译文：
研究了一种广义脉码调制控制的非对称数字阀，利用不同编码方式可实现阀正反向节流面积比率可调，同一个阀能适应两作用腔面积比不同的非对称缸控制要求。提出了广义脉码调制编码的一般原则，与实验相结合，研究了该系统的控制策略及控制方法，得出一种对广义脉码调制液压位置伺服系统有效的控制方法。 关键词：广义脉码调制阀 非对称液压缸 控制 动态特性 ０　引言 非对称液压缸在液压位置／力伺服系统中广泛使用。由于缸两腔的作用面积不等，在正反方向上的速度特性及动态特性不同，导致系统正反方向上的动静态特性存在差异。非对称阀控制非对称缸可有效降低换向时的压力突变及动静态性能的不对称性。普通的非对称阀节流窗口面积梯度之比为固定值，需与缸配套设计使用，互换性差，制造工艺复杂，使阀成本增加。广义脉码调制(generalization　pulse　code　modulation，GPCM)阀采用一定数量、不同流量的节流基元组成，价格低，抗污染能力强，可以根据系统的需要灵活地改变各组成节流阀的节流面积和编码方式，得到不同流量。笔者对GPCM液压伺服控制理论进行了研究，本文对GPCM数字阀控非对称缸的压力和流量特性进行研究。 １　GPCM阀控缸系统 1.1 系统简介 GPCM阀由一个四通方向控制阀和一组节流基元组成，各基元的节流口面积按一定调制规律设定，由脉冲控制信号来控制它们的启闭状态，经组合得到不同的总节流面积，构成回油节流调速系统，从而达到控制系统流量的目的，其流量控制原理见图1。图中，Q1、Q2分别为缸无杆腔和有杆腔压力油流量，m3/s；ps为系统压力，Pa；Qs为系统流量，m3/s；pr为阀出口压力，Pa；Qr为阀出口流量，m3/s；A1、A2分别为缸无杆腔和有杆腔截面面积，m2；p1、p2分别为缸无杆腔和有杆腔压力，Pa；m为系统等效质量，kg。 1.2 GPCM编码规律 当非对称液压缸活塞在不同方向运行时，由于活塞两侧作用面积不对称，在相同速度下，通过阀节流单元群的流量不相同。GPCM阀流量控制为方向阀加回油节流方式，只在一个方向上有流量控制作用。式中，Q为无杆腔回油时GPCM阀流量，m3/s；Cd为流量系数；Ni为脉冲编码值；S0为节流基面积，m2；?p为节流单元节流口压降，Pa；ρ为液体密度，kg/m3。 由于非对称液压缸两腔的有效截面积不同，当非对称液压缸活塞在相反方向运行时，在相同速度下，GPCM阀的流量是不相同的。如忽略液压缸和阀的泄漏以及假设液压油不可压缩，可得活塞具有相同速度的条件为 如果采用对称编码流量控制，在控制过程中，相同的控制输入量将得到不同的速度，使液压缸活塞运动的对称性受到影响，特别是在多缸系统需要同步运动时，使系统运动不协调，控制性能降低。 GPCM伺服控制系统可以利用编码方式，使GPCM阀成为流量非对称阀，可有效地降低非对称缸左右运动不对称特性对系统控制性能的影响。左右运动速度相等的条件对应的编码规则为 即液压缸缩回行程中的编码值为伸出行程编码值的A1/A2倍，可以保证非对称液压缸运动速度的对称性。一般非对称缸两腔的作用面积比近似于1∶2，这为非对称缸的脉冲编码控制带来了方便。控制时，输出脉冲相应地向左移一位就可以达到输出要求。 利用非线性控制理论对GPCM系统的稳定性进行了理论与试验分析研究，推导出GPCM控制阀的节流基元最小节流基面积S0为 缸活塞杆伸出与缩回时阀控制最小节流流量确定后，阀控制的{zd0}流量根据系统要求来确定。 GPCM阀控制最小节流流量称为GPCM阀的分辨率，它是阀的控制流量发生变化的控制最小增量。一般在电液伺服系统处于通常工作状态时，阀分辨率对系统运行影响不大，但当系统处于低速流量运行时，阀分辨率对系统的动态性能就会有大的影响。当系统处于低速运动时，由于阀的量变化很小，即其输入信号变化也较小，此时，阀分辨率就必须加以考虑，一般来说，小流量的伺阀分辨输入信号的能力优于大流量的伺服阀。所以，对GPCM电液伺服系统采取变增益阀的方案液压缸在高速或常速运动情况下，阀呈高增益，当液压缸处于低速运动时，阀呈低增益，以实现高的分辨率，达到高速与高精度控制相结合的目的。据此确定了如下GPCM编码规则：确定最小量，阀的前几位节流单元流量按照二进制比例排列，可以得到较高的分辨率，达到要求的控制性能。 ２　控制策略 GPCM阀控位置伺服系统除了液压伺服系统所固有的非线性特性外，还由于采用了脉冲调制控制，具有流量变化不连续的特点，系统高精度控制困难，系统建模不易且相关参数难以xx确定，使得基于被控对象数学模型的各类控制方法不能有效解决此控制问题。 本文提出了一种新的控制方法应用于GPCM液压伺服控制系统。将GPCM伺服定位系统的响应过程分为三个阶段：①快速启动，系统速度从零增加到{zd0}，位置偏差迅速减小；②减速运行，在运动达到一定范围时，为防止超调开始降低运行速度；③定位保持，稳态时具有强的抗干扰能力。这三个阶段对应阀流量从大到小，刚开始时以较大的组合流量以得到快速响应，随着偏差减少，阀流量逐步降低，到指定位置后保持输出流量为零。 单独使用一种控制算法难以实现系统高速、高精度的控制要求，因此采用了三种控制方法相结合，分别对应系统响应的三个阶段实施控制。{zh1}设计的控制器控制算法如下：①位移误差|e|>ε1时，Bang—Bang控制；②位移误差ε1>|e|>ε2时，PID控制；③位移误差|e|≤ε2时，模糊控制。其中ε1、ε2为切换控制测量的阈值。 系统在启动阶段，利用Bang—Bang控制的快速调节性能，使系统很快达到减速定位过程；在减速过程中，PID控制对动态性能有较好的调节作用，可有效xx和降低超调量，{zh1}利用模糊控制，可以方便地实现非对称脉码输出，达到xx定位。 ３　实验 根据以上理论设计了GPCM阀的样机，由6个节流基元组合控制阀的输出流量，按照控制精度与响应速度要求，根据式(5)确定6个节流基元的过流孔直径分别为0.2mm、0.3mm、0.4mm、0.7mm、1.2mm、2mm。它和非对称缸组成了GPCM位置伺服系统，系统控制框图见图3，液压系统的主要参数为A1=1.256×10-3m2，A2=8.76×10-4m2，m=30kg，ps=7MPa。 控制算法采用计算机实现，能方便地自动实现算法间的切换，在调试时可方便地调整各控制器的参数。 不同控制方式下位置伺服系统的阶跃响应系统仅采用了PID调节控制的实验结果，由于在指定位置附近控制器输出量较小，常使阀工作在死区内，当阀工作在死区时，液压缸停止运动，直到由于误差积分作用使控制器输出量超出死区，阀又突然开启，缸又加速运动，通常会引起大的超调，振荡、过渡时间长，控制精度低。在定位阶段采用模糊控制器，控制器的输出可以快速补偿阀死区非线性，有效克服死区的影响，提高控制精度，见图4b。系统对方波输入信号的响应实验曲线见图5。结果表明非对称缸在两个相反方向上的控制特性基本是对称的，达到了控制目标。 ４　结论 (1)GPCM阀的流量编码规律可以根据系统控制精度和响应速度要求确定，最小节流流量与控制精度有关，而速度与综合流量相关。GPCM电液伺服系统采取变增益阀的方案，前几位节流阀的流量成二进制比例，后几位按照总流量需求确定。 (2)GPCM阀可以通过改变脉冲编码值而实现非对称阀的功能，得到不同正反向节流面积比。 (3)采用Bang-Bang控制、PID控制和模糊控制相结合，用于GPCM阀控非对称缸伺服系统中是可行的，并且不需要知道系统的非线性特性参数，具有较强的实用性。

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原文：
