滑阀驱动式数字液压缸的静动态特性分析与研究

发布时间：2019-04-25 06:51

【摘要】：数字液压缸是一种将控制滑阀内置于液压缸,采用步进电机作为滑阀的电-机械转换部分,以步进电机给定脉冲为输入信号,以液压缸活塞杆输出的步进位移为输出信号,通过精密滚珠丝杆等机构反馈液压缸活塞杆位置的机液数字控制装置。与传统伺服阀或比例阀控制的液压缸构成的系统相比,其具有结构紧凑,工作稳定性好,抗干扰能力强,性价比高,可直接与数字计算机相连构成位置或速度控制系统等优点。但数字液压缸的起动频率对该装置性能有直接的影响,不稳定的起动频率会引起数字液压缸低频起动时的抖动现象和高频起动时的丢步现象；此外在采用单出杆液压缸时,存在因活塞杆伸出和缩回时速度不同而引起控制回环增益的不对称的问题。这些问题严重影响数字液压缸的静动态特性。针对上述问题,本文建立了步进电机稳定起动频率的数学模型,分析了起动频率对数字液压缸性能的影响；并采用非对称滑阀控制非对称缸的结构,解决了该装置回环增益不对称的问题。文章首先在比较分析现存的几种数字液压缸的基础上,确定了滑阀驱动式数字液压缸的总体结构方案；其次,总结了影响数字液压缸稳定起动频率的相关因素并讨论了步进电机起动频率的计算方法。通过对数字液压缸矩频特性的研究,建立了数字液压缸稳定起动频率的数学模型。这为准确地计算数字液压缸的稳定起动频率提供了理论依据。最后,建立了非对称滑阀控制非对称缸的滑阀驱动式数字液压缸的数学模型。并利用MATLAB仿真软件对其在不同结构参数下进行仿真分析。结果表明该型数字油缸具有较好的动态特性和稳态精度。其定位精度可达0.04mm/pulse。
[Abstract]:The digital hydraulic cylinder is a kind of hydraulic cylinder in which the control slide valve is built into the hydraulic cylinder, the step motor is used as the electromechanical conversion part of the slide valve, the input signal is the given pulse of the stepping motor, and the step displacement output from the piston rod of the hydraulic cylinder is taken as the output signal. A machine-hydraulic digital control device that feeds back the position of the piston rod of a hydraulic cylinder through a precise ball screw and other mechanisms. Compared with the hydraulic cylinder controlled by traditional servo valve or proportional valve, the system has the advantages of compact structure, good stability, strong anti-jamming ability, high price-to-performance ratio, and can be connected directly with digital computer to form a position or speed control system. However, the starting frequency of the digital hydraulic cylinder has a direct impact on the performance of the device. The unstable starting frequency will cause the dithering phenomenon of the digital hydraulic cylinder during the low-frequency start-up and the loss of the step phenomenon during the high-frequency start-up. In addition, when the hydraulic cylinder with a single exit rod is used, the asymmetry of the gain of the control loop is caused by the different speed of the piston rod extending and retraction. These problems seriously affect the static and dynamic characteristics of the digital hydraulic cylinder. In order to solve the above problems, the mathematical model of steady starting frequency of stepping motor is established in this paper, and the influence of starting frequency on the performance of digital hydraulic cylinder is analyzed. The asymmetrical sliding valve is used to control the asymmetrical cylinder structure, which solves the problem of asymmetric return ring gain of the device. Based on the comparison and analysis of several existing digital hydraulic cylinders, the overall structure scheme of the slide valve-driven digital hydraulic cylinders is determined in this paper. Secondly, the related factors affecting the steady starting frequency of the digital hydraulic cylinder are summarized, and the calculation method of the starting frequency of the stepping motor is discussed. By studying the moment-frequency characteristic of digital hydraulic cylinder, a mathematical model of steady starting frequency of digital hydraulic cylinder is established. This provides a theoretical basis for the accurate calculation of the steady starting frequency of the digital hydraulic cylinder. Finally, the mathematical model of the digital hydraulic cylinder driven by the unsymmetrical slide valve is established. MATLAB simulation software is used to simulate and analyze it under different structural parameters. The results show that the digital cylinder has good dynamic characteristics and steady-state accuracy. The positioning accuracy can reach 0.04 mm.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TH137.51

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