Cockroach's Turning Strategy Enhanced Hexapod Robot with Flexible Torso

Abstract

The design and control of hexapod robots have become an active research field due to the ability to achieve adaptive and stable multi-terrain locomotion. However, existing hexapod robots focus on the integration of flexible pitch joints to enhance their obstacle-crossing and slope-climbing abilities, and few biological observations have been made to gain insight into the agile steering mechanisms of hexapod insects. Herein, we observed the steering movements of Madagascar cockroaches. Observations showed that cockroaches exhibited specific phase relationships in addition to regular tripod gait pattern during steering. Moreover, we also found that a smaller steering radius resulted in a larger lateral bending angle of the thoracic segments. Inspired by this, a hexapod robot with a flexible torso (F-RHex) was designed and fabricated. Bio-inspired gait patterns were abstracted and simplified into two steering strategies: gait-based and mix-based. Compared to the purely gait-based strategy, the F-RHex testing results demonstrated a ~27.4% reduction in turning radius and ~40% enhancement in steering velocity, implying that the mix-based strategy offers superior steering capability.