| With the continuous advancement of China’s lunar exploration project,higher requirements have been put forward for the lunar surface exploration efficiency and detection range,and the related technologies of manned lunar rover have become the key breakthrough technologies in the next stage of lunar exploration project.Compared with road vehicles,the low gravity on the lunar surface and the bad driving environment on the lunar surface put forward higher requirements for manned lunar rover.In order to make the ride comfort and handling stability of the vehicle more friendly to astronauts,it is necessary to analyze the suspension of manned lunar rover in detail.In this paper,the dynamics characteristics of the suspension of manned lunar rover with wheels off the ground are considered,the performance of the asymmetrical damping suspension,the ride comfort and handling stability of the vehicle and other aspects of multi-objective optimization were studied.The environment of the lunar surface is analyzed,and the driving conditions of the manned vehicle are divided into three categories.The mathematical model and simulation model used to describe the road surface are established.The vertical contact force of the wheel was modeled according to the contact type of the wheel.Aiming at the damping nonlinearity of suspension system,the damping model is simplified into asymmetric damping model,and the asymmetric factor is constructed to represent the asymmetric rate.The two-degree-of-freedom suspension model of manned lunar rover was completed.The vertical contact force of the wheels was derived and calculated by combining the stress integral model and the nonlinear spring damping model,and the suspension model considering the wheels off the ground was constructed.The influence of suspension stiffness coefficient and damping coefficient on suspension performance was studied.The results show that: within a certain range,the increase of damping coefficient will improve the dynamic performance of suspension,while the increase of stiffness coefficient will worsen the dynamic performance of suspension,and the suspension performance is more sensitive to damping coefficient.A seven-degree-of-freedom vehicle model was established based on the suspension model.Using the mathematical models of the suspension and the whole vehicle,the Simulation model was established.According to the test design,the sensitivity analysis of the parameters of the suspension was carried out.The conclusion was drawn that the damping and stiffness coefficients had the most obvious effects on the ride comfort and handling stability of the suspension.On this basis,the suspension stiffness coefficient and damping coefficient are optimized by MOPSO algorithm.The optimization results show that the optimized parameters have a good improvement effect on random road surface,impact road surface and slope road surface,and the sprung mass acceleration and wheel dynamic load of suspension can be significantly improved,which can be reduced by13.96%,9.7% and 9.5% respectively at most,but the dynamic travel of suspension will increase,especially the negative dynamic travel will increase significantly.The optimized parameters can improve the vertical acceleration,pitch Angle acceleration,roll Angle acceleration and wheel dynamic load of the vehicle.Finally,the mathematical model and ADAMS simulation model are co-simulated.The reasons for the poor effect of optimization parameters in group 2 and group 5 during the co-simulation were analyzed,and the conclusion was reached that the ride comfort and handling stability of the vehicle were the best when the asymmetry factor was 3.By comparing the experimental results with the simulation data,the reliability of the simulation analysis and the multi-objective optimization results are verified.Moreover,the optimization parameters have a good optimization effect,which can improve the ride comfort and handling stability of the vehicle. |
