U.S. patent application number 15/493645 was filed with the patent office on 2017-10-26 for sensor system and method for determining a position of a measuring element along a motion path.
The applicant listed for this patent is FESTO AG & Co. KG. Invention is credited to Fabian Albert, Ralf Hartramph, Andreas Veit.
Application Number | 20170307408 15/493645 |
Document ID | / |
Family ID | 60021412 |
Filed Date | 2017-10-26 |
United States Patent
Application |
20170307408 |
Kind Code |
A1 |
Hartramph; Ralf ; et
al. |
October 26, 2017 |
Sensor System and Method for Determining a Position of a Measuring
Element Along a Motion Path
Abstract
A sensor system for detecting a position of a measuring element
movable along a motion path, having a sensor arrangement, which
includes a plurality of sensors arranged at least along a
subsection of the motion path, which in each case are designed for
a contactless detection at least of one physical dimension
dependent on a position of a measuring element along the motion
path as well as for a provision at least of one sensor signal
dependent on the a least one determined physical dimension, as well
as having a processing device, which is connected electrically with
the sensors and which is designed for a processing of the sensor
signals to form at least one position signal, which represents the
position at least of one measuring element along the motion path,
wherein the processing device is designed for a synchronous
detection of sensor signals of the sensors.
Inventors: |
Hartramph; Ralf;
(Albershausen, DE) ; Albert; Fabian; (Kernen,
DE) ; Veit; Andreas; (Filderstadt, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FESTO AG & Co. KG |
Esslingen |
|
DE |
|
|
Family ID: |
60021412 |
Appl. No.: |
15/493645 |
Filed: |
April 21, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01D 5/145 20130101 |
International
Class: |
G01D 5/14 20060101
G01D005/14 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 22, 2016 |
DE |
102016206905.5 |
Claims
1. A sensor system for the detection of a position of a measuring
element movable along a motion path, having a sensor arrangement,
which comprises a plurality of sensors arranged at least along a
subsection of the motion path, which in each case are designed for
the contactless detection at least of one physical dimension
dependent on a position of a measuring element along the motion
path as well as having a processing device, which is connected
electrically with the sensors and which is designed for a
processing of the sensor signals to form at least one position
signal, which represents the position at least of one measuring
element along the motion path, wherein the processing device is
designed for a synchronous detection of sensor signals of the
sensors.
2. The sensor system according to claim 1, wherein the sensors are
designed for a determination at least of one physical dimension
from the group: magnetic field strength, magnetic field direction,
electromagnetic induction, electrical field strength, intensity of
illumination, sound intensity.
3. The sensor system according to claim 2, wherein the sensors are
designed as multidimensional Hall sensors.
4. The sensor system according to claim 1, wherein sensors arranged
adjacently along the subsection of the motion path are arranged in
such a manner that a detection of the measuring element by at least
two sensors, which in each case provide a presettable minimum level
of the sensor signal, is always ensured along the subsection of the
motion path.
5. The sensor system according to claim 4, wherein at least one
part of the sensors is arranged along the subsection of the motion
path uniformly with a first division and/or wherein at least one
part of the sensors are arranged on a mounting path, which runs
parallel to the subsection of the motion path.
6. The sensor system according to claim 5, wherein all sensors are
arranged on the mounting path which runs parallel to the subsection
of the motion path.
7. The sensor system according to claim 5, wherein all sensors are
arranged on a mounting straight line which runs parallel to the
subsection of the motion path.
8. The sensor system according to claim 5, wherein, on at least one
end area of the subsection of the motion path, two adjacently
arranged sensors are arranged with a second division, which is
selected to be smaller than the first division.
9. The sensor system according to claim 8, wherein a first and a
second sensor arranged along the motion path and/or a penultimate
and a last sensor arranged along the motion path are arranged with
a second division, which is selected to be smaller than the first
division.
