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自中科院系统所在20世纪80年代末期开创了自抗扰控制技术的相关理论研究,并于1998年正式提出自抗扰控制器(ADRC)的概念以来[1],自抗扰控制器已经在很多领域获得了成功的应用。近年来,在交流伺服驱动控制方向上也出现了相关的一些研究工作。这些工作要么致力于对传统交流伺服三环控制结构基于经典ADRC技术进行不同形式的改造[2-9],要么是通过对电机模型进行部分辨识与补偿或采用无参数整定的控制策略等方式对ADRC进行适度改进,再应用于交流伺服控制[10-11]。以上各项研究中所构建的交流伺服控制系统无一例外地仅将电机本体作为控制对象,而对于结构更复杂且惯量更大的机电系统均未涉及。另外,ADRC在交流伺服系统中的应用研究目前仍然停留在仿真实验或算法实现的探讨层面[12-13],工程实现的实际案例极少。
本文基于一种实际的电机试验设备,为了有效抑制其三坐标自动定位系统中的显著扰动,构建了包含伺服电机、伺服驱动器以及复杂机械传动环节的一种全闭环位置伺服机电控制系统,并且在系统位置外环控制器中植入先进的ADRC控制算法。在动力学建模与分析的基础上,通过仿真对比分析及相应的测试实验,验证了该全闭环位置伺服控制结构在系统中抑制负载外扰及阻抗内扰的有效性。
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图 1为某型电机试验设备的示意图,该设备的主体之一为一种三坐标自动定位台架,台架具有X、Y、Z三个方向的运动自由度,且每个方向都采用手轮和PMSM交流伺服控制驱动的方式,以“PC+运动控制板卡”作为上位控制器。
在试验台架的X、Y、Z三轴系统中,Z轴升降系统的运动状况最为特殊。一方面,升降平台作上、下运动时其重力荷载造成了Z轴驱动系统的外负载显著不对称,因此当电机驱动参数一定时,即使荷重恒定,也相当于对驱动系统施加了一个恒值负载外扰,造成Z轴升降系统上、下运行时的被控运动参量呈现明显差异,在X、Y、Z三轴作空间曲线的插补运动时,由此带来的位置偏差不容忽视。另一方面,Z轴机械传动部分的环节相对较多并且采用了四杆导向结构,由于制造及装配误差的缘故,安装平台在Z向运动过程中的摩擦力作为内扰因素不仅显著且极不稳定。此外,在持续工作状况下,驱动器的不稳定、电机阻抗的波动等等都会以内扰的形式对系统伺服性能产生负面影响。鉴于此,以下就以Z轴系统作为典型对象来展开讨论。Z轴机械传动模型如图 2示。图中,i为蜗轮蜗杆传动比;Tmi为伺服电机输出转矩;θmi为伺服电机输出转角;J1为轴Ⅰ转动惯量;J2为轴Ⅱ转动惯量;K1为轴Ⅰ扭转刚度;K2为轴Ⅱ扭转刚度;K3为轴Ⅲ直线刚度;B为安装平台运动的速度阻尼系数;M为轴Ⅲ总质量。
如丝杠导程为l,安装台直线位移S折算到电机轴上的等效转角为$\mathit{\Phi } {\rm{ = }}\frac{{i2{\rm{ \mathsf{ π} }}S}}{l} $。假定作用于轴Ⅱ的扭矩为T2,由荷重产生的力矩为TL,则由平衡关系可得下列等式:
$$ {T_{mi}} = K({\theta _{mi}}-\mathit{\Phi } ) $$ (1) $$ {T_{mi}} = {J_1}\frac{{{{\rm{d}}^2}\mathit{\Phi } }}{{{\rm{d}}{\kern 1pt} {t^2}}} + \frac{{{T_2}}}{i} $$ (2) $$ {{{T_2} = \left[{{J_2} + M{{\left( {\frac{l}{{2{\rm{ \mathsf{ π} }}}}} \right)}^2}} \right]} \mathord{\left/ {\vphantom {{{T_2} = \left[{{J_2} + M{{\left( {\frac{l}{{2{\rm{ \mathsf{ π} }}}}} \right)}^2}} \right]} {i\frac{{{{\rm{d}}^2}\mathit{\Phi } }}{{{\rm{d}}{t^2}}} + B{{\left( {\frac{l}{{2{\rm{ \mathsf{ π} }}}}} \right)}^2}\frac{1}{i}\frac{{{\rm{d}}\mathit{\Phi } }}{{{\rm{d}}t}} \pm {T_L}}}} \right. } {i\frac{{{{\rm{d}}^2}\mathit{\Phi } }}{{{\rm{d}}{t^2}}} + B{{\left( {\frac{l}{{2{\rm{ \mathsf{ π} }}}}} \right)}^2}\frac{1}{i}\frac{{{\rm{d}}\mathit{\Phi } }}{{{\rm{d}}t}} \pm {T_L}}} $$ (3) 式(1)中,
$$ K = \frac{{{l^2}{K_1}{K_2}{K_3}}}{{{l^2}{K_2}{K_3} + (4{{\rm{ \mathsf{ π} }}^2}{K_2} + {l^2}{K_3}){l^2}{K_1}}} $$ 由式(2)和式(3),得到Z轴系统的运动方程为:
$$ \frac{{{{\rm{d}}^2}\mathit{\Phi } }}{{{\rm{d}}{\kern 1pt} {t^2}}} = \frac{{i{T_{mi}}}}{{{J^*}}}-\frac{B}{{{J^*}i}}{\left( {\frac{l}{{2{\rm{ \mathsf{ π} }}}}} \right)^2}\frac{{{\rm{d}}\mathit{\Phi } }}{{{\rm{d}}t}} \mp \frac{{{T_L}}}{{{J^*}}} $$ (4) 式中,$ {J^*} = \left\{ {i{J_1} + [{J_2} + M{{\left( {{l \mathord{\left/ {\vphantom {l {2\pi }}} \right. } {2\pi }}} \right)}^2}]/i} \right\}$。
