Design and test of the anti-skid system for self-propelled high-stem crop sprayers

Aiming at the problem of skidding in the operation of a self-propelled high-stem crop sprayer due to uneven road surface and uneven distribution of soil cohesive force,This study proposed a four-wheel drive hydraulic anti-skid control system based on RTM valve.Through theoretical analysis of control components such as the RTM valve and steering cylinder,the control model of the anti-skid drive system of the spray machine is established,and the simulation test is carried out in Matlab/Simulink.The simulation results show that the slip rate of the anti-skid drive system based on the PID control strategy is controlled below 0.05,and the RTM valve keeps the driving pressure of the system basically stable.In order to verify the reliability of the simulation results,the designed drive anti-skid control system was carried out on a spray machine for the field test.The experimental results show that the slip rate of the drive anti-skid system decreases from 86.7%to 1.25%when the anti-skid function is turned on,indicating that the designed drive anti-skid system has good anti-skid performance.

Aircraft Electric Anti-skid Braking System Based on Fuzzy-PID Controller with Parameter Self-adjustment Feature

The principle of electric braking system is analyzed and an anti-skid braking system based on the slip rate control is proposed.The fuzzy-PID controller with parameter self-adjustment feature is designed for the anti-skid braking system.The dynamic model of aircraft ground braking is established in the simulation environment of MATLAB/SIMULINK,and simulation results of dry runway and wet runway are presented.The results show that the fuzzy-PID controller with parameter self-adjustment feature for the electric anti-skid braking system keeps working in the state of stability and the brake efficiencies are increased to 93%on dry runway and 82%on wet runway respectively.

STUDY ON CONTACTING MELTING AND ANTI-SKID TECHNOLOGY FOR A TIRE TRACTION ON ICE

Theoretical analyses and experimental studies of the mechanisms of melting film formation are performed. The results show that frictional heating is the dominant mechanism because temperature behaves in the manner predicted by the theory of frictional heating. A study of the active technology for anti-skid is also made. Conclusions indicate that adjusting tire pneumatic pressure can improve the control stability and the travelling safety of an ice-automobile.

Design and Dynamics Analysis of Anti-skid Braking System for Aircraft with Four-wheel Bogie Landing Gears

In asymmetric conditions,the movement and loads of left/right wheels or front/back wheels of the aircraft with multi-wheel or four-wheel bogie landing gears are inconsistent.There are few open literatures related to anti-skid braking system for multi-wheels due to technology blockade.In China,the research on multi-channel control and non-equilibrium regulation has just started,and the design of multi-channel control system for anti-skid braking,the simulation of asymmetry taxiing under braking are not studied.In this paper,a dynamics model of ground movement for aircraft with four-wheel bogie landing gears is established for braking simulation, considering the six-degree-of-freedom aircraft body and the movement of bogies and wheels.A multi-channel anti-skid braking system is designed for the wheels of the main landing gears with four-wheel bogies.The eight wheels on left and right landing gears are divided into four groups,and each group is controlled via one channel.The cross protection and self-locked protection modules are added between different channels.A multi-channel anti-skid braking system with slip-ratio control or with slip-velocity control is established separately.Based on the aircraft dynamics model,aircraft braking to stop with anti-skid control on dry runway and on wet runway are simulated.The simulation results demonstrate that in asymmetric conditions,added with cross protection and self-locked protection modules,the slip-ratio-controlled braking system can automatically regulate brake torque to avoid deep slipping and correct aircraft course.The proposed research has reference value for improving brake control effect on wet runway.

Design of Small Stone Asphalt Mixture based on Anti-skidding Performance

Small stone asphalt mixture（SSAM） was designed by Bailey method and coarse aggregate voids-filling method.The optimum asphalt content was determined by Marshal test.Surface texture depth for SSAM with different voidage,and the BPN of SSAM and SMA before after wet track abrasion were measured.The experimental results indicate that the surface texture depth increases with the decreasing of asphalt aggregate ratio.The SSAM with the optimal asphalt content has a good skid resistance.BPN of asphalt mixture decreases with the increasing of wearing time,but the extent of reduction is different.The reduction rate of BPN for SSAM is smaller than that of SMA,indicating that SSAM has a good skid resistance attenuation capacity.Finally,the other properties of SSAM are also evaluated,showing that the splitting strength and modulus and SSAM are higher than those of SMA,and the other properties of SSAM,such as high-temperature performance and water stability can also satisfy the technical requirements.

