付茂文 沈丹峰 趙剛 尚國飛 柏順偉
摘 要:為更好地控制經(jīng)紗張力,提高系統(tǒng)動(dòng)態(tài)響應(yīng)性能減小抖振,開發(fā)了一種神經(jīng)反步分?jǐn)?shù)階快速終端滑??刂破鳎≧BF-BCFOFTSMC),通過動(dòng)力學(xué)分析建立了織機(jī)送經(jīng)系統(tǒng)的時(shí)變數(shù)學(xué)模型。同時(shí),推導(dǎo)了一種新的反步分?jǐn)?shù)階快速終端滑??刂品椒?。針對織機(jī)織造過程中系統(tǒng)總干擾上界的未知性和系統(tǒng)時(shí)變性的特點(diǎn),設(shè)計(jì)了自適應(yīng)律來估計(jì)外部干擾的上界值,設(shè)計(jì)神經(jīng)網(wǎng)絡(luò)參數(shù)自適應(yīng)律來逼近真實(shí)的系統(tǒng)狀態(tài),并利用李雅普諾夫穩(wěn)定性證明系統(tǒng)的合理性。通過其與傳統(tǒng)滑模控制(SMC)和神經(jīng)PID控制(RBF-PID)在仿真實(shí)驗(yàn)和實(shí)際工況下的對比,結(jié)果表明:RBF-BCFOFTSMC在經(jīng)紗張力控制方面不僅減小了抖振,并且具有較高的魯棒性和響應(yīng)性能。
關(guān)鍵詞:經(jīng)紗張力;分?jǐn)?shù)階;反步;滑??刂?;神經(jīng)網(wǎng)絡(luò)
中圖分類號:TS103;TP183;TP273
文獻(xiàn)標(biāo)志碼:A
文章編號:1009-265X(2023)04-0130-09
收稿日期:2022-12-15
網(wǎng)絡(luò)出版日期:2023-03-21
基金項(xiàng)目:國家自然科學(xué)基金項(xiàng)目(51805402)
作者簡介:付茂文(1996—),男,山東泰安人,碩士研究生,主要從事送經(jīng)系統(tǒng)張力控制方面的研究。
通信作者:沈丹峰, E-mail: dfshen@xpu.edu.cn
經(jīng)紗張力的穩(wěn)定性對于織機(jī)生產(chǎn)不同花紋和提高織造效率具有舉足輕重的作用,無論是張力過大或者過小都會(huì)降低織造質(zhì)量[1],嚴(yán)重時(shí)還有可能導(dǎo)致紗線崩裂從而停車的現(xiàn)象,需要人工干預(yù)后才能再重新織造,加大了人力成本和降低了織造效率。由于送經(jīng)系統(tǒng)存在電機(jī)振動(dòng)和綜框等運(yùn)動(dòng),想要保持較高的張力穩(wěn)定性,完成更高質(zhì)量和不同的織造要求,設(shè)計(jì)一種魯棒性較高和響應(yīng)性能較快的控制器迫在眉睫。
為了提高送經(jīng)系統(tǒng)的張力穩(wěn)定性,許多智能控制算法被提出用于實(shí)際控制系統(tǒng)中,如自適應(yīng)PID控制[2-3]、反步控制[4-5]、滑模控制[6-7]和神經(jīng)網(wǎng)絡(luò)控制[8-9]等,以提高系統(tǒng)控制性能。崔征山等[10]設(shè)計(jì)擴(kuò)張狀態(tài)觀測器來對系統(tǒng)擾動(dòng)進(jìn)行在線估計(jì),并將估計(jì)到的擾動(dòng)補(bǔ)償?shù)交?刂破髦校芎玫貞?yīng)對了系統(tǒng)中運(yùn)動(dòng)產(chǎn)生的強(qiáng)擾動(dòng),但擴(kuò)張狀態(tài)觀測器的引入增加了控制器的調(diào)參難度。黃道敏等[11]將分?jǐn)?shù)階理論融合到積分滑??