Creating a biologically more accurate spider robot to study active vibration sensing

TL;DR

This study presents a new, biologically accurate spider robot with improved leg morphology and active crouching capabilities, enabling better investigation of vibration sensing mechanisms used by real spiders.

Contribution

A novel eight-legged spider robot with enhanced morphology and active crouching, providing a more accurate model for studying vibration sensing in orb-weaving spiders.

Findings

Robot reproduces key vibration features of real spiders

Deep leg crouching enhances vibration sensing capabilities

Improved biological accuracy over previous models

Abstract

Orb-weaving spiders detect prey on a web using vibration sensors at leg joints. They often dynamically crouch their legs during prey sensing, likely an active sensing strategy. However, how leg crouching enhances sensing is poorly understood, because measuring system vibrations in behaving animals is difficult. We use robophysical modeling to study this problem. Our previous spider robot had only four legs, simplified leg morphology, and a shallow crouching range of motion. Here, we developed a new spider robot, with eight legs, each with four joints that better approximated spider leg morphology. Leg exoskeletons were 3-D printed and joint stiffness was tuned using integrated silicone molding with variable materials and geometry. Tendon-driven actuation allowed a motor in the body to crouch all eight legs deeply as spiders do, while accelerometers at leg joints record leg vibrations. Experiments showed that our new spider robot reproduced key vibration features observed in the previous robot while improving biological accuracy. Our new robot provides a biologically more accurate robophysical model for studying how leg behaviors modulate vibration sensing on a web.