Generation of bipedal walking through interactions among the robot dynamics, the oscillator dynamics, and the environment: Stability characteristics of a five-link planar biped robot

Abstract

We previously developed a locomotion control system for a biped robot using nonlinear oscillators and verified the performance of this system in order to establish adaptive walking through the interactions among the robot dynamics, the oscillator dynamics, and the environment. In order to clarify these mechanisms, we investigate the stability characteristics of walking using a five-link planar biped robot with a torso and knee joints that has an internal oscillator with a stable limit cycle to generate the joint motions. Herein we conduct numerical simulations and a stability analysis, where we analytically obtain approximate periodic solutions and examine local stability using a Poincaré map. These analyses reveal (1) stability characteristics due to locomotion speed, torso, and knee motion, (2) stability improvement due to the modulation of oscillator states based on phase resetting using foot-contact information, and (3) the optimal parameter in the oscillator dynamics for adequately exploiting the interactions among the robot dynamics, the oscillator dynamics, and the environment in order to increase walking stability. The results of the present study demonstrate the advantage and usefulness of locomotion control using oscillators through mutual interactions.

An intermittent control model of flexible human gait using a stable manifold of saddle-type unstable limit cycle dynamics

“…Although the phase resetting strategy is a powerful mechanism for improving gait stability [16,25], it is accompanied by modifications of the gait trajectory (phase-shift) with elevating and lowering patterns in response to external perturbations [4]. Thus, we characterize phase resetting as part of the above-mentioned requirement (ii), according to the classification proposed by Bruijn et al [2].…”

Optimization of humanoid walking controller: Crossing the reality gap

“…f balancing aRoll = −f balancing hRoll (3) i specifies the left or right leg, φ i is the phase of left or right CPG, and parameter A balancing specifies the amplitude of the lateral displacement motion. Leg flexion motion is performed by the unloaded leg.This is shown in eq.…”

“…Most typical approaches when implementing CPGs for bipedal walking use phase oscillators that are fed into pattern generation layers [21], [1], [3], [25] or using neural oscillators [19].…”

Influence of Biped Robot’s Walking Parameters on its Stability

“…Compared with other robots (wheeled, crawler etc. ), the humanoid robot has the following characteristics: Discrete supporting foot, alternately touching the ground, walking stability under different circumstances, increased flexibility, more suitable to replace human work in harsh environments; Walking humanoid robot is a high level, strong coupling, nonlinear multi-degree of freedom system and a typical study in control theory and control engineering fields [1]; Walking humanoid robots have anthropomorphic mobile features and better affinities. They are more suitable for the task together with human; Research on walking gait of humanoid robot can promote the development of kinetic prosthetic and rehabilitation medicine; Research on walking humanoid robot could also promote the development of artificial intelligence, bionics, sensors, communications, computers and other related disciplines [2].…”