分布式电驱动汽车列车横向稳定性控制研究

为了提高分布式电驱动汽车列车的横向稳定性,提出了一种基于线性二次型调节器(Linear Quadratic Regulator, LQR)的极值优化驱动力矩控制策略。建立了三自由度理想汽车列车模型,通过基于LQR的附加横摆力矩控制器得到附加横摆力矩,运用极值法合理分配驱动力矩,采用TruckSim与MATLAB/Simulink联合仿真平台分别进行了中速双移线和高速单移线工况仿真。仿真结果表明,中速双移线工况下,所设计的极值优化驱动力矩控制策略相比于平均分配控制策略,其牵引车的质心侧偏角峰值降低了22.78%,牵引车与挂车的横摆角速度峰值分别降低了5.46%和2.86%;高速单移线工况下,其牵引车与挂车的质心侧偏角峰值分别降低了22.85%和17.19%,横摆角速度峰值分别降低了10.40%和8.16%,提高了分布式电驱动汽车列车中高速行驶时的横向稳定性。为验证极值优化驱动力矩控制策略在实时系统中的控制效果,进行了硬件在环测试,结果表明硬件在环测试结果与仿真结果一致。     

电动车四轮转向与差动驱动的联合仿真研究

为了降低电动车高速行驶时转向失稳带来的危险,提出了四轮转向与差动驱动联合控制策略以提高电动车转向时的高速稳定性。考虑轮胎非线性特性对整车的影响,在MATLAB中建立了电动车四轮转向与差动驱动联合控制下的整车动力学模型。以电动车转向过程中的质心侧偏角与横摆角速度为控制目标,采用模糊控制策略协调四轮转向与差动驱动进行联合控制,从而调节电动车的后轮转角和驱动力分配,使其质心侧偏角和横摆角速度能够跟随理想模型。通过仿真分析得到了转向时电动车的质心侧偏角和横摆角速度的动态响应。结果表明:在四轮转向与差动驱动联合控制下,可以将电动车质心侧偏角与横摆角速度控制在接近理想状态,从而提高电动车在高速时的转向稳定性并加快车辆的侧向响应速度。     

采用卡尔曼滤波的电子稳定性程序分析

汽车的横摆加速度过大会引起过度转向和过多不足转向等危险工况。采用线性二自由度车辆模型计算目标横摆角速度和目标质心侧偏角,运用卡尔曼滤波理论实时估算汽车的质心侧偏角并结合横摆角速度传感器对车辆稳定状态进行监测,提出了基于横摆角速度和质心侧偏角的ESP控制方法,着重介绍了ESP逻辑判断准则,应用Matlab/Simulink软件实现相应的电子稳定控制策略,同时利用AMESim软件中的15自由度整车模型建立AMESim-Simulink联合仿真模型,仿真结果验证了所提出的质心侧偏角估算的可行性及稳定性控制策略的有效性。     

四轮转向车辆的直接横摆力矩控制研究

以四轮转向汽车为研究对象,建立七自由度车辆模型、轮胎模型、理想跟踪模型;设计直接横摆力矩和四轮转向相结合的车辆稳定性控制策略。以跟踪理想的质心侧偏角和横摆角速度为控制目标,设计滑模控制器产生车辆转向所需的横摆力矩和后轮转角,按单侧制动的方法将产生的横摆力矩分配到车辆的四个车轮上,通过制动力矩的分配以及转向角的修正,使车辆转向行驶时的横摆角速度和质心侧偏角跟踪理想模型。针对七自由度模型,在Matlab/Simulink中与比例控制四轮转向进行阶跃输入和正弦输入两种工况下的时域仿真对比。仿真结果表明,基于直接横摆力矩和四轮转向相结合的的控制策略有效减小了质心侧偏角,横摆角速度对理想值有很好的跟踪,提高了车辆的操纵稳定性,同时验证了横摆力矩分配的有效性。     

