9,561 research outputs found

    CSP channels for CAN-bus connected embedded control systems

    Get PDF
    Closed loop control system typically contains multitude of sensors and actuators operated simultaneously. So they are parallel and distributed in its essence. But when mapping this parallelism to software, lot of obstacles concerning multithreading communication and synchronization issues arise. To overcome this problem, the CT kernel/library based on CSP algebra has been developed. This project (TES.5410) is about developing communication extension to the CT library to make it applicable in distributed systems. Since the library is tailored for control systems, properties and requirements of control systems are taken into special consideration. Applicability of existing middleware solutions is examined. A comparison of applicable fieldbus protocols is done in order to determine most suitable ones and CAN fieldbus is chosen to be first fieldbus used. Brief overview of CSP and existing CSP based libraries is given. Middleware architecture is proposed along with few novel ideas

    Working Notes from the 1992 AAAI Spring Symposium on Practical Approaches to Scheduling and Planning

    Get PDF
    The symposium presented issues involved in the development of scheduling systems that can deal with resource and time limitations. To qualify, a system must be implemented and tested to some degree on non-trivial problems (ideally, on real-world problems). However, a system need not be fully deployed to qualify. Systems that schedule actions in terms of metric time constraints typically represent and reason about an external numeric clock or calendar and can be contrasted with those systems that represent time purely symbolically. The following topics are discussed: integrating planning and scheduling; integrating symbolic goals and numerical utilities; managing uncertainty; incremental rescheduling; managing limited computation time; anytime scheduling and planning algorithms, systems; dependency analysis and schedule reuse; management of schedule and plan execution; and incorporation of discrete event techniques

    The construction of oracles for software testing

    Get PDF
    Software testing is important throughout the software life cycle. Testing is the part of the software development process where a computer program is subject to specific conditions to show that the problem meets its intended design. Building a testing oracle is one part of software testing. An oracle is an external mechanism which can be used to check test output for correctness. The characteristics of available oracles have a dominating influence on the cost and quality of software testing. In this thesis, methods of constructing oracles are investigated and classified. There are three kinds of method of constructing oracles: the pseudo-oracle approach, oracles using attributed grammars and oracles based on formal specification. This thesis develops a method for constructing an oracle, based on the Z specification language. A specification language can describe the correct syntax and semantics of software. The contextual part of a specification describes all the legal input to the program and the semantics part describes the meaning of the given input data. Based on this idea, an oracle is constructed and a prototype is implemented according to the method proposed in the thesis

    Aggregate assembly process planning for concurrent engineering

    Get PDF
    In today's consumer and economic climate, manufacturers are finding it increasingly difficult to produce finished products with increased functionality whilst fulfilling the aesthetic requirements of the consumer. To remain competitive, manufacturers must always look for ways to meet the faster, better, and cheaper mantra of today's economy. The ability for any industry to mirror the ideal world, where the design, manufacturing, and assembly process of a product would be perfected before it is put mto production, will undoubtedly save a great deal of time and money. This thesis introduces the concept of aggregate assembly process planning for the conceptual stages of design, with the aim of providing the methodology behind such an environment. The methodology is based on an aggregate product model and a connectivity model. Together, they encompass all the requirements needed to fully describe a product in terms of its assembly processes, providing a suitable means for generating assembly sequences. Two general-purpose heuristics methods namely, simulated annealing and genetic algorithms are used for the optimisation of assembly sequences generated, and the loading of the optimal assembly sequences on to workstations, generating an optimal assembly process plan for any given product. The main novelty of this work is in the mapping of the optimisation methods to the issue of assembly sequence generation and line balancing. This includes the formulation of the objective functions for optimismg assembly sequences and resource loading. Also novel to this work is the derivation of standard part assembly methodologies, used to establish and estimate functional tunes for standard assembly operations. The method is demonstrated using CAPABLEAssembly; a suite of interlinked modules that generates a pool of optimised assembly process plans using the concepts above. A total of nine industrial products have been modelled, four of which are the conceptual product models. The process plans generated to date have been tested on industrial assembly lines and in some cases yield an increase in the production rate

    Supervisory machine control by predictive-reactive scheduling

    Get PDF

    MathSpad : a system for on-line preparation of mathematical documents

    Get PDF
    • …
    corecore