Tele-impedance: Teleoperation with impedance regulation using a body–machine interface

TLDR

Tele‑impedance replaces bilateral force‑reflecting teleoperation by sending a compound reference command that includes both motion trajectory and impedance profile to the slave robot, enabling remote control without explicit operator feedback. This work introduces tele‑impedance as a method for remotely controlling a robotic arm in uncertain environments. The authors derive the reference command from a body–machine interface that uses non‑intrusive arm position and EMG signals, decouples force and stiffness estimates, and employs optical wrist tracking for closed‑loop end‑effector control, evaluating performance under varying stiffness settings. Tele‑impedance was validated in peg‑in‑the‑hole and ball‑catching experiments, demonstrating complementary capabilities of the method.

Abstract

This work presents the concept of tele-impedance as a method for remotely controlling a robotic arm in interaction with uncertain environments. As an alternative to bilateral force-reflecting teleoperation control, in tele-impedance a compound reference command is sent to the slave robot including both the desired motion trajectory and impedance profile, which are then realized by the remote controller without explicit feedback to the operator. We derive the reference command from a novel body–machine interface (BMI) applied to the master operator’s arm, using only non-intrusive position and electromyography (EMG) measurements, and excluding any feedback from the remote site except for looking at the task. The proposed BMI exploits a novel algorithm to decouple the estimates of force and stiffness of the human arm while performing the task. The endpoint (wrist) position of the human arm is monitored by an optical tracking system and used for the closed-loop position control of the robot’s end-effector. The concept is demonstrated in two experiments, namely a peg-in-the-hole and a ball-catching task, which illustrate complementary aspects of the method. The performance of tele-impedance control is assessed by comparing the results obtained with the slave arm under either constantly low or high stiffness.