PID Controller Optimization by GA and Its Performances on the Electro-hydraulic Servo Control System

A proportional integral derivative （PID） controller is designed and attached to electro-hydraulic servo actuator system （EHSAS） to control the angular position of the rotary actuator which control the movable surface of space vehicles. The PID gain parameters are optimized by the genetic algorithm （GA）. The controller is verified on the new state-space model of servo-valves attached to the physical rotary actuator by SIMULINK program. The controller and the state-space model are verified experimentally. Simulation and experimental results verify the effectiveness of the PID controller adaptive by GA to control the angular position of the rotary actuator as compared with the classical PID controller and the compensator controller.

Fuzzy iterative learning control of electro-hydraulic servo system for SRM direct-drive volume control hydraulic press

A new kind of volume control hydraulic press that combines the advantages of both hydraulic and SRM(switched reluctance motor) driving technology is developed.Considering that the serious dead zone and time-variant nonlinearity exist in the volume control electro-hydraulic servo system,the ILC(iterative learning control) method is applied to tracking the displacement curve of the hydraulic press slider.In order to improve the convergence speed and precision of ILC,a fuzzy ILC algorithm that utilizes the fuzzy strategy to adaptively adjust the iterative learning gains is put forward.The simulation and experimental researches are carried out to investigate the convergence speed and precision of the fuzzy ILC for hydraulic press slider position tracking.The results show that the fuzzy ILC can raise the iterative learning speed enormously,and realize the tracking control of slider displacement curve with rapid response speed and high control precision.In experiment,the maximum tracking error 0.02 V is achieved through 12 iterations only.

Compensation for secondary uncertainty in electro-hydraulic servo system by gain adaptive sliding mode variable structure control

Based on consideration of the differential relations between the immeasurable variables and measurable variables in electro-hydraulic servo system,adaptive dynamic recurrent fuzzy neural networks(ADRFNNs) were employed to identify the primary uncertainty and the mathematic model of the system was turned into an equivalent linear model with terms of secondary uncertainty.At the same time,gain adaptive sliding mode variable structure control(GASMVSC) was employed to synthesize the control effort.The results show that the unrealization problem caused by some system's immeasurable state variables in traditional fuzzy neural networks(TFNN) taking all state variables as its inputs is overcome.On the other hand,the identification by the ADRFNNs online with high accuracy and the adaptive function of the correction term's gain in the GASMVSC make the system possess strong robustness and improved steady accuracy,and the chattering phenomenon of the control effort is also suppressed effectively.

Research on improved active disturbance rejection control of continuous rotary motor electro-hydraulic servo system

In order to meet the precision requirements and tracking performance of the continuous rotary motor electro-hydraulic servo system under unknown strong non-linear and uncertain strong disturbance factors,such as dynamic uncertainty and parameter perturbation,an improved active disturbance rejection control(ADRC)strategy was proposed.The state space model of the fifth order closed-loop system was established based on the principle of valve-controlled hydraulic motor.Then the three parts of ADRC were improved by parameter perturbation and external disturbance;the fast tracking differentiator was introduced into linear and non-linear combinations;the nonlinear state error feedback was proposed using synovial control;the extended state observer was determined by nonlinear compensation.In addition,the grey wolf algorithm was used to set the parameters of the three parts.The simulation and experimental results show that the improved ADRC can realize the system frequency 12 Hz when the tracking accuracy and response speed meet the requirements of double ten indexes,which lay foundation for the motor application.

High precise control method for a new type of Piezoelectric electro-hydraulic servo valve

A new type of piezoelectric electro-hydraulic servo valve system was proposed. And then multilayer piezoelectric actuator based on new piezoelectric ceramic material was used as the electricity-machine converter of the proposed piezoelectric electro-hydraulic servo valve. The proposed piezoelectric electro-hydraulic servo valve has ascendant performance compared with conventional ones. But the system is of high nonlinearity and uncertainty, it cannot achieve favorable control performance by conventional control method. To develop an efficient way to control piezoelectric electro-hydraulic servo valve system, a high-precise fuzzy control method with hysteresis nonlinear model in feedforward loop was proposed. The control method is separated into two parts: a feedforward loop with Preisach hysteresis nonlinear model and a feedback loop with high-precise fuzzy control. Experimental results show that the hysteresis loop and the maximum output hysteresis by the PID control method are 4.22% and 2.11 μm, respectively; the hysteresis loop and the maximum output hysteresis by the proposed control method respectively are 0.74% and 0.37 μm, respectively; the maximum tracking error by the PID control method for sine wave reference signal is about 5.02%, the maximum tracking error by the proposed control method for sine wave reference signal is about 0.85%.