10. The sensor system according to claim 1, wherein each of the
sensors is accommodated in a separately designed housing and is
arranged on a printed circuit board extending along the subsection
of the motion path and/or that the processing device comprises a
plurality of sensor interfaces for a parallel coupling with the
sensors, wherein each of the sensor interfaces is connected to a
clock generator, which is designed for a provision of a read-out
signal to the sensor interfaces.
11. The sensor system according to claim 10, wherein the processing
device comprises a plurality of serial-peripheral interfaces for a
parallel coupling with the sensors.
12. The sensor system according to claim 1, wherein the processing
device is connected electrically with an output interface which is
configured for a provision of the at least one position signal to a
communication system.
13. The sensor system according to claim 12, wherein the output
interface is designed as a synchronous serial interface or as a
Drive Cliq bus interface, which is configured for a provision of
the at least one position signal to a multiconductor arrangement or
a bus system.
14. The sensor system according to claim 1, wherein the processing
device is connected electrically with a display device, which
comprises display elements arranged along a mounting path running
parallel to the subsection of the motion path, which is designed
for an output of status signals depending on the determined
position signals and/or that the subsection of the motion path is
formed by a stator of a linear drive system, wherein the measuring
element 3 is assigned to a carrier movable along the stator.
15. A method for determining a position of a measuring element
along a motion path, the method comprising: contactless detection
of at least one physical dimension, which is dependent on the
position of a measuring element along the motion path, with a
plurality of sensors arranged along a subsection of the motion
path; synchronous detection of sensor signals of the sensors by a
processing device, which is connected electrically with the
sensors; and processing of the sensor signals to form at least one
position signal, which represents the position at least of one
measuring element along the motion path.
16. The method according to claim 15, wherein the sensors are
designed for the detection of magnetic field components at least of
one magnetic field provided by at least one measuring element and
that at least two magnetic field components aligned perpendicular
to each other are detected by the respective sensor and are
processed to form a sensor signal, wherein the processing device
compares the synchronously detected sensor signals of the sensors
with a presettable minimum level for the sensor signal and
processes those sensor signals of sensors arranged at least
pairwise adjacent along the subsection of the motion path to form
at least one position signal, which are above the presettable
minimum level.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to a sensor system for detecting a
position of a measuring element movable along a motion path, having
a sensor arrangement, which comprises a plurality of sensors
arranged at least along a subsection of the motion path, which in
each case are designed for a contactless detection at least of one
physical dimension dependent on a position of a measuring element
along the motion path as well as for a provision at least of one
sensor signal dependent on the at least one determined physical
dimension, as well as having a processing device, which is
connected electrically with the sensors and which is designed for a
processing of the sensor signals to form at least one position
signal, which represents the position at least of one measuring
element along the motion path. Furthermore, the invention relates
to a method for determining a position of a measuring element along
a motion path.
[0002] A position sensor device with a plurality of sensor units is
known from EP 2 466 269 B1, wherein the sensor units in each case
contain at least one detection unit suitable for the detection of a
motion component located in its vicinity and are connected with a
communication interface, which is designed for the output of a
uniform position signal based on individual measuring signals of a
plurality of sensor units, wherein the sensor units are designed as
individual sensor modules equipped with electrical interface means,
which can be lined up next to one another in variable number under
mutual electrical linkage and forming a module strand.
SUMMARY OF THE INVENTION
[0003] The object of the invention is to provide a sensor system
and a method for determining a position of a measuring element
along a motion path with improved accuracy.
[0004] This object is achieved for a sensor system for detecting a
position of a measuring element movable along a motion path, having
a sensor arrangement, which comprises a plurality of sensors
arranged at least along a subsection of the motion path, which in
each case are designed for a contactless detection at least of one
physical dimension dependent on a position of a measuring element
along the motion path as well as for a provision at least of one
sensor signal dependent on the at least one determined physical
dimension, as well as having a processing device, which is
connected electrically with the sensors and which is designed for a
processing of the sensor signals to form at least one position
signal, which represents the position at least of one measuring
element along the motion path, wherein the processing device is
designed for a synchronous detection of sensor signals of the
sensors.
