基于plc的張力控制系統(tǒng)的發(fā)展(英文翻譯).doc

Development of PLC-based Tension Control SystemAbstractFiber winding tension is an important factor in the molding techniques of composite material which influences the quality of winding product directly, and the tension control is a key technique in fiber winding techniques. This paper introduces a closed-loop tension control system with the programmable logic controller (PLC) with function modules as its control kernel, the alternating current (AC) servo motor as execute element and the radius-following device to accomplish the real-time radius compensation. The mechanism of the tension control system is analyzed and the numerical model is set up. The compensation technique of the radius of the scroll is analyzed. Experimental results show that the system is well qualified with high control precision and high reaction speed.*The components of composite material fiber winding possess such advantages as low weight, high strength, and high corrosion resistance, and they are widely applied in aviation and aerospace industry. Many researches have shown that improper or unstable tension leads to a strength loss of 20%-30% of the fiber wound components. An ideal tension control system should provide stable and adjustable tension during the winding process 1-3.With the development of the winding machine, tension controllers have, so far, undergone three stages of development, i.e., mechanical tension controller, electrical tension controller and computerized tension controller4-5. With the development of electronic technology and the appearance of the microprocessor of higher cost performance, computerized tension controller came into use. Microprocessor becomes the kernel of the control system and thus cuts down the number of circuits of the electronic control system, which greatly simplifies the system, improves its reliability and makes possible the application of advanced control methods. Therefore, this type of controllers is widely used6-7.The tension control techniques are becoming mature and the specifications are being improved in some developed countries. However, the fiber winding industry of China started up late and still drops behind compared with the western countries.Mechanical tensioners, with low precision and slow response, account for the main part of domestically- applied tensioners, and cannot meet the tension requirements. Therefore, this paper presents a PLC-based tension control system.1 Set-up of the System Scheme1.1 Construction of the systemA winding tension control system generally consists of three main parts, namely the unwinder, the processer and the winder, and it may also include the measuring and control parts, ancillary transport apparatus, and a load cell. The type of the winder and that of the unwinder may be one of the two drive types, surface drive or center drive. The surface drive means that a scroll or belt is set on the surface of the winding material and the drive force is generated through friction. The center drive is to set a drive mechanism on the center shaft of the scroll, where the linear speed and the tension force of the winding fiber vary with the radius of the scroll, leading to the so-called “scroll thick”8. The phenomenon of “scroll thick” makes the tension control very complex, but the center drive mode is widely applied due to its wide applicability.1.2 Design of tension control schemeThis system adopts a scheme with a center drive and outward-draw fiber configuration. Since the output torque of the AC digital servo motor is in direct proportion to the fiber tension force and the scroll radius, the output torque should decrease as the scroll radius decreases to acquire a constant fiber tension. The change of the scroll radius can be measured by a radius following device and the sampled radius change then passes through an analog digital converter and is sent to the PLC. By reading the desired value of the tension force, the radius and tension force are calculated with the preset calculating algorithm. The speed instruction and torque limit instruction are issued and digital- to-analog converted to output the analog voltage signal to control the servo driver. The servo driver controls the rotating speed and output torque to control the fiber tension. The servo motors speed and torque are measured by the pulse encoder and the Hall element and fed back to the PLC system to compose a closed loop system. The mechanism of the system is shown in Fig.1.The main components in the system include(1) A Panasonic programmable controller (FP0-C10RS), a 12-bit FP0-A80 and an FP0-A04Vancilliary conversion module.