On an ambulance stretcher suspension concerned with the reduction of patient's blood pressure variation.

The design process and control of an ambulance stretcher suspension to reduce patient's blood pressure variation (BPV) is discussed. The BPV caused by applying the vehicle brakes may lead to deterioration of a patient's condition. The proposed method can reduce BPV by tilting the stretcher and counterbalancing back-to-front acceleration of the ambulance with gravity. The experimental results obtained when using a manually controlled stretcher confirm that BPV is reduced by tilting the stretcher. A continuous control method that varies the tilting angle is investigated through simulation analysis. The results show that this control method reduces the BPV effectively and achieves safe transport of the patient.