
processes spatial position-specific information from a
transmitter.
[0100] Reelable shall include the term foldable, and shall also
include any other qualities of a material body (e.g., tape) that
allow it to serve as a field-deployable length standard capable of
being stowed or made more compact for storage, carrying, or
additional deployment. The terms unreeling and unreeled shall be
interpreted in a similarly broad manner.
[0101] Rotating laser head shall not require the use of a laser,
and shall refer to any rotating body or rotor that serves to pan,
scan, disseminate, array, divide, disperse, scatter, broadcast or
distribute the output radiation of any light emitting device used
for the purposes of this invention.
[0102] Serpentine shall include any labyrinthine or curved path
that involves angular deviation or turning along that path,
including a necessary path, where the path length is longer than a
straight path.
[0103] Spring bias shall include any biasing mechanism, whether
mechanical, electrical, electromechanical, or of any other type,
which provides a force as a function of deviation from an
equilibrium position.
[0104] Strobe shall include any and all light emitting devices that
are used as a synchronization method serving the purposes of this
invention, such as establishing datum lines or vectors, facilitate
transmitter-receiver communications, or interfacing with peripheral
devices used in conjunction with this invention.
[0105] Tape shall include strings, cables, wires, polymer
extrusions, strands, threads, ropes, filaments or any medium or
material body that is capable of being posed linearly or in any
other manner (e.g., arcuate) to serve the spatial position-marking,
setting, calibrating or referencing purposes of this invention.
[0106] Transmitter shall include any device that broadcasts spatial
position-specific information to a receiver.
DETAILED DESCRIPTION OF THE INVENTION
[0107] Referring to FIG. 1 a cross sectional schematic view of a
transmitter according to the invention is shown. Transmitter base B
is bolted to an upper housing UH which together enclose and support
many active components, including a rotating laser head RH as
shown. Inside rotating laser head RH there are installed one or
more laser diodes LD or any other light emitting devices for
generating a fanned laser beam FLB as shown and discussed above. To
condition the output of laser diode(s) LD, a number of elements are
used in a known manner, including passing the resultant light
through a collimation lens CL, rod lens RL, and passage through a
hermetically sealed exit window EW as shown.
[0108] The entire rotating laser head RH is supported and rotated
at a constant known angular speed via spindle shaft SFT. Spindle
shaft SFT is driven in a precise manner by a known encoder motor
EM, which resides inside spindle assembly SP, and is bearingly
supported inside the spindle assembly SP using shaft bearings SB.
Set inside spindle assembly SP is at least one, but preferably a
plurality (for better distribution and reliability) of strobes S
used for azimuth synchronization as discussed above. Transmitter
base B includes a battery set BAT and a plumb-down laser assembly
and associated exit window EWP which are used in a known manner to
set the transmitter at a known spot or location on the site or
field of measurement. Transmitter base B also includes handle HAN,
keypad KEY, and control electronics CET.
[0109] The spindle assembly SP assembly as a whole is moveable on
base (B)-mounted gimbal pivots GP, with only one such gimbal pivot
shown, so as to provide two tiltable degrees of freedom for
leveling purposes. As is known in the art, each such gimbal pivot
GP also has provision for tilting the spindle assembly SP using a
gimbal motor assembly GMA, with only one such motor shown. Feedback
is provided in a known manner by three single axis level sensors
SALS (one shown), which serve to report to the control electronics
CE the angular position or tilt of the spindle assembly SP and
associated rotating laser head RH. Such single axis level sensors
SALS can be fabricated using known electrolytic vials which are
themselves calibrated independently prior to manufacture.
[0110] Encoder motor EM has a known rotary encoder, such as a disc
with holes and an optical monitor device (not shown) to generate
pulses so the control electronics CE can regulate the motor speed,
and in turn, regulate the azimuthal angular rotation rate of the
fanned laser beam(s) that are relied upon to generate positioning
information.
[0111] At the point where the rotating laser head RH and the
spindle assembly SP are almost touching, there is provided a rotary
transformer RT, which provides power to the rotating laser head RH
in a known manner using common inductively methods, such as used in
a four-head consumer VCR. Just outboard of the rotary transformer
RT as shown is a labyrinth seal LS, which will be discussed in
detail below.