式(4)中的荷重等效负载转矩TL之前的“∓”号,在安装台上升时取“-”号,下降时取“+”号,在式(3)中情况恰好相反,该转矩大小可用下式估算:
$$ {T_L} = \left( {\frac{{Mgl}}{{2{\rm{ \mathsf{ π} }}\eta }} + \frac{{{\mu _0}{F_0}l}}{{2{\rm{ \mathsf{ π} }}}}} \right)\frac{1}{i} $$ (5) 式中,g为重力加速度;η为丝杆传动效率;μ0为预压螺母内摩擦系数;F0为预压荷重。
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设有一非线性系统:
$$ \left\{ \begin{array}{l} {{\dot x}_1}(t) = {x_2}(t)\\ \quad \quad \vdots \\ {{\dot x}_{n-1}}(t) = {x_n}(t)\\ {{\dot x}_n}(t) = f({x_1}, {x_2}, \cdots, {x_n}) + w(t) + bu\\ y = {x_1}(t) \end{array} \right. $$ (6) 式中,$ f({x_1}, {x_2}, \cdots, {x_n})$为未知函数;$ w(t)$为未知外扰;u为系统控制量;b为系统控制增益。
对以上系统式(6),ADRC控制算法最一般的数学模型如下[14-15]:
1) 系统的n阶跟踪微分器为:
$$ \left\{ \begin{array}{l} {{\dot z}_{11}} = {z_{12}}\\ {{\dot z}_{12}} = {z_{13}}\\ \quad \; \vdots \\ {{\dot z}_{1n}} = {R^n}f({z_{11}}-\mu (t), \frac{{{z_{12}}}}{R}, \cdots, \frac{{{z_{1n}}}}{{{R^{n-1}}}}) \end{array} \right. $$ (7) 式中,z11是对系统给定μ(t)的跟踪值;R为跟踪微分器的信号输入界限,即$ \mu (t) < R$;${\dot z_{1k}}\, (k = 2, 3, \cdots, n) $为μ(t)跟踪值的各阶微分值;$ f({z_{11}}-\mu (t)$,$ {z_{12}}/R, \cdots, {z_{1n}}/R)$为一非线性函数。
2) 系统的n+1阶扩张状态观测器为:
$$ \left\{ \begin{array}{l} {{\dot z}_{21}} = {z_{22}}-{g_1}({z_{21}}-{x_1}(t))\\ \quad \;\; \vdots \\ {{\dot z}_{2n}} = {z_{2n + 1}}-{g_n}({z_{21}} - {x_1}(t)) + bu\\ {{\dot z}_{2\, n + 1}} = - {g_{n + 1}}({z_{21}} - {x_1}(t)) \end{array} \right. $$ (8) 式中,z21为y的跟踪值;${\dot z_{2k}}(k = 2, 3, \cdots, n) $为y的跟踪值的各阶微分值;而${\dot z_{2n + 1}} $为对系统外部扰动与未建模部分的实时估计;$ {g_k}( \cdot )\;(k = 1, 2, \cdots, n + 1)$为非线性函数。目前控制工程中使用的非线性函数有多种,多数时候选用以下形式:
$$ {\rm{fal}}(x, \alpha, \delta ) = \left\{ \begin{array}{l} {\left| x \right|^\alpha }{\mathop{\rm sgn}} (x)\, \, {\rm{ }}\;\left| x \right| > \delta > 0\\ \frac{x}{{{\delta ^{(1-\alpha )}}}}\;{\rm{ }}\, \, ~~~~~~~~~\left| x \right| \le \delta \end{array} \right. $$ (9) 式中,α为非线性因子;δ为滤波因子。
3) 针对系统的非线性状态误差反馈控制律(nonlinear state error feed back, NLSEF)为:
$$ {u_0}(t) = \sum\limits_{k = 1}^n {{\beta _k}{\rm{fal}}({\varepsilon _k}, {\alpha _k}, {\delta _k})} $$ (10) 式中,$ {\varepsilon _k} = {z_{1k}}-{z_{2k}}, {\rm{ }}k = 1, 2, \cdots, n$;${\beta _k}\;, \;{\alpha _k}\, , {\delta _k} $分别为误差反馈增益系数、非线性反馈因子、非线性系统滤波因子,通常$0 < {\alpha _k} < 1 $;$ {\delta _1} = {\delta _2} = \cdots = {\delta _n}$。
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令v为Z轴升降台直线运动速度,当升降台位移量为S时,显然$ {\rm{d}}S/{\rm{d}}t = v$。由于各种扰动的影响而引起的速度波动量为:
$$ \frac{{{\rm{d}}S}}{{{\rm{d}}t}} = v + w(t) $$ (11) 由前述自抗扰控制器的特性,如在位置环中引入ADRC,则不需要知道非线性因素$ w(t)$的具体形式,而仅需要通过ADRC对此时变非线性扰动进行实时估计即可。根据Z轴系统的运动方程式(4)及式(7)~式(10),构制出Z轴位置环ADRC的一种低阶模型,其结构框图如图 5所示。
在低阶情况下,跟踪微分器NTD是可以省掉的,因此可得简化的ADRC模型如下:
