void OnInsertEntity(sime.InsertSimulationEntity insert)
        {
            _entity = insert.Body as FourWheelDriveEntity;
            if (_entity != null)
            {
                _entity.ServiceContract = Contract.Identifier;

                if (_entity.ChassisShape != null)
                {
                    _state.DistanceBetweenWheels = _entity.DistanceBetweenWheels;
                    _state.WheelBase             = _entity.WheelBase;
                }
            }
        }
 void OnDeleteEntity(sime.DeleteSimulationEntity delete)
 {
     _entity = null;
 }