[0112] Now referring to FIG. 2, a cross sectional schematic view of
a receiver according to the invention is shown. As envisioned in
the discussion above, the receiver shown comprises a detector DET,
which incorporates a known photosensitive device, such as an
eight-sided device that has eight photocells wired in parallel so
that receipt of a laser fan beam or strobe emission by the
transmitter of FIG. 1 can be recorded over a wide possible range of
entry angles from the field of measurement. Detector DET can
comprises separate detectors tailored for optimal reception of
laser fan beam(s) and strobe emissions. For example, a detector
designed for optimal detection of a strobe emission could have a
larger collection aperture to allow better signal to noise ratios,
especially since the strobe emission falls as inverse square of the
distance, while the laser fan beam(s) fall of as the inverse of the
distance, as is known in the art. The receiver as shown also
includes an LCD (liquid crystal display) LED module, a circuit
board CB for receiver electronics, and one or more connectors
(shown, CONN) for known use with a detector wand, including such a
wand comprising two detectors a known distance apart, akin to the
"stadia" measurement mentioned above. The receiver can also
comprise a user keypad KR, and the housing HR of the receiver as
shown can also accommodate a battery set BATR and include mounting
provisions (not shown) for the field-deployable length standard
discussed in the figures below.
[0113] Now referring to FIG. 3, a schematic block diagram of
possible controls for the receiver according to the invention is
shown. Many possible schemes can be used to control the receiver,
but generally, as known in the art, and discussed in the
above-referenced U.S. patents, the signal path can start as shown
with a DETECTOR ASSEMBLY where the light pulses are encoded or
converted to electrical or electro-optic pulses which are
conditioned by the AMPLIFIER ELECTRONICS for use by TIMING
ELECTRONICS which interpret the temporal spacing of the pulses as
alluded to above. CALCULATION ELECTRONICS then use this information
to generate coordinates as needed. User interfacing with this
information is achieved via a DISPLAY AND KEYPAD as shown.
Processors, including microprocessors with on board memory, cache,
and BIOS (basic input/output system) can accomplish this function
according to software executable instructions as known in the
art.
[0114] Now referring to FIG. 4, a schematic block diagram of
possible controls for the transmitter according to the invention is
shown. TRANSMITTER CONTROL ELECTRONICS as shown provide
functionality to perform transmitter functions, including a MOTOR
DRIVE input to the ROTOR MOTOR which drives the rotating laser head
RH as previously shown (ROTARY HEAD ASSEMBLY, INCLUDING LASERS)
which in turn, via the ROTARY ENCODER gives SPEED FEEDBACK to the
TRANSMITTER CONTROL ELECTRONICS. TRANSMITTER CONTROL ELECTRONICS,
comprising one or more processors, provides selective energizing of
one or light emitting devices, shown here as STROBE ASSEMBLY.
TRANSMITTER CONTROL ELECTRONICS also function to provide a GIMBAL
MOTOR DRIVE to he GIMBAL MOTORS as shown, which in turn
mechanically influence the GIMBAL ASSEMBLY, causing three LEVEL
SENSORS to alter their LEVEL FEEDBACK in a known manner as shown.
This information is used in a known feedback loop to control the
tilt or leveling of the rotating laser head RH.
[0115] The scale reference mentioned above is provided for by use
of a field-deployable length standard, such as a "setup cable" or
similar material body which will be discussed here. The setup cable
is a retractable cable that is integrated into a stadia pole
receiver mount or similar assembly. In one embodiment, the user to
attaches the end of the cable to a fixed object, pulls the cable
out several inches to a first detent, applies tension, and takes a
measurement. Then the user releases the cable lock and backs up
with the receiver until the cable reaches a second detent, which is
exactly 10 m from the first.