(2) A Panasonic AC digital servo driver and servo motor.(3) A radius-following device including a radiusfollowing arm and a rotary potentiometer.2 Mathematical ModeEffective control of the fiber tension is required in fiber winding. Due to the versatility of the core mold shape and winding shape, the linear speed of the fiber is difficult to be kept constant and the variation principle is extremely complex. Therefore, the influence of the speed on the tension force should be taken into consideration in the mechanical analysis of the controlled object. The PLC with function modules as the control systems control kernel, and the needed tension can be enacted from man-machine interface through the serial communication between PLC and upper computer. The input of the radius value, the torque feedback and the velocity feedback, the running of the preset calculating algorithm and the output of the system are done by the PLC with function modules.When the unwinder is considered, the dynamic torque equilibrium equation can be expressed as followsM (t ) = J (t ) (t ) + J (t ) (t ) +TR(t ) + Mf + M0 （1）where T is the yarn tension, R(t) is the real-time scroll radius, M(t) is the resistant moment of the AC servo motor, Mf is the viscous frictional moment, (t) is the angular velocity of the scroll, J(t) is the rotating inertia of the scroll and the yarn roll, and M0 is the dry frictional moment. As shown in Eq.(1), the scroll radius, the resistant moment, the angular velocity of the unwinder and the rotating inertia of the scroll are all functions of time, and the system is thus a complex multivariable time-varying system.Proper simplification of the torque equilibrium equation is carried out with classical control theory based on the following rules:(1) The dry frictional moment and the viscous frictional moment are very little and may be ignored. (2) The influence of J (t ) (t ) on the tension force may be ignored since the instantaneous inertia changes very slightly.(3) The scroll radius is real-time measured and fed back by the radius following device.Eq.(1) is then simplified asTR(t) = M(t) + J (t ) (t ) (2)Therefore, the variations of scroll diameter and scroll angular velocity are the main influencing factors of the yarn tension.3 Compensation of the Radius of the ScrollThe radius change of the scroll causes the change of the scroll moment, i.e., the change of the TR(t ) in Eq.(2). One end of the radius following arm touches the scroll, and the other end is connected to the rotary potentiometer via gear magnifying structure, thus transforming a change in the spindle radius to a change of voltage, as shown in Fig.2where L is the length of radius following arm, Rmax is the maximum radius of scroll, and R(t ) is the instantaneous scroll radius.Suppose the transmission ratio of the gear is i , then the angle of the small gear is given as = iFor the potentiometer, where U is the output voltage of rotary potentiometer, US is the power supply voltage of rotary potentiometer, and s is the total angle of rotary potentiometer.Trimmed as 4 Software Development of the SystemThe software development makes full use of the capabilities of FP0-C10RS, the digital-analogy I/O modules, the hardware and software resources of the PC computer.The precision of the analog-digital or digital analog conversion depends on the number of bits of the analog-digital converter and digital-analog converter. FP0-A80 and FP0-A04V both are 12 bits, and the resolution is 1/4 000 when the output and input range 10V-+10V, while the FP0 is 16 bits, so the control resolution of the system can be assured. The operation speed of each basic instruction is 0.9 s/step, thus 500 steps program needs only 0.5 ms, and the conversion speeds of FP0-A80 and the FP0-A40V both are 1 ms/channel, so the control speed of the system is assured. The PLC ladder diagram is applied to develop the whole control program. However, the input of the parameters is not intuitionistic, neither is the display of the real-time tension and the scroll radius. In order to solve this problem, a control program is developed for the host computer on the interface of which the operator can perform the input of the parameter and the display of the real-time tension, the speed and the scroll radius. The programming port of all the FP PLCs support OPEN MEWTOCOL PROTOCOL. Upper computer sends a COMMAND to PLC as an ASCLL string. Then the PLC automatically returns the RESPONSE based on the COMMAND.The inputs of the system are the voltage