【作者】 潘霞远；

【导师】 马平；

【作者基本信息】 广东工业大学 ， 机械电子工程， 2008， 硕士

【摘要】 在现代加工工业领域,诸如激光切割、高速磨床、精密车床、加工中心等很多场合都需要高速度高精度的直线运动,而传统的方法只能借助于旋转电动机和滚轴丝杆等中间环节来获得直线运动,这就不可避免地存在惯性大、摩擦大、有反向间隙等缺点。近年来,随着直线电机技术的进步,越来越多的场合开始直接应用它来获得直线运动。由于采用直接驱动(Direct Drive)技术,直线电机具有动态响应快,控制精度高,可以超高速运行等优点,而这恰恰满足了高速精密加工技术的要求。为了探索和拓展直线电机在精密加工领域的应用,本文用系统集成的方法设计了一套永磁直线伺服系统,并通过Matlab仿真技术研究其实现高性能、高精度运行的控制算法。首先,本文根据永磁同步直线电动机在d-q坐标系下的状态空间模型,采用磁场定向原理和i_d=0的控制策略,对电机模型进行了解耦和线性化处理,得到了它的频域模型。基于这个模型,我们分别采用H_∞闭环增益成形方法和前馈控制技术,设计了一个速度环的鲁棒PID控制器和一个速度前馈控制环节。仿真结果证明,鲁棒PID控制器不仅具有良好的抗外扰能力,同时对系统的内部参数如动子质量、电枢电阻、主磁极磁链等参数的摄动也具有很强的鲁棒性;而引入前馈环节后,还可以进一步提高系统的响应速度和控制精度。此外,论文还分析了一种伪微分前馈控制方法,它也是一种带前馈的PI控制方法,但由于引入了一个伪造的速度微分反馈项,使它在动态性能和噪声抑制方面都有不少提高。同时,这种控制方法的设计不依赖于对象的模型,比较适合于工程应用。为了实现直线伺服系统的高精度定位控制。本文首先研究由位移指令得到速度指令的速度规划方案,然后根据速度控制的研究基础,设计了一套具有速度和加速度双前馈的P/PI型位置、速度双环控制系统,由前馈通道提供主控指令,而主通道控制器进行误差控制。仿真结果显示,系统具有极高的响应速度和控制品质,其稳态定位误差趋于0,动态定位误差可以控制在微米级。该系统有五个控制参数,本文采用遗传算法对控制参数进行了优化选择,遗传算法的适应度函数综合考虑了系统的控制性能和鲁棒性能,从仿真结果观察,优化参数取得了满意的控制效果。此外,本文还研究了基于伪微分前馈控制方法的位置控制,但其性能与双前馈P/PI方法相去甚远。论文从设备的选型、安装和初步调试,到控制算法的选择和优化,完成了整个永磁直线伺服系统的初期设计任务,为永磁直线伺服系统的开发和应用奠定了基础。更多还原

【Abstract】 In modern machining industry, laser-cutting, high-speed milling and scanning machines require fast and accurate linear motions. But traditional drives need to use rotational motors and lead screw or toothed belts to obtain linear motions, which leads to some mechanical problems such as backlash, large frictional, inertial loads and structural flexibilities. With the development of linear motors, recently, they are becoming increasingly popular in such applications. Due to the direct-drive technology, linear motor exhibits the property of high accuracy, high speed and excellent dynamic responsivity, which just satisfies the requirement of high speed machining (HSM). In order to explore the linear motor applications in machining tools, here, we designed a linear servo system via selecting a permanent magnet synchronous linear motor (PMSLM) and a linear encoder. Our aim is to develop some algorithms to realize high accuracy and high performance control for this linear servo system.First, we applied field-oriented principle and the strategy of i_d = 0 to the state space model of PMSLM in d-q coordinates, and obtained a decoupling model and an approximate linearization model in frequency domain of the motor and driver system. Based on these models, we designed a robust PID controller of speed-loop by means of H_∞closed-loop gain shaping techniques. Moreover, a speed feed-forward block could be obtained easily from the frequency domain model of PMSLM and its driver. The robust PID controller exhibits good robustness against external disturbances and internal parameter perturbation by simulation results. When the feed-forward block is added, the responsive speed and control accuracy of the system will be improved more. Moreover, a pseudo derivative feed-forward (PDFF) method is analyzed in this thesis. As a type of PI control with feed-forward, PDFF can be designed independently from the plant model which is very suitable for engineering applications. Due to the pseudo derivative item of speed feedback, the dynamic performance and noise control of PDFF is improved greatly.In order to realize the high accurate position control, firstly, we made a speed plan through which a speed curve can be obtained from a displacement order. According to speed loop control, we design a P/PI position and speed control system with speed and acceleration double feed-forward path. The feed-forward paths provide the main control signals, speed order signal to the input terminal of speed loop and acceleration signal to the input terminal of current loop, and the main path controls the error of position and speed. Simulation results show that the double closed-loop system has strong robustness and excellent control performance with the dynamic error less than 10μm and static error near to zero. There are five major control parameters in this system, here, these parameters are optimized with genetic algorithm and the satisfied results are achieved. Furthermore, the method of PDFF is investigated, but its accuracy is less than that of above method.This thesis has completed the main design work of the linear servo system from the selections and installations of equipments to the design of control algorithms and the optimization of their parameters. After these work, we will continue to apply these algorithm to the experiment system and realize the design target of system.更多还原