Sensor Fault Diagnosis And Fault Tolerance Control Of Steer-by-wire System For Forklift

With the rapid development of vehicle industry,wire control technology is replacing the traditional mechanical device of forklift.As the electric forklift steer-by-wire(Steer—By—Wire,SBW)system eliminates the mechanical connection between the steering wheel and the steering wheel and is connected electronically,it is easy to integrate with other systems for unified and coordinated control.However,since there is no mechanical connection between steering wheel and steering wheel in SBW system,the robustness of electronic equipment is lower than that of mechanical parts,and the electronic parts are likely to fail without any warning.In order to meet the requirement of reliability and safety of electric forklift,SBW system of electric forklift must adopt fault-tolerant control technology,otherwise unexpected steering will occur.This dissertation introduces the fault diagnosis and fault-tolerant control method of the electric forklift SBW system for sensor from four aspects.First,the established steering execution module model and the three-DOF vehicle model were merged into a dynamic model of the steer-by-wire forklift for sensor fault diagnosis and fault-tolerant control.Second,based on the research of system fault model,considering the system uncertainty and external disturbance,the corresponding linear state equation is constructed as its equivalent forklift sensor fault model;two sliding mode control items are used to suppress interference and eliminate parameter uncertainties,making the observer robust;moreover,the design of multiple observers with sensors can achieve the goal of sensor fault isolation,and realize the fault diagnosis of multiple sensors.Thirdly,according to the fault model and sliding mode control theory,a fault reconstruction method of multiple sensors based on sliding mode observer is proposed,and then multiple adjustable gain parameters in the sliding mode observer are adaptively adjusted along with the fault system change by means of adaptive algorithm,without any prior assumption of fault.Fourthly,sensor fault-tolerant control using a model reference sliding mode fault-tolerant controller can effectively deal with parameter uncertainty and external output interference and fault effects.Finally,the experimental results show that the method is effective and can realize fault diagnosis and fault-tolerant control of electric forklift sensor.