刂浦?,設(shè)計(jì)指數(shù)趨近律,并且為估計(jì)外部擾動(dòng)添加擾動(dòng)估計(jì)項(xiàng),該控制策略具有較快的收斂速度,對于非線性的系統(tǒng)魯棒性較強(qiáng)。鄧檳檳等[12]設(shè)計(jì)了一種新的快速終端滑??刂品椒?,經(jīng)過了有限時(shí)間穩(wěn)定性證明,誤差可在短時(shí)間內(nèi)快速收斂,提高了控制系統(tǒng)的跟蹤精度。梁相龍等[13]將神經(jīng)網(wǎng)絡(luò)和指令濾波融合到滑??刂扑惴ㄖ校噶顬V波器用來信號的估計(jì)和噪聲處理,通過梯度下降算法來自適應(yīng)更新網(wǎng)絡(luò)權(quán)值系數(shù),對于系統(tǒng)的不確定性和外部干擾具有很強(qiáng)的魯棒性。還有一部分學(xué)者也對反步控制進(jìn)行了研究,Razmi等[14]設(shè)計(jì)了一種針對參數(shù)不確定性和外部干擾的控制策略,采用神經(jīng)網(wǎng)絡(luò)自適應(yīng)更新滑模面的系數(shù),增加了系統(tǒng)的瞬態(tài)和穩(wěn)態(tài)性能。Chen等[15]為了提高反步控制的收斂速度和跟蹤性能,設(shè)計(jì)了具有更多自由度的分?jǐn)?shù)階反推控制器,并采用模糊神經(jīng)網(wǎng)絡(luò)估計(jì)系統(tǒng)的不確定性,采用指數(shù)調(diào)節(jié)機(jī)制補(bǔ)償估計(jì)誤差。熊蕊[16]設(shè)計(jì)一種改進(jìn)神經(jīng)網(wǎng)絡(luò)反步控制策略,利用神經(jīng)網(wǎng)絡(luò)逼近外部未知狀態(tài),利用自適應(yīng)律更新神經(jīng)網(wǎng)絡(luò)的參數(shù),實(shí)現(xiàn)了系統(tǒng)的高精度控制。Fu等[17]提出了一種自適應(yīng)神經(jīng)反步動(dòng)態(tài)表面控制算法,采用動(dòng)態(tài)表面來優(yōu)化反步控制算法,采用神經(jīng)網(wǎng)絡(luò)來逼近系統(tǒng)的動(dòng)力學(xué)模型,最終通過實(shí)驗(yàn)證明了控制方法的有效性。通過上述研究和分析可知,送經(jīng)系統(tǒng)是強(qiáng)非線性系統(tǒng),采用高效非線性控制算法有利于提高張力穩(wěn)定性,滑??刂埔蚱渥陨泶嬖诘亩墩窈推娈悊栴},在非線性系統(tǒng)的應(yīng)用中往往需要改進(jìn)或者與其他算法融合,將分?jǐn)?shù)階理論融合到滑??刂浦胁⒆C明有限時(shí)間穩(wěn)定性,可實(shí)現(xiàn)滑??刂频男阅芴嵘?,但是在滑模控制中存在的一些狀態(tài)變量是不容易測量的,因此將反步控制算法應(yīng)用到滑??刂浦泻喕刂屏俊K徒?jīng)系統(tǒng)在運(yùn)行過程中是時(shí)變的,根據(jù)傳統(tǒng)的數(shù)學(xué)建模方法得到的模型信息較難反應(yīng)織機(jī)真實(shí)的狀態(tài),考慮到上述研究采用的神經(jīng)網(wǎng)絡(luò)估計(jì)外部未知狀態(tài)得到了很好的效果,故本文將神經(jīng)網(wǎng)絡(luò)引入到反步快速終端滑??刂浦衼砉烙?jì)未知的建模信息,進(jìn)一步提高算法對系統(tǒng)的控制性能。
1 張力數(shù)學(xué)模型
