Research On Hexapod Walking Robot Based On Asymmetric 3-UPU Parallel Mechanism

The paper presents a new hexapod walking robot which can replace human detection,repair and rescue for dangerous and complicated environment,such as chemical plant with toxic gas leakage or nuclear power station with radioactive material.It combines the advantages of parallel robot and walking robot skillfully,and has the advantages of large carrying capacity,strong passing ability,and easy control and so on.Firstly,the structure of the hexapod walking robot is designed.A design scheme of robot walking based on alternating motion of two platforms of asymmetric 3-UPU parallel mechanism is proposed.The movement mode,configuration characteristics,key component size,sensor type and layout of hexapod walking robot are described in detail.Secondly,the kinematics of asymmetric 3-UPU parallel mechanism is analyzed.A simplified model of the mechanism is established.The forward and negative solutions are obtained by establishing the closed vector loop equation.Using the velocity Jacobian matrix of the mechanism,the singularities of asymmetric 3-UPU parallel mechanism is analyzed to provide a reference for the selection of structural parameters in the design of hexapod walking robot and to avoid the appearance of singularity position.Then the workspace of the mechanism is obtained by MATLAB programming using the limit boundary search method.Then,the stability performance and gait planning of the hexapod walking robot are analyzed.The stability of the robot is analyzed by using the center of gravity projection method.The stability of the robot and the interference of the legs are considered synthetically.The maximum transverse moving stride is designed,and the gait planning of the hexapod walking robot is carried out,including the duty factor of the two groups of legs,the order of motion,the moving stride,the movement trajectory and the change of the equivalent rod length of each branch with the movement of the robot,and so on.Finally,the obstacle negotiation behavior of hexapod walking robot is simulated.The obstacle negotiation ability and motion performance of hexapod walking robot are simulated by using SolidWorks and MATLAB software.The simulation results are compared with the theoretical motion trajectory.It is found that the variation of the center of the upper and lower platforms in the vertical direction is consistent,and the synchronization fluctuation is basically maintained,which verifies the correctness of the kinematics model.The results provide a theoretical reference for the subsequent prototype making.