U.S. patent application number 10/078796 was filed with the patent office on 2003-08-21 for method of increasing location accuracy in an inertial navigational device.
Invention is credited to Koskan, Patrick Douglas, Swope, Charles B., Tealdi, Daniel A..
Application Number | 20030158664 10/078796 |
Document ID | / |
Family ID | 27732906 |
Filed Date | 2003-08-21 |
United States Patent
Application |
20030158664 |
Kind Code |
A1 |
Swope, Charles B. ; et
al. |
August 21, 2003 |
METHOD OF INCREASING LOCATION ACCURACY IN AN INERTIAL NAVIGATIONAL
DEVICE
Abstract
A method of increasing location accuracy in an inertial
navigational device (100) is described herein. The navigational
device (100) generates real-time data to depict its location. The
data comprises at least one of sensor data, motion data, and
location data. The navigational device (100) transmits the
real-time data to a second device (104) in a real-time fashion. The
navigational device (100) receives an update message from the
second device (104), based on a comparison of the real-time data
generated by the navigational device (100) against a second set of
data. The navigational device (100) adjusts its depicted location
based on the update message in order to increase the location
accuracy of the navigational device (100). Alternatively, the
navigational device (100), absent the second device (104), can
compare the real-time data generated against the second set of data
internally and adjust its depicted location accordingly.
Inventors: |
Swope, Charles B.; (Coral
Springs, FL) ; Tealdi, Daniel A.; (Hialeah, FL)
; Koskan, Patrick Douglas; (Lake Worth, FL) |
Correspondence
Address: |
MOTOROLA, INC.
1303 EAST ALGONQUIN ROAD
IL01/3RD
SCHAUMBURG
IL
60196
|
Family ID: |
27732906 |
Appl. No.: |
10/078796 |
Filed: |
February 19, 2002 |
Current U.S.
Class: |
701/505 ;
342/358 |
Current CPC
Class: |
G01C 21/165
20130101 |
Class at
Publication: |
701/214 ;
701/220; 342/358 |
International
Class: |
G01C 021/00 |
Claims
We claim:
1. A method of increasing location accuracy in an inertial
navigational device comprising the steps of: generating real-time
data to depict a location of the inertial navigational device,
wherein the data comprises at least one of sensor data, motion
data, and location data; transmitting the real-time data generated
by the inertial navigational device in a real-time fashion to a
second device; receiving an update message from the second device,
wherein the update message is compiled based on a comparison of the
real-time data generated by the inertial navigational device
against a second set of data; and adjusting the depicted location
of the inertial navigational device based on the update message in
order to increase the location accuracy of the inertial
navigational device.
2. The method of claim 1 wherein the second set of data is
collected off-line.
3. The method of claim 1 wherein the second set of data is based on
output from a positioning system.
4. The method of claim 1 wherein the second set of data is a
collection of gestures that was collected in a given sequence and
stored in a database that reflects movements in a structure.
5. The method of claim 4 wherein the given sequence of the
collection of gestures is either simulated, emulated, or actual
gesture sequences that reflect movement in the structure.
6. The method of claim 1 wherein the second set of data is a
dimensional model of a given structure.
7. The method of claim 6 further comprising the steps of:
displaying the dimensional model of the given structure on a
graphical user interface associated with the inertial navigational
device; and displaying an indicator of the depicted location of the
inertial navigational device in relation to the dimensional
model.
8. A method of increasing location accuracy in an inertial
navigational device comprising the steps of: generating real-time
data to depict a location of the inertial navigational device,
wherein the real-time data comprises at least one of sensor data,
motion data, and location data; comparing the real-time data
against a second set of data; and in response to the step of
comparing, adjusting the depicted location of the inertial
navigational device in order to increase location accuracy of the
inertial navigational device.
9. The method of claim 8 wherein the second set of data is
collected off-line.
10. The method of claim 8 further comprising the step of retrieving
the second set of data from a database.
