Simulation Research On WCPG-based Motion Control Of Quadruped Robots In Complex Environment

Quadruped robots have great potentials in military, transportation and operation in dangerous conditions, however, these application demands couldn't be met by the motion control research of quadruped robots on flat ground in labs. There is a pressing need for the motion control of quadruped robots to extend its research from flat ground to uneven terrains and complex environments with external impact. This thesis starts from a bionic view and bases on the mechanism of rhythmic motions of animals, and then designs the gait generation methods and motion control algorithms for quadruped robots moving on uneven terrains and undergoing lateral impact as well as on flat ground based on Workspace Central Pattern Generators(WCPG).To begin with, this thesis analyzes gait description methods and several typical gait forms of quadruped animals, and by exploring the generation mechanisms of rhythmic motion of animals, the thesis introduces the gait generation method based on CPG. After analyzing both the advantages and disadvantages of the CPG method, this article chooses a gait generation method called WCPG(Workspace Central Pattern Generators), which could be used to generate the foot trajectories of both swing phase and stance phase of the legs. Then the WCPG network for quadruped robots is constructed and applied to generate four typical gaits with the assignment of different gait matrixes.Besides the accomplishment of gait generation algorithms for quadruped robots on flat ground, the methods for quadruped robots to move stably in complex environments should also be taken into consideration. Quadruped robots could not move stably on uneven terrains without the help of contact switches or force sensors or even effective motion control algorithms. Taking the reflex mechanisms of animals on ditch, stair and slope and even undergoing external lateral impact as a reference, this thesis plans the motion control reflex model for quadruped robots in these complex environments, and designs the strategies and algorithms of coordination movements of the four legs and the attitude adjustment of the body for quadruped robots relatively moving on ditch, slope and down stair, and under external lateral impact.Finally, to verify the effectiveness of the gait generation methods and motion control algorithms proposed above, the simulation model of the quadruped robot is established using the ADAMS and Simulink co-simulation platform. Through the utility of designed gait generation algorithms based on WCPG and the reflex strategies of quadruped robots moving in complex environments, this thesis realizes the quick adjustment and return to stable stateswhen moving on ditch, down stair, on slope and even undergoing external lateral impact, as well as the walk and trot gaits of this robot on flat ground. All these simulation results fits the expected stable locomotion performance, which proves that the gait generation methods and reflex strategies proposed have good control effects for quadruped robots in complex environments.