High-gain observer-based integral sliding mode tracking control for heavy vehicle electro-hydraulic servo steering systems

The electro-hydraulic servo steering system (EHSSS) is the key element to determine the handling and stability of heavy vehicles. Accurate steering control is challenged due to its complicated structure and a wide range of steering loads. In this paper, an output feedback integral sliding mode control (ISMC) method based on high-gain observer is proposed to solve this issue. First, a new Hurwitz matrix design method is presented for EHSSS with non-chain integrator, in order to prove the convergence of the observer error dynamics. Then, the Lyapunov stability of the observer-based controller is verified. Finally, a test bench is established to experimentally validate the proposed method's effectiveness through multiple test scenarios. The results show the tracking error of the proposed method is significantly smaller than PI and similar to full-state feedback integral sliding mode controller. This paper provides a valuable reference for high-gain observer-based nonlinear control applied to a typical electro-hydraulic servo steering system.     

电液伺服系统的自适应滑模跟踪控制研究

针对电液伺服系统的跟踪控制问题,在系统模型不确定性参数的界未知的情况下,提出一种自适应滑模控制方案。该方案的主要思想是用滑模方法抑制系统中的外干扰力扰动,对系统不确定性参数进行自适应估计,用估计值来补偿不确定性参数的变化。对于系统全局稳定性,采用李雅普诺夫稳定性理论给出了严格的证明。仿真结果表明了该方案具有良好的跟踪性能和鲁棒性。     

基于ATmega16L的电液伺服控制系统设计

针对电液伺服闭环控制过程中,设定信号不断发生变化,电液阀门位置定位精确度较低的难题.采用AT-mega16L作为核心控制器,并配有高精度A/D、D/A转换器,通过对阀门开度控制信号和位置反馈信号进行采集、转换、计算和比较,发出控制信号决定并执行换向阀的换向、交流伺服电动机的起停运转,推动液压缸推杆的伸缩,进而对阀门转角大小、开度百分比进行精确定位.     

Development of robust motor servo control for rear steering actuator based on two-degree-of-freedom control system

A rear steering system can improve vehicle stability by actively controlling the rear wheel angles. For designing the rear steering system, environmental conditions, performance deterioration due to aging and component variation as a result of manufacturing tolerance under mass production must be taken into consideration. We have applied two-degree-of-freedom (2DOF) feedback control with feed-forward control for the motor servo control so that the rear steering actuator can track the target rear steering angle accurately and stably. The control system is designed based upon a nominal mathematical model and its variation range.As a result, the rear steering actuator can be controlled with excellent performance and high reliability. This paper describes the mathematical model construction in the frequency domain and a robust motor servo controller design based on 2DOF feedback control with feed-forward control.     

Hierarchical control strategies for multi-mode steering system of emergency rescue vehicle

It is difficult for the traditional emergency rescue vehicles (ERVs) to pass through narrow and complicated areas quickly, which leads to the ERVs missing the best time to rescue disasters seriously. How to improve the trafficability and mobility of vehicles effectively in narrow and complex areas has become an urgent technical demand for the ERVs. In this context, this paper proposes a multi-mode steering system to realize four steering modes of the ERVs. A fire rescue prototype vehicle is developed, and its multi-mode steering system is designed in detail. The hierarchical control strategies of the multi-mode steering system consist of the upper controller and the lower controller. The upper controller is responsible for assigning the steering angles of four wheels of the ERVs based on the Ackerman principle. The lower controller is used to control the ERVs to turn four wheels independently based on the electro-hydraulic fractional order PID (FOPID) control strategy, and then the parameters of the FOPID controller are optimized by the adaptive clonal selection algorithm. The multi-mode steering system proposed was tested on the homemade fire rescue prototype vehicle. The numerical simulations and experiments were conducted to verify the effectiveness of the proposed multi-mode steering system.     