織機(jī)送經(jīng)系統(tǒng)的織軸結(jié)構(gòu)簡化原理圖[18]如圖1所示。圖1中,T(t)為經(jīng)紗動(dòng)態(tài)張力,r0為經(jīng)軸初始半徑,r1(t)為經(jīng)軸實(shí)時(shí)半徑,M1(t)為經(jīng)軸電機(jī)電磁轉(zhuǎn)矩,v1(t)為機(jī)上經(jīng)紗線速度,a(t)為機(jī)上經(jīng)紗加速度。伴隨著織機(jī)織造過程不斷進(jìn)行,經(jīng)軸和卷軸半徑不斷變化,又因經(jīng)紗柔性特點(diǎn),因此送經(jīng)系統(tǒng)具有強(qiáng)耦合性和強(qiáng)非線性。
3.2 實(shí)驗(yàn)
為驗(yàn)證上述控制方法在實(shí)際工況中的有效性,將3種控制方法應(yīng)用到搭建的實(shí)驗(yàn)平臺中,分別在張力跟蹤精度上和控制器輸入上進(jìn)行對比。如圖4所示為STM32和FPGA聯(lián)合控制的實(shí)驗(yàn)平臺,兩者之間通過SPI通信傳輸數(shù)據(jù),由FPGA采集信號并傳遞給STM32完成算法運(yùn)算,其中實(shí)驗(yàn)平臺模擬了織軸卷徑的變化、電機(jī)振動(dòng)和綜框運(yùn)動(dòng),綜框運(yùn)動(dòng)的模擬由軸承外徑周圍凸起的轉(zhuǎn)動(dòng)來實(shí)現(xiàn)。實(shí)驗(yàn)分別在設(shè)定張力為1.56 N和2.56 N下進(jìn)行,如圖5為3種控制器的張力跟蹤效果和控制器輸出情況,表2為3種控制器的實(shí)驗(yàn)性能指標(biāo)。
在16 s的運(yùn)行過程中織軸卷徑變化了1 mm,在此期間送經(jīng)電機(jī)輸出合適的轉(zhuǎn)速保持張力穩(wěn)定。由圖5分析可知,由于綜框模擬運(yùn)動(dòng)和電機(jī)振動(dòng)等原因,3種控制器都上下波動(dòng)穩(wěn)定到某一狀態(tài),其中RBF-BCFOFTSMC控制器MAXE最小,跟蹤精度優(yōu)于其他兩種控制器在最靠近張力設(shè)定值附近波動(dòng)。3種控制器的輸出轉(zhuǎn)速都隨織軸卷徑變化和干擾等不斷波動(dòng),在設(shè)定張力1.56 N和2.56 N下的波動(dòng)幅度分別為4.41、5.93、5.48和4.42、5.95、5.50,
其中RBF-BCFOFTSMC波動(dòng)幅度最小,穩(wěn)定性更好?;?刂频淖赃m應(yīng)切換部分和神經(jīng)網(wǎng)絡(luò)能夠?qū)崟r(shí)估計(jì)外部干擾和未建模動(dòng)力學(xué),使得RBF-BCFOFTSMC控制器隨著織軸卷徑變化實(shí)時(shí)調(diào)整,輸出高精度的控制律保持張力穩(wěn)定,總結(jié)可知RBF-BCFOFTSMC跟蹤性能和抗干擾性能較好,具有較高的魯棒性。
通過聯(lián)合FPGA和ARM開發(fā)出的送經(jīng)系統(tǒng)張力控制實(shí)驗(yàn)平臺,不僅控制簡單、成本較低,可對于新型控制算法進(jìn)行穩(wěn)定性驗(yàn)證,擺脫了測試過程需在真實(shí)織機(jī)中運(yùn)行的依賴,極大地減少了經(jīng)紗張力的檢測門檻和技術(shù)難度,為控制算法應(yīng)用到實(shí)際工況中的紗線張力檢測和調(diào)節(jié)提供了新的思路。該實(shí)驗(yàn)平臺通過送經(jīng)與卷取電機(jī)的配合來完成經(jīng)紗送出,在此基礎(chǔ)上對提出的控制算法進(jìn)行有效性驗(yàn)證,但是該實(shí)驗(yàn)平臺與真實(shí)織機(jī)還存在一定差異,對于其中的一些其他運(yùn)動(dòng)也只是采用模擬的方式,后續(xù)研究還有必要在該實(shí)驗(yàn)基礎(chǔ)上追加實(shí)驗(yàn),證明其他運(yùn)動(dòng)對送經(jīng)系統(tǒng)張力的影響。
4 結(jié) 論
