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Technical Paper

A Computer Model for Thermofluid Analysis of Engine Warm-up Process

A general purpose computer model has been developed for analyzing the thermal performance of thermofluid systems. The system thermal behaviour is governed by heat convection and conduction. The model represents a thermofluid system as a thermal network, consisting of several different fluid circuits which are separated by solid walls. The solid walls are represented by hexahedral elements with lumped heat capacitance. The model has the capability to set up and link an equivalent thermal network from input data, using two types of junctions: wall-to-wall and fluid-to-wall. The flow calculations are based on the one-dimensional incompressible flow equation and the heat transfer calculations are based on either forced or natural heat convection for internal and external flows. The heat convection formulae used in the model are in the non-dimensional form which simplifies the program structure.
Technical Paper

A Neural Network Technique for Verification of Dynamometer Parasitic Losses

An on line method for verification of chassis dynamometer operation uses a neural network. During the testing of a vehicle, it is assumed that after a warm up period the parasitic losses remain stable. There is normally no provision for verification of correct dynamometer operation while the test is running. This technique will detect if a component wears or fails during the testing of a vehicle and thus avoid testing under erroneous conditions. A Learning Vector Quantization (LVQ) neural network is trained to recognise poor dynamometer operation in order to signal a fault condition to the operator.
Technical Paper

A Pragmatic Model-Based Product Engineering Process

Complexity of electronics and embedded software systems in automobiles has been increasing over the years. This necessitates the need for an effective and exhaustive development and validation process in order to deliver fault free vehicles at reduced time to market. Model-based Product Engineering (MBPE) is a new process for development and validation of embedded control software. The process is generic and defines the engineering activities to plan and assess the progress and quality of the software developed for automotive applications. The MBPE process is comprised of six levels (one design level and five verification and validation levels) ranging from the vehicle requirements phase to the start of production. The process describes the work products to be delivered during the course of product development and also aligns the delivery plan to overall vehicle development milestones.
Technical Paper

A Refinement of Flame Propagation Combustion Model for Spark-Ignition Engines

This paper describes the development and validation of a refined combustion model for turbulent flame propagation in SI engines. In this model the original differential equation of flame front entrainment remains, but a new difference equation of burning rate is introduced to replace the original differential equation. The model fully embodies the Tennekes-Chomiak mechanism of premixed turbulent combustion, presenting a flame thinner than the original model. A spark ignition model is also suggested. The model treats the electrical spark ignition as a diffusion wave to calculate the entrainment enhancement by the spark ignition. The simple formula of the initial flame propagation has been validated by measured results. Incorporated with this spark ignition model, the three-stage model of premixed turbulent flame velocity, published earlier by the authors, is used in the combustion model.
Technical Paper

A Reliable, Highly Optimized, Lead-Acid Battery (RHOLAB) for Affordable HEVs - A Foresight Vehicle Project

The objective of the Project is to develop an optimized lead-acid battery solution for HEVs based on a novel, individual, spirally wound valve-regulated lead-acid 2V cell optimized for HEV use and low variability. This cell will be used as a building block for the development of a complete battery pack that is managed at the cell level. Following bench testing, this battery pack will be thoroughly evaluated by substituting it for the NiMH pack in a Honda Insight. The paper covers the first half of the 3-year project and will describe work carried out in the following areas: Development of cell and battery testing facilities and identification of mechanisms causing cell lifetime scatter. The design and development of the prototype double-ended cell. The development of the battery pack specification and pack design. The development of the battery management system. The paper will also give details of the test results obtained on the demonstration vehicle with its original NiMH battery.
Technical Paper

A SLIO (Serial Link Input/Output) CAN Implementation

This paper discusses the use of SLIO CAN technology for low speed (<125 Kbit/s) body control system. The architecture of SLIO as well as its benefits and shortcomings are explained and illustrated. A body control system utilising the SLIO CAN technology has been build to investigate the feasibility of its implementation. The flexibility in adding enhancement and fault tolerance feature to the system is also addressed. The prior knowledge of CAN Specification 2.0 is assumed[1].
Technical Paper

Accurate Model Based Hardware-in-the-Loop Test for a Windscreen Wiper System

Hardware-in-the-loop (HIL) simulations have long been used to test electronic control units (ECUs) and software in car manufacturers. It provides an effective platform to the rapid development process of the ECU control algorithms and accommodates the added complexity of the plant under control. Accurate Model based HIL simulation (AMHIL) is considered as a most efficient and cost effective way for exploration of new designs and development of new products, particularly in calibration and parameterization of vehicle stability controllers. The work presented in the paper is to develop a mathematical model of a windscreen wiper system for the purpose of conducting HIL vehicle test and eventually to replace the real component with the model for cost cutting and improved test efficiency. The model is developed based on the electro-mechanical engineering principles.
Technical Paper