[0116] Referring now to FIGS. 5 and 6, oblique exploded views of a
possible stadia mount assembly and spring assembly, respectively,
which are part of a field-deployable length standard for the
receiver according to the invention are shown. These two figures
show variants of what is envisioned as part of the invention. The
field-deployable length standard can be mounted directly on, or
made integral with, the receiver as previously described. Inside
the field-deployable length standard, a spring tape SPT is reeled
upon a center hub CNH, both residing in an inside reel, shown as
portions or views inside reel left (IRL) and inside reel right
(IRR). The inside reel (IRL, IRR) is in turn housed inside an inner
reel, which acts as a housing for a reelable tape or spring tape
SPT. Reelable tape or spring tape SPT is reeled upon a center hub
CNH, both residing inside an inside reel, shown as portions or
views inside reel left (IRL) and inside reel right (IRR). The
inside reel is in turn housed inside an inner reel, which keeps the
spring tape SPT reeled and deployable. Inner reel is shown as
portions or views INL and INR. Spring tape SPT comprises a markable
position, shown MARK, that provides a way of setting a the position
of the receiver. As shown, a detent is used, but any other
mechanism or technique can be used consistent with the definition
above for markable position. The inside reel floats under bias
using spring SC which is affixed to the inside reel as described.
In practice, one deploys the reelable tape or spring tape SPT by
posing or extending spring tape SPT, which can be affixed to a
known feature in the field of measurement, and taking a position
reading using the receiver, while the tape is unreeled and the
inside reel is positioned upon a markable position. A receiver
position reading (not shown) taken at an original position of the
spring tape SPT with respect to the inside reel can provide, with
the position obtain from the markable position, a distance standard
as envisioned. To keep the tension or force loading of the reelable
tape constant from measurement to measurement, the position of the
inside reel can be monitored using an aperture in a reel housing
(shown, OB and OCV), with or without use of a lens L as shown to
allow better alignment of the inside reel with respect to the reel
housing. The use of a detent as the markable position on the spring
tape SPT can be facilitated by the use of a button BUT and button
holder BUTH, as shown, which allow a spring pin SPP to engage or
cause to engage that detent. In this way, a reproducible
field-deployable length standard is provided that is compact and
allows a fair degree of measurement reproducibility. Another
embodiment is provided when the spring tape SPT comprises two
markable positions, in which case the field-deployable length
standard can be posed twice, with receiver position readings taken
for each pose, thus providing a length standard as envisioned
here.
[0117] Now referring to FIG. 7, a portion of the cross-sectional
view of FIG. 1, showing use of a labyrinth seal is shown. One
embodiment of this invention provides for use of a labyrinth seal
LS as shown, at or near the interface between the rotating laser
head RH and the spindle assembly SP, in lieu of felt, rubber, or
other rotary seals which have the disadvantages as cited above. The
transmitter shown can also comprise a rotary transformer RT as
discussed above, and shown in the figure inboard of the labyrinth
seal LS. Contaminants CON are in the ambient environment around the
transmitter, and entry of contaminants in the general direction
shown by the arrow can potentially result in contamination of
spindle shaft SFT and other critical components, resulting in
opening up of tolerances and poor performance. The labyrinth seal
LS incorporates a serpentine path SRP along a necessary path that
the contaminants CON must take to enter critical areas. Such a
labyrinth seal can be a separate component pressed or installed
into the rotating laser head RH and spindle assembly SP, or can be
formed therefrom by machining or other known processes.
[0118] Referring now to FIG. 8, a closer cross-sectional view of
FIG. 7 is shown. An interface volume IV as shown provides a narrow,
serpentine necessary path for contaminants CON and thereby slows
entry into spindle shaft SFT and related areas. The serpentine
nature of the necessary path breaks up laminar flow of contaminants
CON and provide sinks for accumulated contaminants that would
otherwise have an opportunity to enter in an undesirable manner.
Referring now to FIG. 9, the left side portion of the
cross-sectional view of FIG. 8 is shown, showing use of a labyrinth
seal and a rotary transformer having separate inductive portions
RTO and RTI as shown. FIG. 10 shows a close view of the left side
portion of the cross-sectional view of FIG. 9, but with
non-serpentine labyrinth seals to illustrate two things: the rotary
transformer RT can itself be modified, machined, or formed to
operate as a labyrinth seal LS, and the labyrinth seal LS interface
volume can be straight, that is, non-serpentine. Specifically, the
labyrinth seal LS can have a non-serpentine interface volume IVLS
and the rotary transformer RT can have a non-serpentine interface
volume IVR, which individually (separately) or both (if both are
made to be labyrinth seals) can serve to provide a discouraging
necessary path for contaminants CON.
