In last week, the full scale ATN was demonstrated and operated to us and all of us have a brief idea on how the powertrain and the steering system of the bogie functions. However, from my observation vibration and noise is generated when the bogie is rolling along the guide structure. Hence I think possible solution is to add a active damper consists of coil spring or more refined air suspension on to the powertrain. Also braking system consists of automobile brake pad powered by actuator (electric, hydraulic or pneumatic ) can be installed to individual wheels for safety. Disc brake system  from automobile or motorcycle can installed on the drive shaft of the guiding wheel.