二阶非线性扩张状态观测器:
$$ \left\{ \begin{array}{l} {\varepsilon _{01}}{\rm{ = }}{z_{21}}-S\\ {{\dot z}_{21}} = {z_{22}}-{\beta _{01}}{\rm{fal}}({\varepsilon _{01}}, {\alpha _{01}}, {\delta _{01}}) + bu\\ {{\dot z}_{22}} =-{\beta _{02}}{\rm{fal}}({\varepsilon _{01}}, {\alpha _{02}}, {\delta _{02}}) \end{array} \right. $$ (12) 非线性状态误差反馈控制律:
$$ \left\{ \begin{array}{l} {\varepsilon _1} = S*-{z_{21}}\\ {u_0} = {\beta _1}{\rm{fal}}({\varepsilon _1}, {\alpha _1}, {\delta _1})\\ u = {u_0}-\frac{{{z_{22}}}}{b} \end{array} \right. $$ (13) 式中,S*为Z轴升降的位置给定;S为实际检测到的位置信号;α01、α02、α1为非线性因子;δ01、δ02、δ1为滤波因子;z21为对检测反馈位置信号的跟踪值;ε01为位置踪误差;z22为位置环的扰动观测值;控制输出u=v*,v*实际上是速度环的给定值。
A Disturbance Suppression Control Strategy and Its Realization for an Electromechanical Position Servo System
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摘要: 针对某型电机试验设备的三坐标自动定位安装系统存在较严重扰动的问题,探讨了相应的抑扰控制方法。首先建立了内扰因素复杂且重力荷载外扰显著的Z轴升降系统的动力学模型,在此基础上构建了一个交流伺服驱动的全闭环机电位置伺服系统,以初步达到消除系统各种环内扰动影响的目的。为了进一步提高系统的抗扰能力,在全闭环控制系统的位置外环控制器中引入先进的自抗扰控制器(ADRC)算法。基于该全闭环位置伺服系统进行Matlab/Simulink仿真实验,对位置环采用ADRC调节与PID调节的抗扰效果进行了比对分析,结果显示在恒定负载外扰下的位置跟踪性能及电气阻抗内扰下的位置保持性能ADRC控制优于PID控制。最后在试验设备上完成了相应的测试实验,对仿真结果作出了进一步的验证。
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关键词:
- ADRC算法 /
- 扰动抑制 /
- 全闭环控制 /
- 位置伺服系统 /
- Simulink仿真
Abstract: The disturbance-suppression methods are discussed for solving the severe disturbance from the automatic three-coordinate positioning and installation system of a certain type of motor test equipment. Firstly, a kinetic model of the Z-axis lifting system with complicated internal disturbance factors and significant external load is established, and then an AC driven full closed-loop electromechanical position servo system is established to prevent the initial impact of various closed-loop internal disturbances. In order to further improve the system's anti-disturbance abilities, the advanced active-disturbances rejection controller (ADRC) is introduced in the positional loop controller of the fully closed-loop control system. A MATLAB/Simulink simulation test was carried out based on this full closed-loop position servo system and a contrast analysis was made between the disturbance resistance effects of ADRC control and PID control for the position loop. The results show that for the position tracking performance under the external disturbance of a constant load and the position holding performance under the internal disturbance of electrical impedance, the ADRC control is better than the PID control. Finally, the corresponding tests were completed using the test equipment, and the simulation results were further verified. -
