On a CPG-Based Hexapod Robot: AmphiHex-II With Variable Stiffness Legs

Abstract

Amphibious robots have attracted more and more attention from researchers for their broad applications, while it also brings great challenges in designing appropriate propulsion mechanisms and effective control algorithms. In this paper, we reported a newly designed amphibious hexapod robot-AmphiHex-II. This robot possesses six newly designed variable stiffness legs for adapting various complex environments. This novel design of the variable stiffness leg seamlessly incorporates the advantages of both semi-circular walking legs and the swimming flexible flippers. The legs are constructed by rigid fan-shaped frames which work as walking legs for terrestrial locomotion and protect the contained flexible flippers used for aquatic locomotion during terrestrial operations. The stiffness of legs can be adjusted to an effective degree by adjusting the positions of sliders manually. The effect of variable stiffness on locomotion performance was experimentally investigated. Moreover, in order to achieve a smooth and quick gait transition, a Central Pattern Generator (CPG) neural network was introduced to control the system. Different gait generation strategies on land and underwater were demonstrated. A series of field experiments were carried out to evaluate locomotion performance of the AmphiHex-II for terrestrial and aquatic mobility, and the results demonstrate the advantages of the novel leg design and the control system.

Locomotion Strategies for Amphibious Robots-A Review

“…The amphibious quadruped robot legs are multi-functional in the terrestrial environment with crawling, walking, climbing, and throttling gaits [39]. In the aquatic medium, the legs are used for seabed walking [40], underwater walking [41], flipper legs as swimming gait (oscillating and adulating) [42], and complaint feet as water runner on the surface of the water [43]. The formation of a triangular polygon with a minimum number of legs of a quadruped amphibious robot makes them statistically stable.…”

“…The literature reports amphibious hexapods leg designs, all-terrain walking legs for terrestrial locomotion [42], efficient flipper for swimming, and transformable morphing limb design [52]. Amphibious hexapod robots have exploited design from other robots classes to achieve versatile locomotion in the terrestrial mode and outstanding mobility in the water mode.…”

Design and modeling analysis of a changeable stiffness robotic leg working with magnetorheological technology

“…C-type legs have achieved good locomotion performance in terrestrial robots such as RHex (Campbell and Buehler, 2003) and AmphiHex series (Zhang et al, 2016; Zhong et al, 2018). On the basis of our previous work (Jiang et al, 2016), an improved MRF leg with a larger stiffness range is presented in this article.…”

Robotik Uygulamalar İçin Titreşime Dayalı Hareket Eden Amfibik İlerleme Mekanizması

“…Son zamanlarda dikkatleri üzerine çeken amfibik robotlar; altı bacaklı bir amfibik robot olan AmphiHex-II [25] ve bir vatoz gibi silikon yüzgeçlerini kullanarak hareket edebilen Velox' dur [26]. AmphiHex-II, farklı ortamlara adaptasyon sağlayabilmek için tasarlanmış ayarlanabilir ayak sertlikleri ile yüksek ilerleme performansına sahiptir.…”