To make robot manipulators work more compliantly when contacting with the environment, it is necessary to reduce the contact force caused by positioning errors. One of the effective ways to solve this problem is impedance control, which makes the robot manipulator as a second-order mass-spring-damping system in principle.&nbsp; Using fractional calculus, integer-order impedance control can be turned into fractional-order impedance control.&nbsp; In this paper, a position-based &nbsp;fractional-order impedance control design method is proposed for a robot manipulator force control. The end-effector/environment contact model is established, and the closed-loop system with the reference force as input is analyzed. For better force-control performance, a fractional-order impedance parameters design method is proposed, which calculate and optimize parameters through frequency-domain specifications&nbsp;(i.e., phase margin and gain crossover frequency) and time-domain &nbsp;specification (i.e., the smallest JITSE). With the Robotics ToolBox for MATLAB (RTB), an impedance control system based on the robot PUMA560 is established, which is run in the MATLAB/Simulink. The performance comparison between integer-order and fractional-order impedance controls is illustrated in the simulation. The fractional-order impedance control system has a faster response, smaller overshoot and better resistance to external disturbances from environment.Keywords: fractional-order impedance control; &nbsp;impedance control; robot manipulator; force control

Fractional-Order Impedance Control Design for Robot Manipulator

Paper Proceedings: https://asmedigitalcollection.asme.org/IDETC-CIE/IDETC-CIE2021/volume/85369

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