Fail operational vehicle speed estimation through data fusion of 6-DOF IMU, GPS, and radar

• US 9,645,250 B2
• Filed: 04/07/2015
• Issued: 05/09/2017
• Est. Priority Date: 04/07/2015
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Zeng, Shuqing, Sidlosky, David M., Doerr, David W.
• Primary Examiner(s): Nguyen, Cuong H
• Application Number:
  US14/680,894
• Publication Number:
  US 20160299234A1
• Time in Patent Office: 763 Days
• Field of Search: 701 329, 701 70, 701 93, 701 28, 701 36, 340440, 702150-153, 702141-142, 700258, 348140
• CPC Class Codes: G01S 13/588 deriving the velocity value from the range measurement
• CPC Class Codes: G01S 13/86 Combinations of radar systems with non-radar systems, e.g. sonar, direction finder
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G01S 19/52 Determining velocity
• CPC Class Codes: G01S 7/42 Diversity systems specially adapted for radar
• CPC Class Codes: G08G 1/0104 Measuring and analyzing of parameters relative to traffic conditions

Abstract

A method for providing redundant vehicle speed estimation. The method includes providing sensor output signals from a plurality of primary sensors and providing inertial measurement signals from an inertial measurement unit. The method also includes estimating the vehicle speed in a primary module using the primary sensor signals, and buffering the estimated vehicle speed values from the primary module for a predetermined period of time. The method further includes determining that one or more of the primary sensors or the primary module has failed, and if so, estimating the vehicle speed in a secondary module using the buffered vehicle speed values and the inertial measurement signals. The method can use GPS signal data and/or range data from static objects to improve the estimated vehicle speed in the secondary module if they are available.

Claims

1. A method for providing a redundant estimation of speed of a mobile platform, said method comprising:

providing sensor output signals from a plurality of primary sensors;

providing inertial measurement signals from an inertial measurement unit;

estimating the speed in a primary module using the primary sensor signals;

buffering estimated speed values from the primary module for a predetermined period of time;

providing range sensor information from the mobile platform to detected static objects;

determining that one or more of the primary sensors or the primary module has failed; and

estimating the speed in a secondary module using the buffered speed values and the inertial measurement signals if the primary sensors or the primary module has failed, including using the range sensor information to improve the estimation of the speed in the secondary module.

2. The method according to claim 1 wherein providing sensor output signals includes providing sensor output signals from wheel speed sensors, a steering angle sensor, a yaw rate sensor or a longitudinal acceleration sensor.

3. The method according to claim 1 wherein providing inertial measurement signals from an inertial measurement unit includes providing inertial measurement signals from a 6 degree-of-freedom inertial measurement unit including three acceleration values including lateral, longitudinal and up/down acceleration values and three angular rate values including roll, pitch and yaw values.

4. The method according to claim 1 further comprising providing GPS signals identifying the location of the mobile platform, wherein estimating the speed in a secondary module includes using mobile platform location data from the GPS signals to improve the estimation of the speed.

6. The method according to claim 1 wherein estimating the speed in a secondary module includes using kinematics in a body frame.

7. The method according to claim 6 wherein using kinematics in a body frame includes using the equation:

{dot over (v)}^b=−

Ω

v^b+R_a^bg^a+f^b,

where v^b is velocity at a center of the inertial measurement unit in the body frame b, which corresponds to longitudinal, lateral and up/down speed, i.e., v^b=[v_lon,v_lat,v_up]^T, where it is assumed that the mobile platform always touches the ground, particularly a “

virtual”

measurement v_up=0 in Kalman filtering;

Ω

is a skew symmetric matrix of angular velocity ω

in the b-frame;

g^a is the Earth gravitational vector in the inertia frame a, specifically (0,0,−

9.80665)^T m/s²;

R_a^b is a rotation matrix from the b-frame to an inertia frame a;

f^b is acceleration in the b-frame, and ω

is angular rates in the b-frame, and where the skew matrix Ω

is;

8. The method according to claim 6 wherein estimating the speed in the secondary module includes removing data from the inertial measurement signals of platform motion in an up/down direction.

9. The method according to claim 6 wherein estimating the speed in the secondary module includes removing yaw data from the inertial measurement signals.

10. The method according to claim 1 wherein the predetermined period of time is five seconds.

11. The method according to claim 1 wherein the mobile platform is a vehicle.

5. A system for providing a redundant estimation of vehicle speed, said system comprising:

a plurality of primary sensors providing sensor output signals;

an inertial measurement unit providing inertial measurement signals;

primary means for estimating the vehicle speed using the primary sensor signals;

means for buffering estimated vehicle speed values for a predetermined period of time;

means for determining that one or more of the primary sensors or the primary means has failed; and

secondary means for estimating the vehicle speed in a secondary module using the buffered vehicle speed values and the inertial measurement signals.

18. The system according to claim 5 further a GPS receiver for providing GPS signals identifying the location of the vehicle and a range sensor providing range information from the vehicle to detected static objects, wherein the means for estimating the speed in a secondary module includes using location data from the GPS signals and the range sensor information to improve the estimation of the speed.

19. The system according to claim 5 wherein the inertial measurement unit is a 6 degree-of-freedom inertial measurement unit that provides three acceleration values including lateral, longitudinal and up/down acceleration values and three angular rate values including roll, pitch and yaw values.

12. A method for providing a redundant estimation of vehicle speed, said method comprising:

providing sensor output signals from a plurality of primary sensors;

providing inertial measurement signals from a 6 degree-of-freedom inertial measurement unit including three acceleration values including lateral, longitudinal and up/down acceleration values and three angular rate values including roll, pitch and yaw values;

providing GPS signals identifying the location of the vehicle;

providing range sensor information from the vehicle to detected static objects;

estimating the vehicle speed in a primary module using the primary sensor signals;

buffering the estimated vehicle speed values from the primary module for a predetermined period of time;

determining that one or more of the primary sensors or the primary module has failed; and

estimating the vehicle speed in a secondary module using the buffered vehicle speed values and the inertial measurement signals including using vehicle location data from the GPS signals and the range sensor information to improve the estimation of the vehicle speed.

13. The method according to claim 12 wherein providing sensor output signals includes providing sensor output signals from wheel speed sensors, a steering angle sensor, a yaw rate sensor or a longitudinal acceleration sensor.

14. The method according to claim 12 wherein estimating the vehicle speed in a secondary module includes using vehicle kinematics in a vehicle body frame.

15. The method according to claim 14 wherein using vehicle kinematics in a vehicle body frame includes using the equation:

{dot over (v)}^b=−

Ω

v^b+R_a^bg^a+f^b,

where v^b is vehicle velocity at a center of the inertial measurement unit in the vehicle body frame b, which corresponds to vehicle longitudinal, lateral and up/down speed, i.e. v^b=[v_lon,v_lat,v_up]^T, where it is assumed that wheels of the vehicle always touch the ground, particularly a “

virtual”

measurement v_up=0 in Kalman filtering;

Ω

is a skew symmetric matrix of angular velocity ω

in the b-frame;

g^a is the Earth gravitational vector in an inertia frame a, specifically (0,0,−

9.80665)^T m/s²;

R_a^b is a rotation matrix from the b-frame to the inertia frame a;

f^b is acceleration in the b-frame, and ω

is angular rates in the b-frame, and where the skew matrix Ω

is;

16. The method according to claim 14 wherein estimating the vehicle speed in the secondary module includes removing data from the inertial measurement signals of vehicle motion in the up/down direction.

17. The method according to claim 14 wherein estimating the vehicle speed in the secondary module includes removing yaw data from the inertial measurement signals.