Parallel processing is often employed in real-time control systems to reduce execution times. The paper, however, investigates the potential of parallel processing, and one device, in particular, the Inmos transputer,...
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Parallel processing is often employed in real-time control systems to reduce execution times. The paper, however, investigates the potential of parallel processing, and one device, in particular, the Inmos transputer, in the design of a fault-tolerant high-integrity computer module for gas-turbine engine control. Introducing multiple processors into a control system has the potential to render that system less reliable in an operational sense, than a conventional single processor implementation. However, attention to system design can, in fact, exploit parallel-processing capability to result in improved reliability. While three-lane voting systems are commonly favoured in avionics systems, owing to hardware implementation constraints, gas-turbine engine controllers are generally realised as two-lane systems. Transputer system configurations are devised in an attempt to overcome this constraint. In particular, an ‘overlapping triad’ topology is investigated in detail, and both strength and weaknesses of the present transputer architecture are revealed.
Voltage sag and short interruption lead to the tripping of sensitive equipment and cause the economic loss of the industry users. A programmable logic controller (PLC) is essential equipment used in the industrial pro...
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Voltage sag and short interruption lead to the tripping of sensitive equipment and cause the economic loss of the industry users. A programmable logic controller (PLC) is essential equipment used in the industrial process. However, there is no detailed understanding of the sensitivity of PLC under voltage sag and short interruption. The response characteristic of PLC under voltage sag is studied. This study proposes a new testing method, called the dichotomy test method (DTM) to do the test. This study builds the testing platform and tests the sensitivity of six PLCs from five famous PLC manufacturers. The testing considers the characteristics of voltage sag, including magnitude, duration, point-on-wave, phase-angle-jump, different supply voltage, slow recovery voltage sag, multiple voltage sags and so on. The tests prove that DTM has the advantage of accuracy, robustness and workload, compared with the traditional test method. The quantitative and qualitative response characteristics of PLC under voltage sag are obtained.
In the work presented here, we study a cooperative control problem for a network of uninhabited air vehicles (UAVs) where it is assumed that after deployment a set of tasks is given to a group of UAVs and the UAVs mus...
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In the work presented here, we study a cooperative control problem for a network of uninhabited air vehicles (UAVs) where it is assumed that after deployment a set of tasks is given to a group of UAVs and the UAVs must cooperate to decide which UAV should process each task. The cooperation must occur during real-time operation due to a need to repeatedly process each task, in spite of imperfect communications (e.g., messages with random but bounded delays), and the possibility that tasks "pop-up." We show how to view this as a cooperative scheduling problem, and how to derive bounds on mission-level performance metrics. Simulations are used to compare the approach with a noncooperative strategy and to provide design guidelines for the cooperative scheduler.
The compatibility of AC propulsion systems with coded train detection and on-board speed code reception systems is always a concern. A review of an automatic train control system commissioned for Greater Cairo Metro S...
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The compatibility of AC propulsion systems with coded train detection and on-board speed code reception systems is always a concern. A review of an automatic train control system commissioned for Greater Cairo Metro System is presented. The compatibility of track-to-train transmission with the inverter-controlled AC drive and the 750 V DC third-rail power supply is also examined.
An implementation of vector control for induction motors is presented, where there is no need for information concerning the rotor flux position and matrix transformations. It shows how the stator reference phase curr...
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An implementation of vector control for induction motors is presented, where there is no need for information concerning the rotor flux position and matrix transformations. It shows how the stator reference phase currents can be generated and changed in real time from digitally stored sinewaves, so to achieve independent control of torque at constant rotor flux. Experimental evaluation of the new scheme is made for sudden changes in the load torque and for the step changes of the speed reference signal. The arrangement of a DC load system enabling sudden changes in load torque is also described.
Tailoring cloud support for each autonomous-driving application would require maintaining multiple infrastructures, potentially resulting in low resource utilization, low performance, and high management overhead. To ...
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Tailoring cloud support for each autonomous-driving application would require maintaining multiple infrastructures, potentially resulting in low resource utilization, low performance, and high management overhead. To address this problem, the authors present a unified cloud infrastructure with Spark for distributed computing, Alluxio for distributed storage, and OpenCL to exploit heterogeneous computing resources for enhanced performance and energy efficiency.
Cape Town City Council is responsible for the supply of electricity to the city area. To achieve this, the council owns and operates thermal and pumped-storage power stations and extensive HV transmission and LV distr...
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Cape Town City Council is responsible for the supply of electricity to the city area. To achieve this, the council owns and operates thermal and pumped-storage power stations and extensive HV transmission and LV distribution networks. Power is also purchased from the national supply authority. Prior to the introduction of the control system described in this paper limited supervisory control and data acquisition facilities existed to provide some degree of remote control for the network. In addition to duties associated with supervision of both the HV and LV networks, the control centre operators were also responsible for energy management involving generator scheduling and control, and load-shedding when required. To assist the operators in their extensive and onereous duties a new computer-based control centre has been developed and was commissioned in 1984. Because of the unusual mix of power sources special software had to be developed for energy management purposes. Descriptions are given of the functional and practical aspects of the control centre, and of associated hardware and software facilities and also some commissioning experiences.
Self tuning is an important new branch of control which is attracting increasing theoretical and practical interest. The objective of self tuning is to control systems with unknown constant or slowly varying parameter...
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Self tuning is an important new branch of control which is attracting increasing theoretical and practical interest. The objective of self tuning is to control systems with unknown constant or slowly varying parameters, so theoretical interest is concerned with the stability, performance and convergence of the recursive algorithms involved, while practical interest derives from its potential as a simple controller commissioning tool, both as a method for controlling time-varying or nonlinear plant over a range of operating points, and for dealing with batch problems where the plant or materials vary over successive batches. This paper summarises and expands previous work on the design of self-tuning controllers. It discusses the closed-loop properties of various classes of self tuner, convergence concepts and results, and some of the technical problems involved with implementing self tuners on small computers or microprocessors.
Photovoltaic (PV) emulator (PVE) is a non-linear power supply that produces a similar output to that of the PV module. It requires a closed-loop controller such as the proportional-integral (PI) and fuzzy logic contro...
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Photovoltaic (PV) emulator (PVE) is a non-linear power supply that produces a similar output to that of the PV module. It requires a closed-loop controller such as the proportional-integral (PI) and fuzzy logic controllers to operate properly. The PI controller has a low-computational burden and is not robust since the transient response varies under different load conditions. Although the fuzzy logic controller is robust, it requires high-computation capability. This study proposed an alternative approach called the shift controller for the PVE to easily compute and maintain a fast transient response under various load conditions. The performance of the proposed shift controller for the PVE is compared with the performance of the PVEs using the PI and fuzzy logic controllers, respectively. The controllers are simulated using MATLAB/Simulink and implemented using dSPACE ds1104 for experimental validation. The results show that the proposed shift controller computes up to 18 times faster than the fuzzy logic controller. The proposed controller also responds faster to load change than the PI controller.
This article presents an attack-resilient architecture for cyber-physical systems (CPSs). As a case study, the authors build a radio-based train control testbed and validate the proposed resilient design architecture....
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This article presents an attack-resilient architecture for cyber-physical systems (CPSs). As a case study, the authors build a radio-based train control testbed and validate the proposed resilient design architecture. The target CPS application is a hierarchical control system.
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