Internal force-based impedance control for cooperating manipulators

Internal force-based impedance control for cooperating manipulators controls the motion of the objects being manipulated and the internal force on the objects by enforcing a relationship between the velocity of each manipulator and the internal force on the manipulated objects. Each manipulator is directly given the properties of an impedance by the controller, thus eliminating the need to have both a position and force control loop. The controller uses the forces sensed at the robot end effectors to compensate for the effects of the objects´ dynamics and to compute the internal force using only kinematic relationships. Thus, knowledge of the objects´ dynamics are not required. The control is accomplished in Cartesian space eliminating the need for solving the inverse kinematics. The stability of the system is proven using Lyapunov theory, and simulation results are presented validating the proposed concepts