feedback by radius following device, the torque feedback of alternating numeric servo-electromotor and the velocity feedback. The output of the system are alternating numeric servo-electromotor torque and velocity voltage. The software control flow of the tension control system is shown in Fig.3.5 Simulation and Experimental ResultsExperimental research of the tension control in real winding states was carried out through simulating the real working circumstances to test the feasibility and control precision. When the tension was set to 10 N, the constant-tension curve under simulation and experimental conditions can be acquired with a near constant tension, as shown in Fig.4 and Fig.5, respectively. In order to know the work state of the AC servo motor when the tension changes, the tension force was changed from 5 N to 10 N and the variation curves of which are shown in Fig.6 andFig.7 under simulation and experimental conditions, where the overshooting and fluctuation are rather small and the response time is less than 0.3 s.5.1 Analysis of static difference rateStatic difference rate is a very important indexfor evaluating the performance of the system. It canbe expressed as followswhere T = Tmax Tmin ,Tmax is the maximum tension, Tmin is the minimum tension, and Tm is the average tension. The analysis of static difference rate of tension is shown in Table 1.Table 1 The analysis of static difference rate of tension5.2 Analysis of fluctuation rateWhether the tension fluctuating rate meets the requirements is a key index for evaluating the performance of the designed tension control system. Enacted a initialized yarn tension, after compensation calculation, output it. Then, test the actual tension and find out the maximum and minimum tensions. 6 ConclusionsSimulation and experimental results show that the system is feasible with the PLC as the kernel,the AC digital servo motor as the execute element and a radius following device to perform the radius compensation. The characteristics of the system include(1) A Panasonic FP-series PLC and functional modules serve as the control kernels. The small volume, high integrity, high reliability, excellent control capability and the low cost all make the system convenient and compact with high enough reliability and precision.(2) The yarn-retaking device can be left out, because the servo motor can perform the same function.(3) The modularized software design facilitates the construction expansion and the secondary development of the customers.(4) The friendly programming environment of the Panasonic FPWIN_GR software encapsulates the capability of on-line programming. Parameters can be changed on line and the control effects can be seen instantaneously.基于plc的張力控制系統(tǒng)的發(fā)展摘要光纖彎曲力是復合材料影響成型工藝質量的一個重要因素彎曲的產品直接張力器是纖維纏繞工藝的關鍵技術技巧。 本文介紹了閉環(huán)張力控制系統(tǒng)與可編程邏輯控制器(PLC)和功能模塊為控制核心,交流電(AC)伺服電機為執(zhí)行要件、radius-following裝置,實現(xiàn)實時半徑補償。 機理的張力控制系統(tǒng)進行了分析,并對其數(shù)值模型。 補償技術的半徑滾動進行了分析。 實驗結果表明,在較高的控制精度和很高的反應速度下，系統(tǒng)是合格的。復合材料纖維纏的成分繞具有重量輕、強度高,抗腐蝕性等優(yōu)點,廣泛應用于航空、航天工業(yè)。 許多研究表明,不正確或不穩(wěn)定的張力導致纖維損傷的部件有20% - 30%的強度損失。 纏繞過程中一個理想的張力控制系統(tǒng)將提供固定和可調的張力1-3。在繞線機的發(fā)展下,到目前為止,張力控制器經(jīng)歷了三個發(fā)展階段,即:機械張力控制器、電氣張力控制器和計算機化的張力控制器4-5。 隨著電子技術的發(fā)展，微處理器擁有了更高的性能價格比,計算機化的張力控制器也開始使用了。 微處理器成為控制系統(tǒng)的內核,從而降低了電路的數(shù)量的電子控制系統(tǒng),大大簡化了系統(tǒng),有可能應用先進的控制方法改善了其可靠性。 因此,這種類型的控制器得到了廣泛的應用6-7。張力控制技術正在走向成熟，在一些發(fā)達國家其規(guī)格也正在提高。然而，中國的彎曲光纖產業(yè)起步較晚，仍然落后于西方國家。精度低、反應慢機械張力器件，主要面向國內的運用張力器的市場，不能滿足張力要求。因此，本文反映了基于plc的張力控制系統(tǒng)。1、該系統(tǒng)的結構方案1.1系統(tǒng)架構一個彎曲張力控制系統(tǒng)大體上由三部分組成，即放卷機、處理器和卷取機，也包括測量與控制部分，輔助運輸裝置和測力傳感器。放卷機和卷取機是兩種驅動類型之一，表面驅動模式或者中心驅動模式。表面驅動模式指一個卷軸或者帶子開始于彎曲材料的表面，驅動力通過摩擦產生。中間驅動模式是卷軸桿上的中心軸的滾動，纏繞纖維的線速度和張力隨著卷軸的半徑變化而變化，這導致了所謂的“滾動厚”。這種現(xiàn)象使張力控制非常復雜，但是中間驅動模式因其廣泛應用性而被廣泛應用。1.2設計張力控制方案這個系統(tǒng)采用中心驅動的方案和外拉纖維配置。因為交流數(shù)字伺服電動機的輸出轉矩和纖維張力以及卷軸半徑成比例，所以輸出轉矩應該隨著卷軸半徑減小到要求的恒定纖維張力。一種測量半徑的裝置和取樣的半徑變化可以測量卷軸半徑的變化，通過模擬數(shù)字整流器，卷軸半徑變化被發(fā)送給PLC。通過讀取張力的期望值，預算法則可以計算出半徑和張力。系統(tǒng)發(fā)布了速度指令和轉矩限制指令，并把它們轉換成能控制伺服驅動的輸出模擬電壓信號。伺服驅動控制系統(tǒng)控制著轉速和控制纖維張力的輸出轉矩。脈沖編碼器和霍爾開關可以測量伺服電動機的速度和轉矩，并把速度和轉矩反饋給構成閉環(huán)循環(huán)系統(tǒng)的PLC系統(tǒng)。這種系統(tǒng)的原理如圖1所示。系統(tǒng)中的主要成分包括（1）一個日本松下可編程控制器（2）一個日本松下空調交流數(shù)字伺服驅動和伺服電動機（3）一個測量半徑的裝置和旋轉電位計2、數(shù)學模型在纖維纏繞中對張力的有效控制是必要的。由于模型和彎曲形狀的多樣性，張力線速度難以保持不變，變分原理也相當復雜。因此，在機械分析被控對象時，我們應該考慮張力速度的影響。通過PLC和計算機的串行通信，在人機接口處，可以制定PLC的功能模塊如控制系統(tǒng)的控制核心以及所需的張力。PLC的功能模塊可以計算出輸出半徑、轉矩和速率反饋、預算法則的規(guī)律和系統(tǒng)的輸出?？紤]退繞機時，動態(tài)扭矩的平衡方程式可以表示如下M (t ) = J (t ) (t ) + J (t ) (t ) +TR(t ) + Mf + M0 （1）此處T是紗線張力，R(t)是實時滾動半徑，M(t)是交流伺服電動機的粘滯摩擦力矩，J(t)是卷軸的旋轉慣性，以及M0是干摩擦力矩。如公式（1）所示，實時滾動半徑、力矩、角速度