Automotive can network response time analysis with variable jitter

Many methods to calculate message latencies for Controller Area Network (CAN) have previously been presented based upon the static worst-case behaviour of the system. With the use of modern simulation tools however, the behaviour of CAN networks can be simulated dynamically in order to find the likely worst-case response times for CAN messages. This paper shows the development of an automotive body control network model to be used as the basis for further simulations. A method to simulate the Worst-Case Response Time of this model is then presented, taking into account random queuing jitter.<br /

A Comparison of Compositional Schedulability Analysis Techniques for Hierarchical Real-Time Systems

Schedulability analysis of hierarchical real-time embedded systems involves defining interfaces that represent the underlying system faithfully and then compositionally analyzing those interfaces. Whereas commonly used abstractions, such as periodic and sporadic tasks and their interfaces, are simple and well studied, results for more complex and expressive abstractions and interfaces based on task graphs and automata are limited. One contributory factor may be the hardness of compositional schedulability analysis with task graphs and automata. Recently, conditional task models, such as the recurring branching task model, have been introduced with the goal of reaching a middle ground in the tradeoff between expressivity and ease of analysis. Consequently, techniques for compositional analysis with conditional models have also been proposed, and each offer different advantages. In this work, we revisit those techniques, compare their advantages using an automotive case study, and identify limitations that would need to be addressed before adopting these techniques for use with real-world problems

Integrating wireless technologies into intra-vehicular communication

With the emergence of connected and autonomous vehicles, sensors are increasingly deployed within car. Traffic generated by these sensors congest traditional intra-vehicular networks, such as CAN buses. Furthermore, the large amount of wires needed to connect sensors makes it hard to design cars in a modular way. These limitations have created impetus to use wireless technologies to support intra-vehicular communication. In this dissertation, we tackle the challenge of designing and evaluating data collection protocols for intra-car networks that can operate reliably and efficiently under dynamic channel conditions. First, we evaluate the feasibility of deploying an intra-car wireless network based on the Backpressure Collection Protocol (BCP), which is theoretically proven to be throughput-optimal. We uncover a surprising behavior in which, under certain dynamic channel conditions, the average packet delay of BCP decreases with the traffic load. We propose and analyze a queueing-theoretic model to shed light into the observed phenomenon. As a solution, we propose a new protocol, called replication-based LIFO-backpressure (RBL). Analytical and simulation results indicate that RBL dramatically reduces the delay of BCP at low load, while maintaining its high throughput performance. Next, we propose and implement a hybrid wired/wireless architecture, in which each node is connected to either a wired interface or a wireless interface or both. We propose a new protocol, called Hybrid-Backpressure Collection Protocol (Hybrid-BCP), for the intra-car hybrid networks. Our testbed implementation, based on CAN and ZigBee transceivers, demonstrates the load balancing and routing functionalities of Hybrid-BCP and its resilience to DoS attacks. We further provide simulation results, obtained based on real intra-car RSSI traces, showing that Hybrid-BCP can achieve the same performance as a tree-based protocol while reducing the radio transmission power by a factor of 10. Finally, we present TeaCP, a prototype Toolkit for the evaluation and analysis of Collection Protocols in both simulation and experimental environments. TeaCP evaluates a wide range of standard performance metrics, such as reliability, throughput, and latency. TeaCP further allows visualization of routes and network topology evolution. Through simulation of an intra-car WSN and real lab experiments, we demonstrate the functionality of TeaCP for comparing different collection protocols

Diseño e implementación de una herramienta para la planificación de ejecutivos cíclicos

Uno de los planteamientos válidos para realizar la implementación de la gestión de tareas en sistemas de tiempo real periódicos lo constituye la utilización de planificadores cíclicos. Este método de planificación goza de un alto grado de determinismo, previsibilidad, fiabilidad y sencillez de implementación. Además, es un método bien conocido y ampliamente utilizado en entornos industriales. El principal inconveniente de este tipo de planificador es la falta de flexibilidad, ya que cualquier cambio en el conjunto de tareas o en sus características temporales obliga a rehacer el plan de ejecución. Para solventar estos inconvenientes es necesario, y muchas veces indispensable, contar con herramientas que ayuden a los diseñadores del sistema en la creación de la planificación cíclica de forma automática. En este trabajo se describe una herramienta denominada CICLIC, que sirve de soporte en el diseño o regeneración de planificaciones cíclicas. El mecanismo de diseño se basa en algoritmos de búsqueda exhaustiva que utilizan reglas heurísticas para optimizar el camino de búsqueda

Diseño e implementación de una herramienta para la planificación de ejecutivos cíclicos

Uno de los planteamientos válidos para realizar la implementación de la gestión de tareas en sistemas de tiempo real periódicos lo constituye la utilización de planificadores cíclicos. Este método de planificación goza de un alto grado de determinismo, previsibilidad, fiabilidad y sencillez de implementación. Además, es un método bien conocido y ampliamente utilizado en entornos industriales. El principal inconveniente de este tipo de planificador es la falta de flexibilidad, ya que cualquier cambio en el conjunto de tareas o en sus características temporales obliga a rehacer el plan de ejecución. Para solventar estos inconvenientes es necesario, y muchas veces indispensable, contar con herramientas que ayuden a los diseñadores del sistema en la creación de la planificación cíclica de forma automática. En este trabajo se describe una herramienta denominada CICLIC, que sirve de soporte en el diseño o regeneración de planificaciones cíclicas. El mecanismo de diseño se basa en algoritmos de búsqueda exhaustiva que utilizan reglas heurísticas para optimizar el camino de búsqueda