[0119] FIG. 11 shows an end-on surface view of the labyrinth seal
shown in FIG. 7, in a plane perpendicular to spindle shaft SFT. The
concentric rings as shown are indicative of the serpentine nature
of the necessary path for contaminants CON as they start to migrate
across this figure toward the center O as shown.
[0120] Referring now to FIG. 12, a conventional leveling of the
operating axis of an autocollimator, a known process by which an
autocollimator AC secured by an autocollimator foot ACF is leveled
or plumbed to have its operating axis OA as shown to be in
alignment with the gravitational vector. The output of the
autocollimator is set upon a mercury pool HG and the autocollimator
AC is adjusted in position (notably, its operating axis OA) until
the operating axis OA of the autocollimator AC becomes a desired
axis DA, which in this case is determined by gravity. This is done
in a known manner by adjusting autocollimator AC and its operating
axis OA until the place where the reflected beam from mercury pool
HG hits a reticle ACR or functionally similar component or surface
in the same projected location as the originating beam.
[0121] Now referring to FIG. 13, a transmitter calibration
technique is given for the present invention using a mirror affixed
to the rotating laser head RH as shown. It does not matter whether
the mirror M is flat on its underside, or whether it is not level
with respect the rotating laser head RH. The mirror, once affixed
to the rotating laser head RH, defines a rotor axis RA, which may
or may not reflect well the rotation axis (not shown) of the
rotating laser head RH, but the beauty of this method is it does
not matter in terms of affecting the final result.
[0122] Presumably, the rotating laser head RH needs calibration,
and its rotation axis is not true or along a desired axis DA as
shown. For example, after the transmitter levels itself, there may
still be deviation about gimbal axis GA and the rotating laser head
RH may be tilted with respect to the desired axis DA, with the
positioning of the transmitter housing and components TH (shown)
taken into account. One places mirror M on the rotating laser head
RH, and shines the light output of autocollimator AC upon the
mirror with the rotating laser head RH rotating in the normal
manner. The resultant reflected light will give valuable and easily
obtainable information.
[0123] FIG. 14 shows a reticle inside the autocollimator of FIG.
12, illustrating the calibration technique of the present
invention. The resultant reflected light forms a circle, circular
arc or arc ARC which may be divined using the cross hairs CRH or
the equivalent in the autocollimator AC, whose reticle may have
gradations or rulings RSC as shown. In this method, the magnitude
and direction of the deviation of the center GEO of the arc ARC
indicates precisely the misalignment of the rotor spin axis RA, and
the transmitter can be appropriately calibrated to bring the arc
(ARC) center GEO into alignment with the operating axis OA of the
autocollimator AC. The diameter of the arc indicates the amount of
wobble and this information can be discarded, as it is not relevant
to the calibration of the rotating laser head RH spin axis with the
desired axis DA. FIG. 15 shows a transmitter calibration technique
similar to that shown in FIG. 13, but for a transmitter in vertical
mode, where the operating axis OA of the autocollimator AC is set
to a desired axis DA that is other than gravitational, e.g.,
horizontal. For this purpose the autocollimator AC may be aligned
using the known technique given, but this time using a pentaprism
PP or other device in conjunction with mercury pool HG, as is
known.
[0124] To address the fourth requirement given in the background
above, FIG. 16 shows a prior art configuration of strobe light
emitting devices for azimuth synchronization, where a transmitter
on a tripod TRR is set a ground plane GPL in a field of measurement
and strobes are used to periodically light up the field using IREDs
(infra-red emitting diodes) or other light emitting devices. The
strobe devices shown here to illustrate have a half power beam
angular width (HPBW) that is shown nominally at 25 degrees,
resulting in a wide divergence DIV1 and a wide radiant intensity
distribution RID1. Such a distribution can be obtain using IRED
devices under the tradename OPTEK290, for example. Radiant
intensity distribution RID1 results in a range (RANGE1) which is
not long range enough from the transmitter, and results in wasted
energy WST1 which typically spills onto the ground surface. In FIG.