[0005] In this way a creation of a precise position image is made
possible for at least one measuring element, preferably for
several, in particular, for all of the measuring elements arranged
along the motion path. Due to the synchronous detection of the
sensor signals measurement errors can be eliminated, which can be
attributed to a temporally successive and thus sequential detection
of sensor signals of the sensor elements, as is provided in the
prior art. Such a precise position image is of great importance,
particularly when one or several measuring elements are moved with
the same or different speed along the motion path and either an
exertion of influence on the motions of the measuring element or
the measuring elements is provided by means of at least one
determined position signal or an exertion of influence on
processing devices, which are provided for the processing of the
measuring elements or of workpieces assigned to the measuring
elements, is to take place. By way of example, it is possible to
use the at least one determined position signal to exert influence
on a motion device, which is used for a motion of the measuring
element or of the measuring elements, in order to provide the
measuring element/the measuring elements with a presettable speed
profile. Additionally or alternatively provision can be made to
control one or several processing devices by means of at least one
determined position signal, in order to make possible an adjusted
processing of at least one of the measuring elements or of one
workpiece assigned to the respective measuring element. Purely as
an example, for clarification of the influence possibilities, a
laser marking of a workpiece must be mentioned, which is assigned
to a measuring element and which is advanced at a preset or
variable speed on a processing device designed as a laser marking
system, wherein the marking process is adjusted depending on the
speed of the workpiece, in order always to be able to apply the
same marking independently of the speed of the workpiece. Even if
only a single measuring element is positioned or is moved along the
motion path, the processing device according to the present
invention makes possible a highly precise determination of the
position and/or of the motion speed of the measuring element, since
through the synchronous detection of the sensor signals of the
sensor elements in the processing device the influences of
different signal propagation times, as they occur in a serial
readout process for several sensors, can be minimised or completely
eliminated.
[0006] Preferably, in the case of the processing device according
to the present invention a parallel detection is provided of sensor
signals, in particular of all sensor signals of sensors arranged
along the subsection of the motion path. In order to ensure the
synchronicity during the detection of the sensor signals of the
sensors, the processing device can be designed to respond at the
same time to all sensors to be detected synchronously at the same
time and also at the same time to temporarily store the sensor
signals provided by the sensors responded to for a further
processing. By way of example, it is provided to respond to all
sensors to be detected by a single trigger signal, wherein said
trigger signal is outputted on the basis of a clock generator via
parallel-branched lines to all sensors to be detected. When the
trigger signal arrives at the individual sensors the latter
immediately provide their sensor signal to the processing device,
so that the synchronicity is ensured. This is the case in
particular in light of the fact that delays between the sensor
signals arriving at the processing device can occur at most as a
result of different electrical line lengths and/or circuit-related
tolerances of the individual sensors, which, however, are
completely negligible in light of the running times for the
electrical signals and in light of the speeds to be detected,
which, for example, in the case of transport systems can be assumed
to be in the range of a few mm/s to 10 m/s.
[0007] In principle, it can be provided that the sensors are
arranged along the entire motion path. For practical reasons it can
be advantageous if the sensors are arranged only along the
subsection of the motion path, wherein it can be achieved by
suitable measures that a detection of measuring elements is also
possible within a presettable area away from the subsection of the
motion path.
[0008] Advantageous further embodiments of the invention are the
subject matter of the dependent claims.
[0009] It is expedient if the sensors are designed in particular as
multidimensional Hall sensors for a determination at least of a
physical dimension from the group: magnetic field strength,
magnetic field direction, electromagnetic induction, electrical
field strength, intensity of illumination, sound intensity. For
example, it can be provided that the measuring element is designed
as a permanent magnet and a magnetic field is provided, which can
be detected by the respective sensors. The sensors can thereby
exemplarily be designed as Hall sensors, in particular, as at least
two-dimensional Hall sensors. Alternatively, the sensors can also
be designed as coils, in which a voltage is induced by a relative
motion of the measuring element designed as a permanent magnet,
which voltage can also be evaluated as a sensor signal. In the case
of an alternative embodiment of the sensors these are designed in
the form of inductive proximity switches, in which an oscillation
frequency of an oscillating circuit, which comprises an induction
coil, is detuned by the presence, for example, of a ferritic
measuring element and from which information about the relative
position of the measuring element relative to the sensor can be
obtained. Designs of the sensors as capacitive measuring sensors or
optical measuring sensors can also additionally or alternatively be
provided.
