POSITIONING APPARATUS AND GLOBAL NAVIGATION SATELLITE SYSTEM, METHOD OF DETECTING SATELLITE SIGNALS

• US 20160040992A1
• Filed: 03/31/2015
• Published: 02/11/2016
• Est. Priority Date: 08/08/2014
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Colombo, Leonardo, Palella, Nicola Matteo
• Granted Patent: US 10,234,292 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60W 40/107 Longitudinal acceleration
• CPC Class Codes: G01C 21/005 with correlation of navigation data from several sources, e.g. map or contour matching G01C21/30 takes precedence
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems
• CPC Class Codes: G01C 22/00 Measuring distance traversed on the ground by vehicles, persons, animals or other moving solid bodies, e.g. using odometers, using pedometers
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices
• CPC Class Codes: G01C 5/06 by using barometric means
• CPC Class Codes: G01S 19/49 whereby the further system is an inertial position system, e.g. loosely-coupled

Abstract

A positioning apparatus of a vehicle includes a measuring module and a triaxial orientation sensor to provide measured axial accelerations in a Cartesian reference system during a certain time interval. The apparatus also includes a triaxial movement sensor to supply at least one angular variation signal proportional to the axial angular speed of the vehicle during the time interval. A processing unit receives a distance signal proportional to the distance traveled by the vehicle in the time interval, receives the at least one angular variation signal, and supplies at least one reference acceleration of the vehicle. An estimator-calibrator block recursively estimates at least one calibrated acceleration as a function of the measured axial accelerations and of the at least one reference acceleration. The estimator-calibrator block includes a calculation unit to calculate an altitude variation as function of the distance signal and recursively calculates an estimated pitch angle as a function of at least one calibrated acceleration.

Claims

1. A vehicle positioning apparatus, comprising:

a measuring module associable to a vehicle, the measuring module having a triaxial orientation sensor and a triaxial movement sensor, the triaxial orientation sensor configured to provide measured axial accelerations in a Cartesian reference system during a time interval between a previous time and a current time, the triaxial movement sensor configured to supply a first angular variation signal proportional to an axial angular speed of the vehicle during said time interval;

a processing unit configured to;

receive a distance signal proportional to a distance traveled by said vehicle in said time interval;

receive said first angular variation signal; and

supply at least one reference acceleration of said vehicle;

an estimator-calibrator block configured to recursively estimate at least one calibrated acceleration as a function of said measured axial acceleration and of said at least one reference acceleration, wherein said estimator-calibrator block includes a calculation unit configured to calculate an altitude variation as a function of said distance signal and an estimated pitch angle, the estimated pitch angle recursively calculated as a function of at least one calibrated acceleration, wherein said altitude variation is arranged to correct a current position of the vehicle, said current position determined based on a plurality of satellite signals from at least two satellites of a navigation satellite system.

2. The apparatus according to claim 1, wherein said estimator-calibrator block comprises:

a first calibrator configured to recursively and separately calculate a first calibrated acceleration, a second calibrated acceleration, a third calibrated acceleration, and respective calibration parameters of said orientation sensor by using a discrete recursive mathematical model which includes prediction equations and update equations calculated as a function of a first measured axial acceleration, a second measured axial acceleration, a third measured axial acceleration, a first reference acceleration, a second reference acceleration, a third reference acceleration, and estimated error values.

3. The apparatus according to claim 2, wherein said estimator-calibrator block comprises:

a compensation unit, the compensation unit configured to calculate from a second angular variation signal an input pitch angle, the compensation unit further configured to determine, by a discrete recursive mathematical model, an offset pitch angle of the vehicle and a calibration parameter of said movement sensor as a function of said estimated pitch angle obtained by said calculation unit at the current time and of said input pitch angle.

4. The apparatus according to claim 3, wherein said estimator-calibrator block comprises:

a second calibrator configured to receive a measured vertical speed of said vehicle, said offset pitch angle, and said distance signal, said second calibrator configured to calculate by a discrete recursive mathematical model a gain estimated factor and a calibrated altitude variation.

5. The apparatus according to claim 4, further comprising:

a calculation module, the calculation module configured to recursively calculate an estimated altitude value at the current time as a function of said calibrated altitude variation, the calculation module configured to calculate an estimated altitude value at the previous time.

6. The apparatus according to claim 1, wherein the first calibrator, the compensation unit, and the second calibrator are each configured to apply a discrete recursive mathematical model that includes at least one of a Kalman filter, an alpha filter, and a least squares algorithm.

7. The apparatus according to claim 1, wherein said orientation sensor is a micro-electro-mechanical system (MEMS) based accelerometer and said movement sensor is a MEMS-based gyroscope.

