Safely Rendering Small Impedances in Admittance-Controlled Haptic Devices

• Published in: IEEE/ASME transactions on mechatronics Vol. 21; no. 3; pp. 1272 - 1280
• Main Authors: Morbi, Aliasgar, Ahmadi, Mojtaba
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acceleration; Admittance; Admittance control; haptic interaction; Haptic interfaces; humacn-robot interaction; IEEE transactions; Impedance; interaction control; Mechatronics; Stability analysis; haptic interaction; human–robot interaction; interaction control; Admittance control
• ISSN: 1083-4435; 1941-014X
• DOI: 10.1109/TMECH.2015.2506994

This paper introduces a simple and minimal admittance controller capable of rendering small impedances. The proposed controller ensures stable human-robot interactions by dynamically modifying and limiting the commanded acceleration of a haptic device. A Lyapunov stability analysis demonstrates that these dynamic acceleration modifications yield a stable inner position control loop with bounded tracking errors. This paper also discusses results from several experiments performed by healthy subjects who used a one degree-of-freedom haptic device to assist forearm flexion and extension. The results show that the controller is capable of rendering apparent inertia reductions as high as 99.3% while remaining robust to varying operator inputs and dynamics.