Research On Wheeled And Legged Hybrid Quadruped Robot Based On Metamorphic And Variable Metric Mechanism

Wheeled and legged hybrid quadruped robot can move as fast as a vehicle,and it can also pass through rugged terrain like a quadruped animal.Conceive and design a wheeled and legged hybrid quadruped robot,which can realize three kinds of moving modes: step walking,wheeled moving with power wheels and roller skating without power wheels.The structure of wheeled and legged hybrid quadruped robot's mechanical leg is usually fixed series or parallel mechanism,so it is difficult to find a set of parameters to make all of the mechanical leg's performance indexes optimal.This leads that the mechanical leg's mechanical characteristic,and the optimal performances could not be changed in real time according to the specific purpose.By the improved design of the metamorphic joint and variable metric component,the mechanical leg obtains the abilities of metamorphic and variable metric.This can improve the flexibility and environment adaptability of wheeled and legged hybrid quadruped robot.According to the functional requirements of the wheeled and legged hybrid quadruped robot and its mechanical leg,the 3-UPS parallel mechanism with 6-DOF is selected as the basic mechanism of the mechanical leg,and the mechanical leg's kinematic joints and components are designed and distributed.By mechanism modeling of mechanical leg's 3-UPS mechanism,its workspace,kinematics,statics and dynamics models are obtained.By defining evaluation indexes of various mechanism characteristics,the relationships between the mechanical leg's parameters and various evaluation indexes are revealed.By the singularity analysis of mechanical leg,the mechanical leg's singular workspace is shown to be very small.The mechanical leg's parameters are integrated and optimized in the 4 dimensional space model,a set of parameters that take into account various performances is determined,and the virtual prototype of mechanical leg based on 3-UPS is designed.In order to solve the problem that one set of fixed parameters could not optimize the mechanical leg's all performances,and the problem that the mechanical leg could not change the configuration and degree of freedom characteristics according to the needs of the tasks in real time,an improved design method for metamorphic and variable metric is proposed.A metamorphic and variable metric mechanical leg is proposed,and its experimental prototype is developed on the basis of mechanism analysis.The mechanical leg experimental prototype's metamorphic and variable metric ability have been studied deeply.The metamorphic and variable metric rules are set up based on the wheeled and legged hybrid quadruped robot and its mechanical leg's application purpose.A design scheme of wheeled and legged hybrid quadruped robot is proposed,and the general mechanism model of the whole robot is established.Based on the analysis of the mechanism performances,the key scale parameters of the whole robot are determined.The gait of the robot in step walking mode is planned,a continuous dynamic balanced gait is proposed.And the feasibility of the gait is simulated and verified by software.The motor fault tolerance of wheeled and legged hybrid quadruped robot and its mechanical leg is deeply studied,a robot fault tolerance method is proposed.The condition of robot moving in skating mode is established.In order to verify the rationality of the metamorphic and variable metric method,a comprehensive control experimental system is designed and built.A new robot calibration method based on double calibration of 2 calibration robots is proposed.The mechanical leg's electrical control hardware structure is designed,the comprehensive experimental system,software and control interface of the mechanical leg are designed based on the electrical framework.The position errors were measured by calibration experiment,and the motion accuracy of the experimental prototype is improved effectively through error compensation.These researches provide a new idea for the design of wheeled and legged hybrid quadruped robot,and also provide the method and basis for exploring the real-time variable mechanism of configuration and performance.