| As one of the intelligent logistics tools,autonomous forklift is an important part of the intelligent factory and warehousing logistics.In view of the problems of the poor self balance and insuifficient precision of the exisiting automonous forklift in china,this thesis has developed an autonomous forklift based on Mecanum wheels.This thesis also has studied the mechanical properties of the key components and the dynamic characteristics of the autonomous forklift.As to the problems of the poor self balance of autonomous forklift,this thesis has designed a dedicated dynamic counterweight device and finished the general design of autonomous forklift.On the basis of the completion of the general design,the scheme design and theoretical calculation of power device,lifting mechanism,dynamic counterweight device,suspension and frame have been carried out.It lays a theoretical foundation for AGV forklift structure design.The statics and modal analysis of the lifting mechanism and the frame have been carried out.The results of the statics analysis show that the lifting mechanism meets the requirements of rigidity and strength.The strength and rigidity of the frame are redundant.The results of the modal analysis shows that the low-order natural frequency of the inner gantry is close to the zdirection excitation frequency caused by the motion of Mecanum wheels and the columns on both sides are the key factors affecting the modal stiffness of inner gantry.The outer gantry will not work in the resonance area,the columns on both sides are the key factors affecting the modal stiffness.The first-order natural frequency of the frame is much larger than the excitation frequency and the load of goods and the position of counterweight device has little effect on the dynamic characteristic of frame.The result of harmonic analysis shows that the z-direction excitation caused by the Mecanum wheel motion does not cause the inner gantry resonance.On this basis,the lightweight of frame was achieved through the structure optimization and the cost is further reduced.The influence of dynamic counterweight device on the dynamic characteristics of AGV forklift is studied,and the analysis result shows that the counterweight device can solve the problem of deviation and improve steering characteristics.The dynamic model of autonomous forklift with suspension was built to study the effect of the designed suspension on its dynamic characteristics.The result of dynamic analysis show that the autonomous forklift stability was improved by the designed suspension.These conclusions provide theoretical basis for the counterweight device and suspension of autonomous forklift. |
