机、电、液传动控制课程的融合教学探索与实践

机、电、液传动控制课程在智能制造类专业人才培养中具有重要的地位,但目前该课程教学中仍然存在知识点分散、系统性不强、考核实验手段落后等问题。课题组提出,应整合现有机电与液气压传动控制教学资源,重建机、电、液传动控制课程的融合教学体系,并对课程教学内容和实验实践进行了具体设计,将教学内容分为若干教学项目,设计仿真实验,实施过程考核方式。初步实施和测评表明,新的教学体系和考核方式均取得了良好效果。

热磨浆机的机液伺服间隙控制系统研究

介绍了磨盘间隙伺服控制的工作原理,对控制系统作了理论分析和计算。文中建立的模拟试验台对恒载位置精度进行了试验,结果表明,试验数据和理论计算基本吻合。研究所得出的结论可供液压控制系统的设计制造和生产使用。

机械和液压复合控制的往复运动系统

论述了一种能够安全可靠地完成对生产线上的工件压装操作的具有液压和机械复合控制的往复运动系统 ,该系统设计新颖、结构紧凑、工作安全可靠。

仿形刀架机液伺服控制系统设计与仿真分析

通过建立仿形刀架机液伺服控制系统的数学模型,运用Matlab/Simulink软件构建了该试验系统的仿真模型,并采用方波信号对其动态特性进行了仿真分析。结合动态分析与仿真的结果,分析了结构参数对系统的稳定性、快速性和准确性的影响,为机液伺服仿形刀架的设计及结构参数的选择提供了理论依据。

油膜轴承试验台液压加载系统压力控制特性分析

泵控内控式机液控制系统具有结构紧凑、无节流损失、发热量少、能效高的优势,可以满足油膜轴承的载荷施加,实现油膜轴承试验台液压加载系统的压力控制。为此,建立了泵控机液控制系统的压力控制模型,对恒压变量泵控系统进行研究,分析了影响系统动态特性的主要因素。通过MATLAB/Simulink对影响压力控制系统动态特性的主要因素进行了仿真分析。研究了不同调压弹簧刚度、控制滑阀流量增益的恒压变量泵出口压力动态特性。结果表明:增大调压弹簧刚度、减小控制滑阀流量增益可以提高系统稳定性。仿真结果验证了理论分析的正确性。

一种机液伺服车辆转向系统的性能分析

基于MATLAB/Simulink软件,对一种车辆转向机液伺服闭环反馈控制系统的稳定性、稳定裕度以及动态性能进行分析,并探讨了机械连杆反馈机构参数对系统性能的影响,为系统设计提供参考。

Modeling and control of hydraulic excavator's arm

In order to find a feasible way to control excavator’s arm and realize autonomous excavation, the dynamic model for the boom of excavator’s arm which was regarded as a planar manipulator with three degrees of freedom was constructed with Lagrange equation. The excavator was retrofitted with electrohydraulic proportional valves, associated sensors (three inclinometers) and a computer control system (the motion controller of EPEC). The full nonlinear mathematic model of electrohydraulic proportional system was achieved. A discontinuous projection based on an adaptive robust controller to approximate the nonlinear gain coefficient of the valve was presented to deal with the nonlinearity of the whole system, the error was dealt with by robust feedback and an adaptive robust controller was designed. The experiment results of the boom motion control show that, using the controller, good performance for tracking can be achieved, and the peak tracking error of boom angles is less than 4°.

Improved control of intelligent excavator using proportional-integral-plus gain scheduling

Consider the design and implementation of an electro-hydraulic control system for a robotic excavator, namely the Lancaster University computerized and intelligent excavator (LUCIE). The excavator was developed to autonomously dig trenches without human intervention. One stumbling block is the achievement of adequate, accurate, quick and smooth movement under automatic control, which is difficult for traditional control algorithm, e.g. PI/PID. A gain scheduling design, based on the true digital proportional-integral-plus (PIP) control methodology, was utilized to regulate the nonlinear joint dynamics. Simulation and initial field tests both demonstrated the feasibility and robustness of proposed technique to the uncertainties of parameters, time delay and load disturbances, with the excavator arm directed along specified trajectories in a smooth, fast and accurate manner. The tracking error magnitudes for oblique straight line and horizontal straight line are less than 20 mm and 50 mm, respectively, while the velocity reaches 9 m/min.

