Adaptive MPC based on MIMO ARX-Laguerre model

This paper proposes a method for synthesizing an adaptive predictive controller using a reduced complexity model. This latter is given by the projection of the ARX model on Laguerre bases. The resulting model is entitled MIMO ARX-Laguerre and it is characterized by an easy recursive representation. The adaptive predictive control law is computed based on multi-step-ahead finite-element predictors, identified directly from experimental input/output data. The model is tuned in each iteration by an online identification algorithms of both model parameters and Laguerre poles. The proposed approach avoids time consuming numerical optimization algorithms associated with most common linear predictive control strategies, which makes it suitable for real-time implementation. The method is used to synthesize and test in numerical simulations adaptive predictive controllers for the CSTR process benchmark.     

RBF-ARX model-based fast robust MPC approach to an inverted pendulum

In general, the online computation burden of robust model predictive control (RMPC) is very heavy, and the mechanical model of a plant, which is used in RMPC, is hard to obtain precisely in real industry. These issues may largely restrict the applicability of RMPC in real applications. This paper proposes a RBF-ARX (state-dependent Auto-Regressive model with eXogenous input and Radial Basis Function network type coefficients) model-based efficient robust predictive control (RBF-ARX-ERPC) approach to an inverted pendulum system, which is a complete and systematic method for designing robust MPC controller because it integrates the RBF-ARX modeling method and a fast RMPC approach. First, based on the offline identified RBF-ARX model without offset term, two convex polytopic sets are constructed to wrap the globally nonlinear behavior of the system. Then, the optimization problem of implementing a quasi-min–max MPC algorithm including several linear matrix inequalities (LMIs) is formulated, and it is solved offline to synthesize a sequence of explicit control laws that correspond to a sequence of asymptotically stable invariant ellipsoids, of which all the optimization results are stored in a look-up table. During the online real-time control, the controller only needs to carry out a simple state-vector computation and bisection search. The proposed approach is applied to an actual linear one-stage inverted pendulum (LOSIP), which is a fast-responding and nonlinear plant. The real-time control experiments demonstrate the effectiveness of the proposed RBF-ARX model-based efficient RMPC approach.     

A novel tuning strategy for multivariable model predictive control

Model predictive control (MPC) has established itself as the most popular form of advanced multivariable control in the chemical process industry. However, the benefits of this technology cannot be realized unless the controller can be operated with desirable performance for an extended period of time. The objective of this work is to present an easy-to-use and reliable tuning strategy that enables the control practitioner to maintain MPC at peak performance with minimal effort. A novel analytical expression that computes the move suppression coefficients, guidelines to select the additional adjustable parameters, and their demonstration in an overall tuning strategy are some of the significant contributions of this work. The compact form for the analytical expression that computes the move suppression coefficients is derived as a function of a first order plus dead time (FOPDT) model approximation of the process dynamics. With tuning parameters computed. MPC is then implemented in the classical fashion using an internal model formulated from step response coefficients of the actual process. Just as a FOPDT model approximation has proved a valuable tool in tuning rules such as Cohen-Coon. ITAE and IAE for PID implementations, the tuning strategy presented here is significant because it offers an analogous approach for multivariable MPC.     

优化VMD与CNN在齿轮箱故障诊断应用研究

针对齿轮箱的故障诊断的优化问题,提出了一种基于参数优化的变分模态分解（VMD）与卷积神经网络（CNN）相融合的故障诊断方法。该算法首先通过鲸鱼优化算法对VMD算法进行优化,之后通过正交实验法与粒子群优化算法进行了CNN模型中的重要参数进行优化,最后将分解后得到的固有模态分量输入CNN模型中进行训练学习。诊断完成后得到训练与检测结果,其中经过算法优化后CNN模型的训练与检测准确率可达98.7%与95.7%,优于未优化的准确率94.3%与91.8%。通过对结果的分析验证出该算法的可行性以及在诊断成功率方面的优越性,实现了故障特征信息的自适应性提取,并将故障类型进行分类,最终实现齿轮箱故障诊断的智能化。     

Parameterized data-driven fuzzy model based optimal control of a semi-batch reactor

