受饱和约束的车辆转向非线性鲁棒模糊分布控制

针对极限状态下车辆转向非线性和执行器饱和问题,研究主动前轮转向(active front steering, AFS)和直接横摆力矩控制(direct yaw-moment control, DYC)对横摆-侧倾稳定的集成控制。采用Takagi-Sugeon(T-S)方法建立车辆3自由度横摆侧倾模型,结合模糊观测器实时获取模型动态参数。为准确反映车辆转向稳态过程,在T-S框架下建立改进横摆理想参考模型。考虑到极限转向对前轮侧偏特性的影响,构建T-S框架下主动前轮输入的动态饱和阈值。引入松弛因子提高AFS和DYC的执行器利用率,将反馈输入的饱和影响作为有界扰动进行控制。基于分布补偿结构设计状态反馈模糊分布控制器(parallel distributed compensation-TS,PDC-TS),采用范数有界的侧翻稳定阈作为侧倾性能约束,将车辆横摆-侧倾稳定性的H;性能转换为线性矩阵不等式(linear matrix inequalities, LMIs)凸优化问题。最后联合Trucksim-MATLAB/Labview软件进行控制仿真和硬件在环验证,结果表明,PDC-TS方法对强非线性转向过程的控制更加准确,执行器能力利用更充分,并在输入饱和约束下保持控制稳定性。     

受饱和约束的车辆转向非线性鲁棒模糊分布控制

针对极限状态下车辆转向非线性和执行器饱和问题,研究主动前轮转向(active front steering, AFS)和直接横摆力矩控制(direct yaw-moment control, DYC)对横摆-侧倾稳定的集成控制。采用Takagi-Sugeon(T-S)方法建立车辆3自由度横摆侧倾模型,结合模糊观测器实时获取模型动态参数。为准确反映车辆转向稳态过程,在T-S框架下建立改进横摆理想参考模型。考虑到极限转向对前轮侧偏特性的影响,构建T-S框架下主动前轮输入的动态饱和阈值。引入松弛因子提高AFS和DYC的执行器利用率,将反馈输入的饱和影响作为有界扰动进行控制。基于分布补偿结构设计状态反馈模糊分布控制器(parallel distributed compensation-TS,PDC-TS),采用范数有界的侧翻稳定阈作为侧倾性能约束,将车辆横摆-侧倾稳定性的H;性能转换为线性矩阵不等式(linear matrix inequalities, LMIs)凸优化问题。最后联合Trucksim-MATLAB/Labview软件进行控制仿真和硬件在环验证,结果表明,PDC-TS方法对强非线性转向过程的控制更加准确,执行器能力利用更充分,并在输入饱和约束下保持控制稳定性。     

A semi-analytic approach to robust design in the conceptual design phase

One of the most important contributions to quality engineering over the last decades is the concept of robust design and its accomplishment through the use of various experimental methods. However, the prerequisite for successful parameter design in terms of a robust solution principle is seldom discussed. Methods that explicitly aid robust design in the conceptual design phase exist but are few. This article forwards the suggestion to use the principles behind the error transmission formula as a semi-analytic method for evaluation of robustness of concept solutions, prior to entering Taguchi's parameter design stage.     

Piecewise affine systems approach to control of biological networks

In terms of a piecewise affine system representation, which is a kind of hybrid system model, this article discusses a series of approaches to modelling, analysing and synthesizing a biological network such as a gene-regulatory network. First, the input assignment problem, the controllable state set problem (CSP) and the input trajectory generation problem are emphasized as control problems to be addressed for biological networks. Subsequently, after the modelling issue on biological networks developed in the systems and control community is briefly explained, the CSP is described in detail with reference to control of the quorum-sensing system in the pathogen Pseudomonas aeruginosa. Finally, an optimal control design method to the quorum-sensing system is proposed as a solution to the input trajectory generation problem.     

Simulation of the operation of multiuser distributed measurement and control systems

A computer simulation approach to the study of remote multiuser computer systems in educational and scientific research via the internet/intranet is proposed that offers the possibility of an extended analysis of their modes of operation. An example of algorithm and program execution of the proposed approach is discussed and analyzed.     

