Application of Modelica/MWorks on modeling,simulation and optimization for electro-hydraulic servo valve system

Electro-hydraulic servo valve is a typical complicated multi-domain system constituted by mechanical, electric, hydraulic and magnetic components, which is widely used in electro-hydraulic servo systems such as construction machinery, heavy equipment, weapon and so forth. The traditional method of modeling and simulation of servo valve is based on block diagram or signal flow, which cannot describe the servo valve system from components level nor be used in modeling and simulation of overall servo systems. In the procedure of traditional method, computational causality must be involved in modeling of servo valve, which is inconvenient to execute modification on components or parameters. Modelica is an object-oriented modeling language which is suited for large, complex, heterogeneous and multi-domain systems. The key features of Modelica are multi-domain, object-oriented and non-causal, which are suitable for modeling of servo valve and make the model readable, reusable, and easy to modify. The simulation results show similar curves with traditional method. This new servo valve modeling and simulation method can provide the engineers a more efficient way to design and optimize a servo valve and an overall servo system.

Adaptive high precision position control of servo actuator with friction compensation using LuGre model

Adaptive control of servo actuator with nonlinear friction compensation is addressed. LuGre dynamic friction model is adopted to characterize the nonlinear friction and a new kind of slid ing mode observer is designed to estimate the internal immeasurable state of LuGre model. Based on the estimated friction state, adaptive laws are designed to identify the unknown model parameters and the external disturbances, and the system stability and asymptotic trajectory tracking perform ance are guaranteed by Lyapunov function. The position tracking performance is verified by the ex perimental results.

Mathematical Model of Steady State Operation in Jet Pipe Electro-Hydraulic Servo Valve

Jet pipe electro-hydraulic servo valve is the heart of feedback control systems,and it is one of the mechatronic components used for precision flow control application.It consists of several precision and ddicate components.The performance of the jet pipe servo valve depends on many parameters.During the developmental stage,it is very difficult to ascertain the function parameters.The steady-state analysis of jet pipe electro-hydraulic servo valve has been made to simulate its fluid characteristics （flowin,flow-out,leakage flow,recovery or load pressure,etc.） by mathematical modeling.Theoretical model was conducted on various affecting parameters on the pressure,the main flow rate of fluid,or leakage flow through the receiver holes.The major parameters studied are jet pipe nozzle diameters,receiver hole diameters,angle between the two centre-lines of receiver hole,nozzle offset,and nozzle stand-of distance.In this paper the research is important to determine and optimize the structural parameters of jet pipe servo valve.Thus,equations of the pressure and flow characteristics are set up and the optimal structural parameters of jet pipe are established.

Angular Position Controller and Its Design Model Verification for the Electro-Hydraulic Servo Control System

The angular position controller is system （EHSAS） to control the output of the rotary applied to electro-hydraulic servo actuator actuator. It works as a compensator based on the frequency response of the EHSAS. Its design model is verified on the state-space model of EHSAS by using simulation program SIMULINK. Real data used to test the system. Simulation results give a good agreement for the controller and also for the state-space model.

FORCE FEEDBACK MODEL OF ELECTRO-HYDRAULIC SERVO TELE-OPERATION ROBOT BASED ON VELOCITY CONTROL

The tele-operation robotic system which consists of an excavator as the construction robot, and two joysticks for operating the robot from a safe place are useful for performing restoration in damaged areas. In order to accomplish a precise task, the operator needs to feel a realistic sense of task force brought about from a feedback force between the fork glove of slave robot and unfamiliar environment. A novel force feedback model is proposed based on velocity control of cylinder to determine environment force acting on fork glove. Namely, the feedback force is formed by the error of displacement of joystick with velocity and driving force of piston, and the gain is calculated by the driving force and threshold of driving force of hydraulic cylinder. Moreover, the variable gain improved algorithm is developed to overcome the defect for grasping soft object. Experimental results for fork glove freedom of robotic system are provided to demonstrate the developed algorithm is available for grasping soft object.

