Haydn A. Thompson

PID control for a distributed system with a smart actuator

Abstract The emergence of distributed architectures based on smart components and fieldbus networks is promoting changes in proportional-integral-derivative (PID) controller design issues. This paper explores how PID control can benefit from smart actuator and fieldbus technologies. Firstly, this paper discusses a smart actuator scheme to improve the efficiency of PID controller retuning, as well as an implementation using a low-cost stepper-motor. Then, the smart actuator is applied to on-line adaptation of PID parameters using a standard pole-placement design method. Finally, experimental validation of the proposed approach is conducted using a controller area network (CAN) bus-based distributed architecture demonstrator.

A CANbus-based safety-critical distributed aeroengine control systems architecture demonstrator

Abstract Recent advances in microelectronics coupled with ever decreasing costs mean that it is now possible to produce very compact and cheap intelligent modules. For instance, it is now quite common for cars to use a number of intelligent units with intercommunication to implement complex functions such as traction control. There has also been a move towards embedding processing in sensors and actuators directly with application to the process control, automotive and aerospace sectors. When considering aerospace applications there are major benefits to be gained by adopting a distributed controller. However, this has to be carried out within the strict design constraints for safety-critical systems. This paper discusses design tools and a distributed system demonstrator that has been developed to explore future distributed control systems.

Simulation of a Soar-Based Autonomous Mission Management System for Unmanned Aircraft

State-of-the-art unmanned aerial vehicles are typically able to autonomously execute a preplanned mission. However, unmanned aerial vehicles usually fly in a very dynamic environment that requires dynamic changes to the flight plan; this mission management activity is usually tasked to human supervision. Through the use of a set of theoretical concepts that allow the description of a flight plan, a software system that autonomously accomplishes the mission management task for an unmanned aerial vehicle was developed. The system was implemented using a combination of Soar intelligent agents and traditional control techniques, and it is thoroughly described in the first part of the paper. An extensive testing campaign, based on the use of a realistic simulation environment, was performed on the system; the second part of this paper presents results obtained during this campaign. The system was demonstrated to be capable of automatically generating and executing an entire flight plan after being assigned a set of objectives. In conclusion, possible future developments are discussed, focusing in particular on prospective hardware implementation for the system.

Distributed aero-engine control systems architecture selection using multi-objective optimisation

Abstract The cost of embedding intelligence into sensors and actuators directly has dramatically reduced over the past 10 years. This has led to the recent explosion of smart sensors and actuators available from manufacturers. Initially, these have been developed for the process control industries but increasingly applications in aerospace are being found. Integration of intelligent components is being carried out in an ad hoc manner by incorporating smart elements in inherently centralised architectures. This paper discusses the application of a multidisciplinary, multiobjective optimisation approach to a military gas turbine engine control system architecture design, where implementation benefits and penalties must be systematically evaluated.

Decision Support System on the Grid

Aero-engines are extremely reliable machines and operational failures are rare. However, currently great effort is being put into reducing the number of in-flight engine shutdowns, aborted take-offs and flight delays through the use of advanced engine health monitoring technology. This represents a benefit to society through reduced delays, reduced anxiety and reduced cost of ownership of aircraft. This is reflected in a change of emphasis within aero-engine companies where, instead of selling engines to customers, there is a fundamental shift to adoption of power-by-the-hour contracts. In these contracts, airlines make fixed regular payments based on the hours flown and the engine manufacturer retains responsibility for maintaining the engine. To support this new approach, improvements in in-flight monitoring of engines are being introduced with the collection of much more detailed data on the operation of the engine. At the same time advances have been made in Internet technologies providing a worldwide network of computers that can be used to access and process that data. The explosion of available knowledge within those large datasets also presents its own problems and here it is necessary to work on advanced decision support systems to identify the useful information in the data and provide knowledge-based advice between individual aircraft, airline repair and overhaul bases, world-wide data warehouses and the engine manufacturer. This paper presents a practical framework in which to build such a system that is inherent in the emerging Grid computing paradigm that provides the necessary computing resources. A demonstrator system already developed and implemented in the UK E-Science Grid project, DAME, is introduced.

PID Control for a Distributed System with a Smart Actuator

Abstract Recent advances in smart actuator and fieldbus technologies are promoting changes in PID controller design issues. By employing a built-in microprocessor a smart actuator, in general, is capable of self-validation and compensation. In this paper, online retuning of PID controller for a distributed system that contains a smart actuator is explored. The on-line controller retuning is carried out using a set of validation data generated by a smart actuator. The proposed approach is investigated by means of a distributed architecture demonstrator which consists of a set of PCs and a stepper-motor based smart actuator interconnected through fieldbus network.

Transputer-based fault tolerance in safety-critical systems

Abstract This paper discusses the implementation of fault tolerance in parallel processing systems for real-time safety-critical control. The vehicle for this work is the Inmos transputer, a 32-bit processor specifically designed for parallel processing applications. Methods of exploiting the inherent redundancy while at the same time utilizing the parallel processing power are described and the advantages and disadvantages of the Occam language and current transputer hardware are highlighted. Although this paper describes the application of gas turbine engine control the ideas can also be applied to other safety-critical systems.

Service‐oriented architecture on the Grid for integrated fault diagnostics

For industrial fault diagnostics, many model‐based fault diagnosis approaches have been proposed so far and some of them have been put into practice. However, for modern complex processes, owing to the variable nature of faults and model uncertainty, no single method can diagnose all faults and meet different contradictory criteria. In this paper, the importance of integration of different fault detection and isolation schemes in a generic problem‐solving environment is emphasized. A service‐oriented architecture for the integration is proposed, based on Grid technologies. As an engineering implementation, a decision support system for the gas turbine engine fault diagnosis is presented and some deployed services are discussed. Copyright

Implementation of a Smart Sensor Using Analytical Redundancy Techniques

Abstract Increasingly control systems are becoming more distributed in nature. This affords opportunities to enhance fault diagnosis capabilities through the utilisation of distributed fault diagnosis. Smart elements in the system can be used to perform a variety of different diagnostic functions. In this paper we consider integration of analytical redundancy strategies employing model based and fuzzy concepts. A smart element has been developed which incorporates these different techniques and the performance of the element subjected to a variety of faults is presented.

Autonomous mission management for UAVs using soar intelligent agents

State-of-the-art unmanned aerial vehicles (UAVs) are typically able to autonomously execute a pre-planned mission. However, UAVs usually fly in a very dynamic environment which requires dynamic changes to the flight plan; this mission management activity is usually tasked to human supervision. Within this article, a software system that autonomously accomplishes the mission management task for a UAV will be proposed. The system is based on a set of theoretical concepts which allow the description of a flight plan and implemented using a combination of Soar intelligent agents and traditional control techniques. The system is capable of automatically generating and then executing an entire flight plan after being assigned a set of objectives. This article thoroughly describes all system components and then presents the results of tests that were executed using a realistic simulation environment.