无人机全电刹车系统级联快速终端滑模控制

无人机防滑刹车系统具有高阶非线性、强耦合以及参数时变性等特点,会对无人机的地面滑跑性能造成不利影响。提出了一种无人机全电防滑刹车系统快速终端滑模控制方法,实现对最佳滑移率的准确跟踪,并保证刹车系统的稳定性。建立了无人机全电刹车系统整体模型,在控制器设计过程中避免了对地面结合系数拟合公式的依赖。结合反演控制的思想,逐级设计了快速终端滑模控制器实现对滑移率以及刹车压力参考值的精确跟踪,并通过Lyapunov稳定性理论证明了控制器的稳定性。通过仿真测试验证了所提出控制策略的有效性。

Engineering Application and Development of Anti-skid Sand

In view of the increasing cement concrete pavement in China,the proportion of road non-slip surface layer is large,the winter slippery performance is insufficient and the later non-slip treatment is difficult. Through the concrete construction and post-application and development of the anti-skid sand in the road and bridge,the feasible anti-skid optimization measures are put forward.

轨道车辆制动防滑控制系统数值建模与验证

基于轨道车辆制动系统三位式防滑阀工作原理,建立防滑阀数学模型,进行充排气特性仿真分析;依次建立电空转换阀、紧急阀及中继阀等阀类数学模型,构建空气制动单元模型;针对制动防滑控制系统,建立防滑控制单元及制动动力学单元模型,结合空气制动单元模型搭建四轴车辆制动防滑控制数值仿真平台;利用数值仿真平台进行列车制动防滑性能仿真分析,并通过制动距离、车速及滑动量误差量3个指标与实车在线试验数据对比。结果表明:制动距离仿真值与试验值误差小于5%;车速仿真曲线和试验曲线吻合较好,二者任意时刻的差值小于3 km/h;各个滑动间隔内的滑动量误差平均值小于20%;三者均满足指标要求,验证了所建四轴车辆制动防滑控制模型的有效性。

反推模糊滑模控制在无人机制动系统的应用

针对无人机防滑制动系统(ABS),提出了一种反推模糊滑模控制方法。在机电作动器模型的基础上,建立无人机制动系统纵向动力学模型。为了克服制动系统的高阶非线性,采用Barrier Lyapunov函数设计了ABS控制器,确保无人机在制动过程中的滑移率能够在预设范围内跟踪参考值。然后,通过功率快速终端滑模控制算法实现ABS控制器所需的高性能制动压力控制,在此基础上建立模糊校正器以提高机电执行器(EMA)在不同制动压力范围内的动态自适应能力。实验结果表明,所提出的制动压力控制策略能够提高EMA的伺服性能,实验结果表明,所提出的控制策略在各种跑道条件下都具有良好的稳定性。

高空作业车防滑行走液压系统设计

针对高空作业车行走在恶劣工况出现打滑现象,且在高速行走转弯时出现发动机掉速问题进行研究,从行走液压系统角度进行分析。分别设计了大小阻尼切换防滑液压系统,双闭式行走泵防滑液压系统和主动浮动防滑液压系统。正确合理设计行走防滑液压系统,对高空作业车行走安全稳定性具有重要意义。

飞机防滑刹车系统刹车压力自动控制分析

基于飞机防滑刹车系统组成和工作原理,对飞机刹车系统最大刹车压力与刹车机轮径向载荷、轮胎与地面间结合系数间的关系进行研究。提出一种利用刹车控制器测飞机前起落架缓冲器行程,确定机轮径向载荷和刹车盘摩擦面之间的瞬时动摩擦因数,确定刹车过程中机轮瞬时最大刹车压力;调整刹车系统控制参数和防滑控制率,实现刹车系统的刹车压力闭环控制,提高飞机刹车效率,缩短刹车距离,减少轮胎磨损量,提高飞机着陆的安全性、可靠性。

地铁车辆液压制动防滑控制方案设计及效果分析

地铁车辆液压制动系统具有高工作压力、快响应、高效率、结构紧凑的特性。分析了液压制动系统、液压控制单元工作原理、结构组成,研究了地铁车辆制动过程中的滑行原因。综合液压制动用地铁车辆独立轮特性,将制动减速度、减速度变化及时速差作为输入,输出为压力输出系数,根据经验设计模糊规则及隶属度函数,基于模糊控制对液压制动防滑方案进行设计,并通过MATLAB仿真试验、应用验证,获得了预期防滑效果,验证了液压防滑方案中模糊控制的有效性。

