FlexRay Protocol Research Articles

Recursive set‐membership filtering for two‐dimensional shift‐varying systems with FlexRay protocol and hybrid cyber attacks

Recursive set‐membership filtering for two‐dimensional shift‐varying systems with FlexRay protocol and hybrid cyber attacks

Efficient Utilization of Bandwidth in Static Segment of FlexRay Protocol

Efficient Utilization of Bandwidth in Static Segment of FlexRay Protocol

Distributed interval observer-based robust control for multirate systems under the FlexRay protocol

In this paper, an interval observer-based control problem under the FlexRay protocols is investigated for a class of multirate systems in which the noises are assumed to be unknown but bounded. The FlexRay protocol is employed to schedule the information transfer so as to reduce the communication burden. Based on the FlexRay protocol and the multirate sampling mechanism, a new measurement output representation is established with the help of the lifting technique and the augmentation technique, and then, a sufficient condition is proposed to guarantee the interval observer estimation error dynamics are bounded. In addition, the interval observer gain and the H∞ controller gain are obtained by solving the linear matrix inequalities, which further ensure the H∞ performance of the closed-loop system. Finally, a numerical simulation verifies the effectiveness of the FlexRay protocols and interval observer-based controllers.

Average delay analysis of soft deadline messages scheduled in the dynamic segment of FlexRay protocol

The FlexRay communication protocol provides high bandwidth for supporting both hard deadline and soft deadline traffic in in-vehicle communication networks. In this paper, we carry out delay analysis of soft deadline traffic which is handled by the dynamic segment of FlexRay. We model the arrival of these messages as Poisson processes, and use queuing theory to evaluate the average delay that they experience. Initially, we consider three nodes competing for service, assuming that two out of three can transmit messages in any FlexRay cycle and obtain expressions for the evolution of the corresponding queues. We also determine the range of message arrival rates for which the queues are stable. These results are then extended to the general case of N queues. The analytical results are compared with those obtained by simulation for a typical system.

Set-Membership State Estimation for Multirate Nonlinear Complex Networks Under FlexRay Protocols: A Neural-Network-Based Approach.

In this article, the set-membership state estimation problem is investigated for a class of nonlinear complex networks under the FlexRay protocols (FRPs). In order to address practical engineering requirements, the multirate sampling is taken into account which allows for different sampling periods of the system state and the measurement. On the other hand, the FRP is deployed in the communication network from sensors to estimators in order to alleviate the communication burden. The underlying nonlinearity studied in this article is of a general nature, and an approach based on neural networks is employed to handle the nonlinearity. By utilizing the convex optimization technique, sufficient conditions are established in order to restrain the estimation errors within certain ellipsoidal constraints. Then, the estimator gains and the tuning scalars of the neural network are derived by solving several optimization problems. Finally, a practical simulation is conducted to verify the validity of the developed set-membership estimation scheme.

FlexRay protocol based distributed nonfragile dissipative filtering of state-saturated switched stochastic systems

ABSTRACT This article concentrates on the finite-time nonfragile distributed dissipative filtering issue for time-varying switched stochastic systems (SSSs) with state saturations over wireless sensor networks based on FlexRay communication protocol. To effectively deal with the resource restriction problem of the public communication network and energy consumption of the sensor nodes, the FlexRay communication protocol, including the Round-Robin protocol (RRP) and weighted try-once-discard protocol (WTODP), is introduced to schedule the data transmission of each sensor node. In addition, the phenomenon of randomly occurring gain variations (ROGVs) of filter parameters, characterised by the Bernoulli distributed random variables, is taken into consideration for the implementation of desired filter. A sufficient condition under the average dwell time (ADT) restriction is presented to guarantee the mean-square exponential stability and stochastically dissipative property of the augmented filtering error system (AFES) in a finite horizon. Moreover, the gains of the dissipativity-based filters are achieved by solving recursive linear matrix inequalities (RLMIs). Finally, an illustrative example is provided to exhibit the effectiveness of the designed filter.

Ultimately Bounded PID Control for T–S Fuzzy Systems Under FlexRay Communication Protocol

This paper investigates the ultimately bounded proportional-integral-derivative (PID) control problem for a class of discrete-time Takagi-Sugeno fuzzy systems subject to unknown-but-bounded noises and protocol constraints. The signal transmissions from sensors to the remote controller are realized via a communication network, where the FlexRay protocol is employed to flexibly schedule the information exchange. Such FlexRay protocol is characterized by both the time- and event-triggered mechanisms which are conducted in a cyclic manner. By using a piecewise approach, the measurement outputs affected by the FlexRay protocol are established based on a switching model. Then, a fuzzy PID controller is proposed with a concise and realizable structure. To evaluate the performance of the controlled system, a special time-sequence is introduced that accounts for the behavior of the FlexRay protocol. Subsequently, a general framework is obtained to verify the boundedness of the closed-loop system and then the controller gains are designed by minimizing the bound of the concerned variables. In the end, a simulation study is conducted to validate the effectiveness of the developed control scheme.

