Virtual fixtures can be used in haptic-enabled hydraulic telemanipulators to facilitate certain tasks. Using this concept, however, the operator may tend to move the master fast due to relying on the virtual fixture. As a result, the slave manipulator could start to lag due to latency in the hydraulic actuation control system. This paper describes how to mitigate the position errors between master and slave robots by overlaying an augmentation force on the master that is collinear but opposite of the master instantaneous velocity. The magnitude of this force is proportional to the position error at the slave end-effector. Experiments, conducted on a teleoperated hydraulic manipulator to perform several live-line maintenance tasks, show that the augmented scheme exhibits less position error at the slave side, better task quality, but longer task completion time as compared to the virtual fixture alone. 
An augmented virtual fixture to improve task performance in robot-assisted live-line maintenance