The application of H controller synthesis to high speed independent drive systems

This thesis describes work completed on the application of H controller synthesis to the design of controllers for single axis high speed independent drive design examples. H controller synthesis was used in a single controller format and in a self-tuning regulator, a type of adaptive controller. Three types of industrial design examples were attempted using H controller synthesis, both in simulation and on a Drives Test Facility at Aston University. The results were benchmarked against a Proportional, Integral and Derivative (PID) with velocity feedforward controller (VFF), the industrial standard for this application. An analysis of the differences between a H and PID with VFF controller was completed. A direct-form H controller was determined for a limited class of weighting function and plants which shows the relationship between the weighting function, nominal plant and the controller parameters. The direct-form controller was utilised in two ways. Firstly it allowed the production of simple guidelines for the industrial design of H controllers. Secondly it was used as the controller modifier in a self-tuning regulator (STR). The STR had a controller modification time (including nominal model parameter estimation) of 8ms. A Set-Point Gain Scheduling (SPGS) controller was developed and applied to an industrial design example. The applicability of each control strategy, PID with VFF, H, SPGS and STR, was investigated and a set of general guidelines for their use was determined. All controllers developed were implemented using standard industrial equipment.

Pragmatic approach to the development of robust real-time protocols

This research is concerned with the development of distributed real-time systems, in which software is used for the control of concurrent physical processes. These distributed control systems are required to periodically coordinate the operation of several autonomous physical processes, with the property of an atomic action. The implementation of this coordination must be fault-tolerant if the integrity of the system is to be maintained in the presence of processor or communication failures. Commit protocols have been widely used to provide this type of atomicity and ensure consistency in distributed computer systems. The objective of this research is the development of a class of robust commit protocols, applicable to the coordination of distributed real-time control systems. Extended forms of the standard two phase commit protocol, that provides fault-tolerant and real-time behaviour, were developed. Petri nets are used for the design of the distributed controllers, and to embed the commit protocol models within these controller designs. This composition of controller and protocol model allows the analysis of the complete system in a unified manner. A common problem for Petri net based techniques is that of state space explosion, a modular approach to both the design and analysis would help cope with this problem. Although extensions to Petri nets that allow module construction exist, generally the modularisation is restricted to the specification, and analysis must be performed on the (flat) detailed net. The Petri net designs for the type of distributed systems considered in this research are both large and complex. The top down, bottom up and hybrid synthesis techniques that are used to model large systems in Petri nets are considered. A hybrid approach to Petri net design for a restricted class of communicating processes is developed. Designs produced using this hybrid approach are modular and allow re-use of verified modules. In order to use this form of modular analysis, it is necessary to project an equivalent but reduced behaviour on the modules used. These projections conceal events local to modules that are not essential for the purpose of analysis. To generate the external behaviour, each firing sequence of the subnet is replaced by an atomic transition internal to the module, and the firing of these transitions transforms the input and output markings of the module. Thus local events are concealed through the projection of the external behaviour of modules. This hybrid design approach preserves properties of interest, such as boundedness and liveness, while the systematic concealment of local events allows the management of state space. The approach presented in this research is particularly suited to distributed systems, as the underlying communication model is used as the basis for the interconnection of modules in the design procedure. This hybrid approach is applied to Petri net based design and analysis of distributed controllers for two industrial applications that incorporate the robust, real-time commit protocols developed. Temporal Petri nets, which combine Petri nets and temporal logic, are used to capture and verify causal and temporal aspects of the designs in a unified manner.

