# Slip estimation model for traversability-based motion planning of cargo rover on extraterrestrial surface

## TL;DR

This paper introduces a model to estimate wheel slip for cargo rovers on rough extraterrestrial terrain, enabling safer and more efficient motion planning.

## Contribution

A novel parametric slip estimation model that accounts for varying payload mass and terrain conditions for cargo rovers.

## Key findings

- The slip estimation model was validated using multi-body dynamics analysis datasets.
- The model reduces computational load, making it suitable for onboard implementation.
- Motion planning simulations showed improved safety and target reachability regardless of payload.

## Abstract

As part of the robotics technologies required for In-situ resource utilization (ISRU), the development of cargo rovers for transporting resources is needed. However, these cargo rovers have unique technical challenges that differ from conventional exploration rovers, including the need to traverse rough terrains with their varying mass due to transporting payloads. Moreover, research addressing these challenges has been limited, and the relevant technologies have not been fully established. To address these challenges, this paper proposes a parametric model for estimating wheel slippage. The model is formulated as a function of four input parameters: slope angle, rover heading angle, payload mass, and wheel angular velocity, and is applicable to resource-transporting rovers with varying mass. Additionally, the use of a parametric model reduces computational load, which offers advantages for onboard implementation. The proposed estimation model was quantitatively evaluated by comparing datasets obtained from multi-body dynamics analysis. This paper also introduces a new traversability assessment model which incorporates the proposed slip estimation model. We demonstrated the proposed model by integrating it into a sampling based motion planning. The simulation result of the motion planning show that the planner with our model can generate safer motions and enables the rover to reach the target regardless of the cargo payload.