基于Modelica的交流伺服控制系统建模与仿真

永磁同步电机(PMSM)在交流伺服系统中应用十分广泛,其数学模型具有非线性、多变量、强耦合的特点。为提高建模与分析效率,并兼顾PMSM模型在复杂多领域系统中的通用性等问题,提出一种基于Modelica的交流伺服控制系统的建模方法。采用模块化建模与Modelica语言实现了PMSM的非因果建模,在MWORKS平台建立了伺服系统的仿真模型,并在位置控制、速度控制方面测试了3类典型工况。实验表明,所提方法跟随误差小、动态响应快,验证了建模方法和系统模型构建的正确性和合理性,为伺服控制系统和多领域建模与仿真技术的发展提供了新思路。

基于Modelica语言的电液伺服阀非因果建模仿真

针对电液伺服阀这一典型机械、电子、磁场、液压与控制耦合的复杂系统,考虑其多领域、多层次化的特点,应用多领域建模仿真语言Modelica对电液伺服阀进行建模仿真。不同于传统的电液伺服阀控制框图建模分析方法,Modelica语言的非因果性与面向对象性,使得该方法具有强可读性,强可用性,便于修改等特点,克服了传统方法不能从底层元件反映伺服阀特性、考虑因果性、不易修改与重用的缺点。仿真结果显示,该方法可以反映电液伺服阀的动态特性,同时可以方便地通过参数修正对电液伺服阀进行优化设计,为电液伺服工程技术人员提供了电液伺服阀设计的更为高效便捷的手段。

基于Modelica的多领域伺服系统的研究

在实际应用需求中,跨领域建模与仿真已经变得越来越普遍。面向对象物理建模语言Modelica使多领域建模变得相对简单,并能在完全支持Modelica语言环境下的Dymola平台上进行仿真。采用Mod-elica语言分别对开环伺服系统和半闭环伺服系统进行了建模,并在Dymola上仿真。仿真结果表明,多领域的伺服系统动态响应性能效果良好,与分析基本上吻合。利用Modelica语言的开放性,根据研究对象的需要建立一些相关的模型,同时也完善了模型库。Modelica/Dymola为伺服系统的研究提供了一种方法。

基于级联惯性负载转矩观测器的永磁伺服电机复合抗扰控制

针对永磁伺服电机在运行时位置跟踪精度差和抗干扰性能弱等问题,提出一种模型预测位置控制与非奇异快速终端滑模速度控制相结合的复合模型预测控制策略。该控制策略采用非奇异快速终端滑模设计速度控制器,以有效提高响应速度及系统鲁棒性;采用模型预测位置控制提高位置跟踪精度;同时,采用基于转动惯量观测和负载转矩观测器相结合的级联惯性负载转矩观测器观测负载转矩并进行前馈补偿,进一步提高系统的抗干扰性能。通过仿真和实验结果可得,所提复合模型预测控制可有效提高永磁伺服电机的动态响应速度和抗负载扰动能力。

Sliding Mode Controller Design for Position and Speed Control of Flight Simulator Servo System with Large Friction

Flight simulator is an important device and a typical high-performance position and speed servo system used in the hardware-in-the-loop simulation of flight control system. Friction is the main nonlinear resistance in the flight simulator servo system, especially in a low-speed state. Based on the description of dynamic and static models of a nonlinear Stribeck friction model, this paper puts forward sliding mode controller to overcome the friction, whose stability is

Hybrid Adaptive Compensation Control Scheme for High-Precision Servo System

In this paper,a hybrid adaptive compensation control scheme is proposed to compensate the friction occurrence and other nonlinear disturbance factors that exist in the high-precision servo system.An adaptive compensation controller with a dual-observer structure is designed,while the LuGre dynamic friction model with non-uniform parametric uncertainties characterizes the friction torque.Considering the influence of the periodic disturbance torque and parametric uncertainties,fuzzy systems and a robust term are employed.In this way,the whole system can be treated as a simple linear model after being compensated,then the proportional-derivative (PD) control law is applied to enhancing the control performance.On the basis of Lyapunov stability theory,the global stability and the asymptotic convergence of the tracking error are proved.Numerical simulations demonstrate that the proposed scheme has potentials to restrain the impact of disturbance and improving the tracking performance.