Computerised control of cellular manufacturing systems

This thesis reviews the existing manufacturing control techniques and identifies their practical drawbacks when applied in a high variety, low and medium volume environment. It advocates that the significant drawbacks inherent in such systems, could impair their applications under such manufacturing environment. The key weaknesses identified in the system were: capacity insensitive nature of Material Requirements Planning (MRP); the centralised approach to planning and control applied in Manufacturing Resources Planning (MRP IT); the fact that Kanban can only be used in repetitive environments; Optimised Productivity Techniques's (OPT) inability to deal with transient bottlenecks, etc. On the other hand, cellular systems offer advantages in simplifying the control problems of manufacturing and the thesis reviews systems designed for cellular manufacturing including Distributed Manufacturing Resources Planning (DMRP) and Flexible Manufacturing System (FMS) controllers. It advocates that a newly developed cellular manufacturing control methodology, which is fully automatic, capacity sensitive and responsive, has the potential to resolve the core manufacturing control problems discussed above. It's development is envisaged within the framework of a DMRP environment, in which each cell is provided with its own MRP II system and decision making capability. It is a cellular based closed loop control system, which revolves on single level Bill-Of-Materials (BOM) structure and hence provides better linkage between shop level scheduling activities and relevant entries in the MPS. This provides a better prospect of undertaking rapid response to changes in the status of manufacturing resources and incoming enquiries. Moreover, it also permits automatic evaluation of capacity and due date constraints and hence facilitates the automation of MPS within such system. A prototype cellular manufacturing control model, was developed to demonstrate the underlying principles and operational logic of the cellular manufacturing control methodology, based on the above concept. This was shown to offer significant advantages from the prospective of operational planning and control. Results of relevant tests proved that the model is capable of producing reasonable due date and undertake automation of MPS. The overall performance of the model proved satisfactory and acceptable.

The development and diffusion of industrial robots

This thesis describes the history of robots and explains the reasons for the international differences in robot diffusion, and the differences in the diffusion of various robot applications with reference to the UK. As opposed to most of the literature, diffusion is examined with an integrated and interdisciplinary perspective. Robot technology evolves from the interaction of development, supply and manufacture, adoption, and promotion. activities. Emphasis is given to the analysis of adoption, at present the most important limiting factor of robot advancement in the UK. Technical development is inferred from a comparison of surveys on equipment, and from the topics of ten years of symposia papers. This classification of papers is also used to highlight the international and institutional differences in robot development. Analysis of the growth in robot supply, manufacture, and use is made from statistics compiled. A series of interviews with users and potential users serves to illustrate the factors and implications of the adoption of different robot systems in the UK. Adoption pioneering takes place when several conditions exist: when the technology is compatible with the firm, when its advantages outweigh its disadvantages, and particularly when a climate exists which encourages the managerial involvement and the labour acceptance. The degree of compatibility (technical, methodological, organisational, and economic) and the consequences (profitability, labour impacts, and managerial effects) of different robot systems (transfer, manipulative, processing, and assembly) are determined by various aspects of manufacturing operations (complexity, automation, integration, labour tasks, and working conditions). The climate for adoption pioneering is basically determined by the performance of firms. The firms' policies on capital investment have as decisive a role in determining the profitability of robots as their total labour costs. The performance of the motor car industry and its machine builders explains, more than any other factor, the present state of robot advancement in the UK.

The control of technological change in the motor industry:a case study

This thesis is based upon a case study of the introduction of automated production technologies at the Longbridge plant of British Leyland in the period 1978 to 1980.The investment in automation was part of an overall programme of modernization to manufacture the new 'Mini Metro' model. In the first Section of the thesis, the different theoretical perspectives on technological change are discussed. Particular emphasis is placed upon the social role of management as the primary controllers of technological change. Their actions are seen to be oriented towards the overall strategy of the firm, integrating the firm's competitive strategy with production methods and techniques.This analysis is grounded in an examination of British Leyland's strategies during the 1970s.. The greater part of the thesis deals with the efforts made by management to secure their strategic objectives in the process of technological change against the conflicting claims of their work-force. Examination of these efforts is linked to the development of industrial relations conflict at Longbridge and in British Leyland as a whole.Emphasis is placed upon the struggle between management in pursuit of their version of efficiency and the trade unions in defence of job controls and demarcations. The thesis concludes that the process of technological change in the motor industry is controlled by social forces,with the introduction of new technologies being closely intertwined with management!s political relations with the trade unions.