Study of a generalized pulse code modulation control asymmetric digital valve, the use of different encoding can be realized the pros and cons to the throttle valve area ratio adjustable, with a valve to adapt to the role of cavity area ratio of two different non-symmetrical cylinder control requirements. Of the generalized pulse code modulation encoding general principles combined with the experimental study of the system control strategy and control methods, come up with a generalized pulse code modulation of hydraulic position servo system of effective control methods. Keywords: Generalized Pulse Code Modulation of asymmetric hydraulic cylinder control valve dynamic characteristics of 0 Introduction Asymmetric hydraulic cylinder in the hydraulic position / force servo system widely used. As the cylinder 2 the role of cavity size ranges, in the positive and negative direction of the velocity characteristics and dynamic characteristics of different, cause the system to positive and negative direction of the dynamic and static characteristics are different. Asymmetrical Asymmetrical cylinder valve control can effectively reduce the pressure when the change to the static and dynamic properties of the mutation and asymmetry. Ordinary, non-symmetric valve throttling the window area of a fixed value of the ratio of the gradient required to complete the design with the cylinders used interchangeability poor, the complex manufacturing process, so that valve costs. Generalized Pulse Code Modulation (generalization pulse code modulation, GPCM) valve uses a number of different traffic throttling primitive form, the price is low, anti-pollution ability, according to the system's need for flexibility to change the composition of the throttle throttle size and encoding, get a different flow rate. The author of the GPCM hydraulic servo-control theory has been studied, the paper GPCM asymmetric digital valve cylinder pressure and flow characteristics of research. 1 GPCM valve-cylinder system 1.1 System Introduction GPCM valve consists of a four-way directional control valve and a group of primitive composition of throttling, the primitives of the throttle orifice area according to a certain modulation rules set by the pulse control signals to control their open and close state, obtained by the combination of different Total cutting area, constitutes a return to the oil throttle speed control system, so as to achieve the purpose of traffic control system, its flow control principle shown in Figure 1. The figure, Q1, Q2, respectively rodless cylinder rod cavity pressure chamber and the oil flow rate, m3 / s; ps for the system pressure, Pa; Qs for the system flow rate, m3 / s; pr for the valve outlet pressure, Pa; Qr as valve exit flow rate, m3 / s; A1, A2, respectively rodless cylinder rod chamber and cavity cross-sectional area, m2; p1, p2, respectively Rodless cylinder rod chamber and cavity pressure, Pa; m for the system is equivalent to the quality, kg. 1.2 GPCM coding rules When a non-symmetrical hydraulic cylinder piston running in different directions, due to the role of the piston on both sides of an area of asymmetry, at the same speed through the throttle valve is not the same as the flow cell groups. GPCM valve flow control valve for the direction of the oil to add back the throttle, only in one direction on the role of flow control. Where, Q-cavity without a shot when GPCM oil return valve flow, m3 / s; Cd is discharge coefficient; Ni value for the pulse code; S0 for cutting the base area, m2; Δp pressure drop for the throttling unit throttling port , Pa; ρ is liquid density, kg/m3. Because the non-symmetrical chamber of hydraulic cylinder effective cross-sectional area of two different, when a non-symmetrical hydraulic cylinder piston running in the opposite direction at the same speed, GPCM flow valve is not the same. If ignoring the leakage of hydraulic cylinder and valve and the assumption that hydraulic oil can not be compressed, available with the same piston speed conditions for If we adopt the symmetric code flow control, in the control process, the same amount of control input will be at different speeds, so that the symmetry of hydraulic cylinder piston movement affected, especially