Research On Gait And CPG Adjustment For Movement Of A Quadruped Robot

Quadruped robot has high dynamic performance and stronger ability to adapt to the environment.It has been an important part in the field of robotics research.The basic theory and key technology of quadruped robot still need further study.This paper centers on the theory about central pattern generator(CPG)that is used to adjust the gait of quadruped robots.The research has established a virtual prototype and a physical prototype for experiments.In this paper,main work can be listed as follows:First of all,the paper analyzes the leg structure characteristics of common four-legged creatures in the nature,so hound is selected for bionic object.According to its physical characteristics and relationship between limb movements,to simplify the design,the size of quadruped robot is determined and the configuration is adopted as elbow joint for front legs and knee joint for back legs.Each leg has two active degrees of freedom(hip and knee)and a passive degrees of freedom(ankle).After kinematics analysis on simplified model,the foot end trajectory planning can be made rationally.Then,in view of the quadruped robot structure characteri stics and the implementation of gait features,design of robot rhythmic movement can be accomplished by CPG network model.Through the design of hip and knee mapping function,the CPG network model is simplified by four oscillator models coupling into full y symmetric network model.The output signal of CPG network can be transformed by mapping function into control signal used in joint angle of a virtual prototype.Coupling relationship between four oscillators can be expressed with a rotation matrix,quadruped robot can realize walk gait,trot gait and smooth gait transition between the two gaits by adjusting the parameters in the rotation matrix and the CPG network.Finally,the corresponding virtual prototype of quadruped robot is built in the ADAMS software,CPG network model is built in the Matlab/Simulink.Co-simulation experiment have been carried out through the exchange of two software.The corresponding physical prototype of quadruped robot is designed with the driver called pneumatic muscle and the control system have been debugged.In the environment of virtual prototype and physical prototype,gait verification experiments have been implemented by adjusting the parameters of the CPG network model.As a result,quadruped robot can walk stably,it verify the effectiveness of the CPG theory in achieving gait transition of the quadruped robot.