Design And Analysis Of Continuous Electric Driven Quadruped Robot

Quadruped robot has better stability compare with biped robot,and has strong load capacity,simple structure and easy control compare with six-legged robot or multi-legged robot.It is one of the hot point in the research of legged robot.At present,a lot of research work has been done on the structure and mobility at home and abroad.There are still many problems in terms of high-speed,heavy-load,low energy consumption and so on.The application of quadruped robots in reality still has a long distance.Therefore,this thesis surrounds the need of quadruped robot such as miniaturization,heavy load,low energy consumption,and high efficiency.Aimed at the problems such as electric drive legged robot motor drive needs to change direction,high leg weight ratio(the ratio of leg weight and total weight of the robot),large inertia,etc.,a continuous electric driven(that is,the motor ratates cyclically to drive the leg to swing and stpe)quadruped robot leg program is proposed.The quadruped robot key problems of leg structure,foot trajectory,kinematics,dynamics,and gait planning etc.are researched in-depth.The main contents are as follows:(1)A continuous electric driven quadruped robot leg program is proposed.Robotic leg structure with one-degree-of-freedom double crank composite link mechanism is designed,which is combined Chebyshev mechanism and five-bar mechanism.Adopting the leg configuration of front elbow and hind knee,the overall structure of quadruped robot is obtained.The robot 3D model is also built.Through the leg structure kinematics analysis,the displacement expression of the foot is established.(2)The characteristics of the quadrupedal animal foot trajectory in the process of movement were analyzed,and the foot trajectory requirements applicable for robot are concluded.Using quintic polynomial interpolation method gets proved modified cycloidal which has the smooth trajectory,non-mutation,and continuous derivative.And it is used to plan robot foot trajectory.Then,regarding achieving the planned foot trajectory as the optimization objective,the size of leg mechanism is obtained with genetic algorithm and interior point method of global search algorithm.Based on the second type of Lagrangian equation,adding the constrained undetermined multiplier establishes robotic leg dynamic model,and the expression of the equation of the driving torque and the joint rotation angle acceleration is obtained.(3)By the analysis of quadrupedal animal stepping regular pattern during the process of movement,the common gait used in quadruped robots is summarized.The stability conditions of static gait and dynamic gait are analyzed using the gravitational projection method and zero-moment method,and the stability criteria based on reaction time is also proposed.On this basis,the gait planning of crawl(walk)gait,trot gait,bound gait and pace gait is carried out for designed quadruped robot.And variable gait control parameter planning is developed for the gait switching problem during the quadruped robot movement.(4)The robot simulation model is established.Using Adams software simulation analyzes the foot movement characteristics of the robot leg mechanism,and verifies the robot's motion characteristics in the planned gait.The prototype of continuous electric driven quadruped robot is set up.And the trajectory tracking experiment of single leg's foot,the gait movement experiment of trot and pace are carried out.And the results verify that the designed robotic leg structure is feasible.This research provides a theoretical reference for the design of quadruped robot and continuous electric driven legged structure.