# Reinventing the wheel: a simulation-aided design of a soft, shape-adapting, lugged wheel for locomotion on sandy terrains

## TL;DR

This paper presents a new soft, shape-changing wheel design for robots to move efficiently on sandy terrains using simulation.

## Contribution

A co-simulation framework combining DEM and MBD is used to design a soft, shape-adapting wheel for sandy terrain locomotion.

## Key findings

- Shape-adapting wheels improve performance on sandy terrains, including slopes and obstacles.
- Soft wheels enhance obstacle climbing, while lugged configurations work best on loose, dry sand.
- The DEM-MBD co-simulation reduces the need for physical prototyping in terrain locomotion design.

## Abstract

Locomotion over granular terrain poses significant challenges for autonomous robotic systems, particularly in coastal regions characterized by loose, shifting sands. To optimize the locomotion on these challenging terrains, a simulation-aided design approach was used to develop a soft, shape-adapting, wheeled locomotion system. A co-simulation framework combining the discrete element method (DEM) and multibody dynamics (MBD) is employed to simulate the locomotion of a wheeled robot on varying sandy soils, covering both dry and wet sandy soil conditions. A shape-adapting wheel design is proposed, incorporating soft, inflatable elements that enable the wheel to transform between lugged and circular configurations. A discretized flexbody approach is adopted to model the interactions between the sandy soil and the soft, flexible bodies of the shape-adapting wheel design. Simulation results demonstrate improved performance of the shape-adapting wheels across a variety of sandy terrains, including slopes and obstacles. Integrating softness into the wheel improves obstacle climbing performance, while a lugged wheel configuration performs particularly well on loose, dry sandy slopes. This DEM-MBD co-simulation further enables efficient evaluation of locomotion strategies without the need for extensive physical prototyping.