Risk identification and safety assessment of human-computer interaction in integrated avionics based on STAMP

To solve the problem of risk identification and quantitative assessment for human-computer interaction(HCI)in complex avionics systems,an HCI safety analysis framework based on system-theoretical process analysis(STPA)and cognitive reliability and error analysis method(CREAM)is proposed.STPACREAM can identify unsafe control actions and find the causal path during the interaction of avionics systems and pilot with the help of formal verification tools automatically.The common performance conditions(CPC)of avionics systems in the aviation environment is established and a quantitative analysis of human failure is carried out.Taking the head-up display(HUD)system interaction process as an example,a case analysis is carried out,the layered safety control structure and formal model of the HUD interaction process are established.For the interactive behavior“Pilots approaching with HUD”,four unsafe control actions and35 causal scenarios are identified and the impact of common performance conditions at different levels on the pilot decision model are analyzed.The results show that HUD's HCI level gradually improves as the scores of CPC increase,and the quality of crew member cooperation and time sufficiency of the task is the key to its HCI.Through case analysis,it is shown that STPACREAM can quantitatively assess the hazards in HCI and identify the key factors that impact safety.

Hierarchical resource allocation for integrated modular avionics systems

Recently the integrated modular avionics （IMA） architecture which introduces the concept of resource partitioning becomes popular as an alternative to the traditional federated architecture. A novel hierarchical approach is proposed to solve the resource allocation problem for IMA systems in distributed environments. Firstly, the worst case response time of tasks with arbitrary deadlines is analyzed for the two-level scheduler. Then, the hierarchical resource allocation approach is presented in two levels. At the platform level, a task assignment algorithm based on genetic simulated annealing （GSA） is proposed to assign a set of pre-defined tasks to different processing nodes in the form of task groups, so that resources can be allocated as partitions and mapped to task groups. While yielding to all the resource con- straints, the algorithm tries to find an optimal task assignment with minimized communication costs and balanced work load. At the node level, partition parameters are optimized, so that the computational resource can be allocated further. An example is shown to illustrate the hierarchal resource allocation approach and manifest the validity. Simulation results comparing the performance of the proposed GSA with that of traditional genetic algorithms are presented in the context of task assignment in IMA systems.

Health management based on fusion prognostics for avionics systems

Health management permits the reliability of a system and plays a increasingly important role for achieving efficient system-level maintenance.It has been used for remaining useful life（RUL） prognostics of electronics-rich system including avionics.Prognostics and health management（PHM） have become highly desirable to provide avionics with system level health management.This paper presents a health management and fusion prognostic model for avionics system,combining three baseline prognostic approaches that are model-based,data-driven and knowledge-based approaches,and integrates merits as well as eliminates some limitations of each single approach to achieve fusion prognostics and improved prognostic performance of RUL estimation.A fusion model built upon an optimal linear combination forecast model is then utilized to fuse single prognostic algorithm representing the three baseline approaches correspondingly,and the presented case study shows that the fusion prognostics can provide RUL estimation more accurate and more robust than either algorithm alone.

Deploying Safety-Critical Applications on Complex Avionics Hardware Architectures

Aviation electronics (avionics) are sophisticated and distributed systems aboard an airplane. The complexity of these systems is constantly growing as an increasing amount of functionalities is realized in software. Thanks to the performance increase, a hardware unit must no longer be dedicated to a single system function. Multicore processors for example facilitate this trend as they are offering an increased system performance in a small power envelope. In avionics, several system functions could now be integrated on a single hardware unit, if all safety requirements are still satisfied. This approach allows for further optimizations of the system architecture and substantial reductions of the space, weight and power (SWaP) footprint, and thus increases the transportation capacity. However, the complexity found in current safety-critical systems requires an automated software deployment process in order to tap this potential for further SWaP reductions. This article used a realistic flight control system as an example to present a new model-based methodology to automate the software deployment process. This methodology is based on the correctness-by-construction principle and is implemented as part of a systems engineering toolset. Furthermore, metrics and optimization criteria are presented which further help in the automatic assessment and refinement of a generated deployment. A discussion regarding a tighter integration of this approach in the entire avionics systems engineering workflow concludes this article.

