Development of Active Controlled Pendulum type Bed for Ambulance

本研究的目的是减轻病人在救护车床上的疼痛。为了实现这一目的，人们提出了一种主动控制摆型床。这种床系统可以防止救护车转弯时病人在床上摇晃，也可以防止救护车增加或减少速度时病人在床上晃动。该系统设计中引入了摆杆机构，以提供被动安全性，并在有限的电源下对床面进行控制。此外，使床的旋转中心与患者的重心一致，以防止患者晕车并提供控制器的鲁棒性。利用最优控制理论，设计了一种LQ倾床控制系统。制作了主动控制摆床的半比例模型，并将其装在皮卡车上。数值模拟和控制实验证实了床系统的有效性。结果，平行于床平面的加速度小于影响车辆的加速度的20%。并且，通过从行驶时的LQ控制切换到停车时的LQI控制，抑制稳态偏差。然后，构成前馈系统，抑制影响车辆急剧变化的加速度中的与床面平行的残留加速度。该系统从方向盘的旋转角度和车辆速度估计横向加速度，并且从制动踏板的下压力估计纵向减速度。控制实验证实了具有前馈系统的主动控制摆床的有效性。结果，加速度小于一半。

Purpose of this study is to reduce the pain on a patient laid in the bed of ambulance. An active controlled pendulum type bed is being proposed in order to achieve this purpose. This bed system prevents the patient from swaying on the bed as the ambulance turns around a corner and from surging as the ambulance increases or decreases the speed. The system is designed introducing the pendulum mechanism to provide the passive safety and to control the bed plane in limited power source. Also, the center of rotation of the bed is made to agree with the patient center of gravity to prevent the patient from getting carsick and to provide the robustness of the controller. A LQ control system tilting the bed is developed using the optimal control theory. A half scale model of the active controlled pendulum type bed is produced and loaded on a pickup truck. The numerical simulations and the control experiments have been conducted to confirm the effectiveness of the bed system. As the results, the acceleration parallel to the bed plane is less than 20% of the acceleration affecting the vehicle. And the steady-state deviation is suppressed by switching to the LQI control in the stoppage from the LQ control in the running.Then, a feedforward system is constructed to suppress the remaining acceleration parallel to the bed plane in the acceleration affecting the vehicle changing rapidly. The system estimates the transverse acceleration from the rotation angle of the steering wheel and the vehicle speed, and the longitudinal deceleration from the depressing force of the brake pedal. The control experiments have been conducted to confirm the effectiveness of the active controlled pendulum type bed with the feedforward system. As the result, the acceleration is less than the half.