Method and apparatus for navigation with nonlinear models

Patent metadata

Field	Value
Publication number	US-9784582-B2
Application number	US-201214345170-A
Country	US
Kind code	B2
Filing date	Feb 15, 2012
Priority date	Sep 14, 2011
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

A navigation module and method for providing an INS/GNSS navigation solution for a device that can either be tethered or move freely within a moving platform is provided, comprising a receiver for receiving absolute navigational information from an external source (e.g., such as a satellite), an assembly of self-contained sensors capable of obtaining readings (e.g. such as relative or non-reference based navigational information) about the device, and further comprising at least one processor, coupled to receive the output information from the receiver and sensor assembly, and operative to integrate the output information to produce an enhanced navigation solution. The at least one processor may operate to provide a navigation solution by benefiting from nonlinear models and filters that do not suffer from approximation or linearization and which enhance the navigation solution of the device.

First claim

The embodiments in which an exclusive property or privilege is claimed are defined as follows:

1. A navigation module, for providing an integrated navigation solution for a device within a moving platform, the module comprising:
a receiver for receiving absolute navigational information about the device from an external source, and producing an output of navigational information indicative thereof,
an assembly of self-contained sensors comprising at least three accelerometers and at least three gyroscopes and capable of obtaining readings relating to navigational information about the device and producing an output indicative thereof, wherein said sensor readings may contain sensor errors, and
at least one processor, coupled to receive and integrate the output information from the receiver and the sensor assembly, operative to produce a navigation solution for the device, wherein the navigation solution consists of estimated position, velocity and attitude, and programmed to:
utilize a nonlinear error-state model, wherein the error-state model is without approximation, to reduce errors in the estimated position, velocity and attitude, whereby the processor predicts the errors in the position, velocity and attitude, and the sensor errors, and utilizes the nonlinear error-state model to relate: a) the errors in the estimated position and velocity, and b) the errors in the estimated attitude and the sensor errors;
utilize the output information from the receiver to improve the estimation of the errors in the position and velocity, and whereby the relation of a) and b) indirectly improves the estimation of the errors in the attitude and sensor errors, wherein the device may be tethered or non-tethered to the moving platform; and
produce a navigation solution compensated by the nonlinear error-state model.

2. A navigation module, for providing an integrated navigation solution for a device within a moving platform, the module comprising:
a receiver for receiving absolute navigational information about the device from an external source, and producing an output of navigational information indicative thereof,
an assembly of self-contained sensors comprising at least three accelerometers and at least three gyroscopes and capable of obtaining readings relating to navigational information about the device and producing an output indicative thereof, wherein said sensor readings may contain sensor errors from the at least three accelerometers and the at least three gyroscopes, and
at least one processor, coupled to receive and integrate the output information from the receiver and the sensor assembly, operative to produce a navigation solution for the device, the navigation solution consisting of estimated position, velocity and attitude, and programmed to utilize a nonlinear total-state model and updates for at least the errors from the at least three accelerometers and the errors from the at least three gyroscopes, wherein the updates are derived from the output information from the receiver, wherein the device may be tethered or non-tethered within the moving platform, and wherein the navigation solution is output by the nonlinear total-state model.

3. The navigation module in claim 1 or 2 , wherein the receiver for receiving absolute navigational information is a GNSS receiver.

4. The navigation module in claim 3 , wherein the GNSS receiver is a Global Positioning System receiver.

5. The navigation module in claim 1 or 2 , wherein the at least one processor is programmed to use a state estimation technique.

6. The navigation module in claim 5 , wherein the state estimation technique is non-linear.

7. The navigation module in claim 6 , wherein the state estimation technique is a Particle Filter.

8. The navigation module in claim 6 , wherein the state estimation technique is a Mixture Particle Filter.

9. The navigation module in anyone of claims 5 to 8 , wherein the state estimation technique uses a system and measurement model.

10. The navigation module in claim 1 or 2 , wherein the moving platform is a vehicle, a vessel or a person.

11. The navigation module in claim 1 or 2 , wherein the processor has an additional means for obtaining speed information about the platform using a wired or wireless connection to the module.

12. The navigation module in claim 1 or 2 , wherein the navigation solution is determined via an algorithm comprising a loosely coupled integration scheme, or a tightly coupled integration scheme.

13. The navigation module in claim 1 or 2 , wherein the absolute navigational information is degraded or denied.

14. The navigation module in anyone of claim 1 or 2 , wherein the at least one processor is further programmed to either: (a) use an algorithm capable of modeling the errors in the sensor readings, (b) use an algorithm capable of modeling advanced models of the errors in the sensor readings, (c) use an algorithm capable of modeling advanced models of the errors in the sensor readings, such that the advanced model of the errors in the sensor readings are non-linear or linear models with increased memory length, or (d) anyone of (a), (b), or (c) wherein the at least one processor is further programmed to provide additional measurement updates for the errors in the sensor readings.

15. The navigation module in anyone of claim 1 or 2 , wherein the at least one processor is further programmed to either: (a) automatically assess the output of absolute navigational information and detect degradation or denial of the information, (b) automatically switch between a loosely coupled integration scheme and a tightly coupled integration scheme, (c) automatically assess the measurements from each external source visible to the receiver and detect degraded measurements, when in tightly coupled integration scheme, (d) perform (a) and (b), (e) perform (b) and (c), or (f) perform (a), (b) and (c).

16. The navigation module in anyone of claim 1 or 2 , wherein the at least one processor is further programmed to calculate misalignment between the sensor assembly and the platform.

17. The navigation module in anyone of claim 1 or 2 , wherein the at least one processor is further programmed to perform a mode detection routine to detect the mode of conveyance.

18. The navigation module in anyone of claim 1 or 2 , wherein the at least one processor is further programmed to calculate pitch and roll values from the output of the at least three accelerometers, and to use the pitch and roll values as measurement updates.

19. The navigation module in claim 17 or 18 , wherein the calculated pitch and roll values are dependent on the detected mode of conveyance.

20. The navigation module in claim 17 , wherein the detected mode of conveyance is walking mode and wherein the at least one processor is further programmed to perform pedestrian dead-reckoning and to use the positioning results as a measurement update for the navigation solution.

21. The navigation module in anyone of claim 1 or 2 wherein the at least one processor is further programmed to perform one of: (a) static period detection, or (b) static period detection and use zero velocity updates as a measurement update.

22. The navigation module in anyone of claim 1 or 2 , wherein the at least one processor is further programmed to utilize motion constraints on the moving platform.

23. The navigation module in claim 22 , wherein the motion constraints on the moving platform are non-holonomic

Assignees

• Georgy Jacques
• Noureldin Aboelmagd
• Syed Zainab
• Goodall Chris
• Invensense Inc

Inventors

• Georgy Jacques
• Noureldin Aboelmagd
• Syed Zainab
• Goodall Chris

Classifications

• G01C21/1654

  with electromagnetic compass · CPC title

• G01S19/49

  whereby the further system is an inertial position system, e.g. loosely-coupled · CPC title

• G01C21/18 Primary

  Stabilised platforms, e.g. by gyroscope · CPC title

• G01C21/165

  combined with non-inertial navigation instruments · CPC title

• G01S19/47 Primary

  the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial · CPC title