8. The apparatus according to claim 1, comprising:

a compensation module configured to calculate offset angles for each axis of the measuring module to align axes X, Y, and Z of the Cartesian reference system of said measuring module with axes of a frame of the vehicle, wherein the measuring module includes a pressure sensor configured to measure an estimated altitude value of said vehicle at the previous time.

9. A navigation device, comprising:

a satellite receiver configured to extract output signals from a plurality of satellite signals supplied by a satellites constellation of a global navigation satellite system;

a positioning apparatus having;

a triaxial orientation sensor and a triaxial movement sensor, the triaxial orientation sensor configured to provide measured axial accelerations in a Cartesian reference system during a time interval between a previous time and a current time, the triaxial movement sensor configured to supply a first angular variation signal proportional to an axial angular speed of the navigation sensor during said time interval; and

a processing block having a calculation module and a quality evaluation module, the calculation module configured to obtain current position, speed, and time information of said navigation device, and the quality evaluation module configured to obtain error parameters of said output signals.

10. The navigation device according to claim 9, wherein said processing block is configured to receive a distance signal proportional to a distance traveled by said navigation device in said time interval.

11. The navigation device according to claim 9, wherein said estimator-calibrator comprises:

a compensation unit configured to calculate an input pitch angle and a calibration parameter of said triaxial movement sensor as a function of said estimated pitch angle and of said input pitch angle.

12. The navigation device according to claim 9, wherein said estimator-calibrator block comprises:

a calibration module configured to generate calibration parameters of said triaxial orientation sensor.

13. The navigation device according to claim 9, wherein said estimator-calibrator block comprises:

a calibration module configured to calculate a calibrated altitude variation.

14. The navigation device according to claim 9, wherein said estimator-calibrator block comprises:

a calculation module configured to calculate an estimated altitude value at the current time and an estimated altitude value at the previous time.

15. A hybrid navigation method integrating satellite-based signals with local motion detector signals, comprising:

performing a local calibration routine, the local calibration routine configured to modify axial acceleration values generated by a triaxial orientation sensor;

receiving a plurality of calibrated axial acceleration values generated by the triaxial orientation sensor;

receiving a plurality of angular variation signals proportional to an axial angular speed of a vehicle;

generating three-dimensional position data based on said plurality of calibrated axial acceleration values and said angular variation signals;

receiving a plurality of satellite signals from at least two satellites of a navigation satellite system;

analyzing said plurality of satellite signals to obtain parameters associated with a vehicle, said parameters including a current position, a current speed, and a current time;

calculating noise associated with the plurality of satellite signals, wherein calculating said noise includes defining a latitude error, defining a longitude error, and defining an altitude error; and

integrating said three-dimensional position data with said parameters associated with the vehicle to generate updated parameters associated with the vehicle, said integrating based on said calculated noise.

16. The hybrid navigation method according to claim 15, comprising:

calculating an altitude variation of said vehicle based on said current position, said current speed, said current time, said latitude error, said longitude error, and said altitude error.

17. The hybrid navigation method according to claim 15, wherein calculating noise associated with the plurality of satellite signals comprises:

performing a confidence calculation on said parameters associated with the vehicle, wherein said confidence calculation includes determining a first confidence value as a function of said at least two satellites'"'"' position and determining a second confidence value as a function of said vehicle'"'"'s speed;

comparing said second confidence value with a confidence threshold value;

when said second confidence value exceeds said confidence threshold value;

providing a lower confidence threshold;

providing an upper confidence threshold;

based on said upper and lower confidence thresholds, determining a reject region of said plurality of satellite signals, an intermediate region of said plurality of satellite signals, and an acceptance region of said plurality of satellite signals;

comparing said first confidence value with at least one of said reject region, said intermediate region, and said acceptance region;

based on comparing said first confidence value, defining a belonging region of said first confidence value, wherein said latitude, longitude, and altitude errors are defined based on said belonging region of said first confidence value.

18. The hybrid navigation method according to claim 15, comprising:

performing a signal metrics calculation, wherein performing said signal metrics calculation includes filtering said parameters associated with the vehicle to define at least one estimated precision of a satellite position, a precision error of estimated satellite speed, and a carrier-noise ratio; and

evaluating, based on said signal metrics calculation, if said parameters associated with the vehicle are reliable;

19. The hybrid navigation method according to claim 15, comprising:

comparing each of said plurality of satellite signals with at least one parameter threshold value; and

rejecting ones of said plurality of satellite signals that do not meet said threshold value.

20. The hybrid navigation method according to claim 15, wherein performing the local calibration routine comprises:

performing a calibration function to generate correction factors associated with the triaxial orientation sensor;

recursively estimating at least one calibrated acceleration as a function of axial acceleration;

recursively calculating an estimated pitch angle as a function of said at least one calibrated acceleration; and

calculating an altitude variation as a function of a distance signal and said estimated pitch angle.