导　　师： 梁昔明

学科专业： 081101

授予学位： 硕士

作　　者： ;

机构地区： 中南大学

摘　　要： 金属铣削加工过程是一种具有非线性、时变性和影响因素不确定的复杂系统，难以用精确的数学模型来描述。随着加工技术和生产自动化程度的提高，对加工系统自动控制的鲁棒性能要求越来越高。而传统的基于精确数学模型的控制算法对此类复杂系统的控制难于胜任，因此，不依赖数学模型的智能控制将为加工过程提供新的控制方法。基于这种考虑，本文将模糊控制引入到铣削加工过程，并结合pid控制，构成模糊pid复合控制方法，以期实现对铣削加工过程中诸如变工况的一类不确定信息进行有效而稳定的控制。 本文在分析闭环铣削加工控制系统的不确定性的基础上，论述了pid控制的原理，讨论了pid参数对其控制性能的影响。接着提出了铣削加工过程的pid控制，通过假定一些工况的变化模拟加工过程中出现的不确定信息。计算机仿真实验结果显示在背吃刀量突变时超调量很大。为了克服这一缺点，进而提出铣削加工过程的模糊控制，以使得切削力尽可能快速、无差、稳定地跟踪设定的期望值。文中讨论了模糊控制器的设计方法和步骤，分析了模糊控制的特点，构建了铣削加工过程的模糊控制器并进行了仿真实验。 在此基础上，提出了铣削加工过程的模糊pid控制。用matlab软件分别对这三种控制方法进行了仿真实验，并对仿真结果进行了深入的分析。最后，在xk5140数控铣床上，实现了对变工况铣削过程的闭环控制，针对上述的控制方法进行了实际切削加工的实验。 计算机仿真结果表明，铣削加工过程的模糊控制响应速度很快，鲁棒性能好，但存在一定的稳态误差；pid控制的稳态性能很好，但超调量比较大；模糊pid控制保持了pid控制良好的稳态性能，超调量明显减小，响应速度很快。对比三种控制方法，可以说，利用模糊逻辑整定pid参数，可实现性能良好的模糊pid复合控制，对于变工况为代表的一类不确定信息的控制具有很强的鲁棒性能。这在实际加工实验中得到了验证。 The metal-milling manufacturing system is a time-varying nonlinear dynamic system. As the improvement of machining technology and production automation, the robust performance requirements of automatic control of manufacturing system are higher and higher. The conventional control algorithms based on accurate mathematical models are not competent for controlling the complicated dynamic systems. Therefore, intelligent control, which is not based on accurate mathematical model, will provide a new approach for those complicated dynamic systems. In this paper, fuzzy control is imported to the milling process control system, combined with PID, for controlling the manufacturing process. In the thesis, the uncertainty of closed loop milling control system is discussed in detail. Principle of PID control is discussed, and the effect of PID parameters on the performance of PID controller is analysised. And then, PID control for machining process is proposed. And then Fuzzy Controller /(FC/) for machining process is proposed to make cutting force reach the set desired value rapidly, steadily, and without error. The mechanism and peculiarity of FC is analyzed deeply, and fuzzy controller for milling process is designed. By assuming variation of the Depth of cutting, uncertainty of milling process is simulated, and simulation of both of the two way of control for the milling process is excuted with personal computer/(PC/), and results is analysised deeply. Basing on the work above, fuzzy PID controller for milling process is proposed. By presupposition of the variety of work situation, using Matlab to simulate the three controllers aboved for uncertain milling process. At the end, an experiment based on these controllers is progressed, with a closed loop milling control system by milling machine XK5140. It is indicated, from the results of the simulations and the experiments, that the response speed of FC for milling process is rapid, but a little steady-state error exists; to PID, the result is steady but overshoot is much larger; fuzzy PID has strongpoints but not defect, comparing with FC and conventional PID. In a word, it is advisable to import fuzzy mechanism to setting the parameters of PID for uncertain milling process.

关 键 词： 铣削加工 模糊 控制 自动控制 金属切削加工

分 类 号： [TG547 TP273.4]

领　　域： [金属学及工艺] [自动化与计算机技术] [自动化与计算机技术]