private void CreateControllers()
    {
        Assert.IsNull(_trackedController, "Controller expected to be null");
        string name = _vrControllerPrefab.name + " [" + _type.ToString() + "]";

        _trackedController      = Instantiate <VRController>(_vrControllerPrefab);
        _trackedController.name = name;
        _trackedController.transform.SetParent(transform);
        _trackedController.transform.localPosition = Vector3.zero;
        _trackedController.transform.localScale    = Vector3.one;
        _trackedController.AssignController(_type, transform);
    }