Diff: Steering.h

Revision:

0:a3b128cdb78b

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Steering.h	Wed Apr 27 18:55:38 2011 +0000
@@ -0,0 +1,45 @@
+
+#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);
+    
+  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