A parameterized data-driven fuzzy (PDDF) model structure is proposed for semi-batch processes, and its application for optimal control is illustrated. The orthonormally parameterized input trajectories, initial states and process parameters are the inputs to the model, which predicts the output trajectories in terms of Fourier coefficients. Fuzzy rules are formulated based on the signs of a linear data-driven model, while the defuzzification step incorporates a linear regression model to shift the domain from input to output domain. The fuzzy model is employed to formulate an optimal control problem for single rate as well as multi-rate systems. Simulation study on a multivariable semi-batch reactor system reveals that the proposed PDDF modeling approach is capable of capturing the nonlinear and time-varying behavior inherent in the semi-batch system fairly accurately, and the results of operating trajectory optimization using the proposed model are found to be comparable to the results obtained using the exact first principles model, and are also found to be comparable to or better than parameterized data-driven artificial neural network model based optimization results.     

逐步优化 GM(1,1)预测模型在金属切削理论研究中的应用

运用灰色系统理论及方法，在GM(1，1)建模思想的基础上提出了一种基于直接建模的逐步优化的建模方法，它通过优化背景值与差商调节系数来估计模型参数。该模型不仅适合于等间距建模，也适合于非等间距建模，且突破了发展系数的绝对值较大时，不能用GM(1，1)模型的禁区，提高了建模的精度。应用该模型对金属切削试验数据处理，为金属切削试验提供了科学的方法。     

基于Matlab与T—S模糊系统的压电驱动器磁滞特性建模及实验验证

针对压电驱动器的磁滞特性，提出了一种基于MISO模糊系统的磁滞建模方法，将一维输入空间中的多值函数映射为多维输入空间的单值函数，有效地解决了磁滞曲线多值映射的问题。基于Matlab7．1软件，该方法根据磁滞系统的输入输出数据，在最大隶属度、最近邻居和超半径概念的基础上，基于1阶T—S型模糊推理对模糊系统进行训练和参数优化，从而精确地建立了压电驱动器的磁滞特性模型。     

Fuzzy model predictive control of non-linear processes using convolution models and foraging algorithms

In this paper, a fuzzy model predictive control (FMPC) approach is introduced to design a control system for nonlinear processes. The proposed control strategy has been successfully employed for representative, benchmark chemical processes. Each nonlinear process system is described by fuzzy convolution models, which comprise a number of quasi-linear fuzzy implications (FIs). Each FI is employed to describe a fuzzy-set based relation between control input and model output. A quadratic optimization problem is then formulated, which minimizes the difference between the model predictions and the desired trajectory over a predefined predictive horizon and the requirement of control energy over a shorter control horizon. The present work proposes to solve this optimization problem by employing a contemporary population-based evolutionary optimization strategy, called the Bacterial Foraging Optimization (BFO) algorithm. The solution of this optimization problem is utilized to determine optimal controller parameters. The utility of the proposed controller is demonstrated by applying it to two non-linear chemical processes, where this controller could achieve better performances than those achieved by similar competing controller, under various operating conditions and design considerations. Further comparisons between various stochastic optimization algorithms have been reported and the efficacy of the proposed approach over similar optimization based algorithms has been concluded employing suitable performance indices.     

Data-driven modeling and predictive control for boiler–turbine unit using fuzzy clustering and subspace methods

This paper develops a novel data-driven fuzzy modeling strategy and predictive controller for boiler–turbine unit using fuzzy clustering and subspace identification (SID) methods. To deal with the nonlinear behavior of boiler–turbine unit, fuzzy clustering is used to provide an appropriate division of the operation region and develop the structure of the fuzzy model. Then by combining the input data with the corresponding fuzzy membership functions, the SID method is extended to extract the local state-space model parameters. Owing to the advantages of the both methods, the resulting fuzzy model can represent the boiler–turbine unit very closely, and a fuzzy model predictive controller is designed based on this model. As an alternative approach, a direct data-driven fuzzy predictive control is also developed following the same clustering and subspace methods, where intermediate subspace matrices developed during the identification procedure are utilized directly as the predictor. Simulation results show the advantages and effectiveness of the proposed approach.     