in the multi-cylinder system needs to synchronize movement, so that movement of the system mismatch , the control performance degradation. GPCM servo control system can make use of coding, so that a flow of non-symmetric GPCM valve valve, which can effectively reduce the non-symmetric about cylinder movement asymmetry characteristics of system control performance. Velocity about equal to the corresponding conditions for the encoding rules Stroke hydraulic cylinder that is retracted in the encoding value encoding value of A1/A2 extended trip times can guarantee the non-symmetrical hydraulic cylinder velocity symmetry. General non-symmetric cylinder 2 the role of cavity area ratio is similar to 1:2, this non-symmetrical cylinder pulse code control of the advantage. Control, the output pulse corresponding to the left one can achieve output requirements. Use of non-linear control theory is stability of the system GPCM theoretical and experimental analysis is deduced GPCM primitive throttle control valve throttling the smallest of the base area of S0 Cylinder piston rod extended and retracted when the throttle valve control minimum flow rate established, the maximum flow rate valve control according to system requirements to determine. GPCM valve control flow is called the minimum throttle valve GPCM resolution, which is the control valve to control flow changes the smallest increment. Electro-hydraulic servo system is generally normal working state, the valve Resolution little impact on the system running, but when the system is in low-speed flow of run-time, the valve resolution of the dynamic performance of the system will have a big impact. When the system is in slow motion, because the amount of valve very few changes, that is, its input signal change is also smaller, at this time, valve resolution must be taken into account, in general, the small flow servo valve input signal is the ability to identify priority in large flow servo valve. So, for GPCM electro-hydraulic servo valve system to take the program variable gain high-speed hydraulic cylinder or the movement of constant speed, the valve was high-gain, when the hydraulic cylinder in a low-speed movement, the valve was low gain in order to achieve high resolution, to achieve a combination high-speed and high-precision control purposes. Accordingly identified the following GPCM encoding rules: Determine the minimum amount of throttle valve unit flow of the first of several arranged in accordance with the proportion of the binary, you can get a higher resolution, the required control performance. Two control strategies GPCM valve position servo system of hydraulic servo system apart from the inherent nonlinear characteristics, but also thanks to the pulse modulation control, with the characteristics of flow rate changes are not continuous, the system difficult for high-precision control, system modeling is not easy and the relevant parameters difficult to accurately OK, makes the mathematical model of controlled object based on the various types of control methods can not effectively solve the control problem. This paper presents a new control method is applied to GPCM hydraulic servo control system. GPCM servo positioning systems will be the response process is divided into three stages: ① quick start, the system speeds from zero to the largest position error decreases rapidly; ② slow running the campaign reaches a certain range, in order to prevent overshoot and begins to lower operating speed; ③ position to maintain, steady state with a strong anti-interference ability. These three stages correspond to valve flow descending, just start with a large portfolio flows to obtain quick response, with the bias