METHOD AND SYSTEM FOR PREDICTING A FUTURE POSITION OF A VEHICLE USING NUMERICAL INTEGRATION

• US 20080071469A1
• Filed: 10/30/2006
• Published: 03/20/2008
• Est. Priority Date: 09/14/2006
• Status: Active Grant

• Current Assignee: Toyota Motor Corporation
• Original Assignee: Toyota Motor Engineering & Manufacturing North America Incorporated (Toyota Motor Corporation)
• Inventors: Caveney, Derek S.
• Granted Patent: US 7,865,299 B2
• Time in Patent Office: Days
• US Class Current: 701/207
• CPC Class Codes: B60W 2050/0013 Optimal controllers
• CPC Class Codes: B60W 2050/002 Integrating means
• CPC Class Codes: B60W 2050/0033 Single-track, 2D vehicle model, i.e. two-wheel bicycle model
• CPC Class Codes: B60W 2540/18 Steering angle
• CPC Class Codes: B60W 2556/50 of positioning data, e.g. GPS [Global Positioning System] data
• CPC Class Codes: B60W 50/0097 Predicting future conditions
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence

Abstract

A method and system for predicting a future position of a horizon time T_h of an automotive vehicle. The method determines the position of the vehicle at time T₀ using GPS and the speed, acceleration and angle of the steering wheel at time T₀ from appropriate sensors on the vehicle. A nonlinear mathematical model utilizing these factors is then created while the position of the vehicle at time T₀+T_h is determined through numerical integration of the mathematical model using an adjustable step size T_step. The step T_step is modified adaptively in accordance with the accuracy requirements of the vehicle.

Claims

1. A method for predicting a future position of an automotive vehicle having a steering control comprising the steps of:

determining the position of the vehicle at time T₀,

determining the translational and rotational speeds of the vehicle at time T₀,

determining the translational and rotational accelerations of the vehicle at time T₀,

determining an angle of the steering control at time T₀,

creating a mathematical model of the vehicle using the position, speeds, accelerations and steering control angle at time T₀,

calculating the position of the vehicle at a horizon time T₀+T_h through numerical integration of the mathematical model.

2. The invention as defined in claim 1 wherein said calculating step further comprises the step of calculating the position of the vehicle at time T₀+T_h, through a Runge-Kutta numerical integration of the mathematical model.

3. The invention as defined in claim 1 wherein said calculating step further comprises the step of calculating the position of the vehicle at time T₀+T_h through a Runge-Kutta-Fehlberg numerical integration of the mathematical model.

4. The invention as defined in claim 1 wherein said calculating step further comprises the steps of:

calculating the position of the vehicle at time T₀+T_h through numerical integration of the mathematical model of a first order of accuracy utilizing a step size T_step,

calculating the position of the vehicle at time T₀+T_h through numerical integration of the mathematical model of a second order of accuracy,

determining a truncation error between the first and second order of the calculated position of the vehicle at time T₀+T_h,

adjusting T_step as a function of the determined truncation error.

5. The invention as defined in claim 4 wherein said adjusting step comprises the step of reducing T_step whenever the truncation error exceeds a predetermined threshold.

6. The invention as defined in claim 4 wherein said adjusting step comprises the step of increasing T_step whenever the truncation error is less than a predetermined threshold.

7. The invention as defined in claim 1 wherein said position determining step comprises the step of determining the position of the vehicle using the global position system.

8. The invention as defined in claim 1 wherein said angle determining step comprises the step of reading a steering wheel angle sensor.

9. The invention as defined in claim 1 wherein said speeding determining step comprises the step of reading a vehicle speed sensor.

10. The invention as defined in claim 1 wherein said mathematical model creating step comprises the step of creating a mathematical model selected from the group of a constant acceleration kinematic model, kinematic unicycle model or classic bicycle model.

11. A system for predicting a future position of an automotive vehicle having a steering control comprising:

means for determining the position of the vehicle at time T₀,

means for determining the translational and rotational speeds of the vehicle at time T₀,

means for determining the translational and rotational accelerations of the vehicle at time T₀,

means for determining an angle of the steering control at time T₀,

means for creating a mathematical model of the vehicle using the position, speeds, accelerations and steering control angle at time T₀,

means for calculating the position of the vehicle at a horizon time T₀+T_h through numerical integration of the mathematical model.

12. The invention as defined in claim 11 wherein said means for calculating further comprises means for calculating the position of the vehicle at time T₀+T_h through a Runge-Kutta numerical integration of the mathematical model.

13. The invention as defined in claim 11 wherein said means for calculating further comprises means for calculating the position of the vehicle at time T₀+T_h through a Runge-Kutta-Fehlberg numerical integration of the mathematical model.

14. The invention as defined in claim 11 wherein said means for calculating further comprises:

means for calculating the position of the vehicle at time T₀+T_h through numerical integration of the mathematical model of a first order of accuracy using step size T_step,

means for calculating the position of the vehicle at time T₀+T_h through numerical integration of the mathematical model of a second order of accuracy,

means for determining a truncation error between the first and second order of the calculated position of the vehicle at time T₀+T_h,

means for adjusting T_step as a function of the determined truncation error.

15. The invention as defined in claim 14 wherein said means for adjusting comprises means for reducing T_step whenever the truncation error exceeds a predetermined threshold.

16. The invention as defined in claim 14 wherein said means for adjusting comprises means for increasing T_step whenever the truncation error is less than a predetermined threshold.

17. The invention as defined in claim 11 wherein said position determining means comprises means for determining the position of the vehicle using the global position system.

18. The invention as defined in claim 11 wherein said angle determining means comprises means for reading a steering wheel angle sensor.

19. The invention as defined in claim 11 wherein said speeding determining means comprises means for reading a vehicle speed sensor.

20. The invention as defined in claim 11 wherein said mathematical model creating means comprises means for creating a mathematical model selected from the group of a constant acceleration kinematic model, kinematic unicycle model or classic bicycle model.

21. The invention as defined in claim 11 wherein said calculating means comprises a microprocessor.