Design of a robotic walking simulator for neurological rehabilitation

The restoration of walking capability is a key goal after stroke, traumatic brain injury and spinal cord injury. Conventional training methods, e.g. treadmill training, require great physical effort from the therapists to assist the patient. A robotic device which enables the therapist to let the machine move the patients feet on programmable foot trajectories (e.g. walking on the ground, stepping stairs up and down, walking on rough surfaces, disturbances during walking) would be of great help. On this device the patients feet are permanently fixed on two footplates. Force sensors are mounted on the footplates in order to enable the incorporation of compliance control algorithms for online adaptation of the foot trajectories to the patients walking capabilities. Furthermore the kinematic and kinetic design parameters of the robotic system will enable the machine to be used as a universal walking simulator, not only for rehabilitation purposes. In 'haptic mode', i.e. ma ximum compliance during foot swing phase, the machine behaves as a haptic foot device for a variety of virtual ground conditions. Due to the high dynamic range, needed to guide real walking trajectories, conventional industrial robots are not suitable for this task. Hence the authors have developed a special robot system with high dynamics. This paper describes development aspects of the design process of the new walking simulator. A prototype of the developed system is currently under construction.