Position Adjustment Control of A Nursing-care Robot Holding A Patient in Its Arms

The demand for robotics to tackle the problems resulting from the ageing society is increasing. For the safety of a dual-arm transfer robot which can lift and move a care receiver from a bed to a wheelchair or the back, this paper proposes a novel control strategy for motion control. The robot arms and the subject being held by the robot constitute a strong coupling system which is under-actuated and nonlinear. To solve the above problem, we divide the manipulation of the system into posture adjustment of the subject in holding and arm-position adjustment when the arms leave the subject for an instance to avoid friction. The posture adjustment of the subject was realized by using a sliding mode control method, while a neural network was introduced to build the control model and identify the parameters, and impedance control was introduced in arm-position adjustment. The effectiveness of the control strategy was confirmed by numerical simulation.