Synchronous modeling of avionics applications using the SIGNAL language

International audienceIn this paper, we discuss a synchronous, component-based approach to the modeling of avionics applications. The specification of the components relies on the avionics standard ARINC 653 and the synchronous language SIGNAL is considered as modeling formalism. The POLYCHRONY tool-set allows for a seamless design process based on the SIGNAL model, which provides possibilities of high level specifications, verification and analysis of the specifications at very early stages of the design, and finally automatic code generation through formal transformations of these specifications. This suits the basic stringent requirements that should be met by any design environment for embedded applications in general, and avionics applications in particular

An Architecture Pattern Enabling Safety at Lower Cost and with Higher Performance

International audienceIn both avionic and automotive systems, it might become very costly and/or restricting the functional performance, to prove functions safe in all operational conditions and for 100% of the mission time. This is especially true if the quality of sensor data and of communication data may vary very much. One way to solve this trade-off paradox is to leave part of the safety assessment from design-time to run-time. This paper proposes a general architectural pattern for this, and also how to instantiate this pattern in Integrated Modular Avionics (IMA) for the avionic domain, and in AUTOSAR for the automotive domain. The solutions imply some extensions of ARINC 653 and of AUTOSAR respectively, but they are not in conflict with the existing concepts. The proposed solutions are also fully in-line what is prescribed by the standards for functional safety of the two domains

An Optimization Based Design for Integrated Dependable Real-Time Embedded Systems

Moving from the traditional federated design paradigm, integration of mixedcriticality software components onto common computing platforms is increasingly being adopted by automotive, avionics and the control industry. This method faces new challenges such as the integration of varied functionalities (dependability, responsiveness, power consumption, etc.) under platform resource constraints and the prevention of error propagation. Based on model driven architecture and platform based design’s principles, we present a systematic mapping process for such integration adhering a transformation based design methodology. Our aim is to convert/transform initial platform independent application specifications into post integration platform specific models. In this paper, a heuristic based resource allocation approach is depicted for the consolidated mapping of safety critical and non-safety critical applications onto a common computing platform meeting particularly dependability/fault-tolerance and real-time requirements. We develop a supporting tool suite for the proposed framework, where VIATRA (VIsual Automated model TRAnsformations) is used as a transformation tool at different design steps. We validate the process and provide experimental results to show the effectiveness, performance and robustness of the approach

Dynamic software randomisation: Lessons learnec from an aerospace case study

Timing Validation and Verification (V&V) is an important step in real-time system design, in which a system's timing behaviour is assessed via Worst Case Execution Time (WCET) estimation and scheduling analysis. For WCET estimation, measurement-based timing analysis (MBTA) techniques are widely-used and well-established in industrial environments. However, the advent of complex processors makes it more difficult for the user to provide evidence that the software is tested under stress conditions representative of those at system operation. Measurement-Based Probabilistic Timing Analysis (MBPTA) is a variant of MBTA followed by the PROXIMA European Project that facilitates formulating this representativeness argument. MBPTA requires certain properties to be applicable, which can be obtained by selectively injecting randomisation in platform's timing behaviour via hardware or software means. In this paper, we assess the effectiveness of the PROXIMA's dynamic software randomisation (DSR) with a space industrial case study executed on a real unmodified hardware platform and an industrial operating system. We present the challenges faced in its development, in order to achieve MBPTA compliance and the lessons learned from this process. Our results, obtained using a commercial timing analysis tool, indicate that DSR does not impact the average performance of the application, while it enables the use of MBPTA. This results in tighter pWCET estimates compared to current industrial practice.The research leading to these results has received funding from the European Community’s FP7 [FP7/2007-2013] under the PROXIMA Project (www.proxima-project.eu), grant agreement no 611085. This work has also been partially supported by the Spanish Ministry of Science and Innovation under grant TIN2015-65316-P and the HiPEAC Network of Excellence. Jaume Abella has been partially supported by the Ministry of Economy and Competitiveness under Ramon y Cajal postdoctoral fellowship number RYC-2013-14717.Peer ReviewedPostprint (author's final draft

Sequential Circuit Design for Embedded Cryptographic Applications Resilient to Adversarial Faults

In the relatively young field of fault-tolerant cryptography, the main research effort has focused exclusively on the protection of the data path of cryptographic circuits. To date, however, we have not found any work that aims at protecting the control logic of these circuits against fault attacks, which thus remains the proverbial Achilles’ heel. Motivated by a hypothetical yet realistic fault analysis attack that, in principle, could be mounted against any modular exponentiation engine, even one with appropriate data path protection, we set out to close this remaining gap. In this paper, we present guidelines for the design of multifault-resilient sequential control logic based on standard Error-Detecting Codes (EDCs) with large minimum distance. We introduce a metric that measures the effectiveness of the error detection technique in terms of the effort the attacker has to make in relation to the area overhead spent in implementing the EDC. Our comparison shows that the proposed EDC-based technique provides superior performance when compared against regular N-modular redundancy techniques. Furthermore, our technique scales well and does not affect the critical path delay

