Tunnel-shaped potential force fields for improved hand-guiding of robotic arms

In this paper we introduce a new approach for improving hand-guiding of robotic arms. We present the tunnel-shaped potential force field (TSPFF) which guides the user along a reference trajectory in order to improve the user comfort of handling robots. The reference trajectory is computed using the learning data of experienced users. The TSPFF is realized by an impedance control of the robot. The main focus of this paper is to find a robust parametrization of the TSPFF. For this purpose the stability of user-robot interaction is analyzed by means of the Lyapunov stability theory. The results are complemented by simulation studies in which the influence of the parametrization on control performance and user comfort is analyzed. The resulting rules for parametrization are validated by experimental studies with a robot with six degrees of freedom.