基于模型预测控制的大口径快摆镜随动系统

为了满足地基大口径望远镜精密稳像系统的需求,对大口径快摆镜(FSM)的控制方法进行了研究。为了解决三促动器FSM的运动解耦为系统辨识带来的困难,通过解析法和系统辨识法相结合建立了FSM的传递函数模型。依据该模型,设计了PID控制器与模型预测控制器(MPC),采用仿真和实验两种方式比较了两种控制器的效果。仿真结果表明,在受到阶跃扰动后,MPC控制器的恢复速度是PID控制器的45倍。在50 Hz正弦信号下,由于FSM的大惯量特点,PID控制器有严重的时滞,而MPC控制器能以1.224×10^-6″的误差稳定跟随。在噪声抑制方面,对实时加入10%幅值噪声的随机信号,MPC控制器的噪声抑制效果是PID控制器的13.3倍。实验结果表明,MPC控制器能以0.430″的误差稳定跟随50 Hz正弦信号,其跟踪精度是PID控制器的3.212倍,采用MPC控制器的快摆镜能满足快摆镜高带宽和高精度的需求。     

Modeling, control, and validation of an electro-hydraulic steer-by-wire system for articulated vehicle applications

X-by-wire control systems in automotive applications refer to systems where the input device used by the operator is connected to the actuation power subsystem by electrical wires, as opposed to being connected by mechanical or hydraulic means. The "X" in the X-by-wire is replaced by "steer", "throttle", and "brake" to represent the steer-by-wire, throttle-by-wire, and brake-by-wire systems. Common to all of these subsystems is that the operator control input device (i.e., steering column, acceleration pedal, and brake pedal) is not connected to the actuation devices mechanically. Rather, it is connected to an embedded computer which, in turn, sends the control signals to the actuation devices. Current state of art steering systems used in articulated vehicles are hydro-mechanical type systems, i.e., the steering column motion is transmitted and amplified by the main hydraulic circuit by hydro-mechanical means. This paper presents a new steer-by-wire (SBW) system which we designed, modeled, analyzed, and tested on wheel type loader construction equipment. The simulation results and tests conducted on a prototype development vehicle (a medium size wheel type loader) show very good agreement. The control algorithm is modeled using graphical modeling tools similar to Simulink and StateFlow. A real-time control algorithm is implemented on a Motorola 68332 microprocessor-based embedded controller. The operational performance of the steer-by-wire system has been convincingly demonstrated.     

Modeling and control of steering system of heavy vehicles for automated highway systems

This work presents modeling, analysis, and controller design of the steering subsystem of heavy vehicles as a subsystem of vehicle lateral control system for the automated highway systems. A physical model of the steering subsystem is derived where the hydraulic power assist unit is modeled as a family of static nonlinear boost curves. Based on open-loop frequency tests and analysis of the physical model structure and its dynamical characteristics, a nominal second order linear model of the steering subsystem is obtained. Then, a linear robust loop-shaping controller is designed to provide a good tracking performance of the closed-loop dynamics of the steering subsystem for varying gain cross over frequencies which is a result of the nonlinear characteristics of the hydraulic power assist. The controller has been successfully incorporated as an inner-loop controller into the nested lateral control architecture for autonomous driving and its efficacy has been demonstrated experimentally.     

Time optimal control for induction motor servo system

A time-optimal position control scheme based on Pontryagin's minimum principle is proposed for a current-source-inverter (CSI) fed induction motor system. The induction motor with field-oriented control is modeled with a fast time-optimal position control system of second order which has two modes of operation: the first bang-bang mode operates until the position is close to target, followed by second DC braking mode which gives asymptotic stability. In order to realize this aim, the time-optimal controller is added instead of the speed controller to the conventional field oriented control loop of the CSI-fed induction motor. The validity of the time-optimal control solution has been verified by an experimental test. Experimental results are in close agreement with a digital simulation     

Fault tolerant real time control system for steer-by-wire electro-hydraulic systems