Robust input design for nonlinear dynamic modeling of AUV

Input design has a dominant role in developing the dynamic model of autonomous underwater vehicles (AUVs) through system identification. Optimal input design is the process of generating informative inputs that can be used to generate the good quality dynamic model of AUVs. In a problem with optimal input design, the desired input signal depends on the unknown system which is intended to be identified. In this paper, the input design approach which is robust to uncertainties in model parameters is used. The Bayesian robust design strategy is applied to design input signals for dynamic modeling of AUVs. The employed approach can design multiple inputs and apply constraints on an AUV system’s inputs and outputs. Particle swarm optimization (PSO) is employed to solve the constraint robust optimization problem. The presented algorithm is used for designing the input signals for an AUV, and the estimate obtained by robust input design is compared with that of the optimal input design. According to the results, proposed input design can satisfy both robustness of constraints and optimality.     

Identification of hinging hyperplane autoregressive exogenous model using efficient mixed-integer programming

A computationally efficient algorithm for hinging hyperplane autoregressive exogenous (HHARX) model identification via mixed-integer programming technique is proposed in this paper. The HHARX model is attractive since it accurately approximates a general nonlinear process as a sum of hinge functions and preserves the continuity even in a piecewise affine form. Traditional mixed-integer programming-based method for HHARX model identification can only be applied on small-scale input/output datasets due to its significant computational demands. The contribution of this paper is to develop a sequential optimization approach to build accurate HHARX model more efficiently on a relatively large number of experimental data. Moreover, the proposed framework can handle more difficult and practical cases in piecewise model identification, such as: limited submodel switching, missing output data and specified steady state. Finally, the efficiency and accuracy of the proposed computational scheme are demonstrated through modeling of two simulated examples and a pilot-scale heat exchanger.     

人工神经网络在赤潮预报中的应用仿真研究

赤潮是目前世界沿海国家面临的十分紧迫的海洋环境问题之一，也是一种全球性的海洋灾害。建立有效的赤潮灾害监测和预报系统已迫在眉睫。本文利用人工神经网络中的BP网络，建立赤潮生物密度与环境因子的人工神经网络的预报模型。以各种理化因子：水温．溶解氧．盐度、总氰．可溶性无机磷．浮游植物密度等为参数．试验人工神经网络的预报效果。针对BP网络训练易陷入局部最优的缺点．本文采用了遗传算法改进网络训练方法，保证网络达到全局最优。结果证明、采用人工神经网络进行赤潮预报是行之有效的。     

Fuzzy Clustering in Problems of Determining the Aerodynamic Characteristics and Modeling the Aircraft Dynamics

A modified method of fuzzy clustering is proposed for determining the aerodynamic characteristics of an aircraft from flight test data. This approach allows one to describe the aerodynamic characteristics of an aircraft in the form of a black box model with inputs in the form of telemetry data, such as accelerations, angular velocities, thrust, and dynamic pressure, and with outputs in the form of dimensionless aerodynamic coefficients of forces and moments. Results of modeling in the MATLAB/Simulink environment are reported.     

Accurate simplistic predictive modeling of nonlinear dynamic processes

In this article, a new simplistic way of predictive modeling of process variables in nonlinear dynamic processes is introduced. This approach, which is semi-empirical, is demonstrated on a simulated continuous stirred tank reactor. Model development uses a first-order-plus-dead-time structure and only two or three input changes for determining the coefficients. This approach is evaluated for a variety of situations which include measured output, unmeasured output, extrapolation beyond the input range, various levels of dead time, various levels of measurement error, large dynamics, and various levels of nonlinear behavior. In the situation of unmeasured output, the proposed approach is very accurate and in the other cases it is extremely accurate and far superior to linear regression and artificial neural twork models.     

