Research On Active Steering Control Strategy Of Steer-by-wire System For Electric Forklift

Electric forklift is an important logistics tool.Because of its environmental protection,easy and nimble operation,high reliability,etc.,electric forklift is more and more favored by the market.Steer-by-wire system of electric forklift is free from the shackles of the traditional mechanical steering,and the steering characteristics can be freely designed.The steer-by-wire system is the hotspot of the current electric forklift steering system,and the active steering control plays an important role on improving the steering performance of the electric forklift steer-by-wire system.Active steering control technology,based on steer-by-wire(SBW),can control the parameters which reflect vehicle steering performance: yaw rate,sideslip angle,turning radius,etc.in ideal range,to avoid the lack of vehicle steering,excessive steering and other phenomena,thereby improving the vehicle's handling stability and mobility.Taking the all-wheel steering system of three-wheel electric forklift as the research subject,the further study on control strategy for electric forklift steer-by-wire system is carried out in this paper.First based on the Newtonian mechanics principle and ackermann angle principle,a 2-dof model of all-wheel steering system of three-wheel forklift is established,to provide a platform model for later steering control strategy research;Then combined with the stability and maneuverability of the performance,considering the narrow workplace,frequent steering,load changes and other work requirements of forklift,two kinds of control strategies are proposed in this paper,one uses the method of decoupling control,and the other uses the method of the isometric reverse rotation at front and rear wheel.According to actual data of the forklift TFC20,the ability to resist load disturbance and measurement interference of the two kinds of control strategies mentioned above is studied,also in the four conditions of high-speed slope,high-speed sine,low-speed slope and low-speed sine,the steering performance simulation of the two kinds of control strategies mentioned above is given.The simulation results show that the decoupling control strategy has the advantages of high anti-interference ability,high stability and high fastness,and the front and rear wheel isometric reverse rotation control strategy has the advantages of good anti-interference ability and high mobility.Finally,combined with the actual situation of forklift storage and transportation operation of electric forklift,the two kinds of special steering operation modes of oblique lines and pivot steering are studied.