A steer-by-wire (SBW) control system is presented with emphasis on safety issues. The applications are in articulated vehicles such as the wheel type loaders, articulated trucks, and others. The electro-hydraulic (EH) power circuit is controlled by two embedded electronic control modules (ECM), the primary ECM and backup ECM. The two ECMs monitor each others condition. If one detects fault in the other, it takes over the control functions. There are two main control algorithms that run in the ECMs in real-time: the steering valve control algorithm and the failure detection algorithm. The valve control algorithm basically generates command signal to the steering valve based on operator steering column signal as well as other machine condition sensors.The failure detection algorithm implements a fault detection logic for both input sensors and output drivers, and flags the corresponding warning for to the operator, and take a predefined action depending on the type of the failure detected. A unique fault strategy organization is implemented by inspecting the failure behavior on both the component and the system levels. The failure detection algorithm also determines the most likely “good” sensor signal from a set of redundant sensors for each critical measurement. Based on these good sensors data, the steering control algorithm sends two output signals: the control signal to the steering EH circuit valve and the control signal to the steering wheel force feedback device (i.e. a brake or a motor) to give operator feedback about the steering conditions.Finite state machine (FSM) concept is used to design the fault handling algorithms for both the component level and the system level failure. The probability of the system being at normal steering state or at any other steering failure state is determined. Failure mode probabilities of steering system components are also determined.     

无人机用MINS/光流组合导航系统

目的：减小因为惯导系统在无人机长航时飞行时的误差。方法：提出了一种用INS/光流/磁强计组合导航方案,基于扩展卡尔曼滤波,将INS与光流数据融合,估计无人机的速度和位置。当无人机静止或匀速运动时,将陀螺仪与加速计、磁强计的数据融合,估计无人机的姿态;当无人机加速或减速时,用陀螺仪估计无人机的姿态。结果：在不使用组合导航时,在大约50米的行驶路程中,就出现了近8米的累积误差,而使用组合算法后,所产生的误差不超过1米。结论：该方案有效的减少导航时的速度、位置和姿态的误差,提高导航精度。     

Design and experimental research of observer-based adaptive type-2 fuzzy steering control for automated vehicles with prescribed performance

Steer-by-Wire (SbW) system is a significant electromechanical subsystem of automated vehicles. This paper proposes an observer-based type-2 fuzzy control method for the SbW system with uncertain nonlinearity, unknown modeling parameters, and unavailable state. First, an interval type-2 fuzzy logic system (IT2 FLS) and an IT2 FLS-based state observer are constructed to estimate the uncertain nonlinearity and unavailable state of SbW systems. Then, a prescribed performance control (PPC) method is proposed to achieve the prescribed tracking performance of SbW systems. Much importantly, a modified performance function is incorporated in this control method, such that the prescribed tracking performance can be guaranteed within a finite time regardless of the initial state. Finally, simulation and vehicle experiments are given to verify the effectiveness and superiority of the proposed methods.     

车载"动中通"伺服系统的研究与仿真

分析了"动中通"中的关键技术天线稳定与波束跟踪,并讨论了它们的不同实现方法.给出了一种把天线稳定和波束跟踪相结合的方法,并把几种实现方式分别在Simulink中进行了仿真,仿真结果表明该方法不仅具有有效性,而且对于误差的修正时间也比较短.     

Throttle actuator control system for vehicle traction control

Accurate and quick positioning of the throttle valve in a gasoline engine is required to implement various systems such as traction control systems (TCS), cruise control systems and drive-by-wire systems. In this research, the throttle actuator system for TCS application was developed. Unlike other systems, this system consists of only one throttle body to obtain small volume and low manufacturing cost, and uses a DC servo motor for quick and accurate responses. In order to drive the DC motor, a PWM signal generator and PWM amplifier were built and interfaced to the motor and controller. This paper also presents the position control logic of the throttle actuator with the TDC (time delay control) scheme with a variable reference model. By varying the reference model based on the size of the step changes in the target throttle angle, the TDC scheme yields good transient response characteristics in that both overshoot prevention and a quick response time are achieved. Actual vehicle tests with this developed system incorporated with the TCS system show that it satisfies all the conditions required for the TCS operation.     