Integration and validation of embedded flight software on space-qualified multicore architectures

In the recent decades, the importance of software on space missions has notably increased, reflecting the need to integrate advanced on-board functionalities. With multicore processors being lately introduced to host critical high-performance applications, the complexity to validate software has significantly raised with respect to single core architectures. While there has been a big step forward in avionics after the publication of the CAST-32A paper, the ECSS-E-ST-40C software engineering standard used by the European Space Agency (ESA) is still not providing validation support for multicore processors. Hence, it is expected that standardising guidelines to develop software on such platforms will become a recurring topic in the industry to match the demands of future space exploration missions

Fault management via dynamic reconfiguration for integrated modular avionics

The purpose of this research is to investigate fault management methodologies within Integrated Modular Avionics (IMA) systems, and develop techniques by which the use of dynamic reconfiguration can be implemented to restore higher levels of systems redundancy in the event of a systems fault. A proposed concept of dynamic configuration has been implemented on a test facility that allows controlled injection of common faults to a representative IMA system. This facility allows not only the observation of the response of the system management activities to manage the fault, but also analysis of real time data across the network to ensure distributed control activities are maintained. IMS technologies have evolved as a feasible direction for the next generation of avionic systems. Although federated systems are logical to design, certify and implement, they have some inherent limitations that are not cost beneficial to the customer over long life-cycles of complex systems, and hence the fundamental modular design, i.e. common processors running modular software functions, provides a flexibility in terms of configuration, implementation and upgradability that cannot be matched by well-established federated avionic system architectures. For example, rapid advances of computing technology means that dedicated hardware can become outmoded by component obsolescence which almost inevitably makes replacements unavailable during normal life-cycles of most avionic systems. To replace the obsolete part with a newer design involves a costly re-design and re-certification of any relevant or interacting functions with this unit. As such, aircraft are often known to go through expensive mid-life updates to upgrade all avionics systems. In contrast, a higher frequency of small capability upgrades would maximise the product performance, including cost of development and procurement, in constantly changing platform deployment environments. IMA is by no means a new concept and work has been carried out globally in order to mature the capability. There are even examples where this technology has been implemented as subsystems on service aircraft. However, IMA flexible configuration properties are yet to be exploited to their full extent; it is feasible that identification of faults or failures within the system would lead to the exploitation of these properties in order to dynamically reconfigure and maintain high levels of redundancy in the event of component failure. It is also conceivable to install redundant components such that an IMS can go through a process of graceful degradation, whereby the system accommodates a number of active failures, but can still maintain appropriate levels of reliability and service. This property extends the average maintenance-free operating period, ensuring that the platform has considerably less unscheduled down time and therefore increased availability. The content of this research work involved a number of key activities in order to investigate the feasibility of the issues outlined above. The first was the creation of a representative IMA system and the development of a systems management capability that performs the required configuration controls. The second aspect was the development of hardware test rig in order to facilitate a tangible demonstration of the IMA capability. A representative IMA was created using LabVIEW Embedded Tool Suit (ETS) real time operating system for minimal PC systems. Although this required further code written to perform IMS middleware functions and does not match up to the stringent air safety requirements, it provided a suitable test bed to demonstrate systems management capabilities. The overall IMA was demonstrated with a 100kg scale Maglev vehicle as a test subject. This platform provides a challenging real-time control problem, analogous to an aircraft flight control system, requiring the calculation of parallel control loops at a high sampling rate in order to maintain magnetic suspension. Although the dynamic properties of the test rig are not as complex as a modern aircraft, it has much less stringent operating requirements and therefore substantially less risk associated with failure to provide service. The main research contributions for the PhD are: 1.A solution for the dynamic reconfiguration problem for assigning required systems functions (namely a distributed, real-time control function with redundant processing channels) to available computing resources whilst protecting the functional concurrency and time critical needs of the control actions. 2.A systems management strategy that utilises the dynamic reconfiguration properties of an IMA System to restore high levels of redundancy in the presence of failures. The conclusion summarises the level of success of the implemented system in terms of an appropriate dynamic reconfiguration to the response of a fault signal. In addition, it highlights the issues with using an IMA to as a solution to operational goals of the target hardware, in terms of design and build complexity, overhead and resources

Modeling and Analysis of Mixed Synchronous/Asynchronous Systems

Practical safety-critical distributed systems must integrate safety critical and non-critical data in a common platform. Safety critical systems almost always consist of isochronous components that have synchronous or asynchronous interface with other components. Many of these systems also support a mix of synchronous and asynchronous interfaces. This report presents a study on the modeling and analysis of asynchronous, synchronous, and mixed synchronous/asynchronous systems. We build on the SAE Architecture Analysis and Design Language (AADL) to capture architectures for analysis. We present preliminary work targeted to capture mixed low- and high-criticality data, as well as real-time properties in a common Model of Computation (MoC). An abstract, but representative, test specimen system was created as the system to be modeled