Spring-Brake! Handed Shearing Auxetics Improve Efficiency of Hopping and Standing

TL;DR

This paper introduces a novel Handed Shearing Auxetic (HSA) mechanism that improves energy efficiency in legged robots by combining spring and break functions in a single, lightweight component, enhancing static and dynamic performance.

Contribution

The paper presents a new auxetic-based compliant mechanism that reduces energy consumption and system complexity in legged robots by integrating dual functionality in a single element.

Findings

HSA reduces electrical power during hopping by acting as a spring.

HSA supports heavy static loads without motor torque.

HSA matches the efficiency of state-of-the-art compliant hoppers.

Abstract

Energy efficiency is critical to the success of legged robotics. Efficiency is lost through wasted energy during locomotion and standing. Including elastic elements has been shown to reduce movement costs, while including breaks can reduce standing costs. However, adding separate elements for each increases the mass and complexity of a leg, reducing overall system performance. Here we present a novel compliant mechanism using a Handed Shearing Auxetic (HSA) that acts as a spring and break in a monopod hopping robot. The HSA acts as a parallel elastic actuator, reducing electrical power for dynamic hopping and matching the efficiency of state-of-the-art compliant hoppers. The HSA\u2019s auxetic behavior enables dual functionality. During static tasks, it locks under large forces with minimal input power by blocking deformation, creating high friction similar to a capstan mechanism. This allows the leg to support heavy loads without motor torque, addressing thermal inefficiency. The multi-functional design enhances both dynamic and static performance, offering a versatile solution for robotic applications.