GPS-enhanced vehicle velocity estimation

• US 9,285,485 B2
• Filed: 11/12/2009
• Issued: 03/15/2016
• Est. Priority Date: 11/12/2009
• Status: Expired due to Fees

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: O'Dea, Kevin A., Ryu, Jihan, Nardi, Flavio, Tan, Hualin
• Primary Examiner(s): Tissot, Adam
• Application Number:
  US12/616,933
• Publication Number:
  US 20110112739A1
• Time in Patent Office: 2,315 Days
• Field of Search: 701/70, 701/1, 701/23, 701/41, 701/472, 701/71, 318/587, 340/429, 340/440
• US Class Current: 1/1
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01S 19/52 Determining velocity

Abstract

A method is provided for estimating vehicle velocity for a vehicle using a single-antenna global positioning system (GPS). An absolute speed and a course angle of the vehicle is measured using the single-antenna GPS. The yaw rates of the vehicle are measured independently of the GPS. An integrated yaw rate of the vehicle is calculated as a function of the measured yaw rates over a period of time. A yaw angle is determined as a function of a reference yaw angle and the integrated yaw rate. Aside slip angle is calculated as a function of the estimated yaw angle and the course angle provided by the GPS. The vehicle velocity is determined as a function of the absolute speed and the side slip angle. The vehicle velocity is provided to a vehicle dynamic control application.

Claims

1. A method of estimating vehicle velocity for a vehicle using a single-antenna global positioning system (GPS), the method comprising the steps of:

measuring an absolute speed and a course heading angle of the vehicle using the single-antenna GPS;

measuring yaw rates of the vehicle independently of the GPS;

calculating an integrated yaw rate of the vehicle as a function of the measured yaw rates over a period of time;

determining a yaw angle as a function of an initialized yaw angle and the integrated yaw rate;

calculating a side slip angle as a function of the yaw angle and the course heading angle provided by the GPS;

determining the vehicle velocity as a function of the absolute speed and the side slip angle; and

providing the vehicle velocity to a vehicle dynamic control application.

2. The method of claim 1 wherein the vehicle velocity includes a lateral velocity.

3. The method of claim 2 wherein the lateral velocity is determined by the formula:

{circumflex over (v)}_x=∥

V_GPS∥

cos({circumflex over (β

)})

where {circumflex over (v)}_x is the lateral velocity, ∥

V_GPS∥

is the absolute speed, and {circumflex over (β

)} is the side slip angle.

4. The method of claim 1 wherein the vehicle velocity includes a longitudinal velocity.

5. The method of claim 4 wherein the lateral velocity is determined by the formula:

{circumflex over (v)}_y=∥

V_GPS∥

sin({circumflex over (β

)})

where {circumflex over (v)}_y is the lateral velocity, ∥

V_GPS∥

is the absolute speed, and β

is the side slip angle.

6. The method of claim 1 wherein the yaw angle and the integrated yaw rate are re-initialized after the period of time.

7. The method of claim 6 wherein the period of time is approximately 25 seconds.

8. The method of claim 6 wherein re-initializing the yaw angle further comprising the steps of:

detecting when vehicle is traveling in a straightforward direction; and

setting the yaw angle equal to the course angle in response to detecting the vehicle traveling in the straightforward direction.

9. The method of claim 6 wherein re-initializing the integrated yaw rate comprises the steps of:

initializing the time period to zero;

initializing the yaw rate to zero;

measuring yaw rates of a next period of time;

calculating an integrated yaw rate of the vehicle as a function of the measured yaw rates over the next period of time.

10. The method of claim 1 wherein the side slip angle is determined by the following equation:

β

=γ

_m^GPS−

{circumflex over (ψ

)}

where β

is the slide slip angle;

γ

_m^GPS is the course angle as determined by the GPS, and {circumflex over (ψ

)} is the estimated yaw angle.

11. The method of claim 1 wherein determining the vehicle velocity further includes compensating for a delay in an update rate of the GPS measurements.

12. The method of claim 11 further comprising the steps of:

determining a delay of the GPS measurements as a result of the processing time of a received GPS signal;

buffering sensor measurements provided by vehicle sensors;

associating the sensor measurements with a timestamp;

determining a discrete vehicle velocity for each timestamp over the period of the delay, each discrete vehicle velocity being determined as a function of the calculated vehicle velocity and the buffered sensor measurements at each time stamp.

