Gait Transition from Pacing by a Quadrupedal Simulated Model and Robot with Phase Modulation by Vestibular Feedback

Takahiro Fukui,Souichiro Matsukawa,Yasushi Habu,Yasuhiro Fukuoka

doi:10.3390/robotics11010003

Takahiro Fukui, Souichiro Matsukawa + Show 2 more

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https://doi.org/10.3390/robotics11010003

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Abstract

We propose a method to achieve autonomous gait transition according to speed for a quadruped robot pacing at medium speeds. We verified its effectiveness through experiments with the simulation model and the robot we developed. In our proposed method, a central pattern generator (CPG) is applied to each leg. Each leg is controlled by a PD controller based on output from the CPG. The four CPGs are coupled, and a hard-wired CPG network generates a pace pattern by default. In addition, we feed the body tilt back to the CPGs in order to adapt to the body oscillation that changes according to the speed. As a result, our model and robot achieve stable changes in speed while autonomously generating a walk at low speeds and a rotary gallop at high speeds, despite the fact that the walk and rotary gallop are not preprogramed. The body tilt angle feedback is the only factor involved in the autonomous generation of gaits, so it can be easily used for various quadruped robots. Therefore, it is expected that the proposed method will be an effective control method for quadruped robots.

Highlights

Quadruped mammals choose a gait according to their speed [1]
Grillner [20] and Golubitsky et al [21] reported that gait transition occurs as a result of each leg swinging reflexively with a central pattern generator (CPG), which is a neural circuit existing in the spinal cord
It was confirmed by experiments that no gait other than pacing appeared in walking without vestibular modulation, and that changes in the values of speed parameters had no effect on gait transition

Summary

Introduction

Most quadruped mammals choose a walk at low speeds, while at medium and high speeds the chosen gait varies depending on species. There are quadruped simulation models [22,23,24,25,26] and quadruped robots [23,24,27,28,29,30] that autonomously produce gaits not defined by CPG. These autonomously modify the phase differences between the four legs by using external factors such as sensory feedback and, as a result, some gaits emerge.

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