[1] 韩京清.自抗扰控制器及其应用[J].控制与决策, 1998, 13(1):19-23. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=kzyc801.003&dbname=CJFD&dbcode=CJFQ HAN Jing-qing. Active-disturbances rejection controller and its applications[J]. Control and Decision, 1998, 13(1):19-23. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=kzyc801.003&dbname=CJFD&dbcode=CJFQ [2] 孙凯, 许镇琳, 盖廓, 等.基于自抗扰控制器的永磁同步电动机位置伺服系统[J].中国电机工程学报, 2007, 27(15):43-46. doi: 10.3321/j.issn:0258-8013.2007.15.008 SUN Kai, XU Zhen-lin, GAI Kuo, et al. A novel position controller of PMSM servo system based on active-disturbance rejection controller[J]. Proceedings of the CSEE, 2007, 27(15):43-46. doi: 10.3321/j.issn:0258-8013.2007.15.008 [3] 周腊吾, 严伟, 匡江传.基于变结构自抗扰控制器的永磁同步电动机伺服系统[J].微特电机, 2012, 40(2):55-58, 64. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=wtdj201202016 ZOU La-wu, YAN Wei, KUANG Jiang-chuan. PMSM servo system based on variable structure active-disturbance rejection controller[J]. Small & Special Electrical Machines, 2012, 40(2):55-58, 64. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=wtdj201202016 [4] 谢先铭, 兰志勇, 廖克亮, 等.基于串级自抗扰控制器的永磁同步电动机位置伺服系统[J].微电机, 2015, 48(1):68-71. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=wdjz201501015&dbname=CJFD&dbcode=CJFQ XIE Xian-ming, LAN Zhi-yong, LIAO Ke-liang, et al. Research of PMSM position servo system based on cascaded active-disturbance rejection controller[J]. Micromotors, 2015, 48(1):68-71. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=wdjz201501015&dbname=CJFD&dbcode=CJFQ [5] 滕福林, 胡育文, 李宏胜, 等.基于自抗扰控制器的交流位置伺服系统[J].电气传动, 2011, 41(11):46-50, 58. doi: 10.3969/j.issn.1001-2095.2011.11.011 TENG Fu-lin, HU Yu-wen, LI Hong-sheng, et al. AC position servo system based on active-disturbance rejection controller[J]. Electric Drive, 2011, 41(11):46-50, 58. doi: 10.3969/j.issn.1001-2095.2011.11.011 [6] 吕永健, 杨铭.永磁同步电动机单闭环位置伺服系统设计[J].微特电机, 2015, 43(10):60-63. doi: 10.3969/j.issn.1004-7018.2015.10.017 LÜ Yong-jian, YANG Ming. Design on single closed Loop position servo system of permanent magnet synchronous motor[J]. Small & Special Electrical Machines, 2015, 43(10):60-63. doi: 10.3969/j.issn.1004-7018.2015.10.017 [7] 刘清. 基于自抗扰控制器的永磁同步电动机伺服系统控制策略的研究及实现[D]. 天津: 天津大学, 2011. http://www.wanfangdata.com.cn/details/detail.do?_type=degree&id=Y2082122 LIU Qing. Research and implementation on control strategy of PMSM servo system based on active disturbance rejection controller[D]. Tianjin: Tianjin University, 2011. http://www.wanfangdata.com.cn/details/detail.do?