Foot-operated Tele-impedance Interface for Robot Manipulation Tasks in Interaction with Unpredictable Environments

Tele-impedance increases interaction performance between a robotic tool and unstructured/unpredictable en-vironments during teleoperation. However, the existing tele-impedance interfaces have several ongoing issues, such as long calibration times and various obstructions for the human operator. In addition, they are all designed to be controlled by the operator's arms, which can cause difficulties when both arms are used, as in bi-manual teleoperation. To resolve these issues, we designed a novel foot-based tele-impedance control method inspired by the human limb stiffness ellipse modulation. The proposed mechanical interface design includes a disc and a foot pressure sensor that controls the orientation and size/shape of the stiffness ellipse, respectively. We evaluated the disc interface control method in an experimental study with 12 participants, who performed a complex drilling task in a virtual environment. The results show the ability of the operator to use the proposed interface in order to dynamically adapt to different phases of the task and changes in the environment. In addition, a comparison with low and high uniform impedance modes demonstrates a superior interaction performance of the proposed method.