Technical innovation in industrial production

New techniques in manufacturing, popularly referred to as mechanization and automation, have been a preoccupation of social and economic theorists since the industrial revolution. A selection of relevant literature is reviewed, including the neoclassical economic treatment of technical change. This incorporates alterations to the mathematical production function and an associated increase in the efficiency with which the factors of production are converted into output. Other work emphasises the role of research and development and the process of diffusion, whereby new production techniques are propagated throughout industry. Some sociological writings attach importance to the type of production technology and its effect on the organisational structure and social relations within the factory. Nine detailed case studies are undertaken of examples of industrial innovation in the rubber, automobile, vehicle components, confectionery and clothing industries. The old and new techniques are compared for a range of variables, including capital equipment, labour employed, raw materials used, space requirements and energy consumption, which in most cases exhibit significant change with the innovation. The rate of output, labour productivity, product quality, maintenance requirements and other aspects are also examined. The process by which the change in production method was achieved is documented, including the development of new equipment and the strategy of its introduction into the factory, where appropriate. The firm, its environment, and the attitude of different sectors of the workforce are all seen to play a part in determining the motives for and consequences which flow from the innovations. The traditional association of technical progress with its labour-saving aspect, though an accurate enough description of the cases investigated, is clearly seen to afford an inadequate perspective for the proper understanding of this complex phenomenon, which also induces change in a wide range of other social, economic and technical variables.

Automation, rationalisation and concentration : a case study in the British chemical industry

This thesis is based upon a case study of the adoption of digital, electronic, microprocessor-based control systems by Albright & Wilson Limited - a UK chemical producer. It offers an explanation of the company's changing technology policy between 1978 and 1981, by examining its past development, internal features and industrial environment. Part One of the thesis gives an industry-level analysis which relates the development of process control technology to changes in the economic requirements of production . The rapid diffusion of microcomputers and other microelectronic equipment in the chemical industry is found to be a response to general need to raise the efficiency of all processes, imposed by the economic recession following 1973. Part Two examines the impaot of these technical and eoonomic ohanges upon Albright & Wilson Limited. The company's slowness in adopting new control technology is explained by its long history in which trends are identified whlich produced theconservatism of the 1970s. By contrast, a study of Tenneco Incorporated, a much more successful adoptor of automating technology, is offered with an analysis of the new technology policy of adoption of such equipment which it imposed upon Albright & Wilson, following the latter's takeover by Tenneco in 1978. Some indications of the consequences by this new policy of widespread adoptions of microprocessor-based control equipment are derived from a study of the first Albright & Wilson plant to use such equipment. The thesis concludes that companies which fail to adopt rapidly the new control technology may not survive in the recessionary environment, the long- established British companies may lack the flexibility to make such necessary changes and that multi-national companies may have an important role jn the planned transfer and adoption of new production technology through their subsidiaries in the UK.

Evaluating the impact of institutional logic on the corporate Internet reporting by Egyptian listed companies

This study explores the institutional logic(s) governing the Corporate Internet Reporting (CIR) by Egyptian listed companies. In doing so, a mixed methods approach was followed. The qualitative part seeks to understand the perceptions, believes, values, norms, that are commonly shared by Egyptian companies which engaged in these practices. Consequently, seven cases of large listed Egyptian companies operating in different industries have been examined. Other stakeholders and stockholders have been interviewed in conjunction with these cases. The quantitative part consists of two studies. The first one is descriptive aiming to specify whether the induced logic(s) from the seven cases are commonly embraced by other Egyptian companies. The second study is explanatory aiming to investigate the impact of several institutional and economic factors on the extent of CIR, types of the online information, quality of the websites as well as the Internet facilities. Drawing on prior CIR literature, four potential types of logics could be inferred: efficiency, legitimacy, technical and marketing based logics. In Egypt, legitimacy logic was initially embraced in the earlier years after the Internet inception. latter, companies confronted radical challenges in their internal and external environments which impelled them to raise their websites potentialities to defend their competitive position; either domestically or internationally. Thus, two new logics emphasizing marketing and technical perspectives have emerged, in response. Strikingly, efficiency based logic is not the most prevalent logic driving CIR practices in Egypt as in the developed countries. The empirical results support this observation and show that almost half of Egyptian listed companies 115 as on December 2010 possessed an active website, half of them 62 disclosed part of their financial and accounting information, during December 2010 to February 2011. Less than half of the websites 52 offered latest annual financial statements. Fewer 33(29%) websites provided shareholders and stock information or included a separate section for corporate governance 25 (22%) compared to 50 (44%) possessing a section for news or press releases. Additionally, the variations in CIR practices, as well as timeliness and credibility were also evident even at industrial level. After controlling for firm size, profitability, leverage, liquidity, competition and growth, it was realized that industrial companies and those facing little competition tend to disclose less. In contrast, management size, foreign investors, foreign listing, dispersion of shareholders and firm size provided significant and positive impact individually or collectively. In contrast, neither audit firm, nor most of performance indicators (i.e. profitability, leverage, and liquidity) did exert an influence on the CIR practices. Thus, it is suggested that CIR practices are loosely institutionalised in Egypt, which necessitates issuing several regulative and processional rules to raise the quality attributes of Egyptian websites, especially, timeliness and credibility. Beside, this study highlights the potency of assessing the impact of institutional logic on CIR practices and suggests paying equal attention to the institutional and economic factors when comparing the CIR practices over time or across different institutional environments in the future.

