Static Analysis of a 3-link Object for Posture Maintenance Control by Nonprehensile Robot without Compensating Friction

Recently, many researchers have focused on nursing-care assistant robot systems for helping solve the shortage of the caregivers in hospital or nursing home. In this paper, a nonprehensile robot is considered to realize holding motion for keeping a 3-link object (regarded as a care-receiver) stable on the robot arms. By using Newton-Euler equations of motion, the dynamic model of the robot system is obtained. Considering the fact that the robot arms are often driven slowly at the caregiving workplace, the obtained dynamic model is simplified to static model and then the stable regions for keeping 3-link object not falling down from robot arms are obtained by utilizing static friction instead of compensating it. The experiment is conducted to validate the simulation result.