Adding Depth: Establishing 3D Display Fundamentals for Automotive Applications

The advent of 3D displays offers Human-Machine Interface (HMI) designers and engineers new opportunities to shape the user's experience of information within the vehicle. However, the application of 3D displays to the in-vehicle environment introduces a number of new parameters that must be carefully considered in order to optimise the user experience. In addition, there is potential for 3D displays to increase driver inattention, either through diverting the driver's attention away from the road or by increasing the time taken to assimilate information. Manufacturers must therefore take great care in establishing the ‘do’s and ‘don’t's of 3D interface design for the automotive context, providing a sound basis upon which HMI designers can innovate. This paper describes the approach and findings of a three-part investigation into the use of 3D displays in the instrument cluster of a road car, the overall aim of which was to define the boundaries of the 3D HMI design space.
Technical Paper

An Investigation into the Future of Automotive In-Vehicle Control Networking Technology

The Controller Area Network (CAN) has seen enormous success in automotive body and powertrain control systems. However, there is a change in emphasis arising in the industry in which CAN is seen as too powerful and expensive for simple digital body control applications, but not robust or fast enough for more safety critical applications such as the envisaged Drive-by-Wire systems of future passenger cars. The emerging protocols Local Interconnect Network (LIN), the Time Triggered Protocols (TTP/A, TTP/C), Time Triggered CAN (TTC) and Byteflight are examined in terms of their application and likelihood for future success. The paper is concluded with comments concerning a newly announced protocol known as FlexRay.
Technical Paper

Analysis and Diagnostics of Time Triggered CAN (TTCAN) Systems

The Controller Area Network (CAN) has seen enormous success in automotive body and powertrain control systems, as well as industrial automation systems using higher layer protocols such as CANopen and DeviceNet. Now, the CAN standard ISO11898 is being extended to Time Triggered CAN (TTCAN) to address the safety critical needs of first generation drive-by-wire systems. However, their successful development depends upon the availability of silicon and software support, and appropriate development & analysis tools. Warwick Control Technologies and the University of Warwick are tasked with prototyping a TTCAN analyser within the European Union Media+ project Silicon Systems for Automotive Electronics (SSAE) consortium, and with funding from the British Department of Trade and Industry (DTI). This paper briefly outlines the current status of both CAN & TTCAN technology and describes the requirements of a TTCAN analyser over that of a traditional CAN analyser.
Technical Paper

Comparing the Harness Cost of Hardwired and Networked Integrated Door Systems

The objective of the research discussed in this paper is to propose a methodology for comparing candidate electrical architectures on a cost basis at the very beginning of the architecture design process. To achieve this objective, historical data concerning the cost of a wiring harness for a driver’s door electrical system is analysed along with information on an electrical architecture for the door system of a small four door passenger car. The study is focused around a driver’s door electrical system based on LIN and hardwired integration. However, it is concluded that the results are applicable to other types of automotive electrical architectures.
Technical Paper

EMC Susceptibility Testing of a CAN Car

A Rover car equipped with a Controller Area Network (CAN) system was tested for radio frequency susceptibilities in the Electromagnetic Compatibility (EMC) chamber at Rover Gaydon Test Centre. The system consisted of four electronic control units linked together using a serial network (CAN) to share signal information. The car was configured in turn with two different types of twisted pair wire and a flat pair for the CAN data bus. Each type of wire was tested in the chamber at a range of frequencies and with various antenna positions. The CAN data was collected and stored on a commercially available personal computer (PC) based network analyzer for later analysis to determine bus latency under EMC error conditions.
Technical Paper

Investigation on the Self-Stabilization Feature of HCCI Combustion

The combustion timing, work output and in-cylinder peak pressure for HCCI engines often converge to a stable equilibrium point, which implies that the HCCI combustion may have a self-stabilization feature. It is thought that this behavior is due to the competing residual-induced heating and dilution of the reactant gas. As one of the most important features of HCCI combustion, the self-stabilization behavior can give great guidance to people for designing controller for HCCI engine control. The self-stabilization features of HCCI combustion had been observed by many researchers and mentioned in some publications. However, there is no report to experimentally analyze this phenomenon individually. Due to the fuel injection normally ending during the NVO process and the spark plug is turned off for HCCI engines, there is no direct control approach between the Intake Valve Close (IVC) and the start of combustion.
Technical Paper

Modelling of Network Communications Stack Software ROM and RAM Requirements

For a typical communications C-language software stack, its size in terms of ROM and RAM will be dependent upon the network properties such as number of nodes, schedules, messages and signals. A lot of this information is part of a more detailed design and during architecture selection only signal and nodal information will be available. Messages and schedule information will be part of a much more detailed part of the design process. The objective of the study described in this paper is to ascertain whether ROM and RAM requirements can be estimated from only node and signal information only as this is the information that tends to be available at the very beginning of the electrical architecture design process. Historical data from a LIN design and its associated communications stack is statistically analysed and used to develop a methodology for ROM and RAM requirement estimation.
Technical Paper