[0010] In the case of the use of Hall sensors three-dimensional
Hall sensors in particular can be provided, which are designed for
a determination of magnetic field strengths in three spatial
directions perpendicular relative to each other. Preferably, for a
purely position detection only one evaluation of two signals of the
three-dimensional Hall sensor is provided, which are caused by two
field strength components aligned perpendicularly relative to each
other, while a third signal, which is determined by a third field
strength component, remains unnoticed. Particularly preferably it
is provided that the two magnetic field strength components used
for the position detection are determined with the same Hall sensor
measuring cell, which is read out alternatingly in directions
perpendicular relative to each other.
[0011] In the case of an advantageous further development of the
invention it can be provided that sensors arranged adjacently along
the subsection of the motion path are arranged such that along the
subsection of the motion path a detection of the measuring element
is always ensured by at least two sensors, which in each case
provide a presettable minimum level of the sensor signal. Thus, a
comparison can always be made of sensor signals of adjacently
arranged sensors, in order to obtain a particularly precise
position signal. If the sensors are arranged relative to each other
in different, at particularly irregular distances along the
subsections of the motion path, it can be provided, to undertake an
error compensation in the processing device for the sensor signals,
in order to eliminate the different distances between the sensors
and the deviations in the sensor signals resulting therefrom. Such
a compensation can, for example, occur by a preceding calibration
of the sensor system, in which one or several measuring elements
are provided with a highly precise path measuring system and sensor
signals of the path measuring system are compared with the sensor
signals of the sensor system and, for example, are stored in the
form of a calibration curve in the processing device.
[0012] In a further embodiment of the invention it is provided that
at least a part of the sensors is arranged uniformly with a first
division or equal spacing along the subsection of the motion path
and/or that a part of the sensors, in particular, all sensors, are
arranged on a mounting path, in particular, a mounting straight
line, which runs parallel to the subsection of the motion path.
[0013] In this connection, the distance of the adjacent sensor
cells is regarded as a division or equal spacing, which are
accommodated in each case in discretely designed housings, while a
distance of the adjacent housing is referred to as a housing
distance. The sensor signals of those sensors, which are arranged
uniformly with the first division along the motion path, can
preferably be used without a preceding calibration of the sensor
system, since position deviations of these sensors depend only on a
mounting tolerance, which result during the mounting of the
sensors, for example, on a printed circuit board. Since such
position deviations are usually in the range of a few 1/100
millimetres, it is possible to compare sensor signals provided by
said sensors purely mathematically with each other. Preferably it
is provided that the arrangement of the sensors with the first
division leads to a housing distance between discretely designed,
individually mounted sensors, which is measured by means of the
detection ranges of the sensors and an influence area of the
measuring elements and which, in practical terms, corresponds, for
example, to at least 50 percent of an extent of the housing used
for the sensors along the motion path. Thus, a cost-effective
sensor system is made possible, in which an advantageous compromise
between the required overlapping of detection areas of adjacent
sensors and the number of sensors used can be made.
[0014] Preferably, it is provided that the measuring elements are
applied to the movable components, such as, for example, rotors of
the linear motor system such that adjacent measuring elements
always have a distance relative to each other, which corresponds to
at least nearly a 2-fold division of the sensors arranged in a
regular first division. Thus, an undesired exertion of influence of
a more remote measuring element on sensor signals of sensors can be
suppressed, which are supposed to detect a measuring element which
is arranged closer.