一阶系统模型参考自适应辨识及位置控制

针对新建系统或负载变化导致的模型参数不确定问题,对交流伺服系统进行研究,提出模型参考自适应辨识(model reference adaptive identification,MRAI)算法,对一阶系统模型参数进行在线辨识。首先对一阶系统进行数学模型构建,然后根据李雅普诺夫(Lyapunov)稳定理论选择参考模型,并设计自适应控制律,在此基础上对一阶系统进行模型参数在线辨识。当参数收敛后,根据系统要求的自然频率和阻尼比,在线设计位置控制器参数,并进行跟踪定位控制。仿真和实验结果表明,模型参考自适应在线辨识算法能快速精准地辨识出系统模型参数,通过在线设计控制器参数实现了对参考信号的快速跟踪。

Adaptive Robust Motion Trajectory Tracking Control of Pneumatic Cylinders with LuGre Model-based Friction Compensation

Friction compensation is particularly important for motion trajectory tracking control of pneumatic cylinders at low speed movement. However, most of the existing model-based friction compensation schemes use simple classical models, which are not enough to address applications with high-accuracy position requirements. Furthermore, the friction force in the cylinder is time-varying, and there exist rather severe unmodelled dynamics and unknown disturbances in the pneumatic system. To deal with these problems effectively, an adaptive robust controller with LuGre model-based dynamic friction compensation is constructed. The proposed controller employs on-line recursive least squares estimation（RLSE） to reduce the extent of parametric uncertainties, and utilizes the sliding mode control method to attenuate the effects of parameter estimation errors, unmodelled dynamics and disturbances. In addition, in order to realize LuGre model-based friction compensation, the modified dual-observer structure for estimating immeasurable friction internal state is developed. Therefore, a prescribed motion tracking transient performance and final tracking accuracy can be guaranteed. Since the system model uncertainties are unmatched, the recursive backstepping design technology is applied. In order to solve the conflicts between the sliding mode control design and the adaptive control design, the projection mapping is used to condition the RLSE algorithm so that the parameter estimates are kept within a known bounded convex set. Finally, the proposed controller is tested for tracking sinusoidal trajectories and smooth square trajectory under different loads and sudden disturbance. The testing results demonstrate that the achievable performance of the proposed controller is excellent and is much better than most other studies in literature. Especially when a 0.5 Hz sinusoidal trajectory is tracked, the maximum tracking error is 0.96 mm and the average tracking error is 0.45 mm. This paper constructs an adaptive robust controller which can compensate the friction force in the cylinder.

直流电机位置伺服系统新型控制策略研究

针对伺服系统控制器参数设计的复杂性和系统抗干扰性低的问题,设计了内模PID速度控制器和基于指数趋近律的滑模变结构位置控制器,并通过李雅普诺夫理论对系统的稳定性进行分析。速度控制器采用内模PID控制,只调节滤波器参数λ,避免了因调参困难而影响伺服系统的控制精度;位置控制器采用滑模控制方式,对参数变化以及外界影响等因素具有强鲁棒性。仿真和实验结果表明,所提控制系统能够满足对直流伺服电机位置控制的快速性和准确性要求。

高性能双轴振镜控制系统设计

针对高速高精度的激光微加工应用,提出一种基于并行处理架构的全数字控制双轴振镜驱动系统设计方案,在高频数字控制下实现了双轴振镜的高动态实时控制。通过建立振镜系统数学模型,以串级闭环控制为基础,采用模型跟踪控制策略提升了位置跟踪性能。实验结果表明所设计的双轴振镜控制系统能够有效提升动态响应速度、降低跟踪误差,满足期望工作性能指标.

