Portable navigation system

Patent metadata

Field	Value
Publication number	US-9651387-B2
Application number	US-69487910-A
Country	US
Kind code	B2
Filing date	Jan 27, 2010
Priority date	Jul 5, 2007
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

A portable navigation module and its method of operation are disclosed for seamlessly providing navigation and positioning information to a user. The module comprises: means, such as a GPS receiver, for receiving a first set of navigational information from an external source, such as satellites; and an inertial sensor unit for generating a second set of navigational information at the module. The navigational information is used by a processor programmed with a core algorithm, to identify the mode of conveyance algorithm and an orientation or misalignment algorithm. The algorithm utilizes the navigational information, aided by the mode of conveyance information and the orientation information, to produce a filtered navigation solution (which comprises position, velocity and attitude). The solution is suitably displayed, preferably on a detachable display unit.
The system has the following attributes: the solution is produced seamlessly, even if one source of navigational information is temporarily out of service; the accuracy of the solution is assisted by use of the mode of conveyance and orientation information; and there is no requirement for the module to be permanently aligned with the direction of movement of the conveyance platform.

First claim

The invention claimed is:

1. A portable navigation system module within a moving body, the module comprising:
a) a receiver for receiving navigational information from an external source and producing an output of absolute navigational information pertaining to the module;
b) an assembly of sensors in the module comprising an accelerometer and a gyroscope for generating navigational information at the module and producing an output in the form of signals indicative thereof; and
c) a processor coupled to receive the outputs from the receiver and sensor assembly and operative to use the navigational information provided thereby to establish a mode of conveyance of the module and a variable relative orientation between the sensors and the moving body in the form of information indicative thereof,
wherein the relative orientation is a difference between a frame of the sensors in the module and a frame of the moving body and is obtained from the accelerometer and the gyroscope, using an estimation filter with measurement updates from physical constraints and the absolute navigational information,
wherein the mode of conveyance comprises the detection of on-foot mode or in-vehicle mode, wherein said detection of on-foot mode or in-vehicle mode uses an analysis of the signals from the accelerometer and the gyroscope along with magnetometer information and barometer information, said processor further being operative to use the outputs of navigational information derived from the receiver and sensors, the mode of conveyance and the relative orientation to determine and produce a navigation solution when the module is in a tethered condition and when the module is in an untethered condition.

2. The module as set forth in claim 1 wherein:
the receiver is a GPS receiver;
the sensor assembly comprises three orthogonal accelerometers for measuring module accelerations, three orthogonal gyroscopes for measuring module turning rates, three orthogonal magnetometers for measuring magnetic field strength for use in determining module heading and a barometer for measuring pressure at the module for use in determining altitude changes of the module; and
the processor is operative to produce the navigation solution seamlessly.

3. The module as set forth in claim 1 wherein:
the processor uses a core algorithm to process the navigational information and aids the core algorithm using the mode of conveyance and the relative orientation information.

4. The module as set forth in claim 1 wherein:
the processor uses a core algorithm to process the navigational information and aids the core algorithm with platform specific aiding and constraints using the mode of conveyance and the relative orientation information.

5. The module as set forth in claim 1 wherein the processor is operative to produce the navigation solution automatically and seamlessly in the event that the receiver is temporarily inoperative.

6. The module as set forth in claim 1 wherein the receiver is a GPS receiver and the processor is operative to produce the navigation solution automatically and seamlessly.

7. The module as set forth in claim 1 wherein:
the receiver is a GPS receiver;
the accelerometer is for measuring module accelerations and the gyroscope is for measuring module turning rates, and
wherein the assembly of sensors further comprises a magnetic field strength measuring device suitable for determining module heading and a measuring device suitable for measuring pressure at the module to determine altitude changes of the module; and
the processor is operative to produce the navigation solution automatically and seamlessly.

8. The module as set forth in claim 1 wherein the processor is programmed to use a conveyance algorithm operative to determine the mode of conveyance, a relative orientation algorithm operative to determine the relative orientation between the sensors and the moving body and a core algorithm operative to determine a filtered navigation solution.

9. The module as set forth in claim 8 wherein:
the core algorithm is an Extended Kalman filter operative to determine and produce seamlessly a filtered navigation solution.

10. A method for producing a navigation solution using a portable navigation system module within a moving body, the method comprising:
receiving navigational information at the module from an external source and producing signals indicative thereof;
generating navigational information at the module using sensors in the module, comprising an accelerometer and a gyroscope, and producing signals indicative thereof;
determining a mode of conveyance of the module using navigational information derived from sensor signals frequencies or the receiver and sensor signals frequencies and producing information indicative thereof, wherein the mode of conveyance comprises the detection of on-foot mode or in-vehicle mode, wherein said detection of on-foot mode or in-vehicle mode uses an analysis of the signals from the accelerometer and the gyroscope means along with magnetometer information and barometer information;
determining a variable relative orientation between the sensors and the moving body and producing information indicative thereof, wherein the relative orientation is a difference between a frame of the sensors in the module and a frame of the moving body and is obtained from the accelerometer means and gyroscope means using an estimation filter with measurement updates from physical constraints and absolute navigational information; and
processing the navigational information, the mode of conveyance information and the relative orientation information as a composite whole to determine and seamlessly produce a filtered navigation solution pertaining to the module when the module is in a tethered condition and when the module is in an untethered condition.

11. A method for producing a navigation solution using a portable navigation system module within a moving body, the method comprising:
providing and using a composite of navigational information, derived from an external source and measured at the module with sensors in the module, to determine a mode of conveyance of the module and a variable relative orientation between the sensors and the moving body, wherein the relative orientation is a difference between a frame of the sensors in the module and a frame of the moving body and is obtained from the composite of navigational information using an estimation filter with measurement updates from physical constraints and absolute navigation information, wherein the mode of conveyance comprises the detection of on-foot mode or in-vehicle mode based at least in part on uses an analysis of readings from an accelerometer, a gyroscope, a magnetometer and a barometer; and
using the composite navigational information, the mode of conveyance information and the relative orientation information to seamlessly produce a navigation solution pertaining to the module when the module is in a tethered condition and when the module is in an untethered condition, wherein the navigation solution can be vehicle navigation or on foot navigation.

Assignees

• Hunter Andrew
• El-Sheimy Naser
• Syed Zainab
• Wright David Bruce
• Goodall Chris
• Invensense Inc

Inventors

• Hunter Andrew
• El-Sheimy Naser
• Syed Zainab
• Wright David Bruce
• Goodall Chris

Classifications

• G01S19/49

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

• G01S19/53

  Determining attitude · CPC title

• G01C21/3626

  Details of the output of route guidance instructions (traffic control systems for road vehicles involving transmission of navigation instructions to the vehicle G08G1/0968) · CPC title

• G01C21/265

  constructional aspects of navigation devices, e.g. housings, mountings, displays (G01C21/3688 takes precedence) · CPC title

• G01S19/35

  Constructional details or hardware or software details of the signal processing chain · CPC title