Research On Anti-rollover And Synchronous Steering Control Of Counterbalanced Forklift

With the rapid and structural development of modern industry,counterbalanced forklifts have become an irreplaceable material handling tool,and their safety issues have attracted more and more attention.Because the counterbalanced forklift has the structural characteristics of high center of mass and small supporting area,it is prone to rollover during sharp turns.At the same time,the full hydraulic steering system of the forklift has serious internal oil leakage.During the steering process,the wheel angle will produce steering deviation,causing the steering to be out of sync.This paper mainly studies the anti-rollover control and synchronous steering control of counterbalanced forklifts.The main research contents and results are as follows:(1)Based on the analysis of the counterbalanced forklift rollover mechanism,the anti-rollover control actuator is determined: the locking cylinder and the active steering system,and the anti-rollover control is performed by adjusting the damping force of the locking cylinder and correcting the wheel angle.The roll dynamics model of the counterbalanced forklift,the mathematical model of the locking cylinder and the active steering system were established,and the model was verified.(2)A comprehensive criterion of forklift rollover stability based on the center of gravity projection point(COG)and the foot turning indicator point(FRI)is proposed.According to the positional relationship between the center of gravity projection point,the foot turning point and the support area,the rollover stable state of the forklift is divided into: static stable state,dynamic stable state,and dynamic unstable state.(3)According to the forklift’s rollover stable state,an anti-rollover control strategy based on the combined control of the lock-up cylinder and active steering is proposed.First,the lock-up cylinder is controlled.If the lock-up cylinder meets the anti-rollover control requirements,active steering Work is not started;if the forklift’s rollover stability continues to deteriorate,the system will continue to perform active steering control.Considering the uncertainty of some parameters of the anti-rollover actuator,an adaptive fuzzy anti-rollover controller with variable universe is designed.(4)By analyzing the mechanism of counterbalanced forklift steering nonsynchronization,a fully hydraulic synchronous steering system that can achieve steering synchronization is designed,and a desired steering curve based on steering efficiency and a method for determining its feasible region are proposed;for disturbance uncertainty And oil leakage nonlinearity,a combined approaching law sliding mode controller was designed;considering the insufficient adaptiveness of combined approaching law gains,the system’s dynamic response capability is poor,an adaptive adjustment of approaching law gains was established to achieve full The hydraulic steering is precisely synchronized and at the same time improves the effect of anti-rollover control.(5)Completed the integrated controller design of counterbalanced forklift that integrates anti-rollover control and full hydraulic synchronous steering control,which mainly includes circuit schematics,PCB plate making,prototype design,program writing and debugging.Finally,a real-vehicle test of anti-rollover control and synchronous steering control was carried out.The measured data of the test and the simulation data were highly consistent,which verified the feasibility of the forklift anti-rollover control and the full hydraulic synchronous steering control strategy,and achieved the design goal of this subject.