17, a longer range prior art configuration of strobe light emitting
devices for azimuth synchronization is shown, with a narrow
divergence DIV2 (using, for example, OPTEK295 IREDs), resulting in
a narrow radiant intensity distribution RID2, giving a long range
RANGE2, but resulting in wasted energy WST2, which actually is a
lack of energy, and results in no appreciable strobe signal in the
WST2 area, limiting the fiduciary volume over which the spatial
positioning system can function. A solution is shown in FIG. 18,
where a configuration of strobe light emitting devices for azimuth
synchronization according to the present invention is shown. One
seeds the array of strobes with light emitting device of both
narrow and wide divergence characteristics, namely, at least one
wide divergence strobe providing a wide radiant intensity
distribution, and at least one narrow divergence strobe providing a
narrow radiant intensity distribution. The result, as shown, gives
a mixed divergence characteristic DIV3, a long range RANGE3, and
good coverage near the transmitter and minimal wasted energy WST3.
Of course, it is envisioned that many strobes can be used, and FIG.
19 shows a unfolded 360 degree view of the strobe light emitting
devices arrayed about a transmitter according to the present
invention. A strobe set SS is shown, with the unfolded 360 degree
view "flattened" into a strip S-STRIP for illustration purposes. In
practice, the strobes are only arrayed about an angular field of
270 degrees, but this shall not be limiting in this disclosure. As
shown, strobes having a narrow divergence distribution NDIST, shown
with "X's" are placed throughout the array. Seeded among these
devices, perhaps one for every three NDIST strobes, are wide
distribution strobes WDIST, as envisioned above and in the appended
claims.
[0125] FIG. 20 shows the detector end of a receiver according to
the present invention, with a detector DET, photodiodes PHT arrayed
inside the detector DET, covered by an infra-red transmissive cover
IRC. The detector DET rides on a photocell base PHB which is
articulatable by a pivot shaft PIVS, and includes a position
sensing switch and detent PSS, which indicates the the receiver
electronics that the detector DET has been flipped up as shown. The
photocell base PHB can include a marking point MRK as well known in
the art.
[0126] Now referring to FIG. 21, the detector end of a receiver
according to the present invention, when used with a transmitter in
a vertical mode, is shown. In this mode, the receiver is posed such
that the detector DET "views" the field of measurement
horizontally, in anticipation of detecting laser fans that are
rotating in a vertical plane, as is known. Photocell base PHB is
flipped down into the receiver housing RHO for this purpose.
Instead of prior art transmitters, where a transmitter must be
dedicated to vertical scanning, the invention allows that the
transmitter electronics and/or the receiver electronics are
"informed" of a vertical positioning of the transmitter by known
position sensors in the unit, and the spatial positioning system is
used in conjunction with the receiver thus described. The fan sweep
frequency for the vertical and horizontal modes can be different to
allow differentiation by processors and calculation engines.
Appropriate vertical vials can be provided and sensed at the
appropriate time. By communicating the vertical mode (by virtue of
position sensing, and not by elaborate setup methods or by
dedication of units) directly to processors, automatic vertical
mode position sensing in the field of measurement, even for tall
buildings, can be obtained.
[0127] The setup cable described above obviates need for a "scale
bar" to determine locations and give a scale to measurements
already accumulated. In the case where there is no two-detector
measurement wand or pole (stadia-type measurements), there is a
need for quick field deployable means for easily setting scale. One
can take numerous (redundant) measurements, which can then be
averaged by processing algorithms. A "carpenter's" folding level is
a possible embodiment for the posing of the field-deployable length
standard.
[0128] Typically, each laser transmitter scans light across a field
extending 270 degrees horizontally and 60 degrees vertically. This
scanning creates a detection or fiduciary volume over which the
transmitter output may be detected by the receiver for position
measurement. Two more transmitters can be positioned so that their
detection volumes overlap. In the shared volume where the detection
volumes overlap, three or more position variables may be obtained,
typically two spatial coordinates (e.g., azimuth, elevation) per
twin beam laser transmitter.
[0129] All publications and references, including but not limited
to patents and patent applications, cited in this specification are
herein incorporated by reference in their entirety as if each
individual publication or reference were specifically and
individually indicated to be incorporated by reference herein as
being fully set forth. Any patent application to which this
application claims priority is also incorporated by reference
herein in its entirety in the manner described above for
publications and references.
* * * * *