Unimodal asymmetric interface for teleoperation of mobile manipulators: A user study

There is demand to develop methods and interfaces for teleoperation of complex systems in mission-critical applications. In this paper, we study three different methods to command a one-arm mobile manipulator from a 6-DOF input device capable of haptic feedback. The linkage between the master and the slave devices is asymmetric, that is, the input haptic interface (master) is much smaller and has different kinematics and dynamics from the robot arm and the mobile base (slave). Three different master-slave motion coordination schemes are compared here (1) workspace clutching, (2) differential end-zone, and (3) position/rate switching. We study repetitive user performance for seven subjects in a static Tower of Hanoi manipulation task and present single case studies for two mobile manipulation tasks: door opening and large-displacement Towers of Hanoi. Our experimental platform consists of a 4-DOF WAM (Whole Arm Manipulator) on a Segway RMP (Robotic Mobility Platform) controlled by a Phantom Omni haptic device. Cameras are used to relay scene images to the remote operator. The human stays in the loop throughout the entire task. The results obtained from user studies provide insight on how to interface and command a mobile manipulator.