A robotic mobility simulator is being developed to allow training on various hapticly simulated surfaces while still being in the safe clinical environment. The simulator is integrated with a rich virtual environment displayed in front of the patient. The system uses two Stewart platform robots to render the walking surface geometry and condition. The hardware components of the platforms and the considerations behind their design are presented here. In addition, the nine state algorithm used for simulating the treadmill functioning is described along with the procedure used to transform the motion of the robots into walking in the virtual environment.