_type=degree&id=Y2082122 [8] SU Y X, ZHENG C H, DUAN B Y. Automatic disturbances rejection controller for precise motion control of permanent-magnet synchronous motors[J]. IEEE Transactions on Industrial Electronics, 2005, 52(3):814-823. doi: 10.1109/TIE.2005.847583 [9] JIN Ming-yang, CHEUNG N C, WU Jie. The auto-disturbance rejection controller for speed regulation in permanent-magnet linear motors[C]//The 30th Annual Conference of the IEEE Industrial Electronics Society. [S. l. ]: IEEE, 2004. http://ieeexplore.ieee.org/xpls/icp.jsp?arnumber=1431732 [10] 刘志刚, 李世华.基于永磁同步电机模型辨识与补偿的自抗扰控制器[J].中国电机工程学报, 2008, 28(24):118-123. doi: 10.3321/j.issn:0258-8013.2008.24.020 LIU Zhi-gang, LI Shi-hua. Active disturbance rejection controller based on permanent magnetic synchronous motor model identification and compensation[J]. Proceedings of the CSEE, 2008, 28(24):118-123. doi: 10.3321/j.issn:0258-8013.2008.24.020 [11] 盖江涛, 黄庆, 黄守道, 等.基于模型补偿的永磁同步电机自抗扰控制[J].浙江大学学报(工学版), 2014, 48(4):581-587. http://www.cqvip.com/QK/90076A/201404/49566116.html GAI Jiang-tao, HUANG Qing, HUANG Shou-dao, et al. Active-disturbance rejection controller for permanent magnet synchronous motor based on model compensation[J]. Journal of Zhejiang University (Engineering Science), 2014, 48(4):581-587. http://www.cqvip.com/QK/90076A/201404/49566116.html [12] 郑伟, 董文妍, 张焕鑫, 等.自抗扰控制器在位置伺服系统中的参数整定及仿真[J].计算机测量与控制, 2015, 23(10):3364-3369. http://industry.wanfangdata.com.cn/yj/Detail/Periodical?id=Periodical_jsjzdclykz201510034 ZHENG Wei, DONG Wen-yan, ZHANG Huan-xin, et al. Tuning and application of PMSM servo system based on active-disturbance rejection controller[J]. Computer Measurement & Control, 2015, 23(10):3364-3369. http://industry.wanfangdata.com.cn/yj/Detail/Periodical?id=Periodical_jsjzdclykz201510034 [13] 林炳善, 任正权, 黄健.自抗扰控制器的实践性研究[J].延边大学学报(自然科学版), 2000, 26(3):196-199, 228. http://industry.wanfangdata.com.cn/dl/Detail/Periodical?id=Periodical_ybdxxb-zrkxb200003012 LIN Bing-shan, REN Zheng-quan, HUANG Jian. Studies of the auto disturbances rejection controller in practice[J]. Journal of Yanbian University(Natural Science), 2000, 26(3):196-199, 228. http://industry.wanfangdata.com.cn/dl/Detail/Periodical?id=Periodical_ybdxxb-zrkxb200003012 [14] 韩京清.从PID技术到自抗扰控制技术[J].控制工程, 2002, 9(3):13-18. http://www.cnki.com.cn/Article/CJFDTOTAL-JZDF200203004.htm HAN Jing-qing. From PID technique to active disturbances rejection control technique[J]. Control Engineering of China, 2002, 9(3):13-18. http://www.cnki.com.cn/Article/CJFDTOTAL-JZDF200203004.htm [15] 韩京清.自抗扰控制技术[M].北京:国防工业出版社, 2008. HAN Jing-qing, Active disturbances rejection control technique[M]. Beijing:National Defence Industry Press, 2008.