Research On Reversing Safety And Guidance Control Of Semi-trailer Train

In recent decades of road transportation,semi-trailer trains has become the main force of logistics and transportation industry because of its advantages such as heavy load,high transportation efficiency,low cost and good fuel saving.However,the dynamic state of the semi-trailer trains composed of tractor and semi-trailer is open-loop stable when driving forward,but because of its high nonlinearity,nonholonomic constraints,instability,uncertainty and other characteristics,the dynamic state of the semi-trailer trains when driving in reverse is open-loop unstable.In the actual transportation process,it is difficult to guarantee the reversing safety of semi-trailer trains,and it is very difficult to reverse,and the reversing efficiency is difficult to improve.Therefore,the main research content of this paper is the reversing safety and guidance control of semi-trailer Train.Through the implementation of linear reversing control,reversing hitch angle estimation and parking path planning,it can improve the safety and efficiency of semi-trailer trains reversing,and provide technical support for auxiliary driving and automatic driving of semi-trailer trains.The main research contents and results are as follows:(1)Based on the analysis of the coupling relationship between the parameters of linear reversing positioning,the theoretical model of semi-trailer train is established.Considering the factors of stability and feasibility,the stable domain and feasible domain of the reversing hitch angle of semi-trailer train are determined by parameter decoupling and accurate linearization.The control strategy of linear reversing of semi-trailer train based on the stable domain and feasible domain is proposed,which is based on ADAMS and MATLAB / Simulink is used for co-simulation.(2)A state estimation method based on multi model information fusion is proposed for hitch angle of semi-trailer trains.It is determined that the failure reason of traditional hitch angle estimator is that the nonlinear disturbance of tire cornering stiffness is too large.Through the concept of nonlinear degree in cryptography,the judgment condition of excessive nonlinear disturbance is established.According to the different types of nonlinear disturbance in low speed,high speed and reversing,a full condition estimation strategy using nested observer and multi theoretical model for information fusion is proposed.It is used to estimate the hitch angle at different stages of reversing.(3)A speed switching parking path planning strategy based on hitch angle stability domain is proposed.This paper analyzes the more complex nonholonomic constraints and open-loop instability characteristics of semi-trailer trains,condenses the difficulties of parking planning by considering the difficulty,flexibility and avoiding local optimal solution;defines the switching cost,reversing cost and hitch angle constraints,proposes the speed switching parking path planning strategy based on the hitch angle stability domain;The corresponding vertical parking and parallel parking conditions are constructed,and the importance of the cost function and hitch angle constraint is verified in the longitudinal direction,and the effectiveness of the proposed path planning strategy is verified in the transverse direction.(4)Based on the stable region and feasible region of articulation angle,the variable universe fuzzy controller and the overall test scheme for linear reversing of semi-trailer trains are designed;Based on Code Warrior,the function program is compiled and debugged,and the function of the linear reversing system is verified under four working conditions: whether the hitch angle of the semitrailer is in the reversing controllable range and whether the expected straight line is on the left and right sides of the vehicle.