Control of rolling contacts in multiple robotic manipulation

When multiple arms are used to manipulate a large object, it is productive and sometimes necessary to maintain and control contacts between the object and surfaces of the robot other than those at the end-effector. Hence, the contact surface of the robot is referred to simply as its effector and includes the surface of any link of the manipulator as well as open palm-like effectors at the arm´s extremity. Such contacts are characterized by holonomic as well as nonholonomic (including unilateral) constraints. In this paper, the control of rolling contact is investigated. Multiarm manipulation systems are typically redundant. In the approach, a minimal set of inputs is employed to control the trajectory of the system while the surplus inputs control the rolling condition at the contacts. A nonlinear feedback scheme for simultaneous force and motion control is presented and a new approach to adaptively adjust a two-effector grasp with rolling contacts is developed. Simulations are used to illustrate the salient features in control and planning.<>