Research On Control Strategy Of Unmanned Straddle Carrier Steering System

With the rapid development of computer Internet technology,intelligence and automation have gradually become the development goals and development direction of various terminals and ports.As the main model in the current port container handling equipment,the straddle carrier began to gradually change from manual driving to unmanned driving.The steering system is an important part of the straddle carrier,and its control mode directly affect the vehicle’s handling stability and driving safety,especially for unmanned straddle carrier.In this paper,the all-wheel electric steering system of an unmanned straddle carrier is taken as the research object,and the control strategy of the unmanned straddle steering system is studied.(1)The overall structure and working principle of the all-wheel electric steering system of the straddle carrier are introduced.The mathematical model of the steering system is established and the kinematic relationship of the steering system in Ackerman steering mode is calculated.The load relationship between the wheels of the straddle carrier and the in-situ steering resistance torque are analyzed,and the force of the piston rod of the electric cylinder is calculated.(2)The lateral dynamics model of the straddle carrier is established.The influencing factors of the yaw angle of the straddle carrier are analyzed,and the mathematical relationship between the variables is determined.A simulation model of straddle steering is built.The relationship between steering input and wheel roll angle is analyzed,and the response feature of straddle angle is solved.(3)Aiming at the problem that the sudden change of wheel steering angular velocity will destroy the accuracy of electric cylinder,the trapezoidal velocity planning method is proposed to plan the angular displacement,and some parameters of the trapezoidal velocity curve are determined through analysis.The steering angular velocity fuzzy controller is designed to determine the trapezoidal velocity curve,and the simulation model of the steering angular velocity fuzzy controller is established.The simulation results demonstrate the effectiveness of the steering angular velocity fuzzy controller.(4)The tracking principle of wheel to angle displacement curve is analyzed.The mathematical model of electric cylinder is established,and the transfer function relationship between motor q-axis voltage and displacement of electric cylinder piston rod is solved.The fuzzy PID controller is proposed and designed,and the simulation model of fuzzy PID controller is built to verify.The simulation results show that the fuzzy PID controller can meet the actual use requirements.