A New Hybrid Teleoperation Control Scheme for Holonomic Mobile Manipulator Robots Using a Ground-based Haptic Device⋆

Teleoperating mobile manipulator (MM) robots using a single ground-based haptic (GBH) device is challenging due to differences in workspaces and mechanical structures. A hybrid control scheme combines navigation and manipulation modes to operate a robot using manual or automatic mode switching. Although an automatic scheme tends to reduce the user’s mental workload, in some cases, the bilateral teleoperation system loses transparency when interacting with the environment; in others, the interaction with the environment may happen in inappropriate operation mode without the user’s awareness. To overcome those challenges, this paper proposes a new hybrid control scheme for bilateral teleoperation of holonomic MM robots. In this scheme, while navigating, the user’s hand motion is restricted by an artificial force to prevent reaching the boundary of the GBH device’s workspace. When the end-effector touches the environment, a method not requiring any exteroceptive sensor automatically switches the operation mode to manipulation mode. After completing the remote task, the user must switch to navigation mode manually. The simulation results indicate that the baseline bubble technique, a widely used automatic scheme, creates over 50% of forces on the haptic interface unrelated to environmental interaction, resulting in transparency deterioration. On the other hand, with our proposed technique, the bilateral system becomes transparent in under 0.3 s.