Dependability Evaluation of Time Triggered Architecture Using Simulation

The method presented in this paper uses a generic C-language written simulation model of an embedded distributed computer system aimed for a safety-critical control application. The considered system is built using Time Triggered Architecture (TTA) concepts. The aim of the presented simulation method is to evaluate the system capability to tolerate a chosen category of faults. The model, being written in ANSI-C, is portable and machine-independent. Its structure is modular and flexible, so that the system to be studied and the experiment setting can easily be changed. The functionality of this model is demonstrated on a set of fault injection experiments aimed mainly to evaluate the correctness of the Time Triggered Protocol (TTP/C) that implements the abstract concepts of TTA. These experiments were done within the EU/IST project Fault Injection for Time triggered architecture (FIT)

Dependability assessment of by-wire control systems using fault injection

This paper is focused on the validation by means of physical fault injection at pin-level of a time-triggered communication controller: the TTP/C versions C1 and C2. The controller is a commercial off-the-shelf product used in the design of by-wire systems. Drive-by-wire and fly-by-wire active safety controls aim to prevent accidents. They are considered to be of critical importance because a serious situation may directly affect user safety. Therefore, dependability assessment is vital in their design. This work was funded by the European project `Fault Injection for TTA¿ and it is divided into two parts. In the first part, there is a verification of the dependability specifications of the TTP communication protocol, based on TTA, in the presence of faults directly induced in communication lines. The second part contains a validation and improvement proposal for the architecture in case of data errors. Such errors are due to faults that occurred during writing (or reading) actions on memory or during data storage.Blanc Clavero, S.; Bonastre Pina, AM.; Gil, P. (2009). Dependability assessment of by-wire control systems using fault injection. Journal of Systems Architecture. 55(2):102-113. doi:10.1016/j.sysarc.2008.09.003S10211355

Safety-Critical Communication in Avionics

The aircraft of today use electrical fly-by-wire systems for manoeuvring. These safety-critical distributed systems are called flight control systems and put high requirements on the communication networks that interconnect the parts of the systems. Reliability, predictability, flexibility, low weight and cost are important factors that all need to be taken in to consideration when designing a safety-critical communication system. In this thesis certification issues, requirements in avionics, fault management, protocols and topologies for safety-critical communication systems in avionics are discussed and investigated. The protocols that are investigated in this thesis are: TTP/C, FlexRay and AFDX, as a reference protocol MIL-STD-1553 is used. As reference architecture analogue point-to-point is used. The protocols are described and evaluated regarding features such as services, maturity, supported physical layers and topologies.Pros and cons with each protocol are then illustrated by a theoretical implementation of a flight control system that uses each protocol for the highly critical communication between sensors, actuators and flight computers.The results show that from a theoretical point of view TTP/C could be used as a replacement for a point-to-point flight control system. However, there are a number of issues regarding the physical layer that needs to be examined. Finally a TTP/C cluster has been implemented and basic functionality tests have been conducted. The plan was to perform tests on delays, start-up time and reintegration time but the time to acquire the proper hardware for these tests exceeded the time for the thesis work. More advanced testing will be continued here at Saab beyond the time frame of this thesis

X-By-Wire via ISOBUS Communication Network

Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 9 (2007): X-By-Wire via ISOBUS Communication Network. Manuscript ATOE 07 002. Vol. IX. July, 2007

Design Optimization of Time- and Cost-Constrained Fault-Tolerant Distributed Embedded Systems

Submitted on behalf of EDAA (http://www.edaa.com/)International audienceIn this paper we present an approach to the design optimization of fault-tolerant embedded systems for safety-critical applications. Processes are statically scheduled and communications are performed using the time-triggered protocol. We use process re-execution and replication for tolerating transient faults. Our design optimization approach decides the mapping of processes to processors and the assignment of fault-tolerant policies to processes such that transient faults are tolerated and the timing constraints of the application are satisfied. We present several heuristics which are able to find fault-tolerant implementations given a limited amount of resources. The developed algorithms are evaluated using extensive experiments, including a real-life example

In-vehicle communication networks : a literature survey

The increasing use of electronic systems in automobiles instead of mechanical and hydraulic parts brings about advantages by decreasing their weight and cost and providing more safety and comfort. There are many electronic systems in modern automobiles like antilock braking system (ABS) and electronic brakeforce distribution (EBD), electronic stability program (ESP) and adaptive cruise control (ACC). Such systems assist the driver by providing better control, more comfort and safety. In addition, future x-by-wire applications aim to replace existing braking, steering and driving systems. The developments in automotive electronics reveal the need for dependable, efficient, high-speed and low cost in-vehicle communication. This report presents the summary of a literature survey on in-vehicle communication networks. Different in-vehicle system domains and their requirements are described and main invehicle communication networks that have been used in automobiles or are likely to be used in the near future are discussed and compared with key references

Synthesis of Fault-Tolerant Embedded Systems with Checkpointing and Replication

We present an approach to the synthesis of fault-tolerant hard real-time systems for safety-critical applications. We use checkpointing with rollback recovery and active replication for tolerating transient faults. Processes are statically scheduled and communications are performed using the time-triggered protocol. Our synthesis approach decides the assignment of fault-tolerance policies to processes, the optimal placement of checkpoints and the mapping of processes to processors such that transient faults are tolerated and the timing constraints of the application are satisfied. We present several synthesis algorithms which are able to find fault-tolerant implementations given a limited amount of resources. The developed algorithms are evaluated using extensive experiments, including a real-life example. 1

Application Agreement and Integration Services

Application agreement and integration services are required by distributed, fault-tolerant, safety critical systems to assure required performance. An analysis of distributed and hierarchical agreement strategies are developed against the backdrop of observed agreement failures in fielded systems. The documented work was performed under NASA Task Order NNL10AB32T, Validation And Verification of Safety-Critical Integrated Distributed Systems Area 2. This document is intended to satisfy the requirements for deliverable 5.2.11 under Task 4.2.2.3. This report discusses the challenges of maintaining application agreement and integration services. A literature search is presented that documents previous work in the area of replica determinism. Sources of non-deterministic behavior are identified and examples are presented where system level agreement failed to be achieved. We then explore how TTEthernet services can be extended to supply some interesting application agreement frameworks. This document assumes that the reader is familiar with the TTEthernet protocol. The reader is advised to read the TTEthernet protocol standard [1] before reading this document. This document does not re-iterate the content of the standard