积分加纯滞后系统的双预测PI控制及其应用

Smith预估控制器控制积分加大纯滞后过程时,鲁棒稳定性差,输出存在静态余差,无实际应用价值.提出了一类基于该过程的双预测PI控制器:具有内环和外环两种预测PI控制器.内环将系统稳定,外环消除输入干扰的影响和改善控制系统的动态性能.这种控制器结构简单,可调参数少,参数的调节方便、直观.仿真和实际应用表明:在干扰和模型失配的情况下,此类控制器仍然具有良好的控制性能和鲁棒稳定性能,是一种值得在实际工程中推广应用的新型控制器.     

精馏过程提馏段温度的前馈和免疫PID-P串级控制研究

借鉴生物免疫反馈响应过程的调节规律,针对精馏过程内部机理复杂、参数动态变化的特点,提出一种前馈补偿和免疫PID-P串级控制方法。内环采用P控制器以快速消除再沸器蒸汽压力不稳定波动,外环采用免疫PID控制器以保证提馏段温度稳定在给定值,同时前馈控制器用于克服外界不可控干扰。结果表明,该控制策略优于常规控制,具有较强的鲁棒性和抗干扰能力。     

基于新型组合积分控制器的积分过程先进控制

针对工业生产过程中常见的积分加纯滞后的过程对象,提出了一类双闭环控制器：内环和外环均使用组合积分控制器。内环用于系统的稳定,外环消除输入干扰的影响和改善控制系统的动态性能。这种控制器结构简单,仅有两个可调参数,且参数整定方便、直观。仿真结果表明：对于积分加纯滞后对象,在模型失配和干扰存在的情况下,该控制算法仍然能够保持稳定的被控输出,具有良好的鲁棒稳定性和动态调节品质,同时对时间常数较大的一阶加纯滞后系统也有着良好的控制效果。     

SOPDT对象的预测PID控制及稳定性分析

提出了基于二阶非振荡及振荡加纯滞后的预测PID控制器的结构形式。这种控制器既具有PID控制器的优点；简单的结构形式、良好的鲁棒性和可靠性，又具有预测的功能；即可以根据以前的控制作用来预测以后的控制作用。通过仿真表明：在干扰、噪音存在和模型失配的情况下，预测PID控制器具有良好的控制性能，特别适合大纯滞后系统的控制。同时运用Monte-Carlo方法分析了其鲁棒稳定性，结果表明：它是一种值得在实际工程中推广应用的新型控制器。     

双闭环控制在熔体粘度测试仪中的应用

文中介绍了高温熔体粘度测试仪的组成和测试原理,分析了硅钼棒加热炉的升温特性。提出了一种电流＋温度的双闭环控制器：内环控制器能有效地克服了硅钼棒随温度升高带来的电阻干扰;外环采用阈值控制和自适应模糊PID控制相结合的复合控制,通过自调整PID参数瞬态输出值,实现无静差控制。仿真研究证明,该控制算法比单回路模糊控制相比具有更优的动态性能和鲁棒性。     

独轮自平衡机器人双闭环非线性PID 控制

针对竖直飞轮独轮自平衡机器人系统,提出一种用于独轮自平衡机器人的平衡及运动控制的双闭环非线性PID控制方法(DLNPID),并给出了该控制方法稳定性的证明.该控制方法是具有横滚倾角内环、俯仰倾角内环和前向位移外环的双闭环控制,其中每个控制环均由非线性PID控制器(NPID)构成.实验结果表明,所提出的基于非线性PID的双闭环独轮自平衡机器人控制方法具有比线性方法更好的鲁棒性能.     

带有自校正的PID预测计算机控制算法研究

常规PID控制有许多不完善之处，其中最主要的问题就是PID控制器参数一旦调整好后。在整个控制过程中都是固定不变的，从而使系统很难达到最佳的控制效果。提出了一种带有自校正的PID预测计算机控制算法，包括控制结构、控制器设计以及变换为具有PID结构形式的过程。仿真结果表明带有白校正的PID预测控制算法调整时间短，平滑性较好，表明该带有自校正的PID预测计算机控制算法的有效性和较好的控制综合性能。     

四旋翼无人机抗干扰轨迹跟踪控制

针对四旋翼无人机轨迹跟踪过程中存在的参数不确定与外界干扰问题,设计一种双闭环自适应控制策略.为了降低控制器设计复杂度,根据四旋翼无人机系统的欠驱动特性将系统分成姿态内环和位置外环.在扰动观测器的基础上,利用积分型反步控制算法完成无人机位置信息在外界干扰下的稳定跟踪控制.在扰动观测器的基础上,利用自适应滑模控制算法完成无人机姿态信息在参数不确定和外界干扰作用下的稳定跟踪控制.与传统PID控制和滑模控制进行仿真对比,验证所提出控制策略的优越性.     

