Whole arm manipulation with effects of static and dynamic friction on body surface

For achieving stable grasping and operation of a large object skillfully utilizing the robot´s whole-arm and whole-body surface, mathematical theories of modeling and control in consideration of static and dynamic friction forces on the body surface must be developed. On this issue, mathematical modeling for the complicated frictional effects is the most fundamental and difficult task that remains to be solved. This paper then proposes a novel approach to robotic whole-arm manipulation taking the frictional effects into account. First, we formulate the system dynamics of a 2-DOF robot arm with contact forces and friction forces between the robot surface and the object reproduced by the LuGre friction model. Both the static and dynamic friction forces can be specified as a single differential equation according to the method of the LuGre friction model. Second, we design a two trajectory tracking control system in order to manipulate the position of the center of mass of the object. The first control system is inverse dynamic control, the second is sliding mode control. Finally, we compare the control performance of two control system in terms of average error norm and average input power. The validity of the proposed method is investigated by numerical simulations.