In this thesis, the Failure Mode and Effect Analysis (FMEA) methodology is implemented for failure analysis in wireless automotive systems. Reliability analysis is done by using Reliability Block Diagrams (RBD). These analyses are performed to develop redundant systems.
The main focus of this thesis is to make the system behavior fail-operation using wireless technology. The implementation of algorithms and protocol design has been done with an MSPEXP430 board and a CC2520 transceiver to detect single point failures. The implementations were then tested to detect different failure levels successfully.
In this modern age, a car has different functionalities and facilities. The implementation is done by using different actuators, sensors and Electronics Control Units (ECUs). Due to the high complexity of wiring and addition of weight to a car, controlling and maintaining these devices is difficult.
As a solution for these complexities and the problem of weight growth, wireless technology has been used with the TDMA method. The approach for replacing wire by wireless technology may, however, not be secure and reliable.
Table of Contents
1. Introduction
1.1. Motivation
1.2. Challenges
2. Related Work
2.1. Previous Research works
2.2. Differences of Existing Wireless Technologies
2.3. Conclusion
3. Requirement Analysis
3.1. Existing System Architecture in eCar
3.2. FMEA Concept
3.2.1. FMEA Overview
3.2.2. FMEA Methodology foundation
3.3. FMEA Table
3.4. FMEA Analysis
3.5. Conclusion
4. Design of a Fail-Operational Wireless System
4.1. Overview of Wireless System with Redundancy
4.2. Analysis of Wireless System with and without Redundancy
4.2.1. Mean Time To Failure
4.2.2. Reliability Block Diagrams
4.3. Algorithm Design
4.3.1. Algorithm Design Overview
4.3.2. Active Node Design
4.4. Conclusion
5. Implementation
5.1. Communication Protocol Design For Redundancy
5.1.1. Redundant Fail-Operational Protocol for UART
5.1.2. Redundant Fail-Operational Protocol for Wireless Channel
5.2. Hardware Platform
5.2.1. MSP-EXP430FXXX Introduction
5.2.2. CC2520 Transceiver
5.3. Software Platform
5.3.1. FreeRTOS Basics
5.3.2. Software Architecture
5.4. Conclusion
6. Experimental Results
6.1. Test Case1 - UART-R and UART-R1 Channel Failures
6.1.1. Experimental detail
6.1.2. Achieved and Expected results
6.1.3. Discussion
6.2. Test Case2 - Node Failures
6.2.1. Experimental detail
6.2.2. Achieved and Expected results
6.2.3. Discussion
6.3. Test Case3 - RSSI Decreases
6.3.1. Experimental detail
6.3.2. Achieved and Expected results
6.3.3. Discussion
6.4. Test Case4 - Wireless Channel Failures
6.4.1. Experimental detail
6.4.2. Achieved and Expected results
6.4.3. Discussion
6.5. Conclusion
7. Conclusion and Future Work
B. Detailed Descriptions
B.1. Code Structure
B.2. Compilation
Research Objectives & Topics
This thesis aims to develop a fail-operational wireless communication system for automotive applications to reduce wiring complexity and weight. It investigates the integration of redundancy into existing wireless architectures to ensure reliability, safety, and real-time performance even in the presence of single-point failures.
- Automotive wireless system design and architectural redundancy.
- Reliability analysis using Failure Mode and Effect Analysis (FMEA).
- Quantitative reliability assessment using Reliability Block Diagrams (RBD).
- Implementation of fail-operational protocols using ZigBee, MSP-EXP430, and FreeRTOS.
- Experimental verification of system resilience against node, UART, and signal channel failures.
Excerpt from the Book
3.2. FMEA Concept
Below are short definition and detail about useful approaches and analysis according to the FMEA, Reliability Analysis Center [2].
The purpose of the FMEA is to identify the results or effects of an item’s failure on system operation and to classify each potential failure according to its severity. The FMEA provides quick visibility of obvious failure modes and identifies potential single failure points which can be eliminated or minimized with redesign.
There are two different implementation approaches with FMEA. They are - Hardware approach and Functional approach. But mostly in complex system both approaches are combined for FMEA implementation.
Qualitative and quantitative analysis are two ways of analysis in FMEA. In qualitative analysis, probability of item’s failures are mentioned with its severity effect level according to the system requirement and usability. But in quantitative analysis, the failure probability and severity effect is used for item failure rate which is useful data source for MIL-HDBK-217 [4]. Qualitative analysis is favorable first for FMEA and after finding probability and severity level, quantitative analysis is done to calculate and evaluate MTTF [5].
Summary of Chapters
1. Introduction: Discusses the motivation for replacing heavy car wiring harnesses with reliable wireless systems and highlights challenges like interference and real-time reliability.
2. Related Work: Reviews existing automotive wireless research, including drive-by-wire applications and comparisons between protocols like ZigBee, Wi-Fi, and Bluetooth.
3. Requirement Analysis: Details the FMEA methodology used to analyze potential system failures and categorize them by severity and probability for the wireless system architecture.
4. Design of a Fail-Operational Wireless System: Describes the design of a redundant system architecture and provides a mathematical reliability analysis using Mean Time To Failure (MTTF) and Reliability Block Diagrams (RBD).
5. Implementation: Covers the practical realization of the system, including redundant protocols for UART and wireless channels, hardware setup using MSP-EXP430, and software architecture based on FreeRTOS.
6. Experimental Results: Presents the verification and test outcomes for the designed system, focusing on handling UART failures, node failures, and signal strength degradation.
7. Conclusion and Future Work: Summarizes the findings on wireless redundancy and suggests future improvements, such as replacing the UART-based redundancy with purely wireless communication.
Keywords
Wireless communication, Fail-operational system, Automotive, Redundancy, FMEA, Reliability Block Diagram, ZigBee, MSP-EXP430, FreeRTOS, Fault tolerance, UART, Signal integrity, Mean Time To Failure, Automotive safety, Protocol design
Frequently Asked Questions
What is the core focus of this research?
The work focuses on replacing traditional automotive wiring harnesses with a reliable, fail-operational wireless communication system to reduce vehicle weight and complexity.
What are the primary thematic areas covered?
Key areas include wireless system architecture for automobiles, failure mode analysis (FMEA), quantitative reliability assessment (RBD), protocol development for redundancy, and real-time software implementation.
What is the main research objective?
The objective is to design and implement a redundant wireless system capable of maintaining operational integrity even in the event of a single-point failure.
Which scientific methods are utilized in this work?
The research employs qualitative and quantitative failure analysis (FMEA and RBD), mathematical modeling of failure rates (MTTF), and practical empirical testing of protocol implementations.
What does the main part of the thesis address?
It provides a comprehensive methodology for analyzing system requirements, designing a redundant architecture, implementing communication protocols, and experimental validation of failure mitigation strategies.
Which keywords characterize this work?
The work is characterized by terms such as automotive wireless systems, redundancy, fail-operational behavior, reliability block diagrams, ZigBee, and failure detection.
How is the "Active Node Design" implemented in this system?
The active node design utilizes redundant communication paths, specifically UART connections and redundant wireless channels, coupled with monitoring algorithms that detect errors and trigger automatic recovery protocols.
What role does the FMEA graph play in the system design?
The FMEA graph visualizes the risk level (severity vs. probability) of various components, allowing the author to identify high-risk areas that require prioritized redundancy and fail-operational features.
- Arbeit zitieren
- Roshan Chulyada (Autor:in), 2014, Reliability Analysis of Wireless Automotive Applications with Transceiver Redundancy, München, GRIN Verlag, https://www.grin.com/document/318837
