Optimization And Kinematics Research On Single Leg Structure Of Hexapod Robot

Compared with traditional walking machines,foot robots have a smaller contact area with the ground and can walk freely even on extremely rugged roads.In addition,the multi-legged walking robots have a variety of walking gaits and walking modes,so it has high fault tolerance and high reliability.The footed robots can adapt to uneven roads such as mountains,snow fields,deserts,hills,etc.And it also has high potential in some special fields,such as extreme terrain rescue and disaster relief,military investigation and anti-terrorism and explosion protection.Therefore,it has become a research hotspot nowadays and will have better development prospects in the future.In this paper,D-H modeling and forward and inverse kinematics calculations are performed on the single-leg mechanism.The mathematical model for determining the foot end point is obtained through the forward kinematics calculation,and then the foot end point space under different leg length ratios is determined by MATLAB simulation.Combining the design requirements and the foot-end landing space under different leg length ratios,a leg length ratio that can better meet the needs was selected.In addition,the inverse kinematics model is also obtained by inverting the positive kinematics model,that is to say,the model that determining the driving joint rotation angle and the contraction amount of the hydraulic cylinder from the position of the foot end.In order to further verify the correctness of the leg length ratio,given the obstacle height and step length,Adams simulation of the single leg under this ratio is performed to determine whether the obstacle crossing and travel requirements can be completed within the preset angle.About the optimization of hinge position,this paper uses an intelligent algorithm-particle swarm algorithm.Under the condition that the basic installation requirements are met,the maximum lever arm of the hydraulic cylinder is the optimization goal,and MATLAB software is used for programming to calculate the hinge point position of each hydraulic cylinder.After a certain number of iterations,the lever arm is finally stabilized at a certain value,and the value of the design variable at this time is the desired value.Because each hydraulic cylinder completes the single-leg walking action is a process,therefore,determining the maximum lever arm may not necessarily reduce the output force of the hydraulic cylinder.In order to determine its actual output,the output of each hydraulic cylinder before and after the optimization was calculated and simulated respectively,and the effectiveness of the above-mentioned hinge point optimization was determined by comparing the results.In order to study the kinematics of the single leg,the foot trajectory was planned and Adams was used to perform the kinematics simulation of the single leg.The calculated foot trajectory was compared with the foot displacement curve obtained from the simulation to confirm the correctness of the kinematics calculation.Using ANSYS workbench to perform static simulation on the existing single-leg mechanical structure to obtaining the stress-strain cloud diagram of the single-leg and performing modal simulation to obtain its natural frequency.Based on the simulation results,a breakthrough in structural lightweighting was sought,and response surface analysis and variable-density topology optimization method were applied to optimize the structure of the base section.After optimization,a static simulation is performed to verify the stiffness and strength of the optimized leg structure.