| Heavy-duty construction vehicles are playing an increasingly important role in modernization construction.They are often driven on "off-road".As a result,vehicles are subjected to severe random vibrations in all directions.In addition,due to the self-heavy weight of the construction vehicle,a large rigidity is demanded to support its weight.But,in case the stiffness is too large,its vibration damping performance is reduced.It can be seen that heavy-duty construction vehicle's drivers are suffered to more severe random vibrations in all directions.Therefore the physical and mental health and operational stability of the driver are seriously affected.In order to solve the problems,this paper proposes a parallel multi-dimensional vibration-damping seat suspension.It can achieve one translation and two rotations(1T2R)movement.And the multi-dimensional vibration reduction characteristics are analyzed.The main contents of the study are given as follows:(1)In view of the multi-dimensional vibration of construction vehicles in the actual working,the design requirements of multi-dimensional vibration damping seat are proposed.Through a comparative analysis of several 1T2R parallel mechanisms,a 3-RPS parallel mechanism with the same motion branches and simple motion pairs is selected as the multi-dimensional damping seat suspension.Based on the single-open-chain theory and the UG model,its spatial degrees of freedom are verified by the theory and virtual prototype.Then,its kinematics is analyzed.The coordinate method is used to solve the forward and inverse equations of the seat suspension.And the influence coefficient method is used to derive the speed and the acceleration matrix of the 3-RPS parallel multi-dimensional damping seat suspension.(2)The kinematic equation of "vehicle-seat-driver" system is established.Based on the idea of splitting,the "vehicle-seat-driver" overall system is split into two subsystems:"vehicle-seat" and "seat-driver".Next,a "vehicle-seat"seven degree of freedom dynamic model and a 3-RPS parallel seat "seat-driver"system dynamic model are established.(3)Based on ADAMS software,a virtual prototype model of the 3-RPS parallel multi-dimensional damping seat passive suspension is established.And a three-dimensional random road surface simulation model is obtained by using the sine wave superposition method.Then,the vibration damping performance in all directions of the parallel seat branches with different installation positions is analyzed.And an installation method is chosen.The vibration damping performance in all directions of the passive seat suspension is simulated and analyzed on the E,F and G road.The results show that under different road,the seat suspension has a vibration damping performance improvement of about 7%to 30%in the above direction.(4)Based on Matlab/Simulink Bouc-wen magnetorheological fluid model and PID control model are established.And a virtual prototype model of a semi-active suspension of the 3-RPS parallel multi-dimensional vibration damping seat with PID control is obtained.Then,Matlab and ADAMS are used to simulate the seat suspension.The vibration damping performance of semi-actively controlled seat suspension and passively controlled seat suspension is simulated and analyzed on the E,F and G road.The results show that compared with passive seats,the semi-actively controlled seats' acceleration drop in those directions are between 38.27%and 79.7%on different roads.Therefore under different of road,the 3-RPS parallel seat suspension has good vibration damping effect in those directions.And the vibration damping effect of the seat suspension with semi-active control is significantly better than the passive. |
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