Sliding mode control for therapeutic pool model control system

In this study we consider the robust control of a therapeutic pool model using Sliding Mode Control (SMC). Therapeutic pool is a warm water pool used for stroke therapy. It makes exercises for stroke patients easier than done outside water because of the water buoyant force which reduces human weight. The therapeutic pool which is designed in this study has two inlets and an outlet for drainage. The first inlet is for the hot water flow and the second is for the cold water flow. The two water flows are mixed in the therapeutic pool. The controlled variable is the mixed water temperature in therapeutic pool. Unsteady thermodynamics and mass balance are used to mathematically model the therapeutic pool. The SMC controller is designed to reject disturbances due to heat transfer from the mixed water to surrounding through the contacting surface between water and the free air stream. The usefulness of this technique is illustrated with a simulation. Desired temperature of therapeutic pool is successfully reached and maintained steady. The performance of SMC controller is compared to conventional PID (Proportional Integral Derivative) controller and the neural model of the conventional one.