| The closed-chain foot robot is regarded as an important research field of leg configuration innovation of bionic robots due to its advantages of small driving number,low energy consumption,large overall stiffness and strong load capacity.This paper mainly studies the passing performance of six closed chain leg mechanisms,and carries out reconfigurable innovative design for one of the single degree of freedom leg mechanisms.A method for analyzing the comprehensive performance of the closed chain mechanism is proposed.The kinematic model of the closed chain linkage mechanism is built and the end trajectory curve is solved.A typical simulation environment is built in combination with the local characteristics of unstructured terrain.Six simplified models of eight legged robots are built and the whole machine dynamics simulation tests under the same working conditions are carried out.The comprehensive performance of the six closed chain leg mechanisms is analyzed,Based on a closed-chain eight link mechanism with composite hinges,a coaxial drive adjustment structure is designed,which realizes the continuous change of the position of the robot’s legs and enriches the motion space of the closed-chain robot.Based on the closed-chain leg mechanism,an eight legged robot model with single drive motor and four adjustment steering gear is designed.The specific research contents include the following aspects:(1)The closed-loop kinematic chain is selected and the kinematic models of six closedchain mechanisms are established.The static performance is analyzed combined with the characteristics of closed-chain mechanism and the parameters of foot end trajectory curve.Starting from the number synthesis of closed-loop kinematic chains,the structural characteristics of general kinematic chains and simplified kinematic chains are analyzed,and a variety of closed-chain mechanisms are obtained.According to the characteristics of four-bar,six bar,eight bar and eight bar mechanisms with composite hinges and the robot design requirements,the closed-chain leg mechanism is selected,the kinematics model of the selected closed-chain mechanism is established,and the kinematics calculation is carried out with MATLAB to obtain the corresponding foot end trajectory curve,The static data of leg length,step proportion,leg lifting proportion,approach angle and departure angle of leg mechanism and trajectory curve are analyzed.(2)The dynamic models of six kinds of Eight Legged closed chain robots are built,and the dynamic performance of the closed chain leg mechanism is analyzed through the simulation of typical working conditions.The modular design of closed chain multi legged robot is carried out,the structural characteristics of closed chain multi legged robot are unified,the influence of different closed chain configurations on the performance of robot is highlighted,the random mathematical model is established for the three-dimensional characteristics of unstructured terrain,and the typical unstructured obstacle terrain is obtained.The dynamic simulation is carried out by ADMAS to analyze the dynamic data of closed chain multi legged robot,such as walking speed,motor torque,climbing ability and climbing ability.(3)The key calculation data are extracted,the performance evaluation content is determined,and the comprehensive performance of six closed chain leg mechanisms is analyzed.Considering the generality and complexity,the performance evaluation index of the closed chain multi legged robot is determined,and the configuration with strong performance is comprehensively selected according to the evaluation contents such as the mobile performance,obstacle crossing performance,mathematical model solving complexity and engineering implementation difficulty of the closed chain mechanism.(4)The reconfigurable design of a closed chain configuration with strong comprehensive performance is carried out,which enriches the motion space of the closed chain robot.This paper summarizes the reconfigurable research of closed chain mechanism,selects the method that has the least impact on the performance of the initial mechanism to carry out the reconfigurable design,uses MATLAB to carry out kinematic calculation on the basis of the mathematical model of the initial mechanism,obtains the foot trajectory cluster,and develops the experimental prototype based on the final configuration. |
