A Manipulability Improving Scheme for Opening Unknown Doors with Mobile Manipulator

The problem of door opening is very fundamental for mobile manipulators operating in domestic environments. In order to successfully achieve the door opening task with wheeled mobile redundant manipulators, a manipulability improving scheme is proposed and investigated in this paper. The scheme treats the wheelchair and the manipulator as a whole system and can improve the manipulator's manipulability when opening the door. And thus remedy the manipulator's manipulability decreasing and/or joint variable' abrupt change as well as the workspace limitations during opening the doors. What's more, the control scheme can drive the wheelchair to move according to the end-effector so as not to collide with the door, and can open door smoothly. Firstly, the velocity of the end-effector is generated with the hybrid position/force control for opening doors, and then the coordinated motion control of mobile platform and the manipulator is adopted to drive the whole system moving to a suitable position to open doors successfully. The control scheme can be used by any mobile manipulator that can be velocity controlled. For verifying the performance of the proposed scheme during opening doors, simulations performed on a wheelchair mounted with a 6-DOF robot arm.