Finite-Horizon $H_{\infty }$ Filtering via a High-Rate Network With the FlexRay Protocol

This paper addresses the finite-horizon <inline-formula><tex-math notation="LaTeX">$H_{\infty }$</tex-math></inline-formula> filtering problem for a class of discrete time-varying nonlinear systems over high-rate networks whose signal exchanges are scheduled by the FlexRay protocol. To improve the efficiency of the data transmission, a high-rate network is deployed for the measurement signals to be broadcasted from the sensors to the filter. The FlexRay protocol is embedded into the high-rate network to orchestrate the transmission rule of the signals with different attributes, thereby further enhancing the transmission flexibility. On the basis of the Round-Robin and Try-Once-Discard protocols, a novel FlexRay-protocol-based measurement model is proposed by using certain data holding strategies. A sufficient condition is provided to guarantee that the filtering error dynamics meets the desirable disturbance attenuation level against exogenous disturbances over a finite horizon. The parameterized form of the filter gain is attained by the solutions to some matrix inequalities. Numerical simulation is carried out to substantiate the proposed filter design algorithm.

Distributed Recursive State Estimation for a Class of Multi-Rate Nonlinear Systems Over Wireless Sensor Networks Under FlexRay Protocols

Distributed Recursive State Estimation for a Class of Multi-Rate Nonlinear Systems Over Wireless Sensor Networks Under FlexRay Protocols

Recursive Set-Membership State Estimation Over a FlexRay Network

In this article, we investigate the set-membership state estimation problem for a class of time-varying systems with non-Gaussian noises over a FlexRay network. To mitigate the communication load and improve the flexibility of the data scheduling, the FlexRay protocol (FRP) governed by both the time-triggered and event-triggered rules is exploited to regulate the signal transmission in a cyclic fashion. A new expression of the input signal to the state estimator is formulated with intention to account for the effect of the FRP. Accordingly, a multirate model (orchestrating the sampling/updating rates of the target plant, sensors, and state estimator) is proposed and then transformed into a single-rate one with the help of the lifting technique and the vector augmentation method. Subsequently, sufficient conditions are provided for the true states to always reside in an ellipsoid at each time instant in the presence of the non-Gaussian noises, and such an ellipsoid is then minimized in the matrix-trace sense. An online optimization algorithm is developed to parameterize the estimator gains by means of the solution to certain recursive matrix inequalities. Numerical results demonstrate the validity of the proposed protocol-based set-membership state estimator design scheme.

Efficient Physical Layer Key Agreement for FlexRay Networks

The FlexRay protocol provides deterministic and fault-tolerant communication for automotive applications with stringent requirements regarding reliability and real-time performance. But the lack of intrinsic security mechanisms makes FlexRay vulnerable to spoofing and DoS attacks while existing features are not sufficient to assure reliable communication in the presence of adversaries. Since adding cryptography mandates for secret shared keys, providing secure key establishment techniques is critical in assuring the intended security objectives. In this paper we propose a backward compatible key agreement scheme for FlexRay communication based on intrinsic characteristics of the FlexRay physical layer. In particular, we determine that the symbol window is suitable for implementing a covert channel based on physical properties of the bus which allows us to bootstrap a secure session key between two nodes or to re-enforce existing shared keys. We evaluate and discuss the performance of software-based implementations of the proposed mechanism on two different automotive embedded platforms relying only on the application level.

Impact Analysis of Electrical Fast Transients on FlexRay In-Vehicle Networks

Distributed vehicular control systems are responsible for safety-critical applications, depending on communication protocols. In this context, the FlexRay protocol is frequently applied for electronic control unit interconnection in critical applications. Thus, it must be tested in different fault scenarios to verify if the protocol could comply with hard timing constraints. Typical faults that have been studied are electrical fast transients, in which power switching systems can generate transients that degrade in-vehicle communication. Recent efforts focus on the specification of test methods for electromagnetic compatibility in communication transceivers, but without considering the negative impact on critical control system messages and its periodicity. This work presents a contribution by exploring the IEC 62228-3:2019 standard to guide the application of a test method with a specific test board to evaluate the impact of these faults on the control law performance of critical automotive control systems based on FlexRay protocol. The results show that during the test scenarios using the fault injection method, the transients cause performance degradation peaks between 2.9 and 94.5 μs, much higher compared to a typical FlexRay delay. The results emphasize that critical control systems must be stressed with consistent tests to map fault behaviors, observing the operation limit under faults.

