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

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.

Another Mechanism for Gait Generation: Mechanical Stabilization Can Spontaneously Realize Walking in a Two-Legged Robot

“…The central pattern generator (CPG) was proposed as a model for the generation of rhythmic locomotion in living organisms based on physiological findings from animal experiments and has been studied by applying a rhythmic generator in the spine as a controller [17][18][19][20][21][22][23][24][25]. The CPG was proposed to be located in the vertebrae of animals [26], starting from the work of Brown et al in the decerebrate cat [27], which is a predecessor of the CPG.…”

“…Therefore, although they are vulnerable to environmental changes, they unprecedentedly perform efficient locomotion [31][32][33][34][35]. Recently, robots that can change gait patterns have been proposed [22][23][24][25]36]. Many of these robots incorporate the CPG, which are mechanisms that generate gait patterns with no explicit predesign via reflexive rhythm generation.…”

Bio-Inspired Gait Transitions for Quadruped Locomotion

“…To circumvent the instabilities engendered by a rudimentary approach of hard-switching gaits, numerous studies in the literature aim to devise methods for seamlessly transitioning between different gaits. A prevalent method of gait generation and transition involves utilising a Central Pattern Generator (CPG) [8], [9]. These studies employ a network to generate a cyclic gait pattern based on a reference velocity, where natural gait transitions occur as velocity increases.…”