Power Control of Converters using Novel Resonant Techniques with Applications

This paper presents novel resonant techniques in controlling the output power of a half-bridge series-parallel load-resonant and a quasi-resonant converter operating at true resonance using simple power electronics techniques. A mathematical model of the load-resonant converter has been designed, analyzed and developed, leading to the building of a practical circuit with multi-resonant frequencies. Operation of the circuit over the entire resonant frequency range maintains essentially zero-current switching, and unity-power factor while operating at high-frequency operation. Different power levels can be delivered to the load at each distinct resonant frequency. Different curves have been drawn to assist the process. The quasi-resonant converter has been constructed using a pair of back-to-back power switches switching around 100kHz. The resonant components consist of only an inductor and a capacitor.
Technical Paper

Real-time Simulation of a Vehicle Door Locking Mechanism on a Hardware-in-the-Loop Platform

An automotive side door latch release mechanism has been modelled for the locking and unlocking vehicle functionality in Dymola. The performance of the developed door lock model is evaluated against an existing model of a similar door locking/unlocking system in Stateflow. The model performance is also compared with measurements from a real vehicle door latch. The model is converted into a Simulink model and built for a real-time environment such as the dSPACE target with a fixed step size solver. It is shown that a step size as small as 1 ms can be used for real-time simulation without task overrunning in the real-time target. The model is also benchmarked on a multiprocessor setup as multiprocessor simulators are common in system-level networked Electronic Controller Unit (ECU) testing facilities for implementing high fidelity closed loop models of integrated ECUs and actuators.
Technical Paper

Robustness Modelling of Complex Systems - Application to the Initialisation of a Hybrid Electric Vehicle Propulsion System

Robustness is particularly important in complex systems of systems due to emergent behaviour. This paper presents two novel, techniques developed as part of a framework for design for robustness of complex automotive electronic systems, but in principle could be applied to a broad range of distributed electronic systems. The overall framework is described to give the context of use for the techniques. The first technique is a “robustness case” which is a structured argument for the robustness of a system analogous to a safety case. The second is a model based approach to early robustness verification of complex systems. The approaches are demonstrated by their application to the system initialisation of the propulsion control system of a hybrid electric vehicle. The hybrid system initialisation process is discussed in terms of the key objectives and the technical implementation, illustrating the level of complexity underlying a simple high level requirement.
Technical Paper

The Application of Low Cost CAN Bus Load Transducer Technology

A low cost CAN bus load transducer, requiring only a few low cost components, has been developed. Traditionally, to ascertain CAN bus loading, an algorithm based upon a number of assumptions executed on a microcontroller is required. This has many disadvantages that include being potentially costly, inaccurate and can take up a significant amount of processing, especially under higher bus load situations causing a higher number of interrupts. However, the CAN bus load transducer developed, is connected to the CAN bus and outputs a varying signal proportional to bus loading. A microcontroller can then simply be used to read the bus load signal and covert it into percentage bus loading as often as is required. The method is inexpensive, accurate and provides a continuous signal for CAN bus loading measurement that does not become expensive in terms of processing under higher bus load conditions. In this paper, the application of the CAN bus load transducer technology is explored.
Technical Paper

The Development and Testing of a Lead-Acid Battery System for a Hybrid Electric Vehicle (Rholab - A Foresight Vehicle Project)

The objective of the Project is to develop a low cost lead-acid battery solution for hybrid electric vehicles based on a novel, individual, spirally wound valve-regulated lead-acid 2V cell optimized for this application. This cell will be used as a building block for the development of a complete battery pack that is managed at the cell level. Following bench testing, this battery pack will be thoroughly evaluated by substituting it for the Nickel/Metal Hydride pack in a Honda Insight A paper given at the Future Car Congress in June 2002 covered the first half of the 3-year project and described work carried out in the following areas: Development of cell and battery testing facilities. The design and development of the prototype double-ended cell. The development of the battery pack specification and pack design. The development of the battery management system. It also gave details of the test results obtained on the demonstration vehicle with its original NiMH battery.
Technical Paper

The Science of Testing: An Automotive Perspective

Increasing automation in the automotive systems has re-focused the industry’s attention on verification and validation methods and especially on the development of test scenarios. The complex nature of Advanced Driver Assistance Systems (ADASs) and Automated Driving (AD) systems warrant the adoption of new and innovative means of evaluating and establishing the safety of such systems. In this paper, the authors discuss the results from a semi-structured interview study, which involved interviewing ADAS and AD experts across the industry supply chain. Eighteen experts (each with over 10 years’ of experience in testing and development of automotive systems) from different countries were interviewed on two themes: test methods and test scenarios. Each of the themes had three guiding questions which had some follow-up questions. The interviews were transcribed and a thematic analysis via coding was conducted on the transcripts.