基于四轮转向与直接横摆力矩的汽车稳定性研究

通过对汽车行驶状态的分析,分别在Simulink和CarSim中建立理想二自由度四轮转向汽车模型和整车模型。在Simulink中建立控制策略,以前轮转角比例控制的方式控制后轮转角;以车辆质心侧偏角和横摆角速度作为控制量,基于模糊控制理论,计算出所需附加横摆力矩,通过所设计的分配策略确定施加在前后车轮的制动力矩。利用CarSim和Simulink搭建联合仿真平台,进行低速角阶跃实验和高速单移线实验,并与前轮转向和其他控制策略下的仿真结果对比分析。仿真结果表明,所设计的控制策略使汽车的质心侧偏角和横摆角速度始终保持在理想值的附近,提高了汽车的灵活性和稳定性。     

四轮独立驱动移动机器人的动力学滑模转弯控制

为解决四轮独立驱动移动机器人在转弯时易出现不稳定的问题,并提高其转弯性能,针对一种四轮独立驱动移动机器人,根据移动机器人各车轮转矩可单独控制的特点,首先,运用达朗贝尔原理建立以质心侧偏角和横摆角速度为状态变量的四轮独立转向动力学模型,然后,运用直接横摆力矩控制方法,设计以质心侧偏角和横摆角速度为控制系统状态变量的指数趋近律动力学滑模控制策略,以使移动机器人质心侧偏角控制在稳定范围内,且其横摆角速度能够很好地跟踪移动机器人期望运动轨迹。最后,通过基于Matlab/Simulink进行转向行驶控制仿真试验,结果表明,与前馈反馈控制方法相比,基于所建立动力学模型所设计滑模控制策略有效改善了移动机器人的转弯控制稳定性。     

横摆与侧偏联合控制在汽车操稳中的应用

汽车操稳性对汽车安全性能起着至关重要的作用,精确建立整车动力学模型和获取车辆运动状态参数,可以提高汽车操稳性控制的鲁棒性。首先建立汽车电子机械制动系统模型及其三闭环控制系统,其次建立整车动力学模型,设计基于卡尔曼滤波算法的状态观测器对车辆运行状态进行最优估计。提出汽车侧偏与横摆联合控制策略,并引入分配系数实现对横摆角速度和质心侧偏角的联合控制。硬件在环试验结果表明,所建立的联合控制策略可有效地控制汽车的横摆与侧偏,有助于改善汽车的操稳性。     

四轮独立驱动电动汽车行驶稳定性分析与联合滑模变结构主动控制

针对四轮毂电机独立驱动汽车各轮力矩解耦可控的特点,分析车辆转向受力对四轮独立驱动电动汽车行驶稳定性的影响,提出四轮独立驱动电动汽车转向稳定性控制策略,为四轮独立驱动电动汽车四轮转矩协调控制,提升整车行驶稳定性提供了思路.基于模型跟踪控制的思想,采用分层控制思想设计控制器,控制器包含参考模型、顶层控制器、底层控制分配器.采用带质心侧偏角约束的2自由度车辆模型作为参考模型,设计出一种新的非线性联合滑模变结构主动控制的顶层控制器,该方法可以在一定程度上实现车辆横摆角速度和质心侧偏角的解耦控制,避免了横摆角速度和质心侧偏角的较大变化,从而保证汽车稳定性.在底层控制分配器中,采用基于轮胎稳定裕度最大化的最优分配方法.在Carsim软件中,搭建四轮轮毂电机独立驱动电动汽车模型,在Simulink软件中搭建控制策略模型.针对双移线工况,Carsim/Simulink联合仿真的结果表明,滑模变结构控制器具有较好的收敛性,控制分配模块可以实现四轮力矩的优化分配,能够提升车辆在极限工况下的稳定性.研究将为轮毂电机驱动车辆分布式协调控制提供理论支撑.     

