基于两级模糊控制器的独立负载液压系统的压力流量复合控制特性研究（英文）

Analysis of pressure and flow compound control characteristics of an independent metering hydraulic system based on a two-level fuzzy controller

目的:常规负载口独立控制研究多采用商业阀进行,因其阀芯位移控制器为封闭式结构,所以阀芯位移的动态特性难以调整,进而影响了系统的压力和流量控制性能。本文旨在探讨负载口独立控制系统中阀芯位移特性对系统压力和流量控制的影响,并研究提高系统压力和流量控制性能的方法。创新点:1.设计基于两级模糊比例积分微分(PID)的压力和流量控制器;2.设计基于阀芯位移反馈的流量控制器;3.建立试验模型,成功实现液压系统高动态压力流量复合控制。方法:1.通过理论分析得到影响系统压力和流量的关键因素(公式(9)和(13));2.提出位移控制为内环、压力和流量控制为外环的两级模糊PID控制算法,并开发相应的控制系统(图2～4);3.通过仿真和实验分析,验证本文提出的控制器所具有的阀芯位移、系统压力和流量的控制效果(图13～18)。结论:1.两级模糊PID控制器具有较好的系统压力和流量控制效果;2.基于阀芯位移反馈的流量控制器具有较高的流量控制精度;3.运用本文设计的可编程控制系统进行液压系统的压力流量复合控制,稳定时间小于200 ms,使系统动态特性得到提高。

An independent metering valve control hydraulic system(IMVCHS)adopts two independent valves to separately control the meter-in and meter-out orifices.This structure increases the degree of freedom of the control,and improves its flexibility and energy-saving performance.In this study,an IMVCHS was established that applies a control system developed to research the pressure and flow compound control performance.A two-level fuzzy control algorithm based on the calculated flow rate feedback from the spool displacement was proposed to realize high precision flow control,and the two-level fuzzy control algorithm based on the pressure feedback was also adopted to enhance the pressure performance under a dynamic load.A simulation model was established,and its key parameters identified experimentally using the simulated load of a hydraulic bridge circuit.The experimental results show that the proposed flow controller has higher control accuracy with an error of less than 2%,and the flow adjustment time for 40 L/min step control is 320 ms.The pressure controller with a two-level closed-loop fuzzy algorithm can significantly improve these pressure dynamic and static performances,and achieve a step response time of less than 180 ms.Combining the pressure and flow controllers,the pressure and flow compound control of the IMVCHS is realized,and the capacity for coping with load fluctuations is also identified,with compound adjustment times of generally less than 200 ms,and occasionally less than 100 ms.This control system therefore achieves a good performance for pressure and flow compound control,and is able to widen the application of independent metering control technology.