Intelligent Cost Modeling Based on Soft Computing for Avionics Systems

In parametric cost estimating, objections to using statistical Cost Estimating Relationships （CERs） and parametric models include problems of low statistical significance due to limited data points, biases in the underlying data, and lack of robustness. Soft Computing （SC） technologies are used for building intelligent cost models. The SC models are systemically evaluated based on their training and prediction of the historical cost data of airborne avionics systems. Results indicating the strengths and weakness of each model are presented. In general, the intelligent cost models have higher prediction precision, better data adaptability, and stronger self-learning capability than the regression CERs.

A formal approach using SysML for capturing functional requirements in avionics domain

In this work,a Model-Based Systems Engineering approach based on Sys ML is proposed.This approach is used for the capture and the definition of functional requirements in avionics domain.The motivation of this work is triple:guide the capture of functional requirements,validate these functional requirements through functional simulation,and verify efficiently the consistency of these functional requirements.The proposed approach is decomposed into several steps that are detailed to go from conceptual model of avionics domain to a formal functional model that can be simulated in its operating context.To achieve this work,a subset of Sys ML has been used as an intermediate modelling language to ensure progressive transformation that can be understood and agreed by system stakeholders.Formal concepts are introduced to ensure theoretical consistency of the approach.In addition,transformation rules are defined and the mappings between concepts of ARP4754 A civil aircraft guidelines and Sys ML are formalized through meta-model.The resulting formalization enables engineers to perform functional simulation of the top-level functional architecture extracted from operational scenarios.Finally,the approach has been tested on an industrial avionics system called the Onboard Maintenance System.

Hybrid partition-and network-level scheduling design for distributed integrated modular avionics systems

Distributed Integrated Modular Avionics(DIMA)develops from Integrated Modular Avionics(IMA)and realizes distributed integration of multiple sub-function areas.Timetriggered network provides effective support for time synchronization and information coordination in DIMA systems.However,inconsistency between processing resources and communication network destroys the time determinism benefiting from partitions and time-triggered mechanism.To ensure such time determinism and achieve guaranteed real-time performance,system design should collectively provide a global communication scheme for messages in network domain and a corresponding execution scheme for partitions in processing domain.This paper firstly establishes a general DIMA model which coordinates partitioned processing and time-triggered communication,and then proposes a hybrid scheduling algorithm using Mixed Integer Programming to produce feasible system schemes.Furthermore,incrementally integrating new functions causes upgrades or reconfigurations of DIMA systems and will generate integration cost.To control such cost,this paper further develops an optimization algorithm based on Maximum Satisfiability Problem and guarantees that the scheduling design for upgraded DIMA systems inherit their original schemes as much as possible.Finally,two typical cases,including a simple fully connected DIMA system case and an industrial DIMA system case,are constructed to illustrate our DIMA model and validate the effectiveness of our hybrid scheduling algorithms.

A Modeling Language Based on UML for Modeling Simulation Testing System of Avionic Software

With direct expression of individual application domain patterns and ideas,domain-specific modeling language（DSML） is more and more frequently used to build models instead of using a combination of one or more general constructs.Based on the profile mechanism of unified modeling language（UML） 2.2,a kind of DSML is presented to model simulation testing systems of avionic software（STSAS）.To define the syntax,semantics and notions of the DSML,the domain model of the STSAS from which we generalize the domain concepts and relationships among these concepts is given,and then,the domain model is mapped into a UML meta-model,named UML-STSAS profile.Assuming a flight control system（FCS） as system under test（SUT）,we design the relevant STSAS.The results indicate that extending UML to the simulation testing domain can effectively and precisely model STSAS.

A critique of reliability prediction techniques for avionics applications

Avionics （aeronautics and aerospace） industries must rely on components and systems of demonstrated high reliability. For this, handbook-based methods have been traditionally used to design for reliability, develop test plans, and define maintenance requirements and sustainment logistics, However, these methods have been criticized as flawed and leading to inaccurate and mis- leading results. In its recent report on enhancing defense system reliability, the U.S. National Academy of Sciences has recently discredited these methods, judging the Military Handbook （MIL- HDBK-217） and its progeny as invalid and inaccurate. This paper discusses the issues that arise with the use of handbook-based methods in commercial and military avionics applications. Alter- native approaches to reliability design （and its demonstration） are also discussed, including similarity analysis, testing, physics-of-failure, and data analytics for prognostics and systems health management.

