Optimal control of active ambulance stretcher suspension based on genetic algorithm

In order to improve the lying patient's ride quality, a 2-Dimensional ambulance-stretcher-lying body system model was established, and the optimal controller was designed for the stretcher. Considering ride comfort and driving stability, eight performance indexes were selected. Weighting matrices of standard LQR controllers cannot achieve global optimum. A method of determining the weighting coefficient by using genetic algorithm (GA) which has the function of global searching ability was proposed. All the states should be measured in the optimal control theory which is based on the whole states feedback. To solve the problem, the Kalman filter was added to the control strategy to estimate the state variables. Numerical calculations were carried out to examine the effectiveness of proposed control scheme. It shows that the optimal control provides significant reduction of vertical and pitch vibration transmission compared with the passive stretcher suspension.