織機(jī)織造過程中,張力過小容易導(dǎo)致出現(xiàn)粗紗或冒紗,降低織物平整度,而當(dāng)張力過大時(shí),又會(huì)導(dǎo)致紗線斷裂停車,從而降低織造效率,由于送經(jīng)系統(tǒng)時(shí)變性和各種干擾的存在,常規(guī)控制算法存在超調(diào)嚴(yán)重和穩(wěn)態(tài)精度低等問題,因此為改善織機(jī)送經(jīng)系統(tǒng)的張力穩(wěn)定性,設(shè)計(jì)了一種神經(jīng)反步分?jǐn)?shù)階快速終端滑模控制算法。首先建立了織機(jī)送經(jīng)系統(tǒng)的數(shù)學(xué)模型,采用自適應(yīng)律實(shí)時(shí)更新控制器參數(shù)達(dá)到對外部干擾估計(jì)的效果,將RBF神經(jīng)網(wǎng)絡(luò)介入滑??刂浦校平徒?jīng)系統(tǒng)的真實(shí)系統(tǒng)狀態(tài),以此得到更為精確的數(shù)學(xué)模型。采用反步控制和滑??刂葡嘟Y(jié)合的方法避免了更多系統(tǒng)變量的使用,簡化了滑??刂频目刂坡?,引入分?jǐn)?shù)階理論給控制器帶來更多的自由度,通過李雅普諾夫函數(shù)驗(yàn)證了控制器的有限時(shí)間收斂性和穩(wěn)定性。最終通過仿真和實(shí)驗(yàn)證明RBF-BCFOFTSMC控制器具有較高的張力穩(wěn)定性,提高了系統(tǒng)的控制精度。所設(shè)計(jì)的控制器改善了織機(jī)的送經(jīng)系統(tǒng)控制水平,對于經(jīng)軸上的紗線退繞下來進(jìn)入綜框運(yùn)動(dòng)時(shí)的張力精度具有提高作用,有利于減少紗線斷頭現(xiàn)象,增強(qiáng)送經(jīng)量的恒定水平,對于提高織機(jī)的生產(chǎn)效率和胚布質(zhì)量具有較高的意義。
參考文獻(xiàn):
[1]馬宏帥,趙世海.基于線性自抗擾控制的放卷張力控制系統(tǒng)[J].現(xiàn)代紡織技術(shù),2019,27(1):87-92.
MA Hongshuai, ZHAO Shihai. Unwinding tension control system based on linear auto disturbance rejection control[J]. Advanced Textile Technology, 2019, 27(1): 87-92.
[2]KARAHAN O. Design of optimal fractional order fuzzy PID controller based on cuckoo search algorithm for core power control in molten salt reactors[J]. Progress in Nuclear Energy, 2021, 139: 103868.
[3]姜磊.智能梳棉機(jī)自調(diào)勻整控制系統(tǒng)設(shè)計(jì)開發(fā)[J].現(xiàn)代紡織技術(shù),2020,28(3):89-96.
JIANG Lei. Design and development of autoleveling control system for intelligent carding machine[J]. Advanced Textile Technology, 2020, 28(3): 89-96.
[4]FANG Y M, FEI J T, YANG Y Z. Adaptive backstepping design of a microgyroscope[J]. Micromachines, 2018, 9(7): 338.
