An antagonistic controller which is to be used in tendon-driven master/slave end-effectors is described. High stiffness was achieved by developing a control law which eliminates one local force loop in the flexion/extension control loops. One force loop maintains tendon cocontraction, while the other force loop is eliminated when the tendon tension is greater than cocontraction. In order to minimize the input impedance or slew drag caused by inertia and intrinsic damping of the system, force compensations were implemented according to the characteristics of the actuators. These techniques have been implemented experimentally on both electromechanical and electrohydraulic systems. A computer analysis of an electromechanical antagonistic control system is included. Servostiffness equations are derived from the transfer function of the electromechanical system.>

Two antagonistic control algorithms are described. These algorithms are used to control manipulator links which are antagonistically driven by two actuators via tendons. They have been simulated and experimentally shown to produce better active and passive performance for an electric test system than control algorithms developed earlier. The algorithms use both positive and negative (push and pull) commands to be given to the actuators. Previous systems generated only pull commands, ensuring that tendons would not go slack and give rise to backlash and other problems. The proposed controllers allow push commands to the actuators but still do not allow tendons to go slack. Each actuator, in addition to being fed back its respective tendon force, is fed back both positive and negative manipulator joint torques. This feature allows both actuators to simultaneously respond to torque errors.>