汽车EPS伺服变幅加载系统PID建立DNN控制优化

为了进一步提高汽车电动助力转向电液伺服加载系统运动精度,设计了一种PID建立DNN控制系统。通过柔性联接的模式构建电液位置伺服系统,确保在瞬态平衡响应过程中快速完成控制。搭建了柔性电液位置伺服调控测试,并开展调控效果分析。研究结果表明:通过PID建立的DNN控制器在校正柔性联接电液位置伺服参数方面发挥了关键作用,整体响应时间大幅缩短,确保系统频段动态控制效果获得明显改善。采用DNN控制器调节柔性连接电液伺服系统时,能够有效增强系统低频负载位移精度,避免发生幅值衰减的问题,能够以更高精度跟踪柔性连接电液位置伺服参数,促进了系统跟踪性能获得明显改善。该研究对提高汽车运行稳定性以及节能具有很好的理论支撑作用。

比例伺服阀非线性液动力模型修正与特性分析

比例伺服阀的高速运行以及油液流动状态直接影响液动力的变化,进而影响比例伺服阀和伺服机构的动静态性能。基于此,为明确比例伺服阀液动力的变化规律和特性,首先基于阀芯和阀体配合的节流口结构建立液动力的理论数学模型。然后结合流场仿真,分析不同开度和不同压差下液动力变化情况,明确液动力仿真结果和理论结果的偏差,修订液动力理论数学模型。最后,基于液动力测试平台,验证了不同开度和压差下液动力变化情况。结果表明:射流角的减小会导致稳态液动力不断增大,阀口开度的增大使稳态液动力呈现先增大后减小的趋势,同时在小开度下压差越大对应稳态液动力的峰值也越大,研究成果为比例伺服阀非线性补偿控制提供理论基础。

电液伺服控制阀动态仿真与试验

电液伺服阀被广泛应用各种自动化装备中,这种复杂的机电控制系统集机、电、液、磁于一体,属于重要的随动跟踪控制元件,伺服控制除了有良好的静态性能外,其动力学特性决定了伺服系统工作精度.运用键合图理论建立电液伺服阀的键图模型;推导模型的状态空间方程和输出方程;运用仿真软件MATLAB/Simulink进行了仿真,分析电液伺服阀系统动态特性.最后在搭建的实验验证平台上验证了系统的动态性能,并与仿真结果进行了比较分析.结果是该电液伺服阀的动态特性指标超调量40%、响应时间13ms、上升时间2ms左右.

电液位置伺服系统的MPC控制仿真分析

电液位置伺服系统广泛应用在大负载、快速、精确反应的控制领域中,然而其存在时变非线性的特性,因此传统控制系统不能达到理想的控制效果。模型预测控制(Model Predictive Control,MPC)具有无需模型、鲁棒性强、抗扰动能力强等优点,较适合应用在时变非线性系统的控制中。分别采用PID控制、线性MPC、自适应MPC和非线性MPC 4种控制策略对电液位置伺服系统的控制性能进行仿真研究。结果表明:线性MPC、自适应MPC和非线性MPC都比PID控制性能好,非线性MPC控制精度较高、响应速度较快、抗扰动能力较强,自适应MPC控制精度、响应速度和鲁棒性次之。

伺服阀旋转直驱超声电机机理与特性

针对某旋转直驱式伺服阀对驱动电机小长径比紧凑型结构形式的设计要求,从伺服阀功率级200 Hz动态响应需求出发,设计了一款环形行波型超声电机。分析了超声电机的基本工作原理并建立了超声电机定子转子摩擦传动模型,搭建了超声电机特性测试实验台并进行了转矩-转速测试,实验结果与仿真结果一致,验证了电机设计的合理性。在此基础上,进行了超声电机驱动频率和驱动电压的影响特性分析,结果表明超声电机在49.8 kHz的驱动频率下具有最大的工作效率,驱动电压大于110 V时可以满足伺服阀转速与转矩工作需求,并且在49.8 Hz的驱动频率和110 V驱动电压条件下可以接近最大的工作效率。