11. The method of claim 8 further comprising the step of receiving
the second set of data from a positioning system in a real-time
fashion.
12. The method of claim 8 further comprising the step of, after the
step of adjusting, transmitting the depicted location of the
inertial navigational device to a second device.
13. The method of claim 8 wherein the second set of a data is a
dimensional model of a structure where the inertial navigational
device is located, and further comprising the step of displaying
the dimensional model of the structure to a graphical user
interface associated with the inertial navigational device.
14. The method of claim 8 wherein the second set of data is a
collection of gestures that was collected in a given sequence that
reflects movements in a structure.
15. A device comprising a processor, which when in operation,
causes the device to perform the following functions: generate
real-time data to depict a location of the inertial navigational
device, wherein the real-time data comprises at least one of sensor
data, motion data, and location data; compare the real-time data
against a second set of data; and in response to the function of
comparing, adjust the depicted location of the inertial
navigational device in order to increase location accuracy of the
inertial navigational device.
16. A device comprising at least a transmitter, a receiver and a
processor, which when in operation, causes the device to perform
the following functions: generate real-time data to depict a
location of the apparatus, wherein the data comprises at least one
of sensor data, motion data, and location data; transmit the
real-time data generated by the apparatus in a real-time fashion to
a second device; receive an update message from the second device,
wherein the update message is compiled based on a comparison of the
real-time data generated by the apparatus against a second set of
data; and adjust the depicted location of the apparatus based on
the update message in order to increase the location accuracy of
the apparatus.
Description
REFERENCE TO RELATED APPLICATION
[0001] The present application is related to the following U.S.
application commonly owned together with this application by
Motorola, Inc.: Ser. No. ______, filed Feb. 19, 2002, titled
"Device For Use With A Portable Inertial Navigation System (PINS)
and Method For Processing PINS Signals" by Swope et al. (attorney
docket no. CM03613J).
FIELD OF THE INVENTION
[0002] The present invention relates generally to a method if
increase location accuracy in an inertial navigation device.
BACKGROUND OF THE INVENTION
[0003] A traditional inertial navigation system ("INS") in its
embodiment utilizes accelerometers, gyroscopes, and support
electronics, such as a processor, in order to translate sensor data
into motional changes. These changes are then translated to
position based on an initial referenced position and the
integration or differentiation of said motion. As time progresses,
the errors associated with the accelerometers and gyroscopes
increase to a point where the translation to position is outside of
the required positional resolution, thus rendering the unit
ineffective or lost.
[0004] In one INS embodiment, the INS device is updated manually by
resetting the INS device using a known fixed position or by
returning back to the original reference position. The user
manually resets the INS unit and positional errors are cleared
until said error occurs again requiring another reset.
[0005] In another embodiment the INS device is updating an
alternate location-finding unit, such as a global positioning
system ("GPS"). In this configuration, the attached GPS is
providing data to a communication link sending back Latitude and
Longitude information. The INS device is utilized when the GPS
position is no longer available due to occulting of the satellites.
The INS device is utilized to provide updates to the last known
position and errors are accumulated at a rate of 2% to 5% of the
distance traveled. The INS device is only used for updating the
embedded GPS unit's location. Once a GPS signal is re-captured, the
INS device is not used.
[0006] Traditionally, INS devices utilize output voltages
representing the second derivative of position to integrate and
determine relative changes in motion. These are applied to the last
known position update and a new one is generated with some small
error. As time progresses, the errors are accumulated and the
computed position is no longer usable by the INS user. A known
location or position is required in order to correct for the
errors. Traditional systems utilize GPS, or cycle through a fixed
reference point to correct those errors.
[0007] Thus, there exists a need for a system that reduces error
accumulation and performs stand-alone tracking in areas where GPS
(or other similar location technologies) can no longer provide
location updates to the user or infrastructure.
