A grasp-based passivity signature for haptics-enabled human-robot interaction: Application to design of a new safety mechanism for robotic rehabilitation

Abstract

In this paper, the biomechanical capability of the human upper limb in absorbing physical interaction energy during human-robot interaction is analyzed. The outcome is a graphical map that can quantitatively correlate the extent of the grasp pressure and the geometry of interaction to the extent of hand passivity. For this purpose, a user study has been conducted for 11 healthy human subjects to characterize the energy absorption capability in their arm and wrist. The above correlation is statistically validated. The identified user-specific grasp-based passivity signature map can be used as a graphical tool to assess the biomechanical capabilities of the upper limb in absorbing interaction energy. In this paper, the proposed grasp-based passivity signature map is utilized in the design of a new stabilizer for haptic systems, that takes into account the variation in energy absorption during haptic task execution. The goal is to optimize the haptic system fidelity while guaranteeing human-robot interaction stability despite the potential existence of delays and a non-passive environment. The controller is termed grasp-based passivity signature map stabilizer. If the user provides minimum to no energy absorption during the interaction, the controller makes the force reflection gate tight to guarantee stability. However, when the user demonstrates high capability in absorbing interaction energy, the controller allows the forces to be reflected. The grasp-based passivity signature map stabilizer is an alternative for both conventional stabilizers of haptic/telerobotic systems and fixed conservative force limits in rehabilitation systems where patient-robot interaction safety is a crucial requirement. This provides the practical motivation for this work. Experimental results are presented.

The effect of tactile augmentation on manipulation and grip force control during force-field adaptation

“…An important issue in physical interaction with robotic devices is stabilityit is critical for the safety of the interaction. Regarding to kinesthetic haptic devices, the effectiveness of robotics for rehabilitation may be limited due to the stability constraints [86][87][88]. Tactile devices do not apply net forces on the users, and therefore, they do not entail instability.…”

Estimation of Energy Absorption Capability of Arm Using Force Myography for Stable Human-Machine Interaction

“…This is achieved by absorbing the destabilizing energy generated by the robot, through the modulation of the arm dynamics [12]. As a result, the passivity of the dynamics projected to the human can be relaxed to increase performance, and only the amount of energy that can be absorbed by the human arm is transferred to the user [13].…”

“…There are various methods to reduce the amount of energy that flows to the user. Among these methods are damping, to flush the excess of energy [7], and scaling or capping of the interaction forces to limit the energy flow [13]. The efficiency of these methods depends on how accurately the arm's energy absorption capability is estimated.…”

A Task Learning Mechanism for the Telerobots

“…The authors analyzed the cost energy of the upper limb via evaluation of hand grasp pressure and passivity interaction for teleoperation. 20 Shahbazi et al presented a passivity method with respect to human upper limb for the purpose of the natural and safe human-robot interaction (HRI). 21 Potential answers were developed to deal with the in°uence factors which involve human in terms of frame rates, image issue, and so on.…”