Delft Haptics Lab

Hybrid design combining position and rate control allows intuitive workspace extension for teleoperation

Abstract

A common method to obtain workspace extension of the slave’s workspace is through rate control because it has an unlimited workspace of the slave. However, when contact interaction with the remote environment is needed, position control is often proposed due to the force feedback. To benefit from the strengths of both of these control types, hybrid designs have been proposed which combine both position and rate control within one design. Human factors evaluation is lacking to compare benefits and limitations of hybrid designs against the two common applied workspace extension designs: indexing and rate control. The objective of this study is to evaluate if a hybrid design can combine the strengths of large free-space motion for rate control, and accurate positioning and executing a force task for indexing. In this research, a hybrid design was developed (based on existing designs) in which force feedback for rate control was added. A within subject human-in-the-loop haptic teleoperation experiment (N=12) was performed to compare performance for this hybrid design against indexing and rate control for a task including traversing a substantial distance (free-space subtask) and exerting a constant force against a remote environment (force subtask). The results show that the hybrid design allowed subjects to realize similar performance for the subtask free-space motion as for rate control, in combination with similar performance for the subtask exerting a force as for position control with clutching. This indicates that this hybrid workspace extension design enables the operator to use the benefits of position and rate control.