Rover: disable turning at low speeds when simple avoidance is active

Rover/mode.cpp

@@ -433,8 +433,16 @@ void Mode::navigate_to_waypoint()
         const float turn_rate = g2.sailboat.tacking() ? g2.wp_nav.get_pivot_rate() : 0.0f;
         calc_steering_to_heading(desired_heading_cd, turn_rate);
     } else {
+        // retrieve turn rate from waypoint controller
+        float desired_turn_rate_rads = g2.wp_nav.get_turn_rate_rads();
+
+        // if simple avoidance is active at very low speed do not attempt to turn
+        if (g2.avoid.limits_active() && (fabsf(attitude_control.get_desired_speed()) <= attitude_control.get_stop_speed())) {
+            desired_turn_rate_rads = 0.0f;
+        }
+
         // call turn rate steering controller
-        calc_steering_from_turn_rate(g2.wp_nav.get_turn_rate_rads());
+        calc_steering_from_turn_rate(desired_turn_rate_rads);
     }
 }