Lionel Havet

NETCARBENCH: A benchmark for techniques and tools used in the design of automotive communication systems

Abstract This paper presents NETCARBENCH, a benchmark devoted to improve the assessment, the understanding and the comparability of techniques and tools used in the design of in-vehicle communication networks. This benchmark is motivated by the increasing use of algorithms intended to optimize the resource utilization in the design and configuration of automotive communication systems. For instance, typical objectives are the minimization of the network bandwidth usage and the reduction of the worst case response times of the frames. The main contribution of NETCARBENCH is to allow a finegrained user-defined parameterization of the generated message sets by means of XML-configuration files that specify the characteristics of the message sets and the variability thereof. Experiments suggest that the outcomes of NETCARBENCH are satisfactory in terms of their closeness to the input specifications. NETCARBENCH and its user manual are freely available under the GNU General Public License.

MPIGate: A Solution to Use Heterogeneous Networks for Assisted Living Applications

Existing sensors and actuators, that can be used in an AAL (ambient assisting living) environment, work on heterogeneous network protocols, e.g., WiFi, Bluetooth, EIB/KNX and Zigbee. For a given sensor/actuator, the choice of its underlying communication protocol is optimized according to its bandwidth and/or energy needs. However, integrating sensors/actuators of heterogeneous network protocols into an AAL system arises interoperability problems. In this paper, we present MPIGate, a multi-protocol gateway and interface for assisted living applications. Besides its multiple communication drivers for supporting the different protocols, MPIGate also proposes a database for storing the last updated sensor data as well as an user interface for both transparent data access and easy application development. MPIGate has been deployed in a smart home technical test bed at our LORIA labs. We presents some first results and discuss the lessons learnt.

Samovar: An evaluation framework for real time applications deployment over WSANs

Wireless Sensor and Actuator Networks (WSANs) combine sensors and actuators interconnected by wireless networks in order to perform distributed sensing and acting tasks. Closed-loop controllers can therefore be deployed on WSANs; such systems have to meet specific requirements in terms of performance, dependability, energy and cost which raises great challenges due to the unreliability of wireless communications. A way to ensure that a system meets the required properties is to model it and go through its analysis. Building a model requires both deep knowledge on the system as well as on the used framework. Therefore there is a need for frameworks well-suited to the targeted systems and to the properties to verify. We propose an approach meeting these conditions and a simulation framework, Samovar, based on Matlab / Simulink, allowing the modeling of the network protocols (Mac and routing services) and the resources sharing policy thanks to the TrueTime toolbox. Several classes of components (application, nodes, networks and middleware) and a clear semantics for their composition are identified. Furthermore, the design of Samovar was also driven by the need to transfer easily software components model between the concrete systems and its simulated model. The modeling and simulation method as well as the Samovar framework are illustrated on a Pursuit Evasion Game.

Timing properties requirements and robustness analysis of a platoon of vehicles

In order to improve mobility in cities, new initiatives of Intelligent Transportation Systems are emerging based on free-access electric vehicles. Making the vehicles everywhere at any time available requires a dispatching of these vehicles over a city, this could be accomplished at a large scale by trailing several vehicles without mechanical link with a leading driven vehicle (platooning). This paper first proposes a methodology to assess the performances of such urban platoon of vehicles using different platooning algorithms, taking into account a real operational architecture which means communications delays, tasks jitters, data sampling and finite resources. As a result some timing properties requirements are provided for the choice of each vehicle operational architecture for the deployment of the platooning function. Secondly an analysis is made on platooning operational architecture in order to evaluate the robustness of the platoon of vehicle under transient faults leading to information losses for the control of the vehicles.

A Model-Driven Co-Design Framework for Fusing Control and Scheduling Viewpoints

Model-Driven Engineering (MDE) is widely applied in the industry to develop new software functions and integrate them into the existing run-time environment of a Cyber-Physical System (CPS). The design of a software component involves designers from various viewpoints such as control theory, software engineering, safety, etc. In practice, while a designer from one discipline focuses on the core aspects of his field (for instance, a control engineer concentrates on designing a stable controller), he neglects or considers less importantly the other engineering aspects (for instance, real-time software engineering or energy efficiency). This may cause some of the functional and non-functional requirements not to be met satisfactorily. In this work, we present a co-design framework based on timing tolerance contract to address such design gaps between control and real-time software engineering. The framework consists of three steps: controller design, verified by jitter margin analysis along with co-simulation, software design verified by a novel schedulability analysis, and the run-time verification by monitoring the execution of the models on target. This framework builds on CPAL (Cyber-Physical Action Language), an MDE design environment based on model-interpretation, which enforces a timing-realistic behavior in simulation through timing and scheduling annotations. The application of our framework is exemplified in the design of an automotive cruise control system.

A model-based development environment for rapid-prototyping of latency-sensitive automotive control software

The innovation in the field of automotive embedded systems has been increasingly relying on software-implemented functions. The control laws of these functions typically assume deterministic sampling rates and constant delays from input to output. However, on the target processors, the execution times of the software will depend on many factors such as the amount of interferences from other tasks, resulting in varying delays from sensing to actuating. Three approaches supported by tools, namely TrueTime, T-Res, and SimEvents, have been developed to facilitate the evaluation of how timing latencies affect control performance. However, these approaches support the simulation of control algorithms, but not their actual implementation. In this paper, we present a model interpretation engine running in a co-simulation environment to study control performances while considering the run-time delays in to account. Introspection features natively available facilitate the implementation of self-adaptive and fault-tolerance strategies to mitigate and compensate the run-time latencies. A DC servo controller is used as a supporting example to illustrate our approach. Experiments on controller tasks with injected delays show that our approach is on par with the existing techniques with respect to simulation. We then discuss the main benefits of our development approach that are the support for rapid-prototyping and the re-use of the simulation model at run-time, resulting in productivity and quality gains.