Taguchi's approach to robust parameter design: A new perspective

Adjustment factors play a crucial role in Taguchi's approach to robust parameter design. However, the notion of adjustment factors is not well defined and ambiguities exist in the selection of those factors. In this article, we propose a criterion for selecting adjustment factors. The proposed criterion can be used to explain and extend Taguchi's approach. The concept is illustrated using two examples.     

A plug-in approach to sparse and robust principal component analysis

We propose a method for sparse and robust principal component analysis. The methodology is structured in two steps: first, a robust estimate of the covariance matrix is obtained, then this estimate is plugged-in into an elastic-net regression which enforces sparseness. Our approach provides an intuitive, general and flexible extension of sparse principal component analysis to the robust setting. We also show how to implement the algorithm when the dimensionality exceeds the number of observations by adapting the approach to the use of robust loadings from ROBPCA. The proposed technique is seen to compare well for simulated and real datasets.     

A systems approach to rural housing

An attempt is made in this paper to arrive at a methodology for generating building technologies appropriate to rural housing. An evaluation of traditional/ ‘ modern ’ technologies currently in use reveals the need for alternatives. The lacunae in the presently available technologies also lead to a definition of rural housing needs. It is emphasised that contending technologies must establish a ‘ goodness of fit ’ between the house form and the pattern of needs. A systems viewpoint which looks at thedynamic process of building construction and thestatic structure of the building is then suggested as a means to match the technologies to the needs. The process viewpoint emphasises the role of building materials production and transportation in achieving desired building performances. A couple of examples of technological alternatives like the compacted soil block and the polythene-stabilised soil roof covering are then discussed. The static structural system viewpoint is then studied to arrive at methodologies of cost reduction. An illustrative analysis is carried out using the dynamic programming technique, to arrive at combinations of alternatives for the building components which lead to cost reduction. Some of the technological options are then evaluated against the need patterns. Finally, a guideline for developments in building technology is suggested.     

A DSS approach to developing systems to support production planning and control in smaller companies

Smaller Manufacturing Enterprises (SMEs) would benefit from manufacturing decision support systems (DSSs) in which the links between customer orders and manufacturing operations were maintained throughout the production planning process. However, systems with this characteristic are not available at prices that most SMEs can afford. This paper describes how a prototype DSS with this feature was developed and validated using data from a manufacturer of fencing materials. A hybrid relational database/object-oriented approach to modelling the manufacturing process is outlined. Static and slowly changing data about the manufacturing system were stored on a relational database, while more dynamic production planning information was built into an object model. The system made use of a 'Bill of Production' for each manufactured item that contained both materials and operation information, and was constructed at the time it was required from information held on the database.     

A robust variational approach to super-resolution with nonlocal TV regularisation term

Abstract

Multi frame super-resolution (SR) reconstruction algorithms make use of complimentary information among low-resolution (LR) images to yield a high-resolution (HR) image. Inspired by recent development on the video denoising problem, we propose a robust variational approach for SR-based on a constrained variational model that uses the nonlocal total variation (TV) as a regularisation term. In our method, a weighted fidelity term is proposed to take into account inaccurate estimates of the registration parameters and the point spread function. Moreover, we introduce the nonlocal TV as a regularisation term in order to take into account complex spatial interactions within images. In this way, important features and fine details are enhanced simultaneously with noise reduction. Furthermore, an alternative nonlocal TV regularisation is proposed based on a better weight function which integrates gradient similarity and radiometric similarity. Experiments show the effectiveness and practicability of the proposed method.     

A stochastic approach to the closure of accessible sets of control systems with application on homogeneous spaces

Given a control system on a compact manifold M, we study conditions for the foliation defined by the accessible sets to be dense in M. For this, we relate the control system to a stochastic differential equation and, by the support theorem, we give a characterization of the density in terms of the infinitesimal generator of the diffusion and its invariant measures.     