[0015] Since preferably it is provided that at least one part of
the sensors, in particular, all sensors, are arranged on the
mounting path, in particular, on a mounting straight line, which
runs parallel to the subsection of the motion path, further
tolerance influences on the sensor signals of the sensors can be
minimised. In particular, a distance between the respective sensors
and the measuring element transversely to the motion path is at
least substantially constant and thus has only a slight, preferably
an insignificant influence on the sensor signals of the sensors.
This is the case in particular when two mutually perpendicular
field components of a magnetic flux provided by the measuring
element are determined by means of a multidimensional Hall sensor,
wherein a first magnetic field component is extended along the
motion path and wherein a second field component is aligned
transversely to a magnetic polarity of the measuring element. In
this case, courses for the respective field components are set on
each of the sensors during a relative motion of the measuring
element, which correspond to a sine function and a cosine function
and which are converted in the sensor or in the processing device
with the aid of an arctangent function into a linearised sensor
signal, which independent of a distance between sensor and
measuring element is in a direction transverse to the motion
path.
[0016] It is advantageous, if two sensors adjacently arranged at at
least one end area of the subsection of the motion path, in
particular, a first and a second sensor arranged along the motion
path and/or a penultimate and a last sensor arranged along the
motion path, are arranged with a second division or equal spacing,
which is selected to be smaller than the first division. Through
these measures it can be achieved that a position of a measuring
element can also be detected with sufficient accuracy even when
this measuring element is located within a presettable measuring
window away from the subsection of the motion path. In this
connection, in the same way as in the case of an arrangement of the
measuring element along the subsection of the motion path it is
assumed that at least two sensors in each case provide a
presettable minimum level of the sensor signal. If the measuring
element is located within the presettable measuring window, for
example, a first and a second sensor arranged along the motion path
or a penultimate and a last sensor arranged along the motion path
in each case provide sensor signals, which satisfy the requirements
of the presettable minimum level for the sensor signal and thus
also make possible a comparison of the two sensor signals, whereby
precision in the position determination is made possible.
Exemplarily it is provided, that the sensor device in each case has
precisely two sensors arranged with respect to each other at end
areas of the subsection of the motion path, while all other sensors
are arranged with respect to each other according to the first
division. From this it results that a first and a second sensor
arranged along the motion path have a distance corresponding to the
second division, while the distance of the second sensor to the
third sensor corresponds to the first division. Furthermore, the
third to last and the penultimate sensor are arranged at a distance
according to the first division, while a distance between the
penultimate sensor and the last sensor corresponds to the second
division. Exemplarily, it can be provided that a housing distance
for sensors, which are arranged according to the first division,
corresponds at least approximately to an extent of the housing
along the motion path, while a housing distance of sensors, which
are arranged according to the second division, is designed, for
example, as a production-related minimum distance between the
adjacent housings of the sensors.
[0017] Preferably, it is provided that each of the sensors is
accommodated in a separately designed housing and is arranged on a
printed circuit board extended along the subsection of the motion
path and/or that the processing device comprises a plurality of
sensor interfaces, in particular, serial-peripheral interfaces for
a parallel coupling with the sensors, wherein each of the sensor
interfaces is connected with a clock generator, which is designed
for a provision of a read-out signal to the interfaces.
[0018] It is advantageous if all of the sensors are accommodated in
identically designed housings, which are designed in particular as
SMD housings for a surface-solder mounting. For a stationary
arrangement of the sensors along the motion path as well as for an
electrical connection of the sensors to the processing device it is
preferably provided to arrange the sensors on a printed circuit
board, which can, for example, be a conductive plate or a flexible
conductive film and which are fixed in a defined manner on a
component, which determines the motion path, in particular, is
designed as a stator of a linear motor arrangement. The processing
device can, for example, be designed as a programmable gate array
(FPGA--Field Programmable Gate Array) and comprises a plurality of
sensor interfaces, so that each of the sensors, which are arranged
along the subsection of the motion path, can communicate with the
processing device by means of its own sensor interface.
Furthermore, it is provided, that each of the sensor interfaces is
connected with a clock generator, which is designed for a provision
of a read-out signal to the interfaces. Preferably, the clock
generator is designed as an oscillator with a presettable or
non-adjustable clock frequency, such that a regular provision of
trigger signals is made to the sensor interfaces, which accordingly
read out their assigned sensors at regular time intervals and can
feed the read-out sensor signals to the further processing.
