Design optimization and realization of a Gough-Stewart platform for hippotherapy

The design of a compact Gough-Stewart platform for physical hippotherapy is presented using pneumatic muscles and a central pre-stressed spring to achieve bidirectional motion. The use of the Gough-Stewart platform is advantageous as it drastically increases the workspace accessible by a therapist. The system is designed to reproduce walk, trot, and gallop trajectories derived from motion capture data. The model-based geometry optimization reduces actuator forces under workspace and collision constraints. The control of the pneumatic muscles combines inverse-dynamics and PID loops with a neural network feedforward. The latter compensates for the nonlinear spring characteristics. Experiments show that the system can generate the desired motion profiles, is robustness regarding variable load, and thus suitable for therapeutic use.