| The wheel loader is a kind of earth and stone construction machinery used in various engineering construction fields.It can carry out mining,road construction,house construction and other constructions in a very complex working environment.It has high work efficiency,fast speed,light operation and maneuverability.Good performance and other advantages,it is one of the construction machinery with good development and high demand in the field of construction machinery.However,because the construction environment is usually harsh,the wheel loader is inevitably impacted by the load,and instability occurs during driving,causing harm.This article relies on the Henan Zhengzhou Road and Bridge Construction Group project,takes wheel loader as the research object,comprehensively considers the structure composition and structural characteristics of the wheel loader,the actual driving process and other factors,establishes the steering dynamics model and the driving dynamics model,and selects The lateral load transfer rate is used as a risk evaluation index to analyze the driving stability of the wheel loader.It analyzes the driving stability of the wheel loader when driving under complex road conditions such as flat road conditions,curved road conditions,slope road conditions,and slope curved road conditions.Perform threshold analysis on the motion parameters and structural parameters that affect the instability of the wheel loader under multiple road conditions,determine the safety threshold range of the parameters,compare the characteristics of different control theories,and determine a reasonable control strategy to control the wheel loader to improve multiple road conditions Stability of the loader under driving.The research content is as follows:(1)Analyze and summarize relevant domestic and foreign literature on wheel loader driving stability modeling,combine the structural characteristics of wheel loader system and the stability evaluation index of lateral load transfer rate,and establish a two-degree-of-freedom dynamic model based on the Newton-Euler method And the driving dynamics model,the model can fully simulate the trajectory and load force of the wheel loader during the driving process,and provide a model reference basis for analyzing the driving stability of the wheel loader.(2)Carry out simulation analysis of the driving process of the wheel loader under16 driving road conditions under flat road conditions,curved road conditions,slope road conditions and slope curved road conditions.The research results show that:(1)The faster the speed,the greater the lateral load rate,and the more unstable the wheel loader is.(2)The load of the loader has a certain influence on the driving stability.The greater the load,the greater the value of the lateral load rate,and the more unstable the driving.However,compared with the load,the speed value has a greater impact on the driving stability of the wheel loader.(3)Under straight and curved road conditions,the loader maintains a reasonable speed range and is in a very stable driving state;due to the existence of the slope angle on the slope road,the stability of the loader fluctuates greatly,and the speed value is too high and it is easy to lose stability;Due to the existence of the slope angle and the arc angle of the curve on the slope curve,the driving stability is the worst and the tipping accident is the most likely to occur.(3)The threshold value analysis of the factors affecting the instability of the wheel loader under multiple road conditions is carried out,and the maximum reasonable threshold value range of different parameters is explored.The results show that:(1)The faster the driving speed and the steering speed,the greater the slope angle and the driving steering angle,the greater the risk of overturning and instability of the wheel loader;the driving speed has the most serious influence on the driving stability among the sports parameters.The driving speed threshold range should be within 0～28km/h,the slope road condition should not exceed 22km/h,and the slope curve condition should not exceed 15km/h;the slope angle threshold range should be between 0～22°,and the slope condition of the slope curve The steering angle should not exceed 17.5°;the steering speed threshold range should be greater than 1.45 s to complete the steering;the driving steering angle threshold range should be between 0 and 37°,the steering angle should not exceed 24° when driving on slopes,and the steering angle should not exceed 24° when driving on slopes and bends.More than 23°.(2)The driving stability of the wheel loader is affected by the height of the center of mass,the distance of the wheel base,and the distance from the different body to the hinge point.The height of the center of mass and the distance of the wheel base have the most serious influence on the driving stability.Among them,the center of mass height threshold range is less than1.5m;the reasonable threshold range of the wheel center distance is less than 2.24m;the reasonable threshold range of the distance from the car body to the hinge point is0.9～1.4m.Comparing the test results of the wheel loader scale model of the State Key Laboratory of Jilin University with the simulation results of this paper,it is shown that the research conclusions on the driving stability of the wheel loader under different road conditions and different parameters are basically consistent with it,which verifies that the results of this paper have Strong reliability.(4)Based on the results of the wheel loader’s driving stability analysis,comprehensively analyze the advantages and disadvantages of different control theories,and use the direct yaw moment control strategy to optimize the driving stability of the wheel loader.The results show that:(1)The LTR value when driving at low speed on straight roads is reduced from 0.198 to 0.128,which is 35.36% less than that under uncontrolled conditions;(2)The LTR value when driving at no load on curved roads is reduced from 0.495 to 0.355,which is more It is reduced by 28.28% when it is not controlled;(3)When driving on slope road conditions,when the height of the center of mass is 1.6m,the LTR value is reduced from 0.651 to 0.606,which is a decrease of6.91% compared with that when it is not controlled;(4)When driving at high speed on slope and curve road conditions,LTR value is reduced from 1.31 to 0.883,which is32.59% less than when it is not controlled,which makes the loader change from an unstable state to a stable driving state.The results given in this paper have a certain reference value for improving the stability and optimizing control of wheel loaders driving on multiple road conditions. |
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