Code for autonomous ground vehicle, Data Bus, 3rd place winner in 2012 Sparkfun AVC.
Dependencies: Watchdog mbed Schedule SimpleFilter LSM303DLM PinDetect DebounceIn Servo
Diff: Actuators/Steering/Steering.h
- Revision:
- 0:826c6171fc1b
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Actuators/Steering/Steering.h Wed Jun 20 14:57:48 2012 +0000 @@ -0,0 +1,66 @@ + +#define PI 3.141592653589 + +/** A class for managing steering angle calculations based on current and desired heading + * and specified intercept distance along the new path. + * + * See Notebook entry: http://mbed.org/users/shimniok/notebook/smooth-steering-for-rc-car/ + */ +class Steering +{ + public: + /** create a new steering calculator + * + * @param wheelbase vehicle wheelbase + * @param track vehicle track width + * @param intercept new course intercept distance + */ + Steering(float wheelbase, float track); + + /** set intercept distance + * @param intercept distance along new course at which turn arc will intercept + */ + void setIntercept(float intercept); + + /** convert course change to average steering angle + * assumes Ackerman steering, with track and wheelbase + * and course intercept distance specified. + * + * See notebook: http://mbed.org/users/shimniok/notebook/smooth-steering-for-rc-car/ + * + * @param theta relative bearing of the new course + * @returns steering angle in degrees + */ + float calcSA(float theta); + + /** convert course change to average steering angle + * assumes Ackerman steering, with track and wheelbase + * and course intercept distance specified. Also, |radius| of turn is limited to limit + * + * See notebook: http://mbed.org/users/shimniok/notebook/smooth-steering-for-rc-car/ + * + * @param theta relative bearing of the new course + * @param limit is the limit of the turn circle radius (absolute value) + * @returns steering angle in degrees + */ + float calcSA(float theta, float limit); + + /** compute steering angle based on pure pursuit algorithm + */ + float purePursuitSA(float hdg, float Bx, float By, float Ax, float Ay, float Bx, float By); + + /** Compute cross track error given last waypoint, next waypoint, and robot coordinates + * @returns cross track error + */ + float crossTrack(float Bx, float By, float Ax, float Ay, float Bx, float By); + + private: + + inline static float angle_radians(float deg) {return (PI/180.0)*deg;} + + inline static float angle_degrees(float rad) {return (180/PI)*rad;} + + float _wheelbase; + float _track; + float _intercept; +}; \ No newline at end of file