Extended sliding mode observer based robust adaptive backstepping controller for electro-hydraulic servo system: Theory and experiment

This paper firstly presents an extended sliding mode observer (ESMO) for the electro-hydraulic servo systems (EHSSs) to deal with nonlinear factors like the external disturbance, parameter uncertainties as well as unmodeled characteristics in the EHSS. The model for the EHSS is established by taking these nonlinear factors into consideration and then the statespace representation is obtained. According to the state space, the ESMO for the EHSS is presented, the equivalence principle is properly utilized to simplify the ESMO and some saturation functions are employed to eliminate high frequency interferences caused by the chattering phenomenon. Based on estimated values from the ESMO, a robust adaptive backstepping controller (RABC) is presented in detail with taking some parameter uncertainties into consideration to further improve the tracking performance. The proposed controller has the following advantages: (1) utilizing the ESMO to cope with these nonlinear factors; (2) parameter online adaptive laws are employed in the RABC design to further improve the tracking performance. In order to verify the performance of the proposed controller, an experiment bench was established. Two sine waves reference signal (one amplitude 0.01 m, 1 Hz; the other 0.015 m, 2 Hz) are employed to verify the performance of the controller. Comparative experimental results show that: (1) the tracking performance of the proposed controller is better than that of a DOs based BC, a BC and a PI controller; (2) estimation values from the ESMO contains fewer noise than two conventional disturbance observers (DOs), which will decrease the control input ripples.     

Road vehicle communication system for vehicle control using leakycoaxial cable

A new road vehicle communication (RVC) system that provides continuous communication between vehicles and control centers using a leaky coaxial cable is presented. The system operates in the quasi-microwave band providing high-quality communication through a well-designed communication protocol. An experimental setup and future directions are also included in this article     

光纤连接器研磨机伺服控制系统设计

为实现光纤连接器研磨机操作台的精确定位,设计了基于可编程控制器(PLC)的研磨机伺服控制系统.将PLC、ED200伺服放大嚣和触摸屏运用于伺服控制系统.伺服放大器内部对象采用顺序编程(Sequencer Programming)的方法赋值,程序段的外部触发信号由PLC提供.PLC插入通讯扩展模块与ED200间建立RS485串行通讯,并通过触摸屏界面实时修改伺服放大器内部目标位置参数.实验结果表明,该系统运行稳定、人机界面友好,加工误差可以控制在±1%范围内.     

导引头伺服机构的控制系统分析与设计

针对导引头伺服装置的特点,推导了装置在搜索和跟踪工作模式下的输入输出特性,并重点分析了在这两种工作模式下,装置指令跟踪性能和扰动隔离性能之间的差异,指出了传统的只考虑陀螺稳定回路的系统隔离度指标确定与测试方法的局限性,同时提出了采用位置回路补偿陀螺随机漂移误差的方法。该研究为导引头伺服装置,以及其相关光电稳定跟踪装置的陀螺选型、控制系统设计及性能指标测试提供了参考和理论依据。     

A sensorless optimal control system for an automotive electric power assist steering system

This paper considers the analysis and design of a double-pinion-type electric power assist steering (EPAS) control system. A simplified model of the augmented steering assembly-electric motor system is developed using Lagrangian dynamics, and an optimal controller structure for the model is proposed. Three main advances to the state of the art are presented in this paper. First, a state-space design model is used rather than an input-output model. A state-space formulation for a system model that incorporates motor electrical dynamics is obtained with the assist motor angular position as the output. Second, linear quadratic regulator (LQR) and Kalman filter techniques are employed to arrive at an optimal controller for the EPAS system. The selection of weighting coefficients for the LQR cost function is discussed. Finally, the authors present a control strategy that eliminates the steering column torque sensor, a critical component in existing EPAS controller designs. The proposed control strategy presents an opportunity to improve EPAS system performance and also reduce system cost and complexity.