Dynamic compensating controller for passive haptic manipulators in teleoperation

Haptic devices allow a human user to physically interact with the virtual or simulated world by generating real forces to represent interactions in the virtual world. By definition, haptic devices exist in the set of robotic systems whose workspaces must overlap with the workspace of the human. For that reason, safety of the human becomes a central concern when developing both the physical hardware and the control systems for new and novel interfaces. Passive haptic devices, ones that display forces to the user by using passive actuators such as brakes, clutches of continuously variable transmissions, address the concerns of stability and safety by using actuators that physically guarantee a bounded output and the safety of the human user. However, a device using passive actuators can only produce a subset of the forces generated by a similar device built around active actuators. The work presented here will explore the use of a passive haptic device specifically with respect to teleoperation and will present a new algorithm for determining feedback that improves the transparency, a dynamic compensating controller. This controller will be implemented in LabVIEW on passive hardware and will be compared to two simpler control schemes in two typical teleoperation tasks, shape identification and point to point motion around an obstacle. The results will show that the passive device provides feedback that allows the user to recognize large surface features. Furthermore, results will show that the dynamic compensating controller proves especially useful in dynamic situations represented by the motion task.