Abstract: Locomotion performance degradation after carrying payloads is a significant challenge for insect-scale microrobots. Previously, a legged microrobot named BHMbot with a high load-carrying capacity based on front-leg actuation configuration and efficient running gait was proposed. However, insects, mammals and reptiles in nature typically use their powerful rear legs to achieve rapid running gaits for predation or risk evasion. In this work, the load-carrying capacity of the BHMbots with front-leg actuation and rear-leg actuation configurations is comparatively studied. Simulations based on a dynamic model with four degrees of freedom, along with experiments, have been conducted to analyze the locomotion characteristics of the two configurations under different payload masses. Both simulation and experimental results indicate that the load-carrying capacity of the microrobots is closely related to their actuation configurations, which leads to different dynamic responses of the microrobots after carrying varying payload masses. For microrobots with body lengths of 15 mm, the rear-leg actuation configuration exhibits a 31.2% enhancement in running speed compared to the front-leg actuation configuration when unloaded. Conversely, when carrying payloads exceeding 5.7 times the body mass (350 mg), the rear-leg actuation configuration demonstrates an 80.1% reduction in running speed relative to the front-leg actuation configuration under the same payload conditions.

Key words: Insect-scale legged microrobots')">Insect-scale legged microrobots, Actuation configurations, Load-carrying capacity, Locomotion analysis