Delay Compensation Observer with Sliding Mode Controller for Rotary Electro-hydraulic Servo System

The hip’s lower limb exoskeleton essential and most important function is to support human’s payload as well as to enhance and assist human’s motion. It utilizes an electro-hydraulic servo manipulator which is required to achieve precise trajectory tracking and positioning operations. Nevertheless,these tasks require precise and robust control,which is very difficult to attain due to the inherent nonlinear dynamic behavior of the electro-hydraulic system caused by flow-pressure characteristics and fluid volume control variations of the servo valve. The sliding mode controller(SMC)is a widely used nonlinear robust controller,yet uncertainties and delay in the output degrade the closed-loop system performance and cause system instability. This work proposes a robust controller scheme that counts for the output delay and the inherent parameter uncertainties. Namely,a sliding mode controller enhanced by time-delay compensating observer for a typical electro-hydraulic servo system is adapted. SMC is utilized for its robustness against servo system parameters’ uncertainty whereas a time-delay observer estimates the variable states of the controller(velocity and acceleration). The main contribution of this paper is improving on the closed loop performance of the electro hydraulic servo system and mitigating the delay time effects. Simulation results prove the robustness of this controller,which forces the position to track the desired path regardless of the changes of the amount of transport delay of the system’s states. The performance of the proposed controller is validated by repeating the simulation analysis while varying the amount of delay time.

Continuous rotary motor electro-hydraulic servo system based on the improved repetitive controller

In order to suppress the periodic interference of the continuous rotary electro-hydraulic servo motor,this paper makes the motor tracking the periodic signals with high accuracy,and improves the influence of friction interference to the performance of continuous rotary electro-hydraulic servo motor.The mathematic model of the electro-hydraulic position servo system of the continuous rotary motor was established,and the compound control method was adopted based on the repetitive control,feed forward and PID to suppress the friction interference.Through the simulation,the result confirms that the compound control method decreases the tracking error of the system,increases the robust performance of the system and improves the performance of the continuous rotary electro-hydraulic servo motor.

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.

Coordinating optimization-based sliding mode variable structure control for electro-hydraulic servo system

A sliding mode variable structure control （SMVSC） based on a coordinating optimization algorithm has been developed. Steady state error and control switching frequency are used to constitute the system performance indexes in the coordinating optimization, while the tuning rate of boundary layer width （BLW） is employed as the optimization parameter. Based on the mathematical relationship between the BLW and steady-state error, an optimized BLW tuning rate is added to the nonlinear control term of SMVSC. Simulation experiment results applied to the positioning control of an electro-hydraulic servo system show the comprehensive superiority in dynamical and static state performance by using the proposed controller is better than that by using SMVSC without optimized BLW tuning rate. This succeeds in coordinately considering both chattering reduction and high-precision control realization in SMVSC.

Parameter-dependent vibration-attenuation controller design for electro-hydraulic actuated linear structural systems

The problem of robust active vibration control for a class of electro-hydraulic actuated structural systems with time-delay in the control input channel and parameter uncertainties appearing in all the mass, damping and stiffness matrices is investigated in this paper. First, by introducing a linear varying parameter, the nonlinear system is described as a linear parameter varying （LPV） model. Second, based on this LPV model, an LMI-based condition for the system to be asymptotically stabilized is deduced. By solving these LMIs, a parameter-dependent controller is established for the closed- loop system to be stable with a prescribed level of disturbance attenuation. The condition is also extended to the uncertain case. Finally, some numerical simulations demonstrate the satisfying performance of the proposed controller.

Study of Dynamic Robustness of Servo Control System on a Water Press

The reliability and robustness of the electro-hydraulic servo control system for heavy-duty forging machine play an important role in forging processes. A mathematic model of 50 MN water press for free forging was created in this research. The dynamic robust compensator integrating with PID control method is designed and applied to the mathematical model simulation. The simulated results approved that the dynamic robust compensator application restrains interference from extra load and improves the electro-hydraulic position servo control system accuracy and stability.

Pseudo Derivative Feedback Control of Electro Hydraulic Speed Servos

The Pseudo-Derivative Feedback (PDF) algorithm is introduced into design of electro-hydraulic speed servos. With limited extra complexity in implementation of controller's electronic circuits, the PDF control enables the electro-hydraulic speed servo to respond to a step command without steady-state error, and also to follow successfully a sinusoidal command at the frequency higher than that the system resulted from traditional design can reach. The numerical example-based comparison in dynamic and static behavior shows also the PDF system is superior to the traditional system in terms of both the capability of handling loads applied to the system and the robustness to ignore variation and uncertainty of the parameters of the hydraulic valve-actuator unit in operation.