Legitimacy building strategies in conditions of discretionary legal enforcement:a logic of social action approach

The present study explores strategies used to legitimize the transfer of organizational practices in a situation of institutional upheaval. We apply the logic of social action (Risse, 2000) to analyze the effectiveness of consequence-based action and communication-based action, in terms of higher coordination, lower conflict, and overall higher economic performance. Consequence-based legitimation is obtained by using a system of distributor incentives tied to performance of specific tasks, while communicative legitimation can be achieved by recommendations and warnings. Our setting is an export channel to European emerging economies. Our results indicate that in the absence of legitimacy, as manifested in discretionary legal enforcement, consequence-based legitimation is more effective than communicative legitimation in reducing conflict, increasing coordination, and ultimately in improving the performance of the export dyad. © 2014 Elsevier Inc.

Frontline employees' collaboration in industrial service innovation:routes of co-creation's effects on new service performance

From a Service-Dominant Logic (S-DL) perspective, employees constitute operant resources that firms can draw to enhance the outcomes of innovation efforts. While research acknowledges that frontline employees (FLEs) constitute, through service encounters, a key interface for the transfer of valuable external knowledge into the firm, the range of potential benefits derived from FLE-driven innovation deserves more investigation. Using a sample of knowledge intensive business services firms (KIBS), this study examines how the collaboration with FLEs along the new service development (NSD) process, namely FLE co-creation, impacts on service innovation performance following two routes of different effects. Partial least squares structural equation modeling (PLS-SEM) results indicate that FLE co-creation benefits the NS success among FLEs and firm’s customers, the constituents of the resources route. FLE co-creation also has a positive effect on the NSD speed, which in turn enhances the NS quality. NSD speed and NS quality integrate the operational route, which proves to be the most effective path to impact the NS market performance. Accordingly, KIBS managers must value their FLEs as essential partners to achieve successful innovation from an internal and external perspective, and develop the appropriate mechanisms to guarantee their effective involvement along the NSD process.

Towards probabilistic synchronization of local controllers

The traditional use of global and centralised control methods, fails for large, complex, noisy and highly connected systems, which typify many real world industrial and commercial systems. This paper provides an efficient bottom up design of distributed control in which many simple components communicate and cooperate to achieve a joint system goal. Each component acts individually so as to maximise personal utility whilst obtaining probabilistic information on the global system merely through local message-passing. This leads to an implied scalable and collective control strategy for complex dynamical systems, without the problems of global centralised control. Robustness is addressed by employing a fully probabilistic design, which can cope with inherent uncertainties, can be implemented adaptively and opens a systematic rich way to information sharing. This paper opens the foreseen direction and inspects the proposed design on a linearised version of coupled map lattice with spatiotemporal chaos. A version close to linear quadratic design gives an initial insight into possible behaviours of such networks.