Disturbance observer based position tracking of electro-hydraulic actuator

A nonlinear controller based on an extended second-order disturbance observer is presented to track desired position for an electro-hydraulic single-rod actuator in the presence of both external disturbances and parameter uncertainties. The proposed extended second-order disturbance observer deals with not only the external perturbations, but also parameter uncertainties which are commonly regarded as lumped disturbances in previous researches. Besides, the outer position tracking loop is designed with cylinder load pressure as output; and the inner pressure control loop provides the hydraulic actuator the characteristic of a force generator. The stability of the closed-loop system is provided based on Lyapunov theory. The performance of the controller is verified through simulations and experiments. The results demonstrate that the proposed nonlinear position tracking controller, together with the extended second-order disturbance observer, gives an excellent tracking performance in the presence of parameter uncertainties and external disturbance.

A New Type of Automotive Braking Actuator for Decentralized Electro-hydraulic Braking System

This paper presents a new type of automotive braking actuator for a kind of brake-by-wire system called decentralized electro-hydraulic braking system( DEHB) to replace the traditional automobile braking system. The actuator of this system is driven by an electrical motor instead of the conventional vacuum booster to make the brake pressure be linearity controlled quickly. Therefore,the system has the advantages of quick response speed,good control performance and simple structure. Firstly,an overview of the actuator and the whole DEHB system is shown. Secondly,the possibility of this new kind of actuator working for the system is ensured based on some braking theories. Thirdly,the appropriate dynamic simulations are done to get some results to show the relations of different parameters and the effect of braking. Eventually,the proper parameters are determined to build a test bench which shows that DEHB system can achieve the maximum pressure of 13 MPa within 100 ms after parametric optimization,and meanwhile,the actuator is able to reduce pressure quickly after maintaining high pressure. All of the bench test results can meet with the design requirements and real demand of vehicle and this actuator may improve vehicle braking effect in the future. Besides,this actuator can be widely applied to the regenerative braking system because of its linear braking performance.

Fuzzy Feedback Control for Electro-Hydraulic Actuators

Electro-hydraulic actuators(EHA)have recently played a significant role in modern industrial applications,especially in systems requiring extremely high precision.This can be explained by EHA’s ability to precisely control the position and force through advanced sensors and innovative control algorithms.One of the promising approaches to improve control accuracy for EHA systems is applying classical to modern control algorithms,in which the proportional–inte-gral–derivative(PID)algorithm,fuzzy logic controller,and a hybrid of these methods are popular options.In this paper,we developed a novel version of the fuzzy control algorithm and linear feedback control method,namely fuzzy lin-ear feedback control,to improve the control performance.To achieve the highest performance,wefirst designed a mathematical EHA model based on the Matlab/Simulink software packages thanks to the selected parameters,which are similar to a real EHA system.Then,we respectively applied PID,fuzzy PID(FPID),and fuzzy linear feedback control(FLFC)before comparing them to have a full view of the outstanding advantages of the proposed algorithm.The simulation results showed that the proposed FLFC algorithm is approximately 99%and 77%super-ior in performance to the PID and feedback control algorithms,respectively.

An Electro-Hydraulic Actuator for the TVC of a Throttlable Kerolox Rocket Engine

An electro-hydraulic actuator for the thrust vector control(TVC)of a throttlable kerolox rocket engine is introduced in this paper.The creative feature is an integrated hydraulic power drive unit,where a constant speed kerosene motor is used to draw high pressure kerosene from the engine and to drive a constant pressure variable displacement piston pump,acting as the power supply for the actuator.Its operational mechanism,to accommodate the varying pressure from the turbo-pump of a throttling engine,lies in a pressure-reducing flow regulator inserted at the motor inlet.Another key point is that the displacement of the motor is reasonably bigger than the pump so that a sufficiently wide range of pressures can be adapted.Modeling analysis and flight test results were well matched,which show the outstanding performance of this novel type actuator.

New Method to Improve Dynamic Stiffness of Electro-hydraulic Servo Systems

Most current researches working on improving stiffness focus on the application of control theories.But controller in closed-loop hydraulic control system takes effect only after the controlled position is deviated,so the control action is lagged.Thus dynamic performance against force disturbance and dynamic load stiffness can’t be improved evidently by advanced control algorithms.In this paper,the elementary principle of maintaining piston position unchanged under sudden external force load change by charging additional oil is analyzed.On this basis,the conception of raising dynamic stiffness of electro hydraulic position servo system by flow feedforward compensation is put forward.And a scheme using double servo valves to realize flow feedforward compensation is presented,in which another fast response servo valve is added to the regular electro hydraulic servo system and specially utilized to compensate the compressed oil volume caused by load impact in time.The two valves are arranged in parallel to control the cylinder jointly.Furthermore,the model of flow compensation is derived,by which the product of the amplitude and width of the valve’s pulse command signal can be calculated.And determination rules of the amplitude and width of pulse signal are concluded by analysis and simulations.Using the proposed scheme,simulations and experiments at different positions with different force changes are conducted.The simulation and experimental results show that the system dynamic performance against load force impact is largely improved with decreased maximal dynamic position deviation and shortened settling time.That is,system dynamic load stiffness is evidently raised.This paper proposes a new method which can effectively improve the dynamic stiffness of electro-hydraulic servo systems.

