Sprawling Quadruped Robot Driven by Decentralized Control With Cross-Coupled Sensory Feedback Between Legs and Trunk

Abstract

Quadruped animals achieve agile and highly adaptive locomotion owing to the coordination between their legs and other body parts, such as the trunk, head, and tail, that is, body–limb coordination. This study aims to understand the sensorimotor control underlying body–limb coordination. To this end, we adopted sprawling locomotion in vertebrate animals as a model behavior. This is a quadruped walking gait with lateral body bending used by many amphibians and lizards. Our previous simulation study demonstrated that cross-coupled sensory feedback between the legs and trunk helps to rapidly establish body–limb coordination and improve locomotion performance. This paper presented an experimental validation of the cross-coupled sensory feedback control using a newly developed quadruped robot. The results show similar tendencies to the simulation study. Sensory feedback provides rapid convergence to stable gait, robustness against leg failure, and morphological changes. Our study suggests that sensory feedback potentially plays an essential role in body–limb coordination and provides a robust, sensory-driven control principle for quadruped robots.

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

“…Suzuki et al reported that a walk is generated by feedback of the joint torque to the CPG, and that the speed increased and the energy consumption improved [48]. We have achieved similar results in our previous work [32], which demonstrated that when the gait transitioned from a trot to a gallop, the speed increased sharply and the energy consumption decreased.…”

Spontaneous Gait Transitions of Sprawling Quadruped Locomotion by Sensory-Driven Body–Limb Coordination Mechanisms

“…Each trial was conducted on flat terrain for 60 s, with the oscillator phases initially set to random. The body size and weight were determined by considering those of a salamander robot developed as a prototype in our previous study (Suzuki et al 2019b). The angular frequency and amplitude of the legs were chosen with physically plausible values.…”

“…The interactions of the sensory feedback from body to limb and limb to body establish the relationship between the legs and trunk, providing longer strides and more powerful pushing-off against the ground. The interactions of the body-to-limb and limb-to-body feedback establish the relationship between the legs and trunk, providing longer strides and more powerful pushing-off against the ground (Suzuki et al, 2019(Suzuki et al, , 2021. Equation ( 7) relates to the body-to-body feedback.…”

“…We aim to understand the contribution of sensory feedback to body-limb coordination. We previously proposed a decentralized control model with cross-coupled sensory feedback from the body to limb, and vice versa, in simulated and real sprawling quadruped robots (Suzuki et al, 2019(Suzuki et al, , 2021. Body-limb coordination was successfully established by sensory couplings without inter-oscillator couplings.…”

Bio-inspired neural networks for decision-making mechanisms and neuromodulation for motor control in a differential robot

“…Other approaches bring us a neat use of CPGs in order to control a sprawling quadruped robot (Suzuki et al, 2021), contributing to decentralized control with cross-couple sensory feedback to shaping body-limb coordination, which differs from previous research based on CPGs that works with inter-oscillator couplings or gait patterns based on geometric mechanics. Ngamkajornwiwat et al (2020) propose an online self-adaptive locomotion control technique based on the integration of a modular neural locomotion control (MNCL) and an artificial hormone mechanism (AHM) for a walking hexapod robot.…”