An integrated approach to determine the block layout,AGV flow path and the location of pick-up/delivery points in single-loop systems

Layout design and material handling system design are two of the major aspects of facility planning. Although both aspects directly influence each other, the classical approach to the layout design is carried out in two separate steps: in the first step the block layout, i.e. the location of the departments in the workshop, is constructed, and in the second step, the material handling system is designed. The separate optimisation of these two aspects of the problem leads to solutions that can be far from the global optimum. In this paper, we develop an integrated algorithm to design the facilities and material handling systems. We focus on single-loop AGV systems. The proposed algorithm determines the block layout, AGV single-loop flow path and pick-up delivery stations, simultaneously. The associated from–to chart and the area of departments are the principal inputs of the algorithm. The objective is minimising total material flow distance among all departments. The results of our computational experiments show the algorithm was coded using MATLAB 7.0, and that our integrated algorithm is more efficient in terms of both the objective function value and the runtime.     

A systems approach to vacuum measurement methods

A general approach is presented to the methodological principles of vacuum metrology: methods of reproducing low-pressure scales and methods of calibrating and checking vacuum gauges and flow meters. This provides a scientific basis for classifying methods and identifying working resources on the basis of gas-dynamic formulas. Translated from Izmeritel’naya Tekhnika, No. 7, pp. 40–44, July, 1999.     

Universal machine control system primitives for modular distributed manipulator systems

The market for programmable machines is still in its infancy, awaiting major changes in machine architectures and functionality. This paper anticipates the evolution of modular distributed manipulator systems and outlines their potential role as generic reconfigurable manufacturing machines. The necessary functionality of the control and mechanical primitive elements of such systems will be described with reference to major SERC-funded research aimed at evolving the primitives of universal machine control systems.     

A modular framework for distributed model predictive control of nonlinear continuous-time systems (GRAMPC-D)

Optimization and Engineering - The modular open-source framework GRAMPC-D for model predictive control of distributed systems is presented in this paper. The modular concept allows to solve optimal...     

Optimal flow path design of unidirectional AGV systems

This paper describes an alternative formulation of the AGV flow path layout (FPL) problem which was first formulated by Gaskins and Tanchoco (1987) as a zero-one integer programming problem. A computationally efficient procedure is proposed which is based on the branch-and-bound technique. An algorithm for satisfying the reachability condition for nodes in the AGV flow path network is also presented. A simple illustrative example is discussed to demonstrate the procedure, and a more complex problem is also given.     

Solution methods for the mathematical models of single-loop AGV systems

Guide path simplification can potentially reduce the complexity inherent in conventional, multi-loop automated guided vehicle systems (AGVs). A single-loop configuration is one alternative. A procedure for designing single-loop AGV systems, the OSL method was presented in a previous paper. In this paper, we suggest faster and more efficient methods for solving the two mathematical models in the OSL procedure. The first model called the valid single-loop problem (VSLP) is used to determine an initial single loop for the procedure. The method suggested is a heuristic procedure that starts from a loop around one of the departments and keeps adding departments to the loop until a valid single loop is constructed. The second model called the single-loop station location problem (SLSLP) is used to determine the location of the pick-up and delivery stations along a given loop. The method suggested converts the mixed integer formulation into a linear formulation.     

Performance of real-time distributed arrival time control in heterarchical manufacturing systems

A highly distributed feedback control algorithm for autonomous part entities in heterarchical manufacturing systems is presented in this paper. A difference equation-based model is developed to analyze the discrete time dynamics of the resulting nonlinear control system. Control parameters are found analytically that guarantee that the system is bounded under disturbances. The dynamic response to: (i) changes in due dates; and (ii) the bulk arrival of parts is presented. The ability of the system to exponentially reduce the mean and variance of due-date deviation in the single machine case makes it an attractive option for real-time control of just-in-time production.     

A client-server architecture for distributed measurement systems

This paper describes a client-server architecture for the remote control of instrumentation over the Internet network. The proposed solution allows multiuser, multi-instrument sessions by means of a queueing and instrument locking capability. Client applications can be easily developed by using conventional high-level programming languages or well-assessed virtual instrumentation frameworks. Performance tests are reported; they show the low overhead due to network operation with respect to the direct control of instrumentation     

A statistical approach to real-time quality control

Modern manufacturing processes characterized by short series, complex part geometry and high refinement values often demonstrate conditions when traditional quality control (QC) methods do not work properly. This paper presents a prototype system for real-time QC where the developed methods and applications are integrated and post-process quality control is applied only as a complement and for reference measurements. All activities are supervised and fed with information from a developed active data acquisition system. The proposed concept contributes to bridging the gap between traditional post-process control and realtime QC of machining processes.