Alternatively, it can also be provided that the clock generator
outputs trigger signals at irregular time intervals, for example,
depending on presettable operating conditions of the sensor system
and/or the condition of a downstream control device.
[0019] Exemplarily, it can be provided that the sensor interfaces
are designed as serial peripheral interfaces
(SPI--Serial-Peripheral Interface), in order to ensure a
cost-effective and robust communication between the sensors and the
processing device.
[0020] It is expedient if the processing device is connected
electrically with an output interface designed in particular as a
synchronous serial interface (SSI or as a Drive Cliq bus interface
(Drive-Cliq is a registered trademark of Siemens AG), which is
configured for a provision of the at least one position signal to a
communication system designed preferably as a multiconductor
arrangement or as a bus system. The output interface has the task
of passing on position signals determined in the processing device
to an, in particular, higher-order control device. This control
device can, for example, be provided to exert an influence on the
measuring elements or on the components assigned to the measuring
elements and/or on the processing devices, which are provided for
processing the measuring elements or the components.
[0021] In a further embodiment of the invention it is provided that
the processing device is connected electrically with a display
device, which comprises display elements arranged along a mounting
path running parallel to the subsection of the motion path, which
display elements are designed for an output of status signals
depending on the determined position signals and/or that the
subsection of the motion path is formed by a stator of a linear
drive system, wherein the measuring element is assigned to a
carrier movable along the stator. For example, the display device
can be formed from light-emitting diodes arranged in a row, which
are activated by the processing device in such a manner that in
each case those light-emitting diodes light up with maximum
intensity, which have a minimum distance to the respective
measuring element. Thus, a particularly rapidly detectable
visualisation is made possible for the position of the measuring
element along the motion path. The sensor system can be used in an
advantageous manner for detection of carriers of an in particular
fluidically operable or electrically operable linear drive system
and is preferably fixed on a stator of the linear drive system,
which is, for example, a cylinder housing of a hydraulic cylinder
or a pneumatic cylinder or a housing of a hydraulic or pneumatic
pivot drive or a coil arrangement of an electrodynamic linear
motor. The carrier can, for example, be a slidingly movable piston
of a fluid cylinder accommodated in a cylinder housing or a rotor
for an electrodynamic linear motor.
[0022] The problem addressed by the invention is solved by a method
for determining a position of a measuring element along a motion
path, which comprises the following steps: contactless detection at
least of one physical dimension, which is dependent on the position
of a measuring element along the motion path, with a plurality of
sensors arranged along a subsection of the motion path, synchronous
detection of sensor signals of the sensors by a processing device,
which is connected electrically with the sensors, processing of the
sensor signals to form at least one position signal, which
represents the position at least of one measuring element along the
motion path.
[0023] In the case of an advantageous further development of the
method it is provided that the sensors are designed for detecting
magnetic field components at least of one magnetic field at least
of one measuring element and that at least two magnetic field
components aligned perpendicular relative to each other are
detected by the respective sensor and are processed to form a
sensor signal, wherein the processing device compares the
synchronously detected sensor signals of the sensors with a
presettable minimum level for the sensor signal and processes those
sensor signals of sensors arranged at least pairwise adjacent along
the subsection of the motion path to form at least one position
signal, which are above the presettable minimum level.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] An advantageous embodiment of the invention is shown in the
drawing, in which:
[0025] FIG. 1 shows a schematic representation of a sensor system,
which is used for the detection of measuring elements, which are
mounted on carriages for a linear drive system which is not shown
in detail, and
[0026] FIG. 2 shows a highly schematised depiction of detection
areas and signal levels of individual sensors of the sensor system
depicted in FIG. 1, and
[0027] FIG. 3 shows a section enlargement of an arrangement of a
plurality of sensors with identical division or equal spacing,
which is not part of the invention.
