Structural Design And Motion Performance Analysis Of Hexapod Robot With Rotatable Trunk

At present,with the development of science and technology,robots as a typical representative of intelligence,widely used in all walks of life.Among them,the walking robot has a wide range of applications,such as space exploration,surveillance and reconnaissance,extreme environment operations,etc.However,small and medium-sized foot robots usually adopt more complex leg structure,and the improvement of the flexibility of the main body still needs to be improved.In order to solve this problem,two torso joints are introduced on the basis of rigid torso hexapod robot to increase the flexibility of robot movement.In this thesis,a movable torso hexapod robot is taken as the research object to explore the influence of movable torso on the robot’s motion performance,and build an experimental platform independently.The research content involves robot structure design,kinematic modeling,motion performance analysis and gait planning.The details are as follows:Firstly,the body types of the creatures with movable bodies were summarized and selected.Two joints which could pitch up and down and twist left and right were added to the body position of the robot.Select the right leg and foot configuration and explore the proportion relationship between the leg base,thigh and calf.The proper distribution mode of legs and feet is selected and the structure of the robot is designed according to the design requirements.ANSYS is used to check the strength of the robot,complete the robot configuration design and material selection.Secondly,the torso kinematics analysis was carried out to analyze the influence of the introduction of the torso joint on the robot’s center of mass and hip joint.The kinematics modeling of the front,middle and back legs was carried out and calculated in MATLAB.At the same time,the motion performance of the robot is studied,and the leg Jacobian matrix is calculated to analyze the leg bearing capacity.Aiming at the rigid torso robot and the movable torso robot,the moving space of the two bodies and feet were respectively compared,and the movable torso robot has a larger working space.The performance of the robot in obstacle crossing is studied and the maximum height of crossing the boss and climbing step is analyzed.Thirdly,the three-legged gait was adopted and improved,and a straight walking gait was designed by introducing twisting joints and pitching joints of the torso.Compared with the rigid torso,the movable torso robot obtained a larger step length.At the same time,a steering gait with the torso twisting joints was designed.Compared with the rigid torso,the movement of the robot could be closer to the origin.A climbing step gait with upper and lower torso pitching joints is also designed.Compared with the traditional rigid torso robot,the movement is more stable and the step length is increased.By comparing the steps,centroid acceleration and joint torque of the traditional trunk robot and the movable trunk robot,the rationality of the new gait improvement is proved.Finally,a prototype of a hexapod robot with movable torso was designed and built,and experiments were carried out on straight walking,turning in place and climbing steps respectively for the traditional torso and the robot with twisting torso joints.Through the analysis and comparison of the movement trajectory of the robot touching the ground node and the movement process of the robot,it is verified that after the addition of the trunk joint,the robot increases the step length in straight walking,has a larger amplitude in the in situ steering and can be closer to the origin,and runs more smoothly in climbing the steps,which proves the effectiveness of the gait optimization.The above experimental results are consistent with the theoretical research and simulation results,which verify the correctness of the theoretical analysis.