低附着条件下的VDC质心侧偏角控制策略

设计了一种基于动态边界的质心侧偏角控制策略,用于低附着路面的车辆动力学控制。分析了汽车在低附着路面上的运动特征,以及低附着路面质心侧偏角控制的策略;根据质心侧偏角、质心侧偏角速度和附着系数的关系,对质心侧偏角赋予与路面附着系数相关的动态控制范围;采用模糊滑模变结构控制算法设计横摆力矩控制器,设计了两个模糊规则表根据路面附着系数的大小,分别调整质心侧偏角偏差在计算附加横摆力矩时的权重,以及附加横摆力矩对质心侧偏角的影响,以有效维持质心侧偏角在低附着路面上始终处于安全的范围。仿真结果证明了该方法的有效性。     

四轮独驱电动车主动转向与横摆力矩集成控制

针对四轮独立驱动电动车主动转向与横摆力矩集成控制问题,基于最优控制理论进行了研究。确定了整车集成控制结构,应用最优控制理论设计了集成控制器,利用四轮独立驱动电动车四轮驱动力矩独立可控的优势,采用规则分配方法设计了驱动力分配器。集成控制器根据实际横摆角速度和期望横摆角速度之差、实际质心侧偏角和期望质心侧偏角之差输出保证汽车稳定行驶所需的附加方向盘转角和附加横摆力矩值,附加方向盘转角直接作用到方向盘上,附加横摆力矩通过驱动力分配器分配实现。选择典型工况,采用驾驶模拟器硬件在环试验台对所研究的控制方法进行实验验证。验证结果表明,主动转向与横摆力矩集成控制提高了汽车行驶稳定性。     

起竖装置的数字式流量控制研究

本文针对某起竖装置流量控制特点,讨论了采用单片机－数字流量阀控制方案,根据对轴角编码器发出的角度值的检测结果,由单片机控制数字流量阀,从而对起竖流量进行控制和对起竖装置进行过速保护的方法。     

无舵机转向系统原理分析与控制研究

针对现有研究中无舵机转向仍处于一个尚未开发的阶段,分析了无舵机转向的原理,并推导了无舵机转向的转向角计算公式。设计了无舵机转向的控制系统,利用模糊PID控制中对偏差的智能化处理,引入智能分段控制概念,根据实际转角与目标转角的差值的大小,改变PID中的控制参数,以自动适应调整转速控制的响应速度等一系列特点,控制电机的转速输出以调节转向角。利用Matlab/Simulink建立了控制系统仿真模型进行了仿真分析,并在实物平板代步车中加以实验验证。     

C6125车床的数控化改装与设计

着重介绍车床的改造部位和设计方法，阐述数控系统硬件设计中各芯片的联接关系，指出采用反推法确定驱动元件的步骤。     

Nonlinear adaptive control for high angle of attack flight

This paper presents a nonlinear methodology for the control of a high angle of attack aircraft, in particular, a modified F-18 aircraft. As a modern combat aircraft demands better maneuverability and performance over domains which include high angles of attack, research in high angle of attack is presently at an advanced stage. An adaptive controller is developed to maneuver an aircraft at a high angle of attack even if the aircraft is required to fly over a highly nonlinear flight regime. The adaptive, controller presented in this paper is based on nonlinear prediction models, and can be constructed to minimize the given cost function or the difference of a described Lyapunov function with respect to the control input at each step. A controller uses system identification parameters to calculate a command signal so that the output of system follows the reference trajectory. The control is calculated to let system follow the reference trajectory under some constraints. This paper shows that nonlinear adaptive control can be utilized effectively to control high performance aircraft such as the F-18 aircraft for rapid maneuvers with large changes in angle of attack.     

Side slip angle based control threshold of vehicle stability control system

Vehicle Stability Control (VSC) system prevents vehicle from spinning or drifting out mainly by braking intervention. Although a control threshold of conventional VSC is designed by vehicle characteristics and centered on average drivers, it can be a redundancy to expert drivers in critical driving conditions. In this study, a manual adaptation of VSC is investigated by changing the control threshold. A control threshold can be determined by phase plane analysis of side slip angle and angular velocity which is established with various vehicle speeds and steering angles. Since vehicle side slip angle is impossible to be obtained by commercially available sensors, a side slip angle is designed and evaluated with test results. By using the estimated value, phase plane analysis is applied to determine control threshold. To evaluate an effect of control threshold, we applied a 23-DOF vehicle nonlinear model with a vehicle planar motion model based sliding controller. Controller gains are tuned as the control threshold changed. A VSC with various control thresholds makes VSC more flexible with respect to individual driver characteristics.     

