Quasi-God Object and Geodesically Restricted 6-DOF Haptic Forces For Compliant Constraints and Low Frequency Simulation

Abstract

Haptic interaction plays a crucial role in enhancing realism and immersion in virtual environments, particularly in applications such as robotic rehabilitation. In these environments, therapy based on serious games that combine VR and haptic feed promise to offer engaging, affordable and reliable treatments. Most 6-DoF haptic methods have focused on precision in the kinematic fidelity of the haptic feedback. However, rehabilitation games for upper limb focus more on the forces exerted by the patient than the kinematic precision of the contacts with the virtual environment, since these exerted forces will be what powers the neuromuscular recovery of lost movement. We believe that a haptic control method with a focus on providing stable compliant and safe collisions is required to further the research into VR rehabilitation gamification. In addition, these solutions often rely on specifically tailored simulators running at very high frequencies. In contrast, commercial game engine that bring the most capabilities for gamification run at very low frequencies in comparison (≃50 Hz). In this work, we present a novel approach that integrates god object and penalty-based methods to achieve a balance between stability and computational efficiency, to enable 6-DoF haptic force generation on a collaborative robot. This is achieved through a relaxed quasi-god object simulation in the game engine and geodesic constraints in the robot’s haptic loop.