Research On Design Theory And Key Technologies Of Biped Robot Legs And Its Actuators

Robot is known as "the pearl on the top of manufacturing industry",and bipedal robot is one of the most difficult categories in robot technology.Biped robot has not really entered the application field and served human in the way that collaborative robots have,mainly in three aspects of motion agility,environmental adaptability and operational diversity are still different from human.These three aspects are related to the design of robot legs,especially the design of robot legs and actuators,the research of these two parts has not fully affected the industrialization of biped robot.With the joint funding of Beijing Municipal Education Commission and Beijing Nature Foundation,through theoretical research and technological innovation,this thesis carries out theoretical and practical research on biped robot leg configuration,actuator parametric design,robot dynamics simulation,lightweight design approach of biped robot leg,and finally forms the design theory and technology of robot leg and its actuator.The above research contents are verified by experiments respectively,experiments are carried out to verify the feasibility and effectiveness of the design theory and key technologies of the robot leg and its actuator.The main research contents are as follows:(1)The leg design criterion of biped robot is established and a new leg configuration with high dynamic performance is proposed.Based on the robot motion control method,a consistency criterion between mechanistic properties of robot leg configuration and motion control dynamics model is proposed.Based on the linear inverted pendulum theory,the design criteria of high mass center and low inertia of leg are established.Considering the safety of robot and environment interaction,safety design criteria are proposed.Using the leg design criteria,a new leg configuration is proposed,in which the knee actuator is positioned up in line with the hip pitch actuator.The knee joint motion is realized by simplifying the five-link mechanism.The ankle actuators are moved up to the knee joint,ankle joint movement is realized by 2-RSU+1U mechanism.(2)A parametric design approach of actuator based on key performance index is proposed.The design flow of the approach is established,and the design content of each step in the flow and the logical relationship between the steps are clarified.According to the key performance indexes of the actuator torque density and responsiveness,the parametric model of the reducer and the motor is established.The function relation between the performance of planetary reducer and the number of teeth of sun gear and the radius of internal gear pitch circle is deduced,and the function relation between the performance of motor and the radius of air gap is established.This parametric design approach is applied to design two kinds of actuators of the leg of the new configuration robot.(3)A robot simulation platform is established.The platform includes five modules: 3D modeling,structural topology optimization,dynamics simulation,motion control and optimization algorithm.The modules consist of three sub-areas: structure optimization,dynamic simulation and parameter optimization.Based on the Walker robot,the joint actuator torque of the robot arm and leg is test,the differences between simulation and test is compared,the validity and accuracy of the platform dynamic simulation area is verified.(4)A lightweight leg design approach for biped robot is proposed.Based on the robot simulation platform proposed in this thesis,the lightweight design approach of robot legs is studied.The approach takes that the robot walk at the specified speed and walk stably as constraint condition,the performance parameters of reducer and motor of the drive trian as design variables and minimize the mass of the robot leg as the objective of optimization.(5)The experimental verification of the new configuration robot and actuator is completed.The experiment of the new configuration robot includes the measurement of walking speed and the extraction and analysis of actuator torque of each joint.The actuator experiments include the torque and speed characteristic curve test of the motor and the actuator,the actuator noise test and actuator absolute positioning accuracy test.Experiments verify the rationality and feasibility of the design criteria established in this thesis,and the innovation and advancement of the proposed new leg configuration of robot.The feasibility and effectiveness of the parametric design approach of actuator,the dynamics simulation platform and the leg lightweight design approach of biped robot are verified by experiments.