Human-Machine Interface Degree of Freedom Effects on Performance in Space Telerobotics

INTRODUCTION: There are many potential human-machine interfaces for controlling complex robotics. However, restrictions in hardware, software, or human capability may pose limits on the input device degrees-of-freedom (DOF). This study examined effects on operational performance and strategy when interface DOF were limited, hypothesizing that different limitations on interface DOF would affect operator performance and technique. METHODS: Experiments used a Canadarm2 simulator with a dual-joystick interface adapted to operate under limited DOF conditions. Four interfaces were compared: full multiaxis (FM), limited translation (TL), limited rotation (RL), and without simultaneous translation/rotation or "non-bimanual"(NB). Subjects were tasked with operating the Canadarm2 in a simulated ISS control scenario to approach and grapple a moving cargo vehicle within a 90-s time limit. RESULTS: No significant difference was seen between FM and RL in task time or grapple success, and both were significantly different from TL. NB exhibited significantly increased task time from FM and RL, but no significant difference in grapple success rate. When rotating, subjects decreased time spent using multirotation for NB over FM. DISCUSSION: Similar performance between FM and RL suggests that restricting rotation may be preferred for interfaces with DOF design limits. For the NB condition, there was increased task time combined with decreased multirotation, highlighting potential use for NB in training for rotation efficiency. Two different strategies were observed during TL to overcome inability to visually track, align with, and move toward the target simultaneously. Examination of these techniques provides insight on which strategic elements were most critical for success.