// Use this for initialization
 void Start()
 {
     controller = FindObjectOfType <QuadcopterController>();
     if (controller == null)
     {
         Debug.LogError("Could not find quadcopter controller");
     }
 }
 // Use this for initialization
 void Start()
 {
     controller     = GetComponent <QuadcopterController>();
     pathController = GetComponent <QuadcopterPathController>();
     controller.AddCalculateDesiredVelocityListener(CalculateDesiredWorldVelocity, 1);
 }