[5]徐子琴,雷明.風(fēng)擾動(dòng)下固定翼無人機(jī)指令濾波反步著陸控制[J].計(jì)算機(jī)仿真,2022,39(9):55-62.
XU Ziqin, LEI Ming. Command filtered backstepping landing control of fixed-wing unmanned aerial vehicle considering wind disturbance[J]. Computer Simulation, 2022, 39(9): 55-62.
[6]ZAIHIDEEM F, MEKHILEF S, MUBIN M. Robust speed control of PMSM using sliding mode control (SMC): Areview[J]. Energies, 2019, 12(9): 1669.
[7]陶慧,艾朋偉.改進(jìn)滑膜控制雙降壓式逆變器的動(dòng)力學(xué)特性[J/OL].電力系統(tǒng)及其自動(dòng)化學(xué)報(bào):1-8[2022-10-21].DOI:10.19635/j.cnki.csu-epsa.001115.
TAO Hui, AI Pengwei. Dynamic characteristics of double buck inverter with improved sliding mode control [J]. Proceedings of the CSU-EPSA: 1-8[2022-10-21].DOI:10.19635/j.cnki.csu-epsa.001115.
[8]WANG H Q, LIU S W, YANG X B. Adaptive neural control for non-strict-feedback nonlinear systems with input delay[J]. Information Sciences, 2020, 514: 605-616.
[9]李建偉,張磊安,黃雪梅,等.基于改進(jìn)徑向基神經(jīng)網(wǎng)絡(luò)的風(fēng)電葉片模溫串級PID控制算法[J].太陽能學(xué)報(bào),2022,43(3):330-335.
LI Jianwei, ZHANG Lei′an, HUANG Xuemei, et al. Cascade PID control algorithm for wind turbine blade mold temperature based on improved RBF neural network [J]. Acta Energiae Solaris Sinica, 2022, 43(3): 330-335.
[10]崔征山,周揚(yáng)忠,張競,等.基于滑模和擴(kuò)張狀態(tài)觀測器的雙繞組無軸承磁通切換電機(jī)轉(zhuǎn)子懸浮控制策略研究[J].儀器儀表學(xué)報(bào),2022,43(6):269-279.
CUI Zhengshan, ZHOU Yangzhong, ZHANG Jing, et al. Research on rotor suspension control strategy of dual-winding bearingless flux-switching permanent magnet machines based on sliding mode control and extended state observer[J]. Chinese Journal of Scientific Instrument, 2022, 43(6): 269-279.
[11]黃道敏,韓麗君,唐國元,等.水下機(jī)械手分?jǐn)?shù)階積分滑模軌跡跟蹤控制方法研究[J].中國機(jī)械工程,2019,30(13):1513-1518.
HUANG Daomin, HAN Lijun, TANG Guoyuan, et al. Fractional integral sliding mode control for trajectory tracking of underwater manipulators[J]. China Mechanical Engineering, 2019, 30(13): 1513-1518.
[12]鄧檳檳,尚偉偉,張彬,等.6自由度繩索牽引并聯(lián)機(jī)器人的快速終端滑模同步控制[J].機(jī)械工程學(xué)報(bào),2022,58(13):50-58.
DENG Binbin, SHANG Weiwei, ZHANG Bin, et al. Fast terminal sliding mode control with synchronization error for a 6-dof cabel-driven parallel robot[J]. Journal of Mechanical Engineering, 2022, 58(13): 50-58.
[13]梁相龍,姚建勇.基于神經(jīng)網(wǎng)絡(luò)的機(jī)電伺服系統(tǒng)非線性控制[J].控制與決策,2023,38(4):1008-1014.
LIANG Xianglong, YAO Jianyong. Nonlinear control of mechatronic servo system based on neural network [J]. Control and Decision,2023,38(4):1008-1014.
[14]RAZMI H, AFSHINFAR S. Neural network-based adaptive sliding mode control design for position and attitude control of a quadrotor UAV[J]. Aerospace Science and Technology, 2019, 91: 12-27.