Scalable Holistic Scheduling of Safety-critical Systems on In-vehicle TDMA Networks

Recently, the authors have proposed a scalable holistic scheduling approach for time-triggered applications on FlexRay, under end-to-end deadline and data dependency constraints. This approach divides the problem to two sub-problems that can be solved separately. The first sub-problem optimally schedules the set of messages to minimize number of used slots, and with respect to information exchanges between tasks and messages, end-to-end deadlines and FlexRay protocol constraints. The second sub-problem optimally schedules the set of tasks to minimize tasks response times, with respect to the solution returned by the first sub-problem. In this paper, our goal is to increase the scalability of our solution to each sub-problem. We propose a greedy heuristic approach for the first sub-problem that can find feasible solutions at a low runtime cost. In addition, to resolve assignment conflicts, we apply rescheduling the conflicted application with offset modification and priority promotion procedures. Furthermore, we show that the task scheduling in the second sub-problem can be divided into K independent child sub-problems, where K is the number of ECUs. Our experiments show high scalability and efficiency of our approaches comparing with our optimization-based approaches in the previous work.

DDS middleware on top of FlexRay networks: Simulink blockset implementation of electrical vehicle using FlexRay protocol and its adaptation to DDS concept

We designed a Simulink vehicle blockset in order to integrate safety, reliability, best condition of luxury and comfort in modern models by adding or modifying some old algorithms, implemented as application layer components. The proposed blockset corresponds to the Society of Automotive Engineers benchmark which is normally connected by the CAN bus that we replaced by the FlexRay bus. We used the Embedded MATLAB tool for implementing this blockset in order to generate a portable C standard code. To connect the designed sub-blocks together, we applied the real-time middleware data distribution service (DDS) and the FlexRay protocol. In this paper, we focused our interest on the implementation of the Simulink blockset with its different sub-blocks and we then identified their DDS entities and their QoS profiles. We also calculated the worst-case response time, based on the full scheduling model, which served to configure the DDS deadline QoS and the FlexRay protocol parameters.

An Integrated Self-Diagnosis System for an Autonomous Vehicle Based on an IoT Gateway and Deep Learning

This paper proposes “An Integrated Self-diagnosis System (ISS) for an Autonomous Vehicle based on an Internet of Things (IoT) Gateway and Deep Learning” that collects information from the sensors of an autonomous vehicle, diagnoses itself, and the influence between its parts by using Deep Learning and informs the driver of the result. The ISS consists of three modules. The first In-Vehicle Gateway Module (In-VGM) collects the data from the in-vehicle sensors, consisting of media data like a black box, driving radar, and the control messages of the vehicle, and transfers each of the data collected through each Controller Area Network (CAN), FlexRay, and Media Oriented Systems Transport (MOST) protocols to the on-board diagnostics (OBD) or the actuators. The data collected from the in-vehicle sensors is transferred to the CAN or FlexRay protocol and the media data collected while driving is transferred to the MOST protocol. Various types of messages transferred are transformed into a destination protocol message type. The second Optimized Deep Learning Module (ODLM) creates the Training Dataset on the basis of the data collected from the in-vehicle sensors and reasons the risk of the vehicle parts and consumables and the risk of the other parts influenced by a defective part. It diagnoses the vehicle’s total condition risk. The third Data Processing Module (DPM) is based on Edge Computing and has an Edge Computing based Self-diagnosis Service (ECSS) to improve the self-diagnosis speed and reduce the system overhead, while a V2X based Accident Notification Service (VANS) informs the adjacent vehicles and infrastructures of the self-diagnosis result analyzed by the OBD. This paper improves upon the simultaneous message transmission efficiency through the In-VGM by 15.25% and diminishes the learning error rate of a Neural Network algorithm through the ODLM by about 5.5%. Therefore, in addition, by transferring the self-diagnosis information and by managing the time to replace the car parts of an autonomous driving vehicle safely, this reduces loss of life and overall cost.

Design Scheme of Communication Node Based on FlexRay Bus

As a high-speed and reliable serial communication bus, the FlexRay bus has gradually become the mainstream of vehicle network systems. In order to verify the feasibility of the bus technology in aerospace applications, this paper designs a FlexRay communication node based on TI's high-performance microcontroller TMS570LS3137 for security systems. In the whole system, with the DSP of core, the FlexRay communication protocol is achieved by using the bus controller TJA1080 to carry out data transmission. This method is suitable for data transmission of pint and medium-sized UAV (unmanned air vehicles) flight control system with high integration and high transmission rate.

