637,033 research outputs found

    Building Blocks for Control System Software

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    Software implementation of control laws for industrial systems seem straightforward, but is not. The computer code stemming from the control laws is mostly not more than 10 to 30% of the total. A building-block approach for embedded control system development is advocated to enable a fast and efficient software design process.\ud We have developed the CTJ library, Communicating Threads for Java¿,\ud resulting in fundamental elements for creating building blocks to implement communication using channels. Due to the simulate-ability, our building block method is suitable for a concurrent engineering design approach. Furthermore, via a stepwise refinement process, using verification by simulation, the implementation trajectory can be done efficiently

    The Averaging Method Applied to the Investigation of Substantial Time Varying Systems of a Higher Order

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    This paper presents an analytical method to solving a system of differential equations describing a substantial time-varying feedback automatic control system. The method provides good results for systems whose characteristic equations have dominant complex conjugated roots. As an example, a five-order system was investigated. The results of the computer simulation proved the validity of applying this method to the above mentioned class of systems

    Formal Analysis of Linear Control Systems using Theorem Proving

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    Control systems are an integral part of almost every engineering and physical system and thus their accurate analysis is of utmost importance. Traditionally, control systems are analyzed using paper-and-pencil proof and computer simulation methods, however, both of these methods cannot provide accurate analysis due to their inherent limitations. Model checking has been widely used to analyze control systems but the continuous nature of their environment and physical components cannot be truly captured by a state-transition system in this technique. To overcome these limitations, we propose to use higher-order-logic theorem proving for analyzing linear control systems based on a formalized theory of the Laplace transform method. For this purpose, we have formalized the foundations of linear control system analysis in higher-order logic so that a linear control system can be readily modeled and analyzed. The paper presents a new formalization of the Laplace transform and the formal verification of its properties that are frequently used in the transfer function based analysis to judge the frequency response, gain margin and phase margin, and stability of a linear control system. We also formalize the active realizations of various controllers, like Proportional-Integral-Derivative (PID), Proportional-Integral (PI), Proportional-Derivative (PD), and various active and passive compensators, like lead, lag and lag-lead. For illustration, we present a formal analysis of an unmanned free-swimming submersible vehicle using the HOL Light theorem prover.Comment: International Conference on Formal Engineering Method

    Broadening the interface bandwidth in simulation based training

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    Currently most computer based simulations rely exclusively on computer generated graphics to create the simulation. When training is involved, the method almost exclusively used to display information to the learner is text displayed on the cathode ray tube. MICROEXPERT Systems is concentrating on broadening the communications bandwidth between the computer and user by employing a novel approach to video image storage combined with sound and voice output. An expert system is used to combine and control the presentation of analog video, sound, and voice output with computer based graphics and text. Researchers are currently involved in the development of several graphics based user interfaces for NASA, the U.S. Army, and the U.S. Navy. Here, the focus is on the human factors considerations, software modules, and hardware components being used to develop these interfaces

    Feedback methods for inverse simulation of dynamic models for engineering systems applications

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    Inverse simulation is a form of inverse modelling in which computer simulation methods are used to find the time histories of input variables that, for a given model, match a set of required output responses. Conventional inverse simulation methods for dynamic models are computationally intensive and can present difficulties for high-speed applications. This paper includes a review of established methods of inverse simulation,giving some emphasis to iterative techniques that were first developed for aeronautical applications. It goes on to discuss the application of a different approach which is based on feedback principles. This feedback method is suitable for a wide range of linear and nonlinear dynamic models and involves two distinct stages. The first stage involves design of a feedback loop around the given simulation model and, in the second stage, that closed-loop system is used for inversion of the model. Issues of robustness within closed-loop systems used in inverse simulation are not significant as there are no plant uncertainties or external disturbances. Thus the process is simpler than that required for the development of a control system of equivalent complexity. Engineering applications of this feedback approach to inverse simulation are described through case studies that put particular emphasis on nonlinear and multi-input multi-output models

    Conceptual design for controller software of mechatronic systems

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    The method and software tool presented here, aims at supporting the development of control software for mechatronic systems. Heterogeneous distributed embedded processors are considered as target hardware. Principles of the method are that the implementation process is a stepwise refinement from control laws to efficient computer code and that all phases are verified by simulation. Simulation is also used as verification tool during physical-system modelling and control law development. Data flow diagrams are used as description language for controller implementations, whereas the physical-system models are expressed in bond graphs. Future work comprises the building of the complete tool, although individual parts are ready

    Simulation of spacecraft attitude dynamics using TREETOPS and model-specific computer Codes

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    The simulation of spacecraft attitude dynamics and control using the generic, multi-body code called TREETOPS and other codes written especially to simulate particular systems is discussed. Differences in the methods used to derive equations of motion--Kane's method for TREETOPS and the Lagrangian and Newton-Euler methods, respectively, for the other two codes--are considered. Simulation results from the TREETOPS code are compared with those from the other two codes for two example systems. One system is a chain of rigid bodies; the other consists of two rigid bodies attached to a flexible base body. Since the computer codes were developed independently, consistent results serve as a verification of the correctness of all the programs. Differences in the results are discussed. Results for the two-rigid-body, one-flexible-body system are useful also as information on multi-body, flexible, pointing payload dynamics

    Computer simulation of scraper-pusher behavior during early open pit mining operations

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    A method has been developed for study and evaluation of overburden removal systems in open pit mining. The computer simulation method shows the effect of vehicle and course characteristics and the control of loading time on overall production and cost per unit of overburden removed. Data are available from vehicle manufacturers and from past mining experience. The data are punched onto processing cards and the system is then simulated and analyzed using a digital computer. The products of the system simulation consist of a tabulated listing of all control variables after each simulated vehicle loading and a system summary predicting shift production, cost per ton, vehicle delay times, and average queue lengths at the load and dump facilities. Mine management can use the results of the system simulation as a tool to help determine optimum fleet size and type for maximum production and minimum cost --Abstract, page i

    Компьютерное моделирование в исследованиях и разработке измерительных информационных систем

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    A method of computer aided structural, mixed structural/schematic and schematic simulation for measuring systems with predictable properties design is presented. Here we demonstrate the proposed technique application on extremal automatic control system simulation. The application itself includes synthesis of the structures set up - a model of the object with a single maximum value of static characteristics and the actual controller with a synchronous detector which determines the gradient of the controlled variable to a control signal. Also we report obtained results of computational experiments and present the gradual transition from the structural to a mixed model
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