Position Control of Electro-hydraulic Actuator System Using Fuzzy Logic Controller Optimized by Particle Swarm Optimization

The position control system of an electro-hydraulic actuator system （EHAS） is investigated in this paper. The EHAS is developed by taking into consideration the nonlinearities of the system： the friction and the internal leakage. A variable load that simulates a realistic load in robotic excavator is taken as the trajectory reference. A method of control strategy that is implemented by employing a fuzzy logic controller （FLC） whose parameters are optimized using particle swarm optimization （PSO） is proposed. The scaling factors of the fuzzy inference system are tuned to obtain the optimal values which yield the best system performance. The simulation results show that the FLC is able to track the trajectory reference accurately for a range of values of orifice opening. Beyond that range, the orifice opening may introduce chattering, which the FLC alone is not sufficient to overcome. The PSO optimized FLC can reduce the chattering significantly. This result justifies the implementation of the proposed method in position control of EHAS.

Fuzzy impedance control of an electro-hydraulic actuator with an extended disturbance observer

In this paper,we deal with both velocity control and force control of a single-rod electro-hydraulic actuator subject to external disturbances and parameter uncertainties.In some implementations,both velocity control and force control are required.Impedance control and an extended disturbance observer are combined to solve this issue.Impedance control is applied to regulate the dynamic relationship between the velocity and output force of the actuator,which can help avoid impact and keep a proper contact force on the environment or workpieces.Parameters of impedance rules are regulated by a fuzzy algorithm.An extended disturbance observer is employed to account for external disturbances and parameter uncertainties to achieve an accurate velocity tracking.A detailed model of load force dynamics is presented for the development of the extended disturbance observer.The stability of the whole system is analyzed.Experimental results demonstrate that the proposed control strategy has not only a high velocity tracking performance,but also a good force adjustment performance,and that it should be widely applied in construction and assembly.

核电厂BERNARD型号电动头常见故障分析及处理措施

电动头作为驱动阀门的执行机构,有许多优点,如驱动力矩大、动作时间短、易于远程控制、有各种保护功能等。同时也存在一些缺点,如结构复杂,易发生故障;电机运行要产生热,如果调节太频繁,易造成电机过热,产生热保护,同时也会加大对减速齿轮的磨损。某核电厂工程建设及商运期间,核岛BERNARD电动头出现诸多故障,文章从该类电动头的结构特点入手,对故障进行分析,并提出了一些预防及处理措施,以提高设备的运行可靠性。

电控气动离合器执行机构气路集成设计与研究

提出一种中央集成式嵌入型电控气动离合器执行机构,并从气路结构的集成设计、气路流体的仿真研究与气路响应性的试验研究3个方面与当前主流的半嵌入型电控气动离合器执行机构进行对比分析。结果表明,嵌入型电控气动离合器执行机构不但在零组件数量、接口数量、重量3方面具有优势,而且响应性更优。

新型压电旋转驱动器的设计与试验研究

为简化压电旋转驱动器的结构,提高能量使用效率,设计和研制一种新型压电旋转驱动器。驱动器采用压电双晶片作为原动件,经运动转换机构将其弯曲变形转化为扭转运动,再通过双离合器的耦合传动将扭转运动转化为旋转运动。使用有限元仿真分析方法和试验对驱动器的物理性能进行深入的研究,测得驱动器的关键参数。针对该驱动器的有限元仿真分析和试验研究表明,压电旋转驱动器的转速与驱动信号的频率、电压近似呈线性关系,驱动器具有一定的承载能力。对试验结果与有限元仿真分析结果进行误差分析,找出产生误差的原因,为驱动器的进一步优化设计提供了参考。研究证明了该压电旋转驱动器设计方法的可行性,使用该方法可以制作出结构简单,体积小,适合在微驱动领域中应用的压电旋转驱动器。

电磁温控液体粘性传动风扇离合器的发展

:简要回顾液体粘性传动风扇离合器的发展历史 ;分析车辆电磁温控液体粘性传动风扇离合器研究的发展和特点 ;讨论国内的发展状况和需要进行的工作。

摩擦片磨损对干式双离合器自动变速器换档特性的影响

主要研究摩擦片磨损对干式双离合器自动变速器(DCT)输出特性的影响.考虑干式双离合器摩擦片的磨损,构建了DCT系统动态模型、双离合器杠杆弹簧和电动执行机构模型.基于杠杆弹簧模型和电动执行机构模型,研究了不同磨损量时双离合器压盘压力曲线的变化规律.基于Matlab/Simulink平台构建了DCT传动系统模型,以磨损时压盘压力变化曲线作为输入,研究了双离合器磨损量对DCT换档特性的影响.