reduced gradually reduce the flow valve, to the designated location to maintain the output flow rate is zero. Single control algorithm uses a system difficult to achieve high-speed, high-precision control requirements, so a combination of three control methods, corresponding to the three stages of system response to exercise control. The final design of the controller algorithm is as follows: ① displacement error | e |> ε1, when, Bang-Bang control; ② displacement error ε1> | e |> ε2, when, PID control; ③ displacement error | e | ≤ ε2, the fuzzy control. Where ε1, ε2 for the switching control measurement threshold. System start-up phase, using Bang-Bang control, quick adjusting performance, allowing the system to slow down very quickly positioning process; in the deceleration process, PID control has better dynamic performance of the regulating role, which can effectively eliminate and reduce the overshoot, Finally the use of fuzzy control, you can easily achieve the non-symmetric pulse code output to achieve precise positioning. 3 Experiment Based on the above theoretical design of the prototype valve GPCM from six elementary combination of throttling the output flow control valve, according to the control accuracy and response speed requirements, according to equation (5) identified six primitive throttle hole diameter of over-current as 0.2mm, 0.3mm, 0.4mm, 0.7mm, 1.2mm, 2mm. It formed a GPCM asymmetric cylinder position servo system, the system control block diagram shown in Figure 3, the hydraulic system's main parameters A1 = 1.256 × 10-3m2, A2 = 8.76 × 10-4m2, m = 30kg, ps = 7MPa. Control algorithm using computer implementation, can easily switch between automated algorithm, in the debugging can easily adjust the various parameters of the controller. Under different control modes position servo system step response system, using only the PID regulator control of the experimental results, due to the specified location near the controller output was smaller, and often makes valves work in the dead zone, when the valves work in the dead zone , hydraulic cylinder stop exercising because of the error integral action until the controller output beyond the dead zone, the valve suddenly opened, cylinder also speed up the movement, often leads to large overshoot, oscillations, transition to a long time, the control and low accuracy. In the pilot phase, by using fuzzy controller, the controller's output can be quickly compensated valve dead-zone nonlinearity, effectively overcome the impact of dead zone, improve control accuracy, shown in Figure 4b. Wave input signal the system to respond to the other experimental curve shown in Figure 5. The results show that the non-symmetric cylinder in two opposite directions on the control characteristic is basically symmetrical, reaching control objectives. 4 Conclusion (1) GPCM valve flow rule can be coded according to the system control precision and response speed required to determine the minimum throttling the flow and control accuracy, but speed and an integrated traffic-related. GPCM variable gain valve electro-hydraulic servo system to take the program, the former a number of proportional throttle the flow into the binary, after a few determined in accordance with the total traffic demand. (2) GPCM valves by changing the value of pulse code to achieve the non-symmetric valve function, get different pros and cons to the throttle area ratio. (3) The Bang-Bang control, PID control and fuzzy control combined for GPCM asymmetric cylinder valve servo system is feasible, and do not need to know the system, non-linear characteristic parameters, with a strong practical .

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