TradHeli: Modify the constrain on the auto throttle controller to prevent it from commanding full down collective if we think we are on the ground still.

ArduCopter/Attitude.pde

@@ -894,9 +894,17 @@ get_throttle_accel(int16_t z_target_accel)
 
     d = g.pid_throttle_accel.get_d(z_accel_error, .01f);
 
-    //
-    // limit the rate
+#if FRAME_CONFIG == HELI_FRAME
+    if (ap.takeoff_complete == true){
+        output =  constrain_float(p+i+d+g.throttle_cruise, g.throttle_min, g.throttle_max);
+    } else {
+        // Avoid harshing the mechanics pushing into the ground
+        // stab_col_min should gently push down on the ground
+        output =  constrain_float(p+i+d+g.throttle_cruise, motors.stab_col_min*10, motors.stab_col_max*10);
+    }   
+#else   
     output =  constrain_float(p+i+d+g.throttle_cruise, g.throttle_min, g.throttle_max);
+#endif // HELI_FRAME         
 
 #if LOGGING_ENABLED == ENABLED
     // log output if PID loggins is on and we are tuning the yaw