Stable and Quick Standing-Sitting Motion of I-PENTAR by Whole-body Motion with Force Control

This paper describes motion control and planning for the standing and sitting motions of an inverted pendulum-type assist robot, I-PENTAR. Whole-body motion based on redundant control that takes positional control of a composite center of gravity(CCoG) and a wrist roller as goal tasks is adopted. Using the motion control, motion planning of the robot can be described intuitively and in a simple manner. Compliance motion of a manipulator by force control of a wrist roller is adopted to move the position of CCoG and to maintain the robot's stability when the wrist roller contacts with the ground, which is an important factor in successfully achieving a sitting motion. Based on this motion control, standing and sitting motion planning is also proposed, which considers the stability and the operational time efficiency of the process. The proposed control method and motion planning were tested experimentally with I-PENTAR, and it was confirmed that standing and sitting motions were achieved stably in a short time period.