带防滑木塑板的液控翻板闸门防洪系统应用

结合苕溪清水入湖河道整治工程(余杭区段),介绍一种带防滑木塑板的液控翻板闸门防洪系统,防洪系统主要由翻板闸门、液控启闭装置、支铰装置、锁定装置、立柱、止水装置、挡墙、牛腿、钢支墩、护栏等组成,既能保障未封闭防洪圈的防洪安全,又较好地利用闸门平卧空间,满足城市生态景观要求,且液控启闭可实现现地控制或远程控制,操控性强,方便工程运行管理,对类似城市防洪的设计具有一定借鉴意义。

飞机起落架数学模型的研究

对飞机起落架组成及工作原理进行较为详细的研究,建立了飞机起落架的数学模型,并在MATLAB/SIMULINK环境下进行系统仿真,给出仿真结果,分析了起落架对飞机防滑刹车系统的影响。仿真结果表明系统模型基本合理、正确,为设计、改进飞机防滑刹车系统,提高刹车效率和刹车性能,具有重要的指导意义。

飞机防滑刹车系统的建模与仿真研究

以某型飞机为对象,在综合考虑了飞机的机体、起落架、轮胎等特性的基础上,建立了防滑刹车系统的数学模型。在Matlab6.1/ Simulink 仿真环境下进行仿真,给出湿跑道条件下的仿真结果,结果表明系统模型合理、正确。

汽车ABS制动过程的道路识别

汽车ABS控制的效果与道路识别有着重要关系,在制动过程中实时对各轮胎所附着道路的附着系数进行识别,可及时地调整制动力,提高道路的附着利用率和制动效能,使汽车ABS控制更加合理.文中通过试验获得了ABS制动过程轮缸的可等效压力函数,由储气缸压力和轮缸压力控制阀开关信号的时间历程,推导出各轮的滑移率,进而得出附着系数,实现了道路识别.道路试验检测验证了该方法的可行性.

城市轨道交通车辆防滑系统故障分析与仿真

介绍了城市轨道交通车辆制动系统以及防滑系统的构成。对防滑阀故障特征进行了分析。提出了用于检测防滑阀的算法流程。采用故障再现理念,基于AMESim仿真软件建立了制动系统仿真模型。该模型能够反映制动发生滑行时防滑控制的特性。在此基础上,模拟了防滑阀的故障状态。仿真结果表明,对防滑阀的故障分析是正确的。

飞机防滑刹车系统自适应控制器的设计与实现

飞机的刹车系统是飞机机电系统的一个重要组成部分,当跑道有冰、雪时,飞机不但不易刹停,还难以保持两侧平衡。本文设计了基于输入输出的某型飞机防滑刹车系统自适应控制器,在机载机电系统综合管理仿真平台中进行仿真试验研究,最后比较了在湿滑路面情况下采用自适应控制器前后的仿真结果。仿真结果证明,采用自适应控制器后,刹车系统性能有很大提高。

基于T-S模糊神经网络的飞机防滑刹车系统研究

航空业的发展对飞机防滑刹车系统提出了更高的要求,而传统PID+PBM控制器存在着低速打滑、刹车效率较低等问题;针对刹车过程中的不确定性和非线性问题,提出采用T-S模糊神经网络来进行防滑刹车控制器设计;在MATLAB/SIMULINK平台建立飞机刹车总体仿真模型,将设计的控制器与传统控制器进行对比仿真试验;仿真结果表明,基于T-S模糊神经网络的控制器解决了传统PID+PBM系统存在的问题,具有良好的控制效果,系统具有鲁棒性,能够适应变化的跑道情况,为飞机防滑刹车控制提供了一种新的方法。

矿用电机车微机防滑系统的研究

矿用电机车是煤炭生产运输系统重要组成部分。在研究矿用电机车防滑制动系统的基础上,以单片机STC89C51为核心,采用模块化的设计方法对其电子控制单元(ECU)进行了硬件设计和软件设计,能够有效地防止矿用电机车产生滑行,达到了良好的制动效果。