Judging the Effectiveness of a Passive Haptic Device in Teleoperation Based on the Average Angular Error in Force Generation

The research presented here focuses on the control limitations imposed by the use of passive actuators such as brakes or clutches in a planar haptic system. Previous research has addressed the issue within the framework of path following applications; however in a teleoperation system, the goal of a haptic interface centers around reproducing a force from the remote environment. As such a realistic haptic experience involves creating a force for the human to feel that matches the remote system both in magnitude or scaled magnitude as well as direction of force. To address the issue of matching force direction, the research presented here introduces the concept of average angle error, Avg(thetas_error), the average difference between an arbitrary desired haptic force and the closest force to it that the dissipative passive haptic device can produce. A portion of the material presented here will discuss the calculation of the value of Avg(thetas_error) for an arbitrary planar passive haptic device, and finally it will be evaluated over the workspace of a representative planar five-bar mechanism with various link lengths.