The base actuator is an off the shelf maxon, with our custom sensors and custom motor controller. In terms of motion control, safety was the most important piece when designing our system. There are safety checks in the mechanical, electrical and the software sub system. There is a maximum force that the controller exerts on the child, which can be lowered or increased for each child. In addition to the child resisting, we also had to account for spasticity and sudden tone while walking. The controller detects high resistance and caps off the max force it sends to the motor.