Force-Sensorless Acceleration-Based Impedance Control for the Inertia Compensation in the Assisted Manipulation of Large Payloads

Abstract

In physical human-robot interaction applications involving the co-manipulation of heavy and bulky payloads, inertia compensation of the load is a key element for the ergonomics, precision and comfort of the task led by a human operator. This letter investigates experimentally the capability and limitations of a force-sensorless, acceleration-based impedance control law to render a reduced virtual inertia of a payload supported by a backdrivable parallel robot. The incentive for the elimination of the force/torque sensor is to extend the deployment of assistive technology to allow the operator to freely manipulate the payload (hands-on-payload interaction) in environments where a force/torque sensor cannot be used. The results are compared with those obtained using a more conventional admittance control scheme using a force/torque sensor implemented on the same physical setup. Experimental results are provided to evaluate the rendered virtual inertia in the frequency domain using Bode plots (magnitude and phase) for both control schemes. A technique is also proposed for the reduction of the time delay induced by the acceleration measurement filtering and its impact on the virtual inertia rendered is evaluated experimentally.