导弹舵机PID-MRAC复合控制仿真研究

PID控制具有结构简单、稳定性能好、可靠性高等优点.提出了一种基于Liapunov稳定性理论、采用传统PID控制和模型参考自适应控制(Model Reference Adaptive Control,MaAC)相结合的导弹电动舵机复合控制方法,利用模型参考自适应控制作为内环控制回路使舵机的动态特性尽量逼近参考模型的动态特性,整个系统的外环控制采用PID控制来提高系统的动态性能和消除舵机负载等因素带来的稳态误差.利用Madab/Simulink对该方法进行建模仿真.仿真结果表明:该方法能够有效地克服导弹飞行过程中舵机系统参数变化对系统性能的影响,具有较强的鲁棒性.     

液压伺服系统的预测函数控制及其仿真研究

为了提高液压伺服系统的跟踪性能和鲁棒性,将预测函数控制(PFC)和PID控制的优点相结合,提出了一种PFC-PID串级控制策略.内环采用PID控制来提高抗十扰性,把内环作为外环PFC控制的广义对象,对广义对象进行拟合简化得到一阶加纯滞后系统,作为PFC的预测模型,外环采用PFC来获得良好的跟踪性能和鲁棒性.通过Matlab建模、仿真及与PID控制的比较表明,PFC-PID串级控制策略能够改善液压伺服系统的控制性能.     

Robust IMC–PID tuning for cascade control systems with gain and phase margin specifications

In this article, an internal model control plus proportional-integral-derivative (IMC–PID) tuning procedure for cascade control systems is proposed based on the gain and phase margin specifications of the inner and outer loop. The internal model control parameters are adjusted according to the desired frequency response of each loop with a minimum interaction between the inner and outer PID controllers, obtaining a fine tuning and the desired gain and phase margins specifications due to an appropriate selection of the PID controller gains and constants. Given the design specifications for the inner and outer loop, this tuning procedure adjusts the IMC parameter of each controller independently, with no interference between the inner and outer loop obtaining a robust method for cascade controllers with better performance than sequential tuning or other frequency domain-based methods. This technique is accurate and simple, providing a convenient technique for the PID tuning of cascade control systems in different applications such as mechanical, electrical or chemical systems. The proposed tuning method explained in this article provides a flexible tuning procedure in comparison with other tuning procedures because each loop is tuned simultaneously without modifying the robustness characteristics of the inner and outer loop. Several experiments are shown to compare and validate the effectiveness of the proposed tuning procedure over other sequential or cascade tuning methods; some experiments under different conditions are done to test the performance of the proposed tuning technique. For these reasons, a robustness analysis based on sensitivity is shown in this article to analyze the disturbance rejection properties and the relations of the IMC parameters.     

Robust tuning of Two-Degree-of-Freedom (2-DoF) PI/PID based cascade control systems

A design approach for Two-Degree-of-Freedom (2-DoF) PID controllers within a cascade control configuration that guarantees robust and smooth control is presented in this paper. The use of a cascade control configuration comes into place when the use of an additional (intermediate) sensor provides the possibility for a compensation of a load-disturbance before it affects the output variable. The rationale of operation associated to both the inner and outer controllers determines the need of good performance for disturbance attenuation (regulation) as well as set-point following (tracking). Therefore, the use of 2-DoF controllers is introduced. However, the use of 2-DoF controllers, introduces additional parameters that need to be tuned appropriately. Specially for the case of PI/PID controllers there are not known clear auto-tuning guidelines for such situation. The approach undertaken in this paper provides the complete set of tuning parameters for the inner (2-DoF PI) controller and the outer (2-DoF PID) controller. The trade-off among control system performance (measured in terms of closed-loop response speed) and robustness allows to derive a recommendation for the design-parameter lower limit. The design equations are formulated in such a way that a non-oscillatory response is specified for both the inner and outer loop. A side advantage of providing the complete set of parameters is that it avoids the need for the usual identification experiment for the tuning of the outer controller.     

Simultaneous closed-loop tuning of cascade controllers based directly on set-point step-response data

This study presents a novel closed-loop tuning method for cascade control systems, in which both primary and secondary controllers are tuned simultaneously by directly using set-point step-response data without resorting to process models. The tuning method can be applied on-line to improve the performance of existing underperforming cascade controllers by retuning controller parameters, using routine operating data. The goal of the proposed design is to obtain the parameters of two proportional-integral-derivative (PID)-type controllers, so that the resulting inner and outer loops behave as similarly as possible to the appropriately specified reference models. The tuning rule and optimization problem related to the proposed design are derived. Based on the rationale behind cascade control, the secondary controller is designed based on disturbance rejection to quickly attenuate disturbances. The primary controller is designed to accurately account for the inner-loop dynamics, without requiring an additional test. In addition, robustness considerations are included in the proposed tuning method, which enable the designer to explicitly address the trade-off between performance and robustness for inner and outer loops independently. Simulation examples show that the proposed method exhibits superior control performance compared with the previous (model-based) tuning methods, confirming the effectiveness of this novel tuning method for cascade control systems.     