System identification and stability evaluation of an unmanned aerial vehicle from automated flight tests

This paper presents a consequence of the systematic approach to identify the aerodynamic parameters of an unmanned aerial vehicle (UAV) equipped with the automatic flight control system. A 3-2-1-1 excitation is applied for the longitudinal mode while a multi-step input is applied for lateral/directional excitation. Optimal time step for excitation is sought to provide the broad input bandwidth. A fully automated programmed flight test method provides highquality flight data for system identification using the flight control computer with longitudinal and lateral/directional autopilots, which enable the separation of each motion during the flight test. The accuracy of the longitudinal system identification is improved by an additional use of the closed-loop flight test data. A constrained optimization scheme is applied to estimate the aerodynamic coefficients that best describe the time response of the vehicle. An appropriate weighting function is introduced to balance the flight modes. As a result, concurrent system models are obtained for a wide envelope of both longitudinal and lateral/directional flight maneuvers while maintaining the physical meanings of each parameter.     

基于函数逼近的双圆弧齿轮齿根强度优化分析

介绍了函数逼近的有限元优化方法基本理论,利用ANSYS的可编程和参数化建模功能建立整个优化分析的流程,程序随着迭代自动生成有限元模型和边界条件.通过优化计算发现,其他参数相同而模数不同的双圆弧齿轮其齿根强度最优的齿形参数一致,且最优齿形是一种接近于公切型双圆弧齿轮的齿形.     

电火花线切割中计算智能集成方法的应用与实现

针对控制复杂、难以精确描述数学模型的复杂加工过程，提出集成遗传算法和人工神经网络的多目标优化方法。把加工工艺参数和工艺指标参数分别看作神经网络的输入和输出，建立相对精确的数学模型，随后借助训练好的神经网络和遗传算法来优化加工参数。由于该方法解决了适应度函数难以获得的问题，为复杂过程多目标优化提供了强有力的工具。在电火花线切割中的应用验证了该方法的可实施性和有效性。     

基于实验数据的航空发动机稳态模型建模

针对基于部件级航空发动机稳态建模过程中完整、准确的航空发动机部件特性数据往往难以获取,建模时间长等现象,提出使用实验数据进行辨识建模的方法;为了建立航空发动机的稳态模型,通过对某轻型飞机实验台的飞行实验数据进行分析整理,提出使用BP神经网络对发动机重要参数进行建模,同时使用粒子群优化算法(Particle swarm optimization,PSO)对BP神经网络的权值和阈值进行优化。最后,使用改进粒子群优化算法(Improved particle swarm optimization algorithm,IPSO)对传统粒子群优化算法进行改进,仿真结果表明IPSO-BP网络建立的发动机模型精度更高,稳定性更好。     

Multi-objective optimization of process parameters in Electro-Discharge Diamond Face Grinding based on ANN-NSGA-II hybrid technique

The effective study of hybrid machining processes (HMPs), in terms of modeling and optimization has always been a challenge to the researchers. The combined approach of Artificial Neural Network (ANN) and Non-Dominated Sorting Genetic Algorithm-II (NSGA-II) has attracted attention of researchers for modeling and optimization of the complex machining processes. In this paper, a hybrid machining process of Electrical Discharge Face Grinding (EDFG) and Diamond Face Grinding (DFG) named as Electrical Discharge Diamond face Grinding (EDDFG) have been studied using a hybrid methodology of ANN-NSGA-II. In this study, ANN has been used for modeling while NSGA-II is used to optimize the control parameters of the EDDFG process. For observations of input-output relations, the experiments were conducted on a self developed face grinding setup, which is attached with the ram of EDM machine. During experimentation, the wheel speed, pulse current, pulse on-time and duty factor are taken as input parameters while output parameters are material removal rate (MRR) and average surface roughness (R_a). The results have shown that the developed ANN model is capable to predict the output responses within the acceptable limit for a given set of input parameters. It has also been found that hybrid approach of ANN-NSGA-II gives a set of optimal solutions for getting appropriate value of outputs with multiple objectives.     

基于Imageware和UG的汽车阀体的反求设计

以汽车阀体零件为研究对象,探讨了逆向工程在汽车零部件设计中的应用.介绍了具有复杂特征的阀体由阀体实物模型到基于三坐标测量仪扫描的点云数据,再到参数化设计的CAD模型,最终形成优化的CAD模型的全过程及Imageware和UG软件在该过程中的应用.提出了一种新的基于点云提取的造型思路,并给出了反求设计的工作流程.