BRIEF DESCRIPTION OF THE FIGURES
[0008] A preferred embodiment of the invention is now described, by
way of example only, with reference to the accompanying figures in
which:
[0009] FIG. 1 illustrates a block diagram of the portable inertial
navigation system ("PINS") architecture in accordance with the
preferred embodiment of the present invention;
[0010] FIG. 2 illustrates a block diagram of a PINS device in
accordance with the preferred embodiment of the present
invention;
[0011] FIG. 3 illustrates a block diagram of a host in accordance
with the preferred embodiment of the present invention;
[0012] FIG. 4 illustrates a software components diagram for the
host process in accordance with the preferred embodiment of the
present invention; and
[0013] FIG. 5 illustrates the preferred embodiment of the invention
illustrating a clear delineation between the inertial navigation
system sensor and the host process platform.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0014] The present invention increases location accuracy in a
Portable Inertial Navigation System ("PINS"). A PINS performs
stand-alone tracking in areas where a Global Positioning System
("GPS"), or other similar location technologies, can no longer
provide location updates to the user or infrastructure. Ideally, a
user can carry a PINS device so that gestures (i.e., body
movements) are translated into position or location. Preferably,
PINS utilizes internal three-axis gyroscopes and accelerometers
(and other technology) to capture the motion of the user and
translates it into positional changes through algorithmic
processing. The processing can occur in the PINS device, the host
or base computer, or any combination of both. Thus, the present
invention maintains a high level of positional accuracy for users
as they traverse through areas where traditional radio frequency
("RF") triangulation is not possible, such as an indoor structure,
heavy foliage, urban canyons, etc.
[0015] In accordance with the present invention, the PINS
technology is coupled with traditional communication devices (e.g.,
two-way radios) to provide a link to the host. The host then tracks
the location of the PINS device by correlating motion history
against a dimensional rendering of a structure or building. In
order to accommodate this task, the following details the
architectural designs for the two primary components in the PINS
architecture: the PINS device 100 and the host 104; these two
components are connected via an over-the-air radio channel 102 as
illustrated in FIG. 1.
[0016] As illustrated in FIG. 2, the PINS device 100 is responsible
for taking measurements of motion-related data (e.g., acceleration,
rotation, direction), and translating this data into motion
commands through sensor signal processing. The motion-related data
is then transmitted to the host that identifies the location of the
PINS device to those requiring resource tracking.
[0017] In the preferred embodiment, the PINS device 100, also
referred to as an inertial measurement unit ("IMU"), receives an
initialization function (e.g., GPS) to provide an initial position
for the PINS device that allows it to utilize its relative metrics
and convert them into an error correction (e.g., a location
update). Although a GPS provides the initial location to the PINS
device in the preferred embodiment, it is not necessary. Since PINS
utilizes a communication infrastructure, a simple voice position
update, or the like, will suffice as the initialization
function.
[0018] The PINS device 100 consists of a host of sensors and
required processing power to pre-process the raw data from the
inertial sensors. There are several different sensors that can be
used in an IMU. Theses sensors include, but are not limited to,
accelerometers, gyroscopes, compass, pressure, and temperature.
[0019] The PINS device 100 is responsible for gathering the
necessary data to determine location. Measuring the several degrees
of freedom of an object to arrive to the desired location
information usually does this. An object has six degrees of freedom
in space; three of them determine the position, while the other
three determine the altitude of the object. The three linear axes
determine the position: x, y, and z; the three rotational axes
determine the altitude: theta (pitch), psi (yaw), and phi
(roll).
[0020] The PINS device 100 is responsible for measuring these
variables that are necessary to track an object in three
dimensions. These six axes are usually measured indirectly through
their first or second moments. For example, theta, psi, and phi are
derived through the measurement of their first moment or angular
velocity rather than angular position; x, y, and z are usually
measured through their second moment or linear acceleration rather
than linear position. Thus, the PINS device 100 relies on the
motion of the object in order to determine its position.
