This article documents investigations into impedance control carried out on a direct drive robot manipulator. Both linear and nonlinear versions of impedance controllers have been investigated. The two impedance controllers have been simulated numerically and implemented on Carleton University's direct drive robot. The performance of these controllers is experimentally compared in terms of force trajectory following and contact stability. The article highlights the practical and experimental limitations of the proposed methods. Furthermore, the experimental results indicate that the controller design, the manipulator kinematics, and the desired task must all be considered and evaluated simultaneously.
International Journal of Robotics Research
Department of Systems and Computer Engineering

McCormick, W. (W.), & Schwartz, H.M. (1993). Investigation of impedance control for robot manipulators. International Journal of Robotics Research, 12(5), 473–489. doi:10.1177/027836499301200507