Abstract
When an ambulance changes a lane or turns a corner, the lateral acceleration acts on a patient. Such acceleration causes patient's discomfort, carsickness and physical pain. To reduce the effect of lateral acceleration on a patient, we made the prototype of an actively-controlled bed for ambulances that rotates the bed around the axis of a patient's body with a DC servo motor. The purpose of this paper is to report the control system design for this actively-controlled bed and to evaluate its control performance in simulation and experiment. In the framework of the principle of matching, the control system is designed as a servo system so that the tracking error and the motor torque are maintained within the tolerable bounds in actual situation. The design problem is formulated to a feasibility problem stated as inequality constraints. A numerical search is performed to find parameters of a controller. In experiment, it is confirmed that the lateral acceleration acting on a patient is reduced to about 25% as compared to use of normal fixed beds. In simulation, the cancellation rate of lateral acceleration is examined when the rotational angle of the bed is restricted to ±5, ±10 or ±15 degrees.
