Analysis of the gait generation principle by a simulated quadruped model with a CPG incorporating vestibular modulation

• Published in: Biological cybernetics Vol. 107; no. 6; pp. 695 - 710
• Main Authors: Fukuoka, Yasuhiro, Habu, Yasushi, Fukui, Takahiro
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-12-2013; Springer; Springer Nature B.V
• Subjects: Adaptation, Physiological; Animals; Applied sciences; Bioinformatics; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Central Pattern Generators - physiology; Complex Systems; Computer Appl. in Life Sciences; Computer science; control theory; systems; Computer Simulation; Control theory. Systems; Exact sciences and technology; Feedback control systems; Fundamental and applied biological sciences. Psychology; Gait - physiology; Humans; Kinesiology; Locomotion - physiology; Mathematics; Models, Neurological; Motor ability; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Muscles; Neurobiology; Neurons; Neurosciences; Nonlinear Dynamics; Original Paper; Peripheral nervous system. Autonomic nervous system. Neuromuscular transmission. Ganglionic transmission. Electric organ; Robotics; Studies; Vertebrates: nervous system and sense organs; Vestibule, Labyrinth - parasitology; Japan; Simulation study; Quadrupedal locomotion; Central pattern generator; Gait generation; Vestibular modulation; Brain; Pattern generator; Gait; Quadrupedy; Central nervous system; Feedback regulation; Nervous system; Modeling; Encephalon; Posture; Oscillation; Muscle; Legged locomotion; Breaking in; Rhythm; Synchronization; Tilt angle; Walking; Animal; Tilt
• ISSN: 0340-1200; 1432-0770
• DOI: 10.1007/s00422-013-0572-4

This study aims to understand the principles of gait generation in a quadrupedal model. It is difficult to determine the essence of gait generation simply by observation of the movement of complicated animals composed of brains, nerves, muscles, etc. Therefore, we build a planar quadruped model with simplified nervous system and mechanisms, in order to observe its gaits under simulation. The model is equipped with a mathematical central pattern generator (CPG), consisting of four coupled neural oscillators, basically producing a trot pattern. The model also contains sensory feedback to the CPG, measuring the body tilt (vestibular modulation). This spontaneously gives rise to an unprogrammed lateral walk at low speeds, a transverse gallop while running, in addition to trotting at a medium speed. This is because the body oscillation exhibits a double peak per leg frequency at low speeds, no peak (little oscillation) at medium speeds, and a single peak while running. The body oscillation autonomously adjusts the phase differences between the neural oscillators via the feedback. We assume that the oscillations of the four legs produced by the CPG and the body oscillation varying according to the current speed are synchronized along with the varied phase differences to keep balance during locomotion through postural adaptation via the vestibular modulation, resulting in each gait. We succeeded in determining a single simple principle that accounts for gait transition from walking to trotting to galloping, even without brain control, complicated leg mechanisms, or a flexible trunk.