中国机器人伺服控制技术竞争力及提升路径

中国机器人核心技术竞争力与国际领先国家相比仍有很大的差距,迫切需要提升以伺服控制技术、减速机技术等为代表的机器人核心技术竞争力。文章采用专利信息数据从专利数量、专利质量、专利价值三个维度对中国机器人伺服控制领域的技术竞争力进行分析,并将其与美国、德国、韩国等领先国家进行比较,剖析中国机器人伺服控制技术发展过程中的优势与不足,最后从技术联合研发、聚焦关键技术、研发方向等方面提出了技术竞争力提升的路径。

基于无人系统的智能视觉控制算法研究

无人系统应用范围的急剧扩大,使得视觉感知环境愈加复杂多变,致使传统视觉控制算法难以有效控制视觉传感器获取精准的视觉感知图像,从而影响无人系统的稳定运行,故提出基于无人系统的智能视觉控制算法研究。应用Gamma曲线非线性变换无人系统视觉感知图像灰度值,再应用灰度世界法来增强图像的对比度。以处理后的图像为基础,计算其图像矩,即空间矩、中心矩和归一化中心矩,以描述图像的全局和局部特性。根据得到的无人系统视觉感知信息,搭建智能视觉控制框架。获取期望图像特征矩阵,提取当前时刻图像特征矩阵,通过基于改进萤火虫算法的极限学习机对摄像机转角进行非线性映射,从而获取智能视觉控制定律,以此消除视觉感知图像误差,实现智能视觉的有效控制。实验结果显示:在不同实验组别背景下,应用提出算法获得的视觉控制平均时间最小值达到了1 s,视觉控制平均误差最小值达到了0.12%,充分证实了提出算法的应用性能更佳。

一种PMSM位置伺服系统的动态建模与控制

本文根据永磁同步电机(PMSM)的基本电磁关系及其动态数学模型建立了位置伺服控制模型,按照闭环负反馈控制原理,设计了具有电流、速度、位置三闭环的位置控制系统。首先,根据PMSM矢量控制的特性,利用3S/2S和2S/2R的坐标变换理论,建立了位置伺服系统在同步坐标系下的动态数学模型,同时给出了按照转子磁场定向的位置控制策略和算法;其次,研究了基于空间矢量脉宽调制(SVPWM)的数字实现,并根据电机的数学模型,在MATLAB/Simulink环境中构建了三环模型,同时搭建了基于DSP实验样机。在仿真和实验中直轴、交轴以及速度和位置均采用PI控制,在控制参数的整定过程中,遵循先内环(电流环),后速度环,再位置环的增量调试原理,实现了同步电机的位置闭环控制;最后,对仿真结果和试验结果进行了对比分析,说明了模型的正确性和有效性。

基于伺服电机的PE管全自动热熔焊机控制系统研制

【目的】传统液压全自动热熔焊机由于液压机的使用存在体积大、重量大、耗能高及环境污染等问题,需要进行改进研发。随着伺服技术的快速进步,现代伺服电机能够提供更高的扭矩,同时具备卓越的控制精度、运行稳定性和过载能力。与传统液压机相比,伺服电机具有体积小巧、重量轻便及节能环保等显著优势。目前,在众多应用领域,伺服电机已经逐渐取代了传统的液压机,成为新一代的动力来源。因此,可基于伺服电机对传统液压全自动热熔焊机进行改进研发,而基于伺服电机研发的PE管全自动热熔焊机与原有液压全自动热熔焊机在设备结构、动力转换方式及控制方式上存在显著差异,需要重新研制控制系统。【方法】根据此需求,文中所研制系统采用昆仑通态嵌入式工业触摸屏作为主控装置,并以此为基础搭建了伺服系统、热板升降系统及温度采集与控制系统,最后根据系统特点进行相应的控制软件设计。【结果】该文提出了一种更适用于该设备的新型焊接工艺。【结论】通过多次焊接测试和拉伸试验验证,该控制系统能够使基于伺服电机研发的PE管全自动热熔焊机按标准工艺和新工艺进行合格的PE管焊接,并且当使用新工艺进行焊接时,能够降此设备使用低能耗同时延长设备使用寿命。

机电一体化技术在精准农业中的应用

精准农业可以提高农业生产效率、降低生产成本、减少对环境的影响,满足人们对食品安全和品质的需求。该文综合分析机电一体化技术在精准农业中的应用原理与优势,总结了机电一体化技术在精准农业中的应用现状和发展趋势,展示了其在提高农业生产效率、降低生产成本、保护环境、提升食品安全和品质方面的重要作用,为推动农业现代化、促进农业可持续发展提供了有益参考。

机器人与伺服压力机控制应用研究

利用系统的非线性动力学,对机器人和工业伺服压力机机构进行了实例分析,并对机器人系统和伺服曲柄压力机进行了识别和仿真研究,获得了系统的动态行为。根据应用所要求的不同运动轨迹,在系统上研究了软计算技术,并且运用传统PID控制技术,通过PSO-NN(粒子群优化神经网络)、BP(反向传播)、PSOPID、PID、CasFF(级联前馈)等控制方法,实现了控制目的。

天线与伺服控制技术在卫星通信中的能耗优化研究

随着社会信息化进程的不断加快,高效且稳定的卫星通信日渐成为人们的需求之一。然而卫星发射器和接收器的能量消耗较高,如何降低其能耗成为当前的研究热点之一。在卫星通信系统中,核心技术是确保地面的天线和卫星能够实时对齐,以便卫星和地面之间能够进行稳定的交流。这种技术被称为天线追踪伺服控制技术,也叫动态中继技术。重点探讨天线与伺服控制技术在卫星通信中能耗优化方面的应用。