Human-Comfort Evaluation for a Patient-Transfer Robot Through a Human–Robot Mechanical Model

Abstract Patient-transfer robot, which can transfer a bedridden care receiver from a bed to a wheelchair or a pedestal pan and back, was not widely used due to inadequate safety and comfort. A human comfort evaluation function based on force analysis was proposed to improve the comfort of a dual-arm transfer robot. First, a human–robot mechanical model was construct by simplifying the structure of human body and the robot. Then, the internal and external forces acting on human body were calculated by the developed human–robot mechanical model. After that, a comfort evaluation function was established through mechanical analysis and a questionnaire investigation method. To assess the validity of the proposed method, first we employed the comfort evaluation function to estimate human comfort, and obtained that the comfort level is proportional to the electromyography (EMG) signal and pressure signal of human. Then we applied the function to a dual-arm patient-transfer robot to optimizing lifting points and transfer posture and found it can effectively reduce the human–robot contact force and the burden of the waist by 44.2%, improving the comfortability of the care receiver.