Research On Structural Design And Motion Planning Of Quadruped Robot

Compared with wheeled or tracked robots,quadruped robots can walk on irregular terrains using legged structures,and are highly adaptable to complex environments.Obviously,quadruped robots have wide potential application prospects,especially in the engineering survey,rescue,disaster relief,anti-terrorism and riot prevention.Aiming at the walking stability of the quadruped robot,this paper focuses on the structural design and motion planning,completes the robot structural design,studies the robot gait and posture adjustment strategies in different environments,analyzes the motion error of endpoints and designs the tracking algorithm,and verifies the results through corresponding simulation and experiments.The main research work is as follows:(1)A campact quadruped robot is designed.According to the structural characteristics and motion characteristics of the quadruped robot,the legged structure and the trunk structure are analysized and designed;The mechanical simulation software is used to perform mechanical analysis and strength checking on the key structural parts to verify the bearing capacity of the quadruped robot structure;Based on the design and analysis of the structure,a mobile platform for the quadruped robot is established.(2)The kinematics model of the quadruped robot is established.The robot coordinate system is established according to the standard D-H method.The kinematics equations of the robot are derived using coordinate transformation.The workspace,differential kinematics,and static transformation are analyzed,which lays the foundation for the trajectory planning and gait design.(3)Crawling gait planning and walking stability of quadruped robot are studied.Based on the ZMP method,the mathematical expression of the stability margin is derived to study the walking stability of the robot.A trajectory planning method based on a compound cycloid is proposed,and the trajectory of endpoints and torso is planned based on this.Experiments show that this method not only makes the trajectory of endpoints and torso smooth,but also improves the obstacle-overcoming ability of the robot.Further,plane walking gait and fixed-point rotation gait are designed and the crawling error is analyzed by simulation experiments.In addition,the slope crawling gait and the step crawling gait are designed based on the plane gait.The corresponding posture adjustment strategies are proposed.The results of the simulation show that under the guidance of the posture adjustment strategies,the robot successfully complete the crawling task on the slope and step,while greatly improving the crawling stability margin.(4)A foot trajectory tracking algorithm based on model predictive control(MPC)is proposed.Based on the differential kinematics of the robot,a foot trajectory error model is established.Based on the MPC algorithm,a foot trajectory tracking controller is designed and simulation experiments are performed for different motion conditions.Simulation experiments show that the trajectory tracking algorithm can make the actual trajectory of the endpoint converge quickly to the reference trajectory under the condition of initial error.