[15]CHEN S Y, LI T H, CHANG C H. Intelligent fractional-order backstepping control for an ironless linear synchronous motor with uncertain nonlinear dynamics[J]. ISA Tran-sactions, 2019, 89: 218-232.
[16]熊蕊.考慮瞬態(tài)性能的工業(yè)機(jī)器人雙臂反步控制方法[J].現(xiàn)代制造工程,2022(8):53-59.
XIONG Rui. Back-stepping control method of industrial robot dual-arm considering transient performance[J]. Modern Manufacturing Engineering, 2022(8): 53-59.
[17]FU C Y, HONG W, LU H Q, et al. Adaptive robust backstepping attitude control for a multi-rotor unmanned aerial vehicle with time-varying output constraints[J]. Aerospace Science and Technology, 2018, 78: 593-603.
[18]XU G W, ZHOU R X, LIU W, et al. The equivalent sliding mode tension control of carbon fiber multilayer diagonal loom[J]. International Journal of Control, Auto-mation and Systems, 2019, 17(7): 1762-1769.
Neural backstepping fractional order fast terminal sliding mode control of warp tension
FU Maowen1, SHEN Danfeng1, ZHAO Gang2, SHANG Guofei 1, BAI Shunwei1
(1.School of Mechanical and Electrical Engineering, Xi'an Polytechnic University, Xi'an 710048, China;
2.Shaanxi Changling Textile Mechanical & Electronic Technological Co., Ltd., Baoji 721013, China)
Abstract:
With the progress of current computer technology and modern control methods and theories, the textile field has been fully developed in the past decade, gradually realizing intelligence and advancement. However, the domestic textile industry still has the problems of low competitiveness and high labor costs. Looms in textile machinery need to be closely integrated with electromechanical equipment. High-quality looms apply more advanced algorithms to looms on the basis of continuous pursuit of higher weaving efficiency and fabric quality, reducing the degree of manual intervention. The performance of the let-off mechanism, a direct tension control mechanism, determines the speed and efficiency of the loom spindle. Studying the let-off system and developing a more efficient control algorithm or structure is an important factor to improve the performance of the loom, which meets the national economic needs and social significance of China.
In order to enhance the matching degree between the let-off mechanism and weaving requirements of looms, the key control algorithm of the let-off mechanism is designed, which is combined with modern control theory to improve the robustness and stability of the control algorithm. This research aims to develop a neural backstepping fractional order fast terminal sliding mode controller (RBF-BCFOFTSMC) to control the warp tension. Firstly, the time-varying mathematical model of the let-off system of the loom was established through dynamic analysis. In order to improve the dynamic response performance of the system and reduce chattering, a new backstepping fractional order fast terminal sliding mode control method was derived. Since there are disturbances such as motor vibration and heald frame motion in the weaving process of the loom, and the upper bound of the total disturbance of the system is unknown, an adaptive law was designed to estimate the upper bound of the external disturbance. The time-varying characteristics of the system make the controller have unmodeled and modeling uncertainties. The neural network parameter adaptive law was designed to approximate the real system state, and the Lyapunov stability was used to prove the rationality of the system. In order to verify the effectiveness of the designed control strategy, it was compared with traditional sliding mode control (SMC) and neural PID (RBFPID) in simulation experiments and actual working conditions. The results show that RBF-FOTSMC not only reduces chattering in warp tension control, but also has high robustness and response performance.
Through the research, the algorithm design and experiment of the let-off control system have been successfully completed, which has greatly improved the control effect, robustness and stability of the system. However, as the loom let-off system is a complex control system, more research needs to be supplemented in the future from two main points. First, it is necessary to study the influence of heald frame, weft insertion, beating up and other movements on loom tension, and analyze the influencing factors for corresponding tension compensation. Second, the adopted hardware needs to be optimized. If the controller with faster processing speed can be replaced, the high-speed and advanced level of the loom will be improved.
Keywords:
warp tension; fractional order; backstepping; sliding mode controller; neural network