Selecting design variables and determining optimal hard⁃point coordinates are subjective in the traditional multiobjective optimization of geometric design of vehicle suspension,thereby usually resulting in poor overa...Selecting design variables and determining optimal hard⁃point coordinates are subjective in the traditional multiobjective optimization of geometric design of vehicle suspension,thereby usually resulting in poor overall suspension kinematic performance.To eliminate the subjectivity of selection,a method transferring multiobjective optimization function into a single⁃objective one through the integrated use of grey relational analysis(GRA)and improved entropy weight method(IEWM)is proposed.First,a comprehensive evaluation index of sensitivities was formulated to facilitate the objective selection of design variables by using GRA,in which IEWM was used to determine the weight of each subindex.Second,approximate models between the variations of the front wheel alignment parameters and the design variables were developed on the basis of support vector regression(SVR)and the fruit fly optimization algorithm(FOA).Subsequently,to eliminate the subjectivity and improve the computational efficiency of multiobjective optimization(MOO)of hard⁃point coordinates,the MOO functions were transformed into a single⁃objective optimization(SOO)function by using the GRA-IEWM method again.Finally,the SOO problem was solved by the self⁃adaptive differential evolution(jDE)algorithm.Simulation results indicate that the GRA⁃IEWM method outperforms the traditional multiobjective optimization method and the original coordinate scheme remarkably in terms of kinematic performance.展开更多
A parallel wheelset suspension(PWS)designed for a heavy-duty lunar vehicle,specifically for a multi-wheeled pressurized lunar rover(MWPLR),is beneficial for adapting wheels to rough terrain and absorbing vertical vibr...A parallel wheelset suspension(PWS)designed for a heavy-duty lunar vehicle,specifically for a multi-wheeled pressurized lunar rover(MWPLR),is beneficial for adapting wheels to rough terrain and absorbing vertical vibrations passively.It is a 2-degree-of-freedom spatial parallel mechanism.However,when a lunar vehicle is driven over rough terrain,the wheelset alignment parameters of the PWS vary substantially,resulting in poor wheel-to-ground contact.This paper aims to address these problems.It first presented a PWS design approach,used simulations to confirm the correctness of the kinematic model,evaluated the initial suspension performance,and established an optimization objective.We then analyzed the suspension’s instantaneous screw axis variations as the wheelset crossed the obstacle.The results help us determine the causes and optimization variables that affect the alignment parameters.Finally,based on the kinematic and simulation analysis methods,the optimized suspension ensured that the variation in the camber,toe,and inclination angle of the steering axis would be[-1°,-1°]when the MWPLR crossed a 0.4 m high obstacle.The simulation demonstrated that the PWS improved the ride comfort of the MWPLR and that the optimized PWS enhanced the straight-line drivability and flexible steering capability of the MWPLR.PWS and its design methodology provide a design reference for other multi-wheeled rovers.展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant No.71871078).
文摘Selecting design variables and determining optimal hard⁃point coordinates are subjective in the traditional multiobjective optimization of geometric design of vehicle suspension,thereby usually resulting in poor overall suspension kinematic performance.To eliminate the subjectivity of selection,a method transferring multiobjective optimization function into a single⁃objective one through the integrated use of grey relational analysis(GRA)and improved entropy weight method(IEWM)is proposed.First,a comprehensive evaluation index of sensitivities was formulated to facilitate the objective selection of design variables by using GRA,in which IEWM was used to determine the weight of each subindex.Second,approximate models between the variations of the front wheel alignment parameters and the design variables were developed on the basis of support vector regression(SVR)and the fruit fly optimization algorithm(FOA).Subsequently,to eliminate the subjectivity and improve the computational efficiency of multiobjective optimization(MOO)of hard⁃point coordinates,the MOO functions were transformed into a single⁃objective optimization(SOO)function by using the GRA-IEWM method again.Finally,the SOO problem was solved by the self⁃adaptive differential evolution(jDE)algorithm.Simulation results indicate that the GRA⁃IEWM method outperforms the traditional multiobjective optimization method and the original coordinate scheme remarkably in terms of kinematic performance.
基金supported by the National Natural Science Foundation of China(Grant Nos.T2388101 and U23A20614)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(Grant No.51521003)+2 种基金the“111”Project,China(Project No.B07018)the Harbin Institute of Technology(HIT)Key Project Research and Development Grant,China(Grant No.HIT2021005)the Self-Planned Task of State Key Laboratory of Robotics and System,HIT,China(Grant No.SKLRS202101A02).
文摘A parallel wheelset suspension(PWS)designed for a heavy-duty lunar vehicle,specifically for a multi-wheeled pressurized lunar rover(MWPLR),is beneficial for adapting wheels to rough terrain and absorbing vertical vibrations passively.It is a 2-degree-of-freedom spatial parallel mechanism.However,when a lunar vehicle is driven over rough terrain,the wheelset alignment parameters of the PWS vary substantially,resulting in poor wheel-to-ground contact.This paper aims to address these problems.It first presented a PWS design approach,used simulations to confirm the correctness of the kinematic model,evaluated the initial suspension performance,and established an optimization objective.We then analyzed the suspension’s instantaneous screw axis variations as the wheelset crossed the obstacle.The results help us determine the causes and optimization variables that affect the alignment parameters.Finally,based on the kinematic and simulation analysis methods,the optimized suspension ensured that the variation in the camber,toe,and inclination angle of the steering axis would be[-1°,-1°]when the MWPLR crossed a 0.4 m high obstacle.The simulation demonstrated that the PWS improved the ride comfort of the MWPLR and that the optimized PWS enhanced the straight-line drivability and flexible steering capability of the MWPLR.PWS and its design methodology provide a design reference for other multi-wheeled rovers.
