Adaptive Dynamic Walking of a Quadruped Robot on Irregular Terrain Based on Biological Concepts

Abstract

We have been trying to induce a quadruped robot to walk with medium walking speed on irregular terrain based on biological concepts. We propose the necessary conditions for stable dynamic walking on irregular terrain in general, and we design the mechanical system and the neural system by comparing biological concepts with those necessary conditions described in physical terms. A PD controller at the joints can construct the virtual spring-damper system as the visco-elasticity model of a muscle. The neural system model consists of a central pattern generator (CPG) and reflexes. A CPG receives sensory input and changes the period of its own active phase. The desired angle and P-gain of each joint in the virtual springdamper system is switched based on the phase signal of the CPG. CPGs, the motion of the virtual spring-damper system of each leg and the rolling motion of the body are mutually entrained through the rolling motion feedback to CPGs, and can generate adaptive walking. We report on our experimental results of dynamic walking on terrains of medium degrees of irregularity in order to verify the effectiveness of the designed neuro-mechanical system. We point out the trade-off problem between the stability and the energy consumption in determining the cyclic period of walking on irregular terrain, and we show one example to solve this problem. MPEG footage of these experiments can be seen at http://www.kimura.is.uec.ac.jp.

Horse-like walking, trotting, and galloping derived from kinematic Motion Primitives (kMPs) and their application to walk/trot transitions in a compliant quadruped robot

“…For this reason many researchers have sought to analyze animal gait (Hoyt and Taylor, 1981), with the aim of reproducing this on robots. Different methods for biological inspirations have been proposed: Collins and Richmond (1994); Fukuoka et al (1999Fukuoka et al ( , 2003; Billard and Ijspeert (2000); Fujii et al (2002); Witte et al (2003); Ishii et al (2004); Son et al (2006); Cappelletto et al (2006Cappelletto et al ( , 2007; Righetti and Ijspeert (2008) ;Rutishauser et al (2008); Liu et al (2009), with the well known theory of Central Pattern Generators (CPG) forming a common theme. According to the theory of CPG, open-loop signals are produced in the spinal cord and sent to the limbs to produce the motion, reducing significantly the complexity of controlling a vast variety of motions.…”

A Dynamical Systems Approach to Learning: A Frequency-Adaptive Hopper Robot

“…In [12] the mechanical stability of spring-mass systems is discussed. Recently, robots with legs including elastic elements have been presented [10,13,14]. Coupled oscillators have been extensively studied for locomotion control [7,20,19,10].…”

“…Recently, robots with legs including elastic elements have been presented [10,13,14]. Coupled oscillators have been extensively studied for locomotion control [7,20,19,10]. However, usually the structure and parameterization of these controllers are fixed by heuristics or are adapted with algorithms which are not formulated in the language of dynamical systems.…”

Co-evolution of Structures and Controllers for Neubot Underwater Modular Robots

“…CPGs have been used in the modular M-Tran system described above [11,12], in "monolithic" robots [13], and in simulated robots [14]. CPGs are interesting for modular robotics because of their distributed nature and their ability to generate efficient locomotion for complex multi-DOF structures while being modulated by simple control signals.…”