Performability analysis of avionics system with multilayer HM/FM using stochastic Petri nets

The integrated modular avionics （IMA） architecture is an open standard in avionics industry, in which the number of functionalities implemented by software is greater than ever before. In the IMA architecture, the reliability of the avionics system is highly affected by the software applications. In order to enhance the fault tolerance feature with regard to software application failures, many industrial standards propose a layered health monitoring/fault management （HM/FM） scheme to periodically check the health status of software application processes and recover the malfunctioning software process whenever an error is located. In this paper, we make an analytical study of the HM/FM system for avionics application software. We use the stochastic Petri nets （SPN） to build a formal model of each component and present a method to combine the components together to form a complete system model with respect to three interlayer query strategies. We further investigate the effectiveness of these strategies in an illustrative system.

Thermal models for avionics pod cabin based on Stochastic Configuration Network(SCN)

The thermal failure of airborne avionics equipment is not optimistic.It is very necessary to establish relatively accurate thermal models for predicting thermal response of avionics equipment under different flight conditions.Traditional thermal modeling methods are often difficult to obtain accurate temperature response in complex conditions.This has severely restricted the application of these models.However,the Stochastic Configuration Network(SCN)model based on random algorithm can weaken the heat transfer mechanism and pay attention to the mining of experimental data,so that a more accurate thermal relationship might be obtained.In this paper,the SCN was used to analyze the experimental data of the avionics pod with a Ram Air Turbine(RAT)cooling system.The thermal models based on the SCN were finally built for avionics pod.Compared with the commonly used Random Vector Functional Link Network(RVFLN)thermal models,the SCN thermal models not only inherit the advantages of simple network structure and low computational complexity,but also have some merits,such as the better learning performance and the less human intervention.The presented SCN models provide a way to predict the thermal response of avionics pod cabin under the full flight envelope for a fighter.

An Intelligent Data Routing Scheme for Multi-UAV Avionics System Based on Integrated Communication Effectiveness

The rapid development of information technology promotes the transformation and development of future air combat,frommechanization to informatization,intelligence,and multiplatform integration.For the multiplatform avionics system in the unmanned aerial vehicle(UAV)-based network,we aim to address the data routing and sharing issues and propose an integrated communication effectiveness metric.The proposed integrated communication effectiveness is a hierarchical metric consisting of link effectiveness,node effectiveness,and data effectiveness.The link quality,link stability,node honesty,node ability,and data value are concurrently taken into account.We give the normal mathematical expression for the integrated communication effectiveness.We propose a hop-by-hop routing scheme based on a Q-learning algorithm considering the proposed effectiveness metric.Simulation results demonstrate that the proposed scheme is able to find the most efficient routing in the UAV network.

Mathematical Modeling and Design of RIS Deployment in a RIS-Assisted Metal Cuboid for WAIC Systems

Wireless avionics intra-communications(WAIC)is an emergent research topic,since it can improve fuel efficiency and enhance aircraft safety significantly.However,there are numerous baffles in an aircraft,e.g.,seats and cabin bulkheads,resulting in serious blockage and even destroying wireless communications.Thus,this paper focuses on the reconfigurable intelligent surface(RIS)deployment issue of RIS-assisted WAIC systems,to solve the blockage problem caused by baffles.We first propose the mirror-symmetric imaging principle for mathematically analyzing electromagnetic(EM)wave propagation in a metal cuboid,which is a typical structure of WAIC systems.Based on the mirror-symmetric imaging principle,the mathematical channel model in a metal cuboid is deduced in detail.In addition,we develop an objective function of RIS's location and deduce the optimal RIS deployment location based on the geometric center optimization lemma.A two-dimensional gravity center search algorithm is then presented.Simulation results show that the designed RIS deployment can greatly increase the received power and efficiently solve the blockage problem in the aircraft.

Human Factors While Using Head-Up-Display in Low Visibility Flying Conditions

Flying an aircraft in low visibility is still a challenging task for the pilot.It requires precise and accurate situational awareness(SA)in real-time.A Head-up Display(HUD)is used to project collimated internal and externalflight information on a transparent screen in the pilot’s forwardfield of view,which eliminates the change of eye position between Head-Down-Display(HDD)instru-ments and outer view through the windshield.Implementation of HUD increases the SA and reduces the workload for the pilot.But to provide a betterflying capability for the pilot,projecting extensive information on HUD causes human factor issues that reduce pilot performance and lead to accidents in low visibility conditions.The literature shows that human error is the leading cause of more than 70%of aviation accidents.In this study,the ability of the pilot able to read background and symbology information of HUD at a different level of back-ground seen complexity,such as symbology brightness,transition time,amount of Symbology,size etc.,in low visibility conditions is discussed.The result shows that increased complexity on the HUD causes more detection errors.

