R. Peter Jones

Probability based vehicle fault diagnosis: Bayesian network method

Fault diagnostics are increasingly important for ensuring vehicle safety and reliability. One of the issues in vehicle fault diagnosis is the difficulty of successful interpretation of failure symptoms to correctly diagnose the real root cause. This paper presents an innovative Bayesian Network based method for guiding off-line vehicle fault diagnosis. By using a vehicle infotainment system as a case study, a number of Bayesian diagnostic models have been established for fault cases with single and multiple symptoms. Particular considerations are given to the design of the Bayesian model structure, determination of prior probabilities of root causes, and diagnostic procedure. In order to unburden the computation, an object oriented model structure has been adopted to prevent the model from overly large. It is shown that the proposed method is capable of guiding vehicle diagnostics in a probabilistic manner. Furthermore, the method features a multiple-symptoms-orientated troubleshooting strategy, and is capable of diagnosing multiple symptoms optimally and simultaneously.

Identifiable pharmacokinetic models: The role of extra inputs and measurements

Single input, single output experiments can result in nonunique solutions for the rate constants of a linear compartmental model used to describe the pharmacokinetics. Where a finite number of solutions exists, a priori knowledge has to be used to distinguish between the solutions. Where there is an infinite number of solutions, assumptions have to be made about the values of some rate constants in order to obtain a unique solution for the others. This paper considers such experiments and determines whether either the addition of an extra input (simultaneously with the first input) or the taking of an extra measurement would result in a unique solution. It is found that perturbing a second input can be useful, but only if the perturbation is of different shape from the first input. Measurements of drug in urine and metabolite in plasma are generally not helpful in resolving identifiability of the drug dynamic model. If a radioactive tracer is used, though, the second measurement (for example, by externally scanning the radioactivity of the liver) can prove useful, but only if the gain of the measuring device is known.

Comprehensive Forward Dynamic HEV Powertrain Modelling Using Dymola and MATLAB/Simulink

Abstract A modelling structure for different architectures of Hybrid Electric Vehicles (HEVs) is presented in this paper. This structure includes physical powertrain components and their controllers, hybrid supervisory controller, and the driver model. The physical powertrain component models are developed in Dymola, whilst the component controllers, hybrid supervisory controllers, and the driver model are developed in MATLAB/Simulink. The structure makes it possible to compare different hybrid vehicle architectures directly with the capability to study the influence of real-world driver behaviour on energy usage. Three types of HEV architectures, including Mild Parallel, Series, and Power Split, are illustrated to show the feasibility of this modelling technique.

Model-based testing of a vehicle instrument cluster for design validation using machine vision

This paper presents an advanced testing system, combining model-based testing and machine vision technologies, for automated design validation of a vehicle instrument cluster. In the system, a hardware-in-the-loop (HIL) tester, supported by model-based approaches, simulates vehicle operations in real time and dynamically provides all essential signals to the instrument cluster under test. A machine vision system with advanced image processing algorithms is designed to inspect the visual displays. Experiments demonstrate that the system developed is accurate for measuring the pointer position, bar graph position, pointer angular velocity and indicator flash rate, and is highly robust for validating various functionalities including warning lights status, symbol and text displays. Moreover, the system developed greatly eases the task of tedious validation testing and makes onerous repeated tests possible.

A study of approaches for model based development of an automotive driver information system

Over the past decades, the use of electronic systems in automotive vehicles has grown exponentially. Automotive systems engineering requires a sustainable integration of new methods, development processes, and tools that are specifically adapted to the automotive domain. This paper describes two approaches to the development of an automotive electronic system via a case study involving the modelling and code generation of a driver information system. The first approach involves the use of the SysML based tool Artisan Studio whilst the second approach involves the use of the MATLAB tools Simulink and Stateflow. The paper compares the two approaches and summarizes the strengths and weaknesses of two approaches respectively. Conclusions are drawn on how to make use of the model based design to meet the challenges in the automotive industry.

A Critical Analysis of Model-Based Formal Verification Efforts within the Automotive Industry

There are a number of software-controlled features in todays automotive vehicles to meet the increasing number of requirements for comfort, safety, infotainment and reduced emissions. To meet the growing demands from such features, the software content is not only increasing rapidly, but also becoming increasingly distributed within the Electronic Control Units (ECUs), leading to the possibility of unwanted interactions and consequent loss of reliability. Therefore, the automotive software-based features have to be designed and verified using sophisticated tools and techniques.Formal methods-based techniques and tools have been used on various industrial designs over the past 6 years by one of the authors in development and applied research projects, collaborating with a number of automotive companies. The challenges faced in large projects are discussed in this context. A large number of industrial users have recounted their own experiences in user conferences and workshops, which will be summarized. The results of a short survey of real users will also be discussed in this context.

Application of System Modeling to Road Load Data Synthesis for Automobile Product Development

A new system-modeling tool has been developed to reduce the need for prototype vehicles for automobile product development by synthesizing Road Load Data. This tool uses MATLAB/Simulink for driver and vehicle control systems and employs a compiled Dymola subsystem within the Simulink environment for the vehicle model itself. This paper describes the design of the tool and its application in the product development process, including an analysis of how the use of system modeling and computer-aided engineering has shortened development time and cut costs. The results presented in this paper show that the methods used in this tool can recreate measured data with an error of less than 13% — this is believed to give greater confidence in the synthesized Road Load Data than other published methods. It is also capable of generating a torque time history for driveline components, and overall load profiles for a number of different vehicle test routes to allow fatigue analysis of those components.Copyright

Characterising heavy-duty fuel systems: a critique of industry practice and challenges

Fuel system components must perform optimally to ensure the maximum fuel economy and the minimum emissions. The key to optimised performance is effective characterisation of the system in the factory. This paper describes methods for discerning the features of a fuel injection system’s performance during built-unit testing. First, a background is given, highlighting the impact of environmental legislation. Next, specifications for a modern fuel system and key functionality characteristics are identified, and a brief overview of the alternative system configurations offered. The injector function is then discussed, with the importance of the key subcomponents being explained. Methods of testing and characterising the fuel injector performance in use are then described. Finally, there is discussion on the future of fuel system testing, and how developing challenges such as measuring the injection timing and the fuelling quantity in high-pressure, high-temperature and high-vibration environments might be overcome with better instruments and novel testing strategies including a paradigm shift away from steady-state testing to fully dynamic system testing.

Implementation of system-level fault diagnostics in vehicles on a generic test platform

In order to verify the effectiveness of the system-level fault diagnostic method which has been designed for the self-healing vehicle (SHV) concept, this paper describes the implementation of the designed diagnostic method on a generic test platform (GTP). The platform represents the distributed and networked electronic control system of a real vehicle. The more important is that in this platform the functions of an individual network node and the whole networked system are able to be configured to operate in different scenarios. This enables the platform to mimic a real vehicle system in the presence of faults which is indispensable for the validation of a diagnostic method.

A generic test platform representing networked embedded systems in vehicles

In order to verify the effectiveness of the system-level fault diagnostic method which has been designed for the self-healing vehicle (SHV) concept, this paper has developed a generic test platform (GTP) on which to implement the designed diagnostic method. The platform represents the distributed and networked electronic control system of a real vehicle. The more important is that in this platform the functions of an individual network node and the whole networked system are able to be configured to operate in different scenarios. This enables the platform to mimic a real vehicle system in the presence of faults which is indispensable for the validation of a diagnostic method.