Comparison of angle standards with the aid of a high-resolution angle encoder

Germany's National Metrology Institute the Physikalisch-Technische Bundesanstalt (PTB) and the DR. JOHANNES HEIDENHAIN GmbH (HEIDENHAIN) have conducted and compared measurements using their primary angle standards, which are realized as angle comparators of similar design. A high-resolution digital angle encoder served as the transfer standard for this comparison. Calibrations of the transfer standard by the two angle comparators resulted in an agreement of ±0.002″. The result proved to be consistent with the measurement uncertainties that the participants attributed to their calibration. PTB succeeded, using an additional comparison with a self-calibration method, in improving the measurement uncertainty of its comparator by a factor of 2.5 to 0.002″ (k = 2). The results of both participants demonstrated the suitability of the digital angle encoder as transfer standard for angle measurement comparisons aimed at uncertainties of a few thousandths of an arcsecond.     

Reference trajectory analysis and trajectory control by bank angle for re-entry vehicle

The re-entry problem consists of guidance design and trajectory control. This paper summarizes the detailed relationships between the velocity, drag acceleration and altitude in determining reference trajectories. The computational issues are also addressed, and the performance of the proposed simple nonlinear control of a bank angle for the longitudinal/lateral trajectory is demonstrated. In particular, the fixed bank angle methods that can reduce the drag acceleration errors at low-speeds are proposed. The importance of bank reversals with respect to the azimuth errors is also elucidated.     

A novel technique for calibration of polygon angles with non-integer subdivision of indexing table

Polygons are basic angle standards for angle measurement, particularly used for calibration of rotary angular indexing, and for measuring equipment such as dividing heads and tables. A main application in daily life is in bar-code readers. Calibration of such angle standards is required for traceability and at the highest accuracy it is a responsibility of national metrology institutes. In order to investigate uncertainty parameters on polygon calibration and to establish the capabilities of national metrology institutes, intercomparision measurements in the name of EUROMET project 371 “angle calibration on precision polygons” between 12 European countries have been carried out. Two precise polygons with 7 and 24 faces have been calibrated by the participants. Difficulties arose for precise calibration of seven-sided polygon for those institutes, which do not have a high-resolution angle comparator or two autocollimators. UME, the National Metrology Institute of Turkey, has applied an alternative technique for precise calibration of seven-sided polygon without using high-resolution angle comparators (i.e., indexing tables or angle dividers) or two autocollimators. The technique is based on the circle closure principle. The pitch and cumulative angles of the polygon are extracted from the angle measurement between some polygon faces (such as one and four (1/4), analogous 2/5, 3/6, 4/7, 5/1, 6/2 and 7/3) the angle of which can be generated close enough by the indexing table. This means that the polygon can be regarded as unfolded in seven 3-pitch angle intervals of 3×360°/7≈154°17′, making up 1080° in total. The method gives the differences between these seven intervals; with the closure condition (the sum must be zero) this gives all absolute angles. A full uncertainty evaluation is given that is based on the model function which relates the measured values to the polygon angles. For the calibration actually carried out, this yielded an uncertainty of 0.24″. Within this uncertainty the measured polygon angles corresponded very well with the reference values of the intercomparison. The method is of use for laboratories which do not have a high-resolution angle comparator (i.e., an indexing table or angle divider) or two autocollimators for the calibration of such angle standards.     

轮胎动态实验台侧倾角高精度自动测控系统

针对轮胎动态实验台侧倾角的测控问题,研制一种由光电编码器、鉴相电路、接口电路和AT89C52单片机组成的侧倾角高精度自动测控系统。经现场使用和实验表明:该系统侧倾角测量误差小于0 02°,具有测量精度高和抗干扰能力强的优点。     

蜗杆蜗轮机构的自锁性

对蜗杆蜗轮的自锁条件进行了较全面的分析，讨论了各种因素对自锁性的影响，并归纳了蜗杆蜗轮机构设计中注意的问题。