The application of robotic manipulators to complex tasks such as assembly, or insertion often requires position/force control of the end-effector, and this has been widely studied. A related task is robot compliant motion over unknown objects. The goal is to move the effector, while maintaining contact, about the object. For this application a dynamic hybrid velocity/force controller is studied. The constraints are characterized in the manner proposed by M. Mason (1981). A nominal velocity trajectory is computed, and nominal hybrid joint commands are explicitly given in terms of the sensed joint coordinates and sensed local contact information. For robustness, servoing is added, and an example design is given. Finally, the step response of the controller is simulated for the case of rolling the effector about an unknown object.>

A mechanism for the control of the heel-off to toe-off motion of a dynamic biped gait is presented. It is argued that the reaction force between the ground and the biped foot is an important factor in a satisfactory implementation of dynamic gait. This force must be properly controlled while the foot is in the heel-off to toe-off phase. Since the foot rolls over the ground surface in this phase and the global description of the surface is unknown, the foot has to execute a nonholonomic constraint motion. The formulations of nonholonomic constraints and system dynamics under the constraints are derived for the roll-over motion. A feedback control mechanism is designed based on the formulations. The formulation and the feedback control mechanism are applied to a four-link biped model. Successful simulation results of the heel-off to toe-off motion prove that the formulation and control mechanism are valid for the nonholonomically constrained motion of the biped.>

The dynamic equations for a two-robot system with and without load are formulated. For control purposes, the constraint forces are derived as functions of input and state. The inverse plant method and computation of the constraint forces are used to coordinate the control of the system. No pressure or force sensors are considered, and no force feedback is used. The effectiveness of the control strategy for point-to-point motion of the coordinated robots performing a lifting task is checked by digital computer simulations.>