Efficient Haptic Rendering of Regolith

Abstract

Driven by the need for physically accurate and haptically convincing models of lunar and planetary regolith for model-mediated teleoperation in space, we present an approach to modelling regolith in an efficient yet realistic way. Model parameters are derived from physical characteristics of the regolith, to render regoliths with different density profiles, cohesion, internal friction and in different gravitational fields.Users could distinguish between changes in parametersspecifically friction and gravity field-and also gave qualitative feedback relevant to modelling regolith. We discuss the challenges in haptically rendering soils and the next steps.

Verification of a virtual lunar regolith simulant

“…The main issue with the scalability of the model is that it relies on checking each particle-particle pair for collisions (Pereira and Schmidt, 2021). This results in N 2 calculations, where N is the number of particles, for each simulation frame.…”

“…Effect of number of particles on computation times of the original algorithm Pereira and Schmidt (2021) and the neighbouring particles algorithm used in this paper. Dashed grey line represents the maximum computation time that would achieve 1 kHz refresh rate required for haptic feedback.…”

“…While the high fidelity of these simulations will be valuable for fine-tuning hardware designs, there are many applications such as early stage prototyping and robot operator training which would benefit from a less resource intensive virtual representation of regolith. Pereira and Schmidt (2021) presented an efficient model of lunar regolith which can compute haptic interactions of particles with a tool in real time, refreshing at rates > 1 kHz. This was achieved using DEM with Smoothed-Particle Hydrodynamics (Cirio et al, 2011) and representing regolith as a collection of individual macroparticles (Hoffmann, 2006).…”

“…The intention of this work was to generate a "convincing haptic feel" of lunar regolith, and, as such, was validated by users for the subjective "feel" of the haptic feedback. In our work, we examine the feasibility of Pereira and Schmidt (2021)'s model in simulating the behaviour of regolith, by verifying it against a physical system.…”

“…In the following sections, we present an updated algorithm to virtually model lunar regolith, followed by an experimental verification of the model vs. a physical regolith simulant. We aim to build on Pereira and Schmidt (2021)'s previous work and attempt to answer the following questions:…”