Control Augmentation and Work Load Reduction by Kinesthetic Information from the Manipulator

Control augmentation and work load reduction by means of kinesthetic information provided by the manipulator are discussed. The control stick is loaded by a torque motor and the system is so interconnected that it presents complete kinesthetic input and output information from the controlled plant. Thus the control task involves the same kinesthetic cues and low work load as in direct handling of objects. It is demonstrated that within 20 rad/s, which is the effective bandwidth in manual control, the method is realizable for a large variety of plants which may be unstable and time varying. Tracking and regulating tests demonstrate that very substantial improvements in accuracy and reduction in workload are obtained in comparison with ordinary isotonic, isomorphic, or isometric manipulators. A test for the fixed set point regulation task involving a second-order plant reveals that the control force law involved is strikingly similar to that of a linear regulator with an energy constraint obeying a quadratic performance criterion. The corresponding theoretical closed-loop transfer function is in agreement with known linear models of the manual neuromuscular system.