Research On Lateral Stability Of Forklift Truck Based On Active Rear Wheel Steering

As the most commonly used material handing machinery,counterbalanced forklift truck has been widely used in various fields.The operating conditions of counterbalanced forklift truck are complex and accidents happened frequently,but the security and stability issues did not cause enough attention in academia.In fact,the counterbalanced forklift truck lifts the goods with mast and fork.The mass,position,state and shape of the goods will have a certain impact on combined center of mass of forklift truck,which results in center of mass changeable and poor lateral stability.The truck keeps steady and lifts the goods,which follows the lever principle.The operating conditions are extremely complex.The forklift truck will roll-over when the centroid is out of the stability region.In this dissertation,the lateral stability of a three-tons counterbalanced forklift truck was studied,the lateral stability of the forklift truck was analyzed when it is unload,full-load or with different lifting height.On this basis,the fuzzy control strategy based on active rear wheel steering was proposed.The main work and results are as follows:(1)The working characteristic of forklift truck was analysed.The main factor of lateral stability about the truck was carried out.The main reason of the forklift instability was studied.The seven-degree-of-freedom model was established by ADAMS.The lateral stability of the forklift truck under different condition of full load,no load and different lifting height was analyzed.(2)The fuzzy control strategy based on the active rear wheel steering was designed with yew rate and roll angle as the control target.Based on the joint simulation of ADAMS and MATLAB/Simulink,the variables which characterize the lateral stability of the truck were selected.The range size and maximum value of the variables were determined.The simulation results show that the fuzzy control strategy based on active rear wheel steering can effectively reduce the degree of roll.It also can improve the lateral stability of forklift.(3)The dynamic stability test base on the standard EN16203: 2014 about forklift has been designed.The lateral stability of forklift is analyzed under the active rear wheel steering control.Test result shows that the active rear wheel steering control strategy can effectively improve the lateral stability of the forklift.