Schedule construction under precedence constraints in flexray in-vehicle networks

As embedded time-triggered applications have widely replaced mechanical systems in modern automobiles, holistic scheduling of tasks and messages of such applications on in-vehicle networks has become a critical issue. For offering QoS (Quality of Service) guarantees, the holistic schedule must satisfy numerous constraints such as protocol specifications, delay constraints and precedence constraints between tasks schedules and messages transmissions. Existing approaches to this problem search through a vast design space of all possible joint task and message schedules. This leads to a high complexity and limits the scalability of such approaches for scheduling the large scale systems. To cope with this problem, we propose an approach that divides the holistic scheduling problem to two sub-problems: the sub-problem of message scheduling and the sub-problem of task scheduling, while precedence relations and end-to-end information passing between task instances and messages are preserved and the end-to-end deadlines are guaranteed. This helps to reduce the workload on the problem solvers and improves efficiency and scalability. In the first sub-problem, our approach optimizes scheduling the set of messages and allocates time windows for scheduling each task with respect to precedence constraints, end-to-end deadlines and FlexRay protocol specifications. The length of each time window helps to preserve the respective tasks schedulability and to provide flexibility for both task and message scheduling. The objective is defined with respect to extensibility issues. In the second sub-problem, our approach optimizes schedule of the set of tasks with respect to their allocated time windows and timing constraints. The objective is defined with respect to latency issues. We optimize the solution to each sub-problem using Mixed Integer Linear Programming optimization framework. Performance evaluations show that, compared with existing holistic scheduling approaches, our approach is more scalable and obtains better solutions in a reasonable amount of time.

Verilog Implementation of Collision Avoidance System based on FlexRay Protocol

Background/Objective: The objective of this paper is to provide an insight into the FlexRay protocol, as well as build a simple collision avoidance system based on it. FlexRay is a next generation intra-vehicular communication protocol that provides fault-tolerant, flexible, high data rate and deterministic communication between the different electronic units in an automobile, mainly used for advanced automobile control and safety-critical applications. Methods/Statistical Analysis: Here, a simple collision avoidance system for an automobile is built using Verilog HDL, where data is transmitted according to the FlexRay protocol. Separate Verilog modules are designed for an ultrasonic sensor and a motor. Data is transmitted in the FlexRay frame format. Simulation of results are tested in ModelSim tool. Findings: It is observed that under the FlexRay protocol, data is transmitted at a much greater speed. Also, there are better fault tolerance and better error detection mechanisms, all of which are quintessential for a safety-critical application like collision avoidance. It also ensures safe communication between the devices inside an automobile. Applications/Improvements: More advanced automotive applications like automatic steering, temperature regulation, etc., can be implemented in a similar manner based on the protocol. The protocol is mainly used for safety-critical applications owing to its huge cost of implementation.

Optimal scheduling of the flexray static segment based on two-dimensional bin-packing algorithm

FlexRay is a reliable and hard real-time in-vehicle communication protocol that is strongly promoted by car manufacturers as the de facto standard in the automotive domain. The protocol offers both a time-triggered and an eventtriggered architecture. This paper focuses on the optimal scheduling of the time-triggered component of FlexRay known as the static (ST) segment using a two-dimensional bin-packing technique. To maximize the bandwidth utilization in the ST segment, a fast heuristic as well as an efficient integer linear programming approach are proposed. Our methods directly schedule signals into slots including frame packing, according to signal-based data scheduling and the slot/ cycle multiplexing mechanisms presented by the latest version of the FlexRay protocol. The benefits of our proposed methods are demonstrated by extensive experiments on synthetic and an automotive X-by-wire system case study. An additional test case is examined to emphasize the superior performance of the proposed approach relative to that of existing optimal scheduling approaches.

A Vehicle SoC Fault Diagnosis Technique using FlexRay Protocol

In this paper, we propose vehicle SoC fault diagnosis platform using FlexRay protocol in order to detect the faults of semiconductor control chip even after vehicle production. Before FlexRay protocol by sending NFI (Null Frame Indicator) bit among the header segment and a specific identifier in the payload segment of FlexRay frame, this technique can be distinguishable from normal mode and test mode. By using this technique, it is possible to detect the faults such as performance degradation of vehicle network system caused by the aging or several problems of vehicle semiconductor chip. Also high reliability and safety of vehicle can be maintained by using structural test for vehicle SoC fault detection.