SenSnake: A snake robot with contact force sensing for studying locomotion in complex 3-D terrain

TL;DR

This paper introduces SenSnake, a snake robot equipped with contact force sensors, enabling systematic study of 3-D locomotion in complex terrains and providing insights into biological snake movement.

Contribution

Developed a 12-segment snake robot with distributed force sensors and compliant shells, facilitating controlled experiments on force-based locomotion in 3-D environments.

Findings

Achieved high repeatability in force measurement during obstacle traversal

Successfully calibrated sensors considering viscoelastic behavior

Enabled systematic experiments for studying force-modulated locomotion

Abstract

Despite advances in a diversity of environments, snake robots are still far behind snakes in traversing complex 3-D terrain with large obstacles. This is due to a lack of understanding of how to control 3-D body bending to push against terrain features to generate and control propulsion. Biological studies suggested that generalist snakes use contact force sensing to adjust body bending in real time to do so. However, studying this sensory-modulated force control in snakes is challenging, due to a lack of basic knowledge of how their force sensing organs work. Here, we take a robophysics approach to make progress, starting by developing a snake robot capable of 3-D body bending with contact force sensing to enable systematic locomotion experiments and force measurements. Through two development and testing iterations, we created a 12-segment robot with 36 piezo-resistive sheet sensors distributed on all segments with compliant shells with a sampling frequency of 30 Hz. The robot measured contact forces while traversing a large obstacle using vertical bending with high repeatability, achieving the goal of providing a platform for systematic experiments. Finally, we explored model-based calibration considering the viscoelastic behavior of the piezo-resistive sensor, which will for useful for future studies.