Design and Characterization of a Low-Profile Haptic System for Telemanipulation

In telemanipulation, supplementary feedback can enhance operator perception and control precision. This study introduces a haptic interface designed to convey temporally discrete tactile cues when remotely controlling a robot. Low-profile piezoelectric sensors were integrated in the thumb of a robotic hand to capture the key events of the manipulation task (i.e., object contact and release). Synchronously with such events, pressure bursts were delivered to the operators fingertip through a soft textile thimble equipped with inflatable pockets. Both this haptic display and the sensing module were individually evaluated. The pneumatic system responsible for pockets inflation was characterized in terms of reaction time, proving suitable for the application with a latency of less than 70 ms. Regarding the sensing module, the behavior of the sensorized thumb was first evaluated under static conditions, identifying contact and release events when grasping with the robotic hand differently shaped objects fixed on a table. Then, the accuracy of the touch event detection was assessed while performing a more complex manipulation task (i.e., a pick and lift task). This evaluation was conducted first with the robot programmed to grasp and lift an object following pre-defined trajectories, where we measured accuracy of 100% for contact and 90% for release event detection. Then, we performed a telemanipulation pilot study involving eight participants, where the system proved capable of correctly detecting object contact and release events with an accuracy of 100 and 86.4%. Despite preliminary, these results confirmed proper functioning of the system and paved the way for the exploration of a new haptic feedback policy in telemanipulation based on temporally discrete tactile events.