Robust force tracking control via backstepping sliding mode control and virtual damping control for hydraulic quadruped robots

In order to improve the force tracking performance of hydraulic quadruped robots in uncertain and unstructured environments,an impedance-based adaptive reference trajectory generation scheme is used.Secondly,in order to improve the robustness to environmental changes and reduce the contact force errors caused by trajectory tracking errors,the backstepping sliding mode controller is combined with the adaptive reference trajectory generator.Finally,a virtual damping control based on velocity and pressure feedback is proposed to solve the problem of contact force disappearance and stall caused by sudden environmental change.The simulation results show that the proposed scheme has higher contact force tracking accuracy when the environment is unchanged;the contact force error can always be guaranteed within an acceptable range when the environment is reasonably changed;when the environment suddenly changes,the drive unit can move slowly until the robot re-contacts the environment.

Identification and optimization for hydraulic roll gap control in strip rolling mill

In order to improve the control performance of strip rolling mill, theoretical model of the hydraulic gap control(HGC) system was established. HGC system offline identification scheme was designed for a tandem cold strip mill, the system model parameters were identified by ARX model, and the identified model was verified. Taking the offline identified parameters as the initial values, online identification using recursive least square was carried out with model parameters changing. For the purpose of improving system robustness and decreasing the sensitivity due to model errors, the HGC system based on generalized predictive control(GPC) was designed, and simulation experiments for traditional controller and GPC controller were conducted. The results show that both controllers acquire good control effect with model matching. When the model mismatches, for the traditional controller, the overshot will increase to 76.7% and the rising time will increase to 165.7 ms, which cannot be accepted by HGC system; for the GPC controller, the overshot is less than 8.5%, and the rising time is less than 26 ms in any case.

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.

Motion control of thrust system for shield tunneling machine

The thrust hydraulic system of the prototype shield machine with pressure and flow compound control scheme was introduced. The experimental system integrated with proportional valves for study was designed. Dynamics modeling of multi-cylinder thrust system and synchronous control design were accomplished. The simulation of the synchronization motion control system was completed in AMESim and Matlab/Simulink software environments. The experiment was conducted by means of master/slave PID with dead band compensating flow and conventional PID regulating pressure. The experimental results show that the proposed thrust hydraulic system and its control strategy can meet the requirements of tunneling in motion and posture control for the shield machine, keeping the non-synchronous error within ±3 mm.

Study on co-simulation model of forging manipulator based on virtual prototyping

Based on the characteristics of integrated virtual prototype technology, the mechanical system sub-model, the hydraulic system sub-model and the control system sub-model of a forging manipula- tor system have been built using a variety of software, and a forging manipulator mtrltidisciplinary co- simulation model has been also built using a method of simulation models interface. Then the simu- lation and experiment are finished, and the result of the experiment is in good agreement with the re- sult of the simulation. It shows that the co-simulation model established can simulate accurately pa- rameter changes in real time during the moving of the forging manipulator such as displacement, ve- locity and pressure flow, which is of important significance for the optimized design of the forging manipulator system to establish the models.

Phase-only Correlation Measurement with Computer-controlled LCD and CCD Image Processing System

Using computer-controlled liquid crystal display (LCD) as an image processor and a CCD camera as a detector, phase-only correlation measurement is performed with the aid of joint transform correlation method (JTC). This computer -controlled LCD-CCD image processing system may be a powerful tool for defect detection, position control and pattern recognition. It enables new possibilities in analog real-time image processing. This is of great interest in microelectronic manufacturing today and in the future.

