Active And Passive Control Of Random Vibration For Ambulance Stretcher

Transport type ambulance is an important link connecting first aid at the scene and hospital. Whether it can be fast, efficient, stable complete shipping tasks directly affects the efficiency of the treatment of the sick and wounded. Most of the current ambulances for transportation are adapted from light commercial vehicles or light SUV whose suspension are passive. Vehicle performance is not satisfactory. A lot of hospitals are equipped with some foreign ambulances in order to meet the demand for high performance ambulance. So actively develop advanced technology, improve the technical level of domestic ambulance is significant.Preview control can contain future information in the control strategy. It has shown good potential for performance in the active and semi-active automobile suspension control. When designing the vibration isolation system for the stretcher, this paper designed a LQR(Linear Quadratic Regulator) control scheme using the preview information based on front axle.In this paper, considering the sensitivity of human body in supine position, a two-dimensional passive isolation system was built. This model took the vertical movement motion and the pitching motion of the controlled object and the correlation between inputs into account. There is an in-depth analysis of the vibration transmission property of the system. The primary stiffness coefficients and damping coefficients of passive vibration isolation components were chosen by theoretical calculation. The coefficients were optimized using genetic algorithms. This improves the precision of parameter selection and the performance of vibration isolation system.In order to further reduce the response peak caused by the natural frequency of the chassis, the scheme of a two-dimensional active isolation system was built. The state space description of the system was derived. To control the vertical vibration and pitch of the stretcher a optimality criterion restricted by the suspension working space was built. The weighting matrix was designed aided by genetic algorithm. The system state variables were reconstructed using Kalman filter through the limited measurements. The system was simulated with the help of MATLAB/Simulink tools. In-depth analysis of the performance potential of the optimal control system was given.Automotive random vibration is usually controlled by feedback control strategy. This leads to time lag. In order to make up for the time lag, this paper considered the time delay between front wheel input and rear wheel input. A preview control system was designed using the surface information detected from the Front axle. The vibration isolation performance of the preview control and the influence of vehicle speed was investigated.