【作者】 尤煜敏；

【导师】 陈昌；

【作者基本信息】 大连理工大学 ， 控制理论与控制工程， 2008， 硕士

【摘要】 在实际工业生产过程中,广泛存在着时滞。时滞的存在对工业控制系统的性能产生不利影响,特别是当时滞较大,惯性时间较长并且过程对象的动态特性随各种因素的影响而发生变化时,采用传统的控制方法,如PID控制方法,很难获得良好的控制效果,甚至会出现不稳定现象。因此,如何改善大滞后控制过程的控制品质是一个有着较大实际意义的课题。本文对自校正控制理论的背景进行了介绍。研究了目前应用于实际工业大滞后系统中常用的PID调节器、Smith预估和自校正控制这三种控制算法,经仿真研究,分析比较了它们在大滞后控制系统应用中的优缺点,得出了自校正控制技术更具有优势的结论。通过仿真研究了算法中参数的设置问题。本文对于模型的阶次,经过仿真发现,可将阶次设置为一个比实际模型的阶次稍大的值,这样既不影响系统的稳定性,又可以适应过程对象模型结构的慢时变性;使用损失函数法来确定模型的滞后时间常数;对于递推参数和协方差矩阵,在仿真开始时,利用自校正控制器先对其进行辨识,但控制器并不对控制输出进行计算,将自校正控制器投入运行时,这两个参数就已经是辨识好的并且适合于本系统的初值。这样设置参数能既保证控制系统的稳定性,又适应系统时变的动态特性。并且针对自校正调节器所存在的问题,即控制器的输出振荡的问题和系统崩溃问题,在控制算法中让遗忘因子等于0.9999,同时对控制器的输出、递推参数、增益向量和协方差矩阵引入加权滤波的控制思想,给出了一种修正的自校正控制算法。最后将修正的自校正控制算法应用到换热元件综合试验室的加热器温度控制系统中进行仿真,这个系统是一个典型的具有大时滞、大惯性及慢时变特性的控制系统。仿真结果表明,其控制性能明显优于常规的PID控制器。更多还原

【Abstract】 The time delay is widely existed in modern industrial process. It has negative effects on the control performance of the system, especially when delay time is large, inertia time is long and dynamic characteristics of the process object is influenced by the various factors. The conventional control method such as PID control can not meet requirements and even cause the stability of the system worse. Therefore, it is an important research with actual meaning to improve the control quality of the system with delay time.In this paper, the theory of the self-tuning control is presented firstly. Then many control algorithms of current large time delay system are studied, for example PID regulator, Smith predictor controller and self-tuning controller. Through simulation, comparing their advantages and disadvantages in the large time delay control system, the result shows that self-tuning control is comparatively the best method.The problem of how to set up the parameter is studied through simulation. In this paper, a lot of simulations show that the order of the model in the algorithm can be set a little larger than the actual object, after setting it like that, the controller do not affect the stability of the system, but also can adapt the time-varying character of the system; loss function is used to determine the time delay constant; and the recursive parameter and covariance matrix has been identified at the beginning of the simulation, the controller do not calculate the output, just identify the recursive parameter and covariance matrix, so when the self-tuning is used, these two parameters has been identified and very fit for the system. With these operations, the controller can not only guarantee stability of the control system, but also adapt the time-varying dynamic characteristics. Aiming at the problem of self-tuning regulator, that is oscillation of the controller output and breakdown of the system. Forgetting factor is determined to 0.9999, and the weighted filtering control thought is introduced into output of the controller, recursive parameter, gain vector, and covariance matrix. These two algorithms are combined together, and a kind of the modified self-tuning control is proposed.At last, the modified self-tuning control arithmetic is applied to the temperature control system of the heater in hot-exchange integrated lab. The system typically possesses heating single direction, large time delay, big inertia and slow time varying characters. The result of the simulation reveals that its performance is much better than PID control.更多还原