DETAILED DESCRIPTION
[0028] A sensor system 1 depicted in FIG. 1 is designed for the
detection of positions of a plurality of measuring elements 3
movable along a motion path 2. Purely as an example, the measuring
elements 3 are designed as cuboid permanent magnets with
north-south magnetisation aligned transversely to the motion path
and symbolised in each case by arrows and is attached to linearly
movable carriage 4 of a linear motor arrangement not shown in
detail, which carriage is movable along the motion path 2. For a
position detection of said carriage 4 the sensor system 1 comprises
a plurality of sensors 5, which exemplarily are accommodated in
rectangular housings 6, wherein the housings 6, for example, are
arranged on a rectangularly designed printed circuit board 7
electrically conductively and connected in a mechanically fixed
manner with the latter. Each of the sensors 5 comprises a measuring
cell not shown in detail, which is designed for the detection of a
physical dimension. In the case of the depicted embodiment the
measuring cells of the sensors 5 are designed, for example, in each
case as multidimensional Hall sensors, which exemplarily can
determine magnetic field components of the magnetic field provided
by the measuring element 3 along the motion path 2 and aligned
normal to the display level of FIG. 1. To identify the position of
the respective measuring cell within the sensor 5 each of the
sensors 5 is provided with a centre point.
[0029] The sensors 5 are in each case connected electrically via
sensor lines 8 with a processing device 9, which is designed for a
synchronous detection of signal levels of the respective sensors 5
and for a processing of the determined signal level to form at
least one position signal. Purely as an example, the processing
device 9 is designed as FPGA and for each sensor includes its own
sensor interface 10. The processing device 9 also comprises an
output interface 11, which can be designed for a communication with
a higher-order control device which is not shown or with a further
sensor system which is also not shown. Exemplarily the output
interface is designed as a Drive-Cliq bus interface and thus makes
possible a bus communication with a higher-order control of the
control manufacturer Siemens, which is not shown, and which is
designed for a coupling of sensors by means of the Drive-Cliq bus
protocol.
[0030] The sensors 5 are, for example, applied on the printed
circuit board 7 along a rectilinear mounting path 12 in the case of
the embodiment shown, running parallel to the motion path. For
example, it can be provided that the sensors 5 are designed for a
surface solder mounting (SMD surface mount device) and in the case
of the production of the sensor system 1 are mounted on the printed
circuit board 7 by means of an automatic mounting system in the
pick-and-place method which is not shown.
[0031] For example, it is provided that the sensors 5 are arranged
along the motion path 2 in two different divisions or equal
spacings. When the sensors 5 are viewed from left to right the
first sensor 5.1 and the second sensor 5.2 are arranged relative to
each other at a minimum distance 15, which results due to the size
of the housings 6. The sensors 5.3, 5.4, 5.5 and 5.6 following the
second sensor 5.2 are, however, arranged at an increased distance
16. The last two sensors 5.6 and 5.7 are, however, arranged again
at the minimum distance 15 relative to each other. The larger
distance 16 can thereby also be referred to as the first division,
while the small distance 15 can also be referred to as the second
division.
[0032] The processing device 9 is configured to process only sensor
signals of those sensors 5, the signal level of which is above a
presettable minimum level. Furthermore, the processing device 9 is
configured to provide a position signal for a position of a
measuring element to the output interface 11 only when at least two
adjacently arranged sensors 5 in each case provide a sensor signal
with a signal level above the presettable minimum level and when a
comparison of the two sensor signals leads to a plausible position
signal. Through these above cited conditions it results that the
sensor system 1 is not designed for a detection of the entire
motion path 2, but rather for a detection of a subsection 17 of the
motion path 2 delineated symbolically in FIG. 1.
[0033] In addition, the processing device 9 can be configured due
to its internal architecture, which can be designed in particular
as FPGA, to detect the sensor signals of all of the sensors 5
synchronously. Thus, error influences are avoided, such as they
could occur, for example, during the detection of moving measuring
elements 3 and a sequential detection of sensor signals of sensors.
