Research On Active Control Strategy And Road Feeling For Steering-By-Wire Forklift

As a specially vehicle which only be used for material handling,forklift has the characteristics of more turning and narrow road.Therefore,the practical performance of the forklift is largely determined by its steering stability and steering maneuverability,and how to improve these two performances of forklift has been widely concerned by more and more people.The Steer-by-Wire(SBW)system is the future trend of vehicle steering system.this dissertation combined forklift with SBW system,mainly researched on active steering and road feeling control strategy for TK30 forklift.Firstly,analyzed the movement and force balance of TK30 forklift from the following three directions: yaw,lateral and roll.Then the nonlinear three degree of freedom forklift model was established using magic formula tire model and considering load transfer,and the linear three degree of freedom forklift model was established subsequently by simplifying the nonlinear three degree of freedom forklift model.The former was used as the simulation object,while the latter was used for system analysis and control strategy design.Secondly,designed an adaptive kalman filter to estimate forklift sideslip angle,because the forklift sideslip angle is not easy to directly measure by sensor.In order to suppress the adverse effect of the model error on the estimation and improve estimation precision,genetic algorithm was adopted to optimize the adaptive factor of the adaptive kalman filter,and the simulation results proved that the proposed method is effective.Thirdly,controller for active steering system was designed by using two proportion controller through multiple feedback to amend the rear wheel angle of forklift with yaw rate and sideslip angle as feedback variables.Simulation results show that this controller can improve forklift lateral stability and enhance forklift handling capability.Finally,researched on the road feeling mechanism of mechanical steering system,and the road feeling control system was designed.In this system,the road feeling torque can be obtained by measuring tire positioning parameters and forklift driving parameters,then transmit it to steering wheel by a brush DC motor.In order to make road feeling torque more clear and more comfortable,kalman filter was adopted.Simulation results show that the overall system is effective.