[0021] The PINS device 100 can be designed to output at least one
type of data, such as sensor data, motion commands, position
location, and/or the like. The radio channel 102 is responsible for
sending the output data of the PINS device 100 over-the-air to the
host 104, typically residing at the base or dispatcher station.
This communication is bi-directional, meaning that not only is data
for the PINS device 100 sent to the host 104, but the host 104 also
must be able to send correction data/messages back to the PINS
device 100 for error correction(s).
[0022] As illustrated in FIGS. 3 and 4, the host 104 is responsible
for receiving the over-the-air data packets from the PINS device
100; this data is logged and formatted for processing by the host
104. The data collected can now be augmented with other location
data, if available, such as RF triangulation 108 or a GPS fix 109,
in order to get a better estimate of the actual location of the
PINS user. The estimated location can be further corrected by using
a verification process; this process may involve correlation with
dimensional building structure information 105, reference gestures
information 106, dispatcher update using voice query information
with the user 107, and/or the like.
[0023] Once the data has been processed and the location correction
coefficient is determined, it is sent back to the PINS device 100
via the radio channel 102 for error corrections and user
visualization if applicable (such as a heads-up display). This data
enables the PINS device 100 to correct itself to drift errors, and
also serve as an indication to the user of where the host/system
considers him to be. On the host side, the location management
software handles the data and can keeps track of the location of
several different PINS devices. The host 104 is responsible for
archiving, displaying, and distributing this location data back to
the PINS device 100. Remote client units, using various wireless
networks, can also receive the location data.
[0024] The following is a process operational flow of how a PINS
device 100 could be used in the field. First, the PINS device 100
is initialized with a known reference location (such as that
provided by a GPS, a voice command, or the like). Next, the PINS
device 100 gathers sensor data and calculates motion commands and
position location from the sensor data. The PINS device 100 sends
the motion commands and position locations to the host 104. The
host 104 uses the position location of the PINS device and further
correlates the received location and received motion commands with
other available non-location data (such as, but not limited to,
verbal communication from the user, structural dimensions,
reference gestures, sensor metrics, and/or the like) in order to
enhance the resolution of the reported location by calculating any
-coefficients. In the preferred embodiment, once the -coefficients
are calculated, the host 104 sends the -coefficients to the PINS
device 100. Upon receipt, the PINS device 100 re-initializes its
current location based on the -processing of coefficients and
further makes necessary modifications to the process of calculating
subsequent motion commands and position locations.
[0025] It should be noted that in the preferred embodiment of the
present invention, the PINS device 100 is updated such that no GPS
or external fixed or manual reference is necessary at the PINS
device to reduce or eliminate accumulated position errors. This is
accomplished by the host 104 receiving or having access to
information other than the data received from the PINS device 100,
such as dimensions of the structure where the PIS device 100 is
being used and/or reference gestures. The host 104 identifies key
update locations that are unique enough for establishing a
reference location (such as stairs, elevators, and hallways). As
the PINS user moves, the updated motion commands provide the host
104 with a probable location of the user. Again, as time
progresses, the PINS device 100 accumulates errors when gathering
data and creating motion commands. The host 104, however,
eventually will detect the occurrence of one of the reference
locations and infer where the PINS user is located; once the error
is detected and corrected, it is sent to the PINS device 100 for
-correction. Hence, the accuracy can be improved without any
intervention from the user.
[0026] While the invention has been described in conjunction with
specific embodiments thereof, additional advantages and
modifications will readily occur to those skilled in the art. The
invention, in its broader aspects, is therefore not limited to the
specific details, representative apparatus, and illustrative
examples shown and described. Various alterations, modifications
and variations will be apparent to those skilled in the art in
light of the foregoing description. Thus, it should be understood
that the invention is not limited by the foregoing description, but
embraces all such alterations, modifications and variations in
accordance with the spirit and scope of the appended claims.
* * * * *