Instead, through a synchronous activation of all of the sensor
interfaces 10 with a clock generator, which is not shown, assigned
to the processing device 9, an also synchronous query of all
sensors 5 is undertaken by the processing device 9. The sensor
signals arriving at the sensor interfaces 10 can subsequently be
processed either in parallel or sequentially in the processing
device 9 to form a position signal or, if applicable, to form
several position signals, this depends on whether only one
measuring element 3 or several measuring elements 3 are located
within the subsection 17 of the motion path 2 detectable by the
sensor system 1.
[0034] As can be learned from the depiction of FIGS. 1 and 2, the
subsection 17 of the motion path 2 extends laterally beyond a
longitudinal extension 18, which is determined by the housings 6 of
the sensors 5. The limits 19, 20 of the subsection 17 result from
an interaction of a magnetic minimum flux density 21 of the
measuring element 3 designed as a permanent magnet, which, is
depicted in a highly schematised manner with in each case purely
exemplarily triangularly designed detection areas 22 of the sensors
5. It is thereby assumed, for example, that a sensor 5 can provide
a sensor signal with a signal level above a presettable minimum
level only when there is an overlapping of the exemplarily
trapezoidally limited magnetic minimum flux density 21 with the
respective detection area 22 of the sensor 5. For example, the
measuring element 3 depicted on the left in FIG. 2 is arranged
precisely so that the minimum flux density 21 overlaps both the
detection area 22 of the sensor 5.1 as well as of the sensor 5.2.
This results in signal levels depicted purely schematically under
the respective sensors 5. In the same way, the right limit 20 for
the subsection 17 results without a corresponding measuring element
3 being arranged here. Therefore, as soon as a measuring element 3
approaches the sensor system 1 coming from the left along the
motion path 2, from that point in time the sensors 5.1 and 5.2
provide usable sensor signals to the processing device 9, from
which the measuring element 3 has passed the left limit 19. From
this point in time the sensor system 1 can always in each case
process at least two usable sensor signals to form a position
signal, until the measuring element 3 passes the right limit 20 and
thus the condition is no longer met, that the detection areas 22 of
at least two sensors 5 are overlapped by the minimum flux density
21.
[0035] Exemplarily the sensor system 1 comprises a display device
30, which is connected electrically with the processing device 9 in
a manner not shown in detail. For example, the display device 30 is
realised as display elements 31 arranged as an array in each case
in the same division, designed in particular as light-emitting
diodes. With the display device 30, for example, determined
position values for measuring elements 3 can be visualised by
lighting up and extinguishing display elements 31 assigned in each
case, as this is depicted exemplarily in FIG. 1.
[0036] FIG. 3 serves to demonstrate the advantage of the
arrangement of the sensors 5 with different divisions 15, 16 along
the motion path 2, as this is realised in the sensor system
according to FIGS. 1 and 2. For this purpose, FIG. 3 shows only the
two left sensors 5.1 and 5.2, as they are known from FIGS. 1 and 2,
wherein in the case of the sensor system according to FIG. 3 all
sensors 5 are arranged in the same division, so that a distance 25
of the two sensors 5.1 and 5.2 is identical to the distance 23 for
the sensors 5.3 to 5.5 known from FIGS. 1 and 2. In the comparison
with FIG. 2 it can be seen that despite the increased distance 16
between the two sensors 5.1 and 5.2 in the case of the embodiment
of FIG. 3 a distance 25 between the left limit 19 and the second
sensor 5.2 is identical to the distance 23 between the left limit
19 and the second sensor 5.2 according to FIG. 2. From this it
results that despite an increase in the longitudinal extension for
the sensor system according to FIG. 3 no increase of the motion
path 2 detectable by the sensors 5 occurs compared to the
embodiment according to FIGS. 1 and 2. Accordingly, with the sensor
system according to the embodiment of FIGS. 1 and 2 a measuring
element 3 can be detected within a subsection 17 of the motion path
2, which is identical to a subsection not shown in detail for the
embodiment of a sensor system according to FIG. 3.
* * * * *