13. The method of claim 12 wherein buffering the sensor measurements includes buffering an acceleration of the vehicle at each time stamp.

14. The method of claim 13 wherein the acceleration includes a longitudinal acceleration, wherein the longitudinal acceleration is represented by the following formula:

a_x,m={dot over (v)}_x,estimate−

r_m·

v_y,sensor+a_x,bias+g·

sin θ

_r+w_ax,m,

where a_x,m is the longitudinal acceleration, {dot over (v)}_x,estimate is the longitudinal velocity derivative at the center of gravity of the vehicle, r_m is a yaw rate at a sensor location, a_x,bias is the longitudinal acceleration bias of the sensor, g is the gravity, θ

is the road grade, and w_ax,m is longitudinal accelerometer noise.

15. The method of claim 14 wherein a vehicle longitudinal velocity at a respective timestamp is represented by the following formula:

{circumflex over (v)}_x(t_k+1)={circumflex over (v)}_x(t_k)+T_s·

(a_x,m+r_m·

{circumflex over (v)}_y(t_k)−

g·

sin θ

_r) 

 

(15)

where {circumflex over (v)}_x(t_k+1) is the longitudinal velocity at timestamp k+1, {circumflex over (v)}_x(t_k) is the longitudinal velocity at timestamp k, T_s is the timestamp at a respective k, r_m is the measured yaw rate, a_x,m is the longitudinal velocity at the timestamp k, {dot over (ψ

)} is the GPS heading angle, {circumflex over (v)}_y(t_k) is the lateral velocity at timestamp k, G is the gravity, and θ

is the road grade.

16. The method of claim 15 wherein a longitudinal vehicle velocity of a current timestamp is based on a synchronization of the measured GPS measurements and the sensor measurement data and is represented by the following formula:

17. The method of claim 13 wherein the acceleration measurements includes a lateral acceleration, wherein the lateral acceleration is represented by the following formula:

a_y,m={dot over (v)}_y,estimate+r_m,i·

v_x,sensor+a_y,bias+g·

sin φ

_r+w_ay,m,

where a_y,m is the lateral acceleration, {dot over (v)}_y,estimate is the lateral velocity derivative at the center of gravity of the vehicle, r_m is a yaw rate at a sensor location, a_y,bias is the lateral acceleration bias of the sensor, g is the gravity, φ

_r is the road grade, and w_ay,m is lateral accelerometer noise.

18. The method of claim 17 wherein a vehicle lateral velocity at a respective timestamp is represented by the following formula:

{circumflex over (v)}_y(t_k+1)={circumflex over (v)}_y(t_k)+T_s·

(a_y,m−

r_m·

{circumflex over (v)}_x(t_k)−

g·

sin φ

_r)

where {circumflex over (v)}_y (t_k+1) is the lateral velocity at timestamp k+1, {circumflex over (v)}_y(t_k) is the lateral velocity at timestamp k, T_s is the timestamp at a respective k, r_m,i is the measured yaw rate, a_y,m is the lateral velocity at the timestamp k, {dot over (ψ

)} is the GPS heading angle, {circumflex over (v)}_x(t_k) is the longitudinal velocity at timestamp k, g is the gravity, and φ

_r is the road grade.

19. The method of claim 18 wherein a lateral vehicle velocity of a current timestamp is based on a synchronization of the GPS measurements and sensor measurement data and is represented by the following formula:

20. A system for determining a vehicle velocity for a vehicle comprising:

a single-antenna global positioning system (GPS) for providing an absolute speed and a course heading angle of the vehicle;

vehicle sensors for providing yaw rate measurements independent of the GPS; and

a processor for calculating an integrated yaw rate, a yaw angle a side slip angle, and a vehicle velocity;

wherein integrated yaw rate of the vehicle is determined as a function of the measured yaw rates over a period of time, wherein the yaw angle is determined as a function of a re-initialized yaw angle and the integrated yaw rate, wherein the side slip angle is determined as a function of the determined yaw angle and the course angle provided by the GPS, wherein the vehicle velocity is determined as a function of the absolute speed and the side slip angle, and wherein the vehicle velocity is provided to a vehicle dynamic control application.