Influence of joint flexibility in the adjustment of impedance controller parameters

The adjustment of stiffness, damping, and apparent mass in an impedance controller is analyzed for a joint linear model which includes flexibility, modeled as a spring effect in the torque transmission between actuator and load. An approximate model to the fourth-order linear model is utilized to analyze the behavior in free space and to obtain a condition on impedance parameters for a nonoscillatory behavior. Joint impedance has four zeros and two poles. The joint in contact with the environment can be unstable. The analysis shows a lower limit in the stiffness defined by the impedance controller if the behavior in free space is not modified through an increase in apparent mass.<<ETX>>

[1]  Phillip J. McKerrow,et al.  Introduction to robotics , 1991 .

[2]  Neville Hogan,et al.  Stable execution of contact tasks using impedance control , 1987, Proceedings. 1987 IEEE International Conference on Robotics and Automation.

[3]  Malcolm Good,et al.  Dynamic Models for Control System Design of Integrated Robot and Drive Systems , 1985 .

[4]  Steven D. Eppinger.  Modeling Robot Dynamic Performance for Endpoint Force Control , 1988 .

[5]  Dale A. Lawrence,et al.  Impedance control stability properties in common implementations , 1988, Proceedings. 1988 IEEE International Conference on Robotics and Automation.

[6]  Andrew A. Goldenberg.  Implementation of force and impedance control in robot manipulators , 1988, Proceedings. 1988 IEEE International Conference on Robotics and Automation.

[7]  Neville Hogan,et al.  Controller design in the physical domain (application to robot impedance control) , 1989, Proceedings, 1989 International Conference on Robotics and Automation.

[8]  Homayoon Kazerooni,et al.  Robust, non-linear impedance control for robot manipulators , 1987, Proceedings. 1987 IEEE International Conference on Robotics and Automation.

[9]  R. Paul.  Robot manipulators : mathematics, programming, and control : the computer control of robot manipulators , 1981 .

[10]  Neville Hogan,et al.  Impedance Control: An Approach to Manipulation: Part I—Theory , 1985 .

[11]  Homayoon Kazerooni,et al.  Direct-drive, active compliant end-effector (active RCC) , 1987, Proceedings. 1987 IEEE International Conference on Robotics and Automation.

[12]  Eugene B. Canfield.  Electromechanical Control Systems and Devices , 1965 .

[13]  J. Y. S. Luh,et al.  Conventional controller design for industrial robots — A tutorial , 1983, IEEE Transactions on Systems, Man, and Cybernetics.