Method and system for steering control of an autonomous vehicle using proportional, integral, and derivative (PID) controller
In one embodiment, an autonomous driving vehicle (ADV) steering control system determines how much and when to apply a steering control to maneuver obstacles of a planned route. The steering control system calculates a first steering angle based on a target directional angle and an actual directional angle of the ADV, a second steering angle based on a target lateral position and an actual lateral position of the ADV to maneuver a planned route, an object, or an obstacle course. The steering control system determines a target steering angle based on the first steering angle and the second steering angles and utilizes the target steering angle to control a subsequent steering angle of the ADV.
1. A computer-implemented method for steering controlling of an autonomous vehicle, the method comprising:
calculating a first steering angle based on a target directional angle and an actual directional angle of the autonomous vehicle to maneuver an obstacle course;
calculating a second steering angle based on a target lateral position and an actual lateral position of the autonomous vehicle to maneuver the obstacle course;
determining a next target steering angle based on the first and second steering angles; and
controlling a subsequent steering angle of the autonomous vehicle based on the next target steering angle.
2. The method of claim 1 , wherein calculating a first steering angle comprises:
determining the target directional angle of the autonomous vehicle to maneuver the obstacle course;
determining the actual directional angle of the autonomous vehicle in motion; and
calculating the first steering angle based on the target and actual steering angles using a first proportion-integral-derivative (PID) controller.
3. The method of claim 2 , further comprising:
determining a current speed of the autonomous vehicle; and
adjusting a proportional coefficient of the first PID controller based on the current speed of the autonomous vehicle.
4. The method of claim 3 , further comprising reducing the proportional coefficient of the first PID controller in response to determining that the current speed is above a predetermined threshold.
5. The method of claim 3 , further comprising adjusting a derivative coefficient of the first PID controller based on the current speed of the autonomous vehicle.
6. The method of claim 2 , further comprising:
determining a turning radius of the autonomous vehicle; and
adjusting a proportional coefficient of the first PID controller based on the turning radius of the autonomous vehicle.
7. The method of claim 6 , further comprising increasing the proportional coefficient of the first PID controller in response to determining that the turning radius is above a predetermined threshold.
8. The method of claim 1 , wherein calculating a second steering angle comprises:
determining the target lateral position of the autonomous vehicle to maneuver the obstacle course;
determining the actual lateral position of the autonomous vehicle in motion; and
calculating the second steering angle based on the target and actual lateral positions using a second proportion-integral-derivative (PID) controller.
9. The method of claim 8 , further comprising adjusting the proportional, integral and derivative coefficients of the second PID controller based on at least one of a current speed of the autonomous vehicle, a current turning radius of the autonomous vehicle for a vehicular path, and a last command of the autonomous vehicle.
10. A non-transitory machine-readable medium having instructions stored therein, which when executed by a processor, cause the processor to perform operations of steering control of an autonomous vehicle, the operations comprising:
calculating a first steering angle based on a target directional angle and an actual directional angle of the autonomous vehicle to maneuver an obstacle course;
calculating a second steering angle based on a target lateral position and an actual lateral position of the autonomous vehicle to maneuver the obstacle course;
determining a next target steering angle based on the first and second steering angles; and
controlling a subsequent steering angle of the autonomous vehicle based on the next target steering angle.
11. The machine-readable medium of claim 10 , wherein calculating a first steering angle comprises:
determining the target directional angle of the autonomous vehicle to maneuver the obstacle course;
determining the actual directional angle of the autonomous vehicle in motion; and
calculating the first steering angle based on the target and actual steering angles using a first proportion-integral-derivative (PID) controller.
12. The machine-readable medium of claim 11 , wherein the operations further comprise:
determining a current speed of the autonomous vehicle; and
adjusting a proportional coefficient of the first PID controller based on the current speed of the autonomous vehicle.
13. The machine-readable medium of claim 12 , wherein the operations further comprise reducing the proportional coefficient of the first PID controller in response to determining that the current speed is above a predetermined threshold.
14. The machine-readable medium of claim 12 , wherein the operations further comprise adjusting a derivative coefficient of the first PID controller based on the current speed of the autonomous vehicle.
15. The machine-readable medium of claim 11 , wherein the operations further comprise:
determining a turning radius of the autonomous vehicle; and
adjusting a proportional coefficient of the first PID controller based on the turning radius of the autonomous vehicle.
16. The machine-readable medium of claim 15 , wherein the operations further comprise increasing the proportional coefficient of the first PID controller in response to determining that the turning radius is above a predetermined threshold.
17. The machine-readable medium of claim 10 , wherein calculating a second steering angle comprises:
determining the target lateral position of the autonomous vehicle to maneuver the obstacle course;
determining the actual lateral position of the autonomous vehicle in motion; and
calculating the second steering angle based on the target and actual lateral positions using a second proportion-integral-derivative (PID) controller.
18. The machine-readable medium of claim 17 , wherein the operations further comprise adjusting the proportional, integral and derivative coefficients of the second PID controller based on at least one of a current speed of the autonomous vehicle, a current turning radius of the autonomous vehicle for a vehicular path, and a last command of the autonomous vehicle.
19. A data processing system, comprising:
a processor; and
a memory coupled to the processor to store instructions, which when executed by the processor, cause the processor to perform operations of steering control of an autonomous vehicle, the operations including
calculating a first steering angle based on a target directional angle and an actual directional angle of the autonomous vehicle to maneuver an obstacle course;
calculating a second steering angle based on a target lateral position and an actual lateral position of the autonomous vehicle to maneuver the obstacle course;
determining a next target steering angle based on the first and second steering angles; and
controlling a subsequent steering angle of the autonomous vehicle based on the next target steering angle.
20. The data processing system of claim 19 , wherein calculating a first steering angle comprises:
determining the target directional angle of the autonomous vehicle to maneuver the obstacle course;
determining the actual directional angle of the autonomous vehicle in motion; and
calculating the first steering angle based on the target and actual steering angles using a first proportion-integral-derivative (PID) controller.
21. The data processing system of claim 20 , wherein the operations further comprise:
determining a current speed of the autonomous vehicle; and
adjusting a proportional coefficient of the first PID controller based on the current speed of the autonomous vehicle.
22. The data processing system of claim 21 , wherein the operations further comprise reducing the proportional coefficient of the first PID controller in response to determining that the current speed is above a predetermined threshold.
23. The data processing system of claim 21 , wherein the operations further comprise adjusting a derivative coefficient of the first PID controller based on the current speed of the autonomous vehicle.
24. The data processing system of claim 20 , wherein the operations further comprise:
determining a turning radius of the autonomous vehicle; and
adjusting a proportional coefficient of the first PID controller based on the turning radius of the autonomous vehicle.
25. The data processing system of claim 24 , wherein the operations further comprise increasing the proportional coefficient of the first PID controller in response to determining that the turning radius is above a predetermined threshold.
26. The data processing system of claim 19 , wherein calculating a second steering angle comprises:
determining the target lateral position of the autonomous vehicle to maneuver the obstacle course;
determining the actual lateral position of the autonomous vehicle in motion; and
calculating the second steering angle based on the target and actual lateral positions using a second proportion-integral-derivative (PID) controller.
27. The data processing system of claim 26 , wherein the operations further comprise adjusting the proportional, integral and derivative coefficients of the second PID controller based on at least one of a current speed of the autonomous vehicle, a current turning radius of the autonomous vehicle for a vehicular path, and a last command of the autonomous vehicle.