AC_Avoid: limit velocity and get-max-speed become public

this allows AP_Follow to use these function

libraries/AC_Avoidance/AC_Avoid.cpp

@@ -229,6 +229,37 @@ void AC_Avoid::adjust_roll_pitch(float &roll, float &pitch, float veh_angle_max)
     pitch = rp_out.y;
 }
 
+/*
+ * Limits the component of desired_vel in the direction of the unit vector
+ * limit_direction to be at most the maximum speed permitted by the limit_distance.
+ *
+ * Uses velocity adjustment idea from Randy's second email on this thread:
+ * https://groups.google.com/forum/#!searchin/drones-discuss/obstacle/drones-discuss/QwUXz__WuqY/qo3G8iTLSJAJ
+ */
+void AC_Avoid::limit_velocity(float kP, float accel_cmss, Vector2f &desired_vel, const Vector2f& limit_direction, float limit_distance, float dt) const
+{
+    const float max_speed = get_max_speed(kP, accel_cmss, limit_distance, dt);
+    // project onto limit direction
+    const float speed = desired_vel * limit_direction;
+    if (speed > max_speed) {
+        // subtract difference between desired speed and maximum acceptable speed
+        desired_vel += limit_direction*(max_speed - speed);
+    }
+}
+
+/*
+ * Computes the speed such that the stopping distance
+ * of the vehicle will be exactly the input distance.
+ */
+float AC_Avoid::get_max_speed(float kP, float accel_cmss, float distance_cm, float dt) const
+{
+    if (is_zero(kP)) {
+        return safe_sqrt(2.0f * distance_cm * accel_cmss);
+    } else {
+        return AC_AttitudeControl::sqrt_controller(distance_cm, kP, accel_cmss, dt);
+    }
+}
+
 /*
  * Adjusts the desired velocity for the circular fence.
  */
@@ -461,37 +492,6 @@ void AC_Avoid::adjust_velocity_polygon(float kP, float accel_cmss, Vector2f &des
     }
 }
 
-/*
- * Limits the component of desired_vel in the direction of the unit vector
- * limit_direction to be at most the maximum speed permitted by the limit_distance.
- *
- * Uses velocity adjustment idea from Randy's second email on this thread:
- * https://groups.google.com/forum/#!searchin/drones-discuss/obstacle/drones-discuss/QwUXz__WuqY/qo3G8iTLSJAJ
- */
-void AC_Avoid::limit_velocity(float kP, float accel_cmss, Vector2f &desired_vel, const Vector2f& limit_direction, float limit_distance, float dt) const
-{
-    const float max_speed = get_max_speed(kP, accel_cmss, limit_distance, dt);
-    // project onto limit direction
-    const float speed = desired_vel * limit_direction;
-    if (speed > max_speed) {
-        // subtract difference between desired speed and maximum acceptable speed
-        desired_vel += limit_direction*(max_speed - speed);
-    }
-}
-
-/*
- * Computes the speed such that the stopping distance
- * of the vehicle will be exactly the input distance.
- */
-float AC_Avoid::get_max_speed(float kP, float accel_cmss, float distance_cm, float dt) const
-{
-    if (is_zero(kP)) {
-        return safe_sqrt(2.0f * distance_cm * accel_cmss);
-    } else {
-        return AC_AttitudeControl::sqrt_controller(distance_cm, kP, accel_cmss, dt);
-    }
-}
-
 /*
  * Computes distance required to stop, given current speed.
  *

libraries/AC_Avoidance/AC_Avoid.h

@@ -62,6 +62,19 @@ public:
     void proximity_avoidance_enable(bool on_off) { _proximity_enabled = on_off; }
     bool proximity_avoidance_enabled() { return _proximity_enabled; }
 
+    // helper functions
+
+    // Limits the component of desired_vel in the direction of the unit vector
+    // limit_direction to be at most the maximum speed permitted by the limit_distance.
+    // uses velocity adjustment idea from Randy's second email on this thread:
+    //   https://groups.google.com/forum/#!searchin/drones-discuss/obstacle/drones-discuss/QwUXz__WuqY/qo3G8iTLSJAJ
+    void limit_velocity(float kP, float accel_cmss, Vector2f &desired_vel, const Vector2f& limit_direction, float limit_distance, float dt) const;
+
+     // compute the speed such that the stopping distance of the vehicle will
+     // be exactly the input distance.
+     // kP should be non-zero for Copter which has a non-linear response
+    float get_max_speed(float kP, float accel_cmss, float distance_cm, float dt) const;
+
     static const struct AP_Param::GroupInfo var_info[];
 
 private:
@@ -98,22 +111,6 @@ private:
      */
     void adjust_velocity_polygon(float kP, float accel_cmss, Vector2f &desired_vel, const Vector2f* boundary, uint16_t num_points, bool earth_frame, float margin, float dt);
 
-    /*
-     * Limits the component of desired_vel in the direction of the unit vector
-     * limit_direction to be at most the maximum speed permitted by the limit_distance.
-     *
-     * Uses velocity adjustment idea from Randy's second email on this thread:
-     * https://groups.google.com/forum/#!searchin/drones-discuss/obstacle/drones-discuss/QwUXz__WuqY/qo3G8iTLSJAJ
-     */
-    void limit_velocity(float kP, float accel_cmss, Vector2f &desired_vel, const Vector2f& limit_direction, float limit_distance, float dt) const;
-
-    /*
-     * Computes the speed such that the stopping distance
-     * of the vehicle will be exactly the input distance.
-     * kP should be non-zero for Copter which has a non-linear response
-     */
-    float get_max_speed(float kP, float accel_cmss, float distance_cm, float dt) const;
-
     /*
      * Computes distance required to stop, given current speed.
      */