综合模块化航空电子系统(IMA)适航认证研究

对综合模块化航空电子系统(IMA)相关适航标准进行了研究,分析了IMA系统适航认证四个阶段的任务,包括模块认可、应用软件/专用硬件的认可、IMA系统的认可、IMA系统的飞机级综合。自此基础上,总结了IMA系统的符合性验证程序,包括硬件模块测试、独立系统功能测试、IMA系统集成测试、机上地面试验和飞行试验,为IMA系统的适航认证提供思路。

Communication Resource Planning Algorithm Based on Time Triggered DIMA Architecture

Traditional scheduling algorithms for avionics communication have the shortcoming of messages accumulation,the efficiency and reliability of the service can be improved by combining the distributed integrated modular avionics(DIMA)system with a time trigger mechanism.To further improve the utilization of system resources,the static scheduling algorithm of time triggered service is studied.By making the time trigger message schedule dispersedly,the stabilities of both the available time slots for the event triggered messages and the system will be improved.An improved two-dimensional bin packing algorithm is also presented to achieve the above-mentioned purpose with an extra benefit of better delay performance.

Admission Control of VL in AFDX Under HRT Constraints

Avionics full duplex switched ethernet（AFDX） is a switched interconnection technology developed to provide reliable data exchange with strong data transmission time guarantees in internal communication of the spacecraft or aircraft.Virtual link（VL） is an important concept of AFDX to meet quality of service（QoS） requirements in terms of end-to-end message deadlines.A VL admission control algorithm in AFDX network under hard real-time（HRT） constraints is studied.Based on the scheduling prin-ciple of AFDX protocol,a packet scheduling scheme under HRT constraints is proposed,and after that an efficient VL admission control algorithm is presented.Analytical proof that the algorithm can effectively determine whether VL should be admitted is given.Finally simulative examples are presented to promote the conclusion.

A novel BIST scheme for circuit aging measurement of aerospace chips

The avionics working environment is bad, easy to accelerate aging of circuits. Circuit aging is one of the important factors that influence the reliability of avionics, so circuit aging testing is of great significance to improve the reliability of avionics. As continuing aging would degrade circuit performance, aging can be monitored through precise measurement of performance degradation. However, previous methods for predicting circuit performance have limited prediction accuracy. In this paper, we propose a novel Built-In Self-Test（BIST） scheme for circuit aging measurement, which constructs self-oscillation loops employing parts of critical paths and activates oscillations by specific test patterns. An aging signature counter is then used to capture the oscillation frequency and in turn measure the aging state of the circuit. We propose to implement this measurement process by BIST. Experimental results show that the proposed in-field aging measurement is robust with respect to process variations and can achieve a precision of about 90%. The application of this scheme has a certain value to improve the reliability of avionics systems.

Transient Thermal Analysis of a Plate Fin Heat Sink with Green＇s Function

The accurate analyses for a plate fin heat sink with the ability to control the temperature of the avionics devices within a pre-set controllable temperature range are required both in the process of circuit design and for the real-time temperature monitoring purposes. In order to provide an insight into the behavior of the temperature of a plate fin heat sink subjected non-uniform heat density on the surfaces, it is necessary to obtain accurate analytical solutions yielding explicit formulas relating the dissipated power to the temperature rise at any point of avionics devices. This paper presents a method for thermal simulation of a plate fin heat sink using an analytical solution of the three-dimensional heat equation resulting from an appropriate plate fin heat sink transient thermal model. The entire solution methodology is illustrated in detail on the particular examples of the plate fin heat sink subjected non-uniform heat density on the surfaces. The transient temperature profiles are obtained for different positions at the surface of the plate fin heat sink. The analytical results are compared with measurements made on the surface of the cold plate and it is found that they are in good agreement with an error of less than 3 K.

An overview on development of miniature unmanned rotorcraft systems

In this article,we attempt to document a technical overview on modern miniature unmanned rotorcraft systems.We first give a brief review on the historical development of the rotorcraft unmanned aerial vehicles(UAVs),and then move on to present a fairly detailed and general overview on the hardware configuration,software integration,aerodynamic modeling and automatic flight control system involved in constructing the unmanned system.The applications of the emerging technology in the military and civilian domains are also highlighted.