新型混合动力车用电动离合器执行机构的设计

分析了用于定轴式混合动力车变速器的电控电动膜片弹簧离合器执行机构的功能需求,提出了将双向超越离合器应用于离合器执行机构的设计,用于同时实现正向高效驱动和反向锁止功能;描述了新型离合器执行机构的基本工作原理和样机的具体机械结构,详细分析了所用单锲块式双向超越离合器实现反向锁止以及正向高效驱动功能的原理;最后通过试验验证了所述新型执行机构的可行性,并分析了样机存在的不足以及改进途径.

自动离合器液压执行机构正向设计方法

以电控机械式自动变速系统为研究对象,建立了自动离合器液压执行机构的正向设计方法。结合离合器控制策略获取离合器执行机构控制目标;以膜片弹簧载荷变形特性为依据计算出执行机构设计的边界条件;完成了液压执行机构主要部件的参数设计及控制算法的制定。仿真结果表明,所设计的执行机构能够准确快速地跟踪目标接合位移,误差小于10%。

一种旋转压电陶瓷驱动器的设计和研究

为发挥压电陶瓷分辨率高、频响高、功耗低及抗电磁干扰能力强等优点,进一步简化压电旋转驱动器的结构,提高压电驱动工作效率,设计和研制一种新型压电旋转驱动器。驱动器以压电陶瓷双晶片为原动件,通过联接机构联接定子和转子,选用滚子结构的超越离合器驱动机构,将双晶片扭转位移运动转化为输出轴的连续旋转运动。驱动器结构简单,体积小。通过理论分析、有限元仿真和试验研究表明,驱动器的转速与驱动信号的频率、电压近似呈线性关系,具有良好的输出特性,步进精确,运行平稳可靠,适于在微驱动领域应用。

离合器操纵系统特性仿真与试验研究

针对汽车厂家和用户对离合器操纵系统性能的要求越来越高,通过分析离合器分离轴承的压紧力和行程变化,结合离合器操纵系统传递特性,建立了离合器液压操纵系统准静力学模型,得到了离合器操纵过程中踏板力和踏板行程变化曲线。通过离合器液压操纵系统性能试验台对理论模型进行了试验验证。结果表明:在踩下踏板开始和松开踏板结束的小段过程中,理论值略高于试验结果,在其他踏板运动过程中,理论值略低于试验结果,但两者的曲线变化趋势基本一致,从而为优化离合器和研究离合器操纵系统特性奠定了理论基础。

电控液压直驱多片离合器非线性压力控制

为解决自动变速器多片离合器液压执行机构质量与体积较大,介质通过电磁阀时会产生较大能量损失以及传统压力控制过程中振荡明显、误差大、鲁棒性差等问题,采用直接控制“电机&泵”的方式实现压力调节.“电机&泵”的显著优势在于结构简单,质量与体积小,效率更高.文中以该种泵控执行机构为研究对象,提出了一种基于模型的非线性3步法控制器控制执行机构内部压力.结果表明:该执行机构压力控制过程中振荡明显减弱,压力控制更加精确,并且具有更短的响应时间.

气动AMT离合器执行机构的动力学仿真

为分析气动AMT离合器执行机构的动力学性能,在对执行机构系统进行深入分析和研究的前提下,推导并建立了单作用气缸、离合器操纵传动机构的动态数学模型.通过Matlab/Simulink离线仿真分析了系统的动态特性.建模过程中考虑了操纵机构的力、位移传递特性,并结合气压驱动的特点对气体运用了等熵模型分析,实车实验结果验证了仿真模型的准确性.

一种高效压电旋转驱动器的设计和研究

为解决压电双晶片旋转驱动器能量利用效率低,转动力学性能差等问题,设计了一种高效压电旋转驱动器。驱动器以压电双晶片组为原动件,通过双离合器机构耦合,将双晶片组正、反两个方向产生的扭转运动全部转化为连续旋转输出,提高了能量利用效率。通过双晶片组对称结构的设计和安装,改善了驱动器力学性能和刚度。通过有限元仿真分析和实际测试,驱动器转速与驱动信号的频率电压基本成线性关系,驱动器承载能力明显提升。驱动器结构紧凑,体积小,普通正弦信号即可驱动,不需要特殊驱动信号或专门时序控制电路,运行稳定可靠,控制简单高效,适用于微驱动领域。

磁控形状记忆合金旋转执行器研究

基于磁控形状记忆合金(magnetically controlled shape memoryalloy,MSMA)在磁场作用下变形并具有形状记忆功能的特性,提出一种通过超越离合器将MSMA元件产生的直线运动变为旋转运动的执行器结构,在永磁体偏置磁场基础上,通过改变控制磁场励磁电流的大小和频率可实现转速控制。采用有限元法进行MSMA执行器的磁场分析与控制特性仿真,分析旋转机构的机械特性,推导了位移与转速表达式。设计并研制MSMA旋转执行器试验样机,将试验结果与理论计算值进行对比,并分析二者存在差异的原因。样机试验结果表明MSMA旋转执行器机理和设计方法可行。