Energy-Saving Design for Hydraulic Tube Bender

Generally speaking, hydraulic control systems can be divided into two different driving concepts. The first one is the well-known hydraulic valve-controlled system and the second one is the pump-controlled system. The former possesses the feature of fast dynamic response. However, the poor energy-saving performance is its major fault. On the contrary, the hydraulic pump-controlled system has the significant advantage of energy-saving which meets the current demand in modem machine design. In this paper, the simulation analysis using MatLab/SimuLink and DSHplus software for a newly developed energy-saving hydraulic tube bender is conducted. Instead of the conventional fixed displacement hydraulic pump, the new hydraulic tube bender utilizes an internal gear pump with AC servomotor as its driving power source. In the new energy-saving hydraulic circuit, the use of conventional pressure relief valve and unloading valve are no longer necessary since the demanded flow-rate and pressure output can be precisely obtained by continuously changing the speed of the AC servomotor. In addition, two closed-loop control schemes using fuzzy sliding-mode controller are adopted and compared. To compare the energy-saving control systems, such as load-sensing control system, constant supply pressure control scheme and conventional hydraulic control scheme. Furthermore, the simulation results also show that the newly developed hydraulic tube bender can save up to 43% of energy consumption in a working cycle as compared to the conventional hydraulic tube bender.

Redundant Hydraulic Secondary Flight Control Systems Behavior in Failure Conditions

The flight control systems, designed in order to assure the necessary safety level even in failure conditions, are generally characterized by a proper redundant layout. The redundancies must be designed in order to assure an adequate system behavior when some failures are present; in fact an incorrect layout may cause serious shortcomings concerning the response when some component is not operational. Therefore the usual correct design activities request the complete analysis of the system behavior in failure condition. The work analyses the response of a redundant secondary flight control hydraulic servo-mechanism equipped with some proper equalization devices, when some of the most probable and representative failures are present. It must be noted that the redundancy layout, designed in order to assure the necessary safety level even in failure conditions, may behave improperly during normal operations, if the system architecture is unsuitable, when manufacturing defects are present. The improper behavior, generally consisting of force fighting or speed fighting caused by different offsets or asymmetries between the two sections of the system, may be usually overcome by means of a suitable equalization device. Therefore, the system behavior during and following the failure transient greatly depends on both its redundancy architecture and related equalization device. The above mentioned problems have been studied by means of an appropriate physical-mathematical model of a typical electro-hydraulic servo-mechanism prepared to the purpose, performing a certain number of simulations of representative actuations in which different types of failures are accurately modeled. In the opinion of the authors, this paper concerns a topic quite neglected but important in the technical literature. At the best of the authors＇ knowledge, no specific scientific work in this field is available, excepting some industrial technical reports.

Research on bionic quadruped robot based on hydraulic driver

A prototype of hydraulically powered quadruped robot is presented. The aim of the research is to develop a versatile robot platform which could travel fleetly in outdoor terrain with long time of en- durance and high load carrying ability. The current version is 1. lm long and 0.48m wide, and weights about 150kg. Each leg has four rotational joints driven by hydraulic cylinders and one pas- sive translational joint with spring. The torso carries the control system and the power system. A no- vel control algorithm is developed based on a Spring-Loaded Inverted Pendulum model and the prin- ciple of joint function separation. The robot can not only cross a 150mm high obstacle in static gait and trot at 2.5km/h and l km/h on the level-ground and 10°sloped-terrain respectively, but also au- tomatically keep balanced under lateral disturbance. In this paper, the mechanical structure and control systems are also discussed. Simulations and experiments are carried out to validate the design and algorithms.

基于帕斯卡原理的支架初撑力增压装置

提出一种基于帕斯卡原理的液压支架初撑力增压装置,可通过手动补液增压,提高支架初撑力。增压装置通过增压缸、增压控制阀等主要部分串并联构成增压式液压系统回路,从逻辑上实现增压装置的机液控制。通过仿真分析和现场试验对比分析增压装置的增压情况,结果表明泵站压力为31.5 MPa情况下,增压装置可使初撑力达到30 MPa以上,可有效提高初撑力,避免由于初撑力不足引起的若干煤矿安全事故。