Backstepping approach for design of PID controller with guaranteed performance for micro-air UAV

Flight controllers for micro-air UAVs are generally designed using proportional-integral-derivative (PID) methods, where the tuning of gains is difficult and time-consuming, and performance is not guaranteed. In this paper, we develop a rigorous method based on the sliding mode analysis and nonlinear backstepping to design a PID controller with guaranteed performance. This technique provides the structure and gains for the PID controller, such that a robust and fast response of the UAV (unmanned aerial vehicle) for trajectory tracking is achieved. First, the second-order sliding variable errors are used in a rigorous nonlinear backstepping design to obtain guaranteed performance for the nonlinear UAV dynamics. Then, using a small angle approximation and rigorous geometric manipulations, this nonlinear design is converted into a PID controller whose structure is naturally determined through the backstepping procedure. PID gains that guarantee robust UAV performance are finally computed from the sliding mode gains and from stabilizing gains for tracking error dynamics. We prove that the desired Euler angles of the inner attitude controller loop are related to the dynamics of the outer backstepping tracker loop by inverse kinematics, which provides a seamless connection with existing built-in UAV attitude controllers. We implement the proposed method on actual UAV, and experimental flight tests prove the validity of these algorithms. It is seen that our PID design procedure yields tighter UAV performance than an existing popular PID control technique.     

A controller tuning methodology for the air supply system of a PEM fuel-cell system with guaranteed stability properties

Fuel cells are electrochemical devices that convert the chemical energy of a gaseous fuel directly into electricity. They are widely regarded as potential future stationary and mobile power sources. The response of a fuel-cell system depends on the air and hydrogen feed, flow and pressure regulation, and heat and water management. In this article, the study is concentrated on the air subsystem that feeds the fuel-cell cathode with oxygen and, in particular, on the problem of providing tuning rules for these controllers ensuring stability of the overall system. Proceeding from a reduced order non-linear model, that preserves the main features of the (by-now classical) ninth order model, we suggest a natural decomposition into interconnected subsystems where one of them is strictly passive, hence finite ?₂-gain stable, and the other one depends on the controller parameters. The proposed tuning methodology consists then on enforcing the required input–output property of the feedback loop, either passivity or a suitable ?₂-gain. For this end, the feedback operator is linearised, then robust Kharitonov-based positive (or bounded) realness conditions are imposed to determine the allowable ranges for the controller gains. We illustrate the methodology with a classical cascaded loop-controller structure with an inner loop feedback linearising controller and an outer loop PI regulator. Simulation results are presented to illustrate the conservativeness of the analysis as well as the performance improvement obtained with a suitable tuning.     

低阶时滞过程的伪预测PI／PID控制

基于单位反馈控制结构,根据期望的闭环传递函数设计得到了一种伪预测PI/PID(ADQPI/ADQPID)控制器。这种控制器只有一个可调参数,可调参数与系统动态响应性能和鲁棒稳定性之间存在直接关系,只需单调的调节控制器参数,便可实现系统的动态响应性能与鲁棒稳定性之间的最佳折衷。仿真实例表明,这种控制器在扰动和模型失配的情况下仍然具有良好的控制性能和鲁棒稳定性,是一种值得在实际工程中推广运用的新型控制器。     

Simultaneous automatic tuning of cascade control systems from closed-loop step response data

This study presents a novel automatic tuning method for cascade control systems in which both primary and secondary controllers are tuned simultaneously using a single closed-loop step test. The proposed technique identifies the required process information with the help of B-spline series representation for the step responses. The two proportional–integral–derivative (PID) controllers are then tuned using an internal model control (IMC) approach. Considering the rationale of cascade control, the secondary controller is designed for faster disturbance attenuation. Without requiring an additional experiment, the primary controller is designed based on an identified process model that accurately accounts for inner loop dynamics. Finally, this study includes robustness considerations in the controller tuning process, and develops explicit guidelines for the selection of the IMC tuning parameters, completing the automatic tuning procedure for cascade control systems. The proposed method is robust to measurement noise because of the filtering property of the B-splines, and can provide superior control performance for both set-point tracking and disturbance rejection. Simulation examples demonstrate the effectiveness of the proposed automatic tuning method.     

A multivariable control scheme for robot manipulators

The article puts forward a simple scheme for multivariable control of robot manipulators to achieve trajectory tracking. The scheme is composed of an inner loop stabilizing controller and an outer loop tracking controller. The inner loop utilizes a multivariable PD controller to stabilize the robot by placing the poles of the linearized robot model at some desired locations. The outer loop employs a multivariable PID controller to achieve input-output decoupling and trajectory tracking. The gains of the PD and PID controllers are related directly to the linearized robot model by simple closed-form expressions. The controller gains are updated on-line to cope with variations in the robot model during gross motion and for payload change. Alternatively, the use of high gain controllers for gross motion and payload change is discussed. Computer simulation results are given for illustration.     

Tracking in scale quad-rotors through adaptive augmentation

This paper illustrates the application of an adaptive flight control architecture to a scale quad-rotor. For autonomous vertical takeoff and landing flight, it is common to separate the control problem into an inner fast loop that controls attitude and an outer slow loop that controls the trajectory tracking. In this paper, we augment a conventional proportional and derivative controller conceived mainly for hovering, with an adaptive element using a real-time tuning single hidden layer neural network in a inner–outer loop combined architecture to account for model inversion error cancelation, issued in the feedback linearization process. The results shown in simulations reveal the superior performance of the augmented controller in tracking maneuvers.