基于SSR和ADS-B混合监视的机载编队防撞系统设计

由于设备性能的限制,民航飞机目前使用的机载防撞系统TCASⅡ不能适用于编队飞 行防撞。为了解决飞机编队飞行防撞以及与民航飞机TCASⅡ兼容的问题,给出了一种基 于二次雷达(SSR)和ADS-B混合监视的机载编队防撞系统的设计方案。该方案采用了TCAS主动 监视和被动监 视相结合的方法,利用唯一的24位S模式地址来识别和归类目标飞机,将TCAS的监视数据和A DS-B的监视数据进行数据融合来完成对目标飞机的监视和跟踪。通过将大型编队划分为多个 编队单元的方法,由长机负责保持各个编队单元之间的安全间距。采用收发器将长机产生的 位置保持和碰撞避免的操纵指令通过高频数据链路传送给各个编队单元,各个编队成员按照 操纵指令调整自己飞机的位置,完成对整个编队的位置保持和碰撞避免的集中控制和分散执 行。该方案可以为机载编队防撞系统的设计和实现提供参考和帮助。     

Computational techniques for the verification of hybrid systems

Hybrid system theory lies at the intersection of the fields of engineering control theory and computer science verification. It is defined as the modeling, analysis, and control of systems that involve the interaction of both discrete state systems, represented by finite automata, and continuous state dynamics, represented by differential equations. The embedded autopilot of a modern commercial jet is a prime example of a hybrid system: the autopilot modes correspond to the application of different control laws, and the logic of mode switching is determined by the continuous state dynamics of the aircraft, as well as through interaction with the pilot. To understand the behavior of hybrid systems, to simulate, and to control these systems, theoretical advances, analyses, and numerical tools are needed. In this paper, we first present a general model for a hybrid system along with an overview of methods for verifying continuous and hybrid systems. We describe a particular verification technique for hybrid systems, based on two-person zero-sum game theory for automata and continuous dynamical systems. We then outline a numerical implementation of this technique using level set methods, and we demonstrate its use in the design and analysis of aircraft collision avoidance protocols and in verification of autopilot logic.     

机载防撞系统垂直防撞的物理模型

如何准确预测和估算本机与入侵飞机相遇时在最接近点的垂直间隔距离,是机载防撞系统(TCAS)在垂直方向上选择防撞措施的关键问题.采用空间相遇几何学的方法,建立了本机与入侵飞机相遇时垂直防撞的两种物理模型,基于该模型推导出了预测两机之间垂直间隔距离的计算公式,并且进行了计算机仿真.仿真结果表明,该模型能够准确预测本机与入侵飞机相遇时在最接近点的垂直间隔距离.最后,给出了本机在垂直方向上选择防撞措施的决策咨询条件和逻辑处理流程.     

一种在一体化TCAS系统中通信编解码的实现方法

当前的飞机防撞系统是由TCAS和S模式应答机两个独立的子系统及其附属设备构成,这种结构给飞机的空间造成了极大的浪费,使得设计成本大大增加,同时庞大的体积也限制了TCAS在军事方面的应用。为解决这一问题,本文引入了一体化TCAS系统的概念,并设计了一体化TCAS系统中的通信编解码,给出了实验结果。     

ADS-B技术在通用航空避撞系统中应用研究

分析了 ADS-B 技术及其在运输航空监视管理系统、通用航空监视管理系统、无人机监视管理系统和避撞系统中应用情况。分析了构建通用航空避撞系统的必要性和构建基于 ADS-B 的通用航空避撞系统的可行性及其优势;研究表明基于 ADS-B 技术的通用航空避撞系统是非常符合我国通用航空特点和需求,在性能上较 TCAS 会有更多优势,除了用于通用航空飞机自身相互避撞外,还可实现通用航空飞机与无人机、运输航空飞机以及地面建筑物和障碍物的避撞。基于 ADS-B 技术对通用航空避撞系统总体构建,包括硬件部分、软件部分、数据部分和通用航空避撞系统规划。     

引入自动驾驶仪时空中交通防撞系统的仿真

空中交通防撞的主要功能是对本机和入侵目标机位置的预测以及在预测后对冲突的处理。在防撞过程中,入侵飞机的轨迹突然发生比较大的机动,则原有的防撞策略失效。2009年欧洲航空安全局认证通过了自动驾驶仪在避撞时与防撞系统耦合的方法,使问题得到了一定的解决。对避撞系统加入自动驾驶仪的方法进行了研究建模,并且对解决的情况进行了仿真,为民航空中交通避撞提出了一种新的思路。     

A Novel Approach towards the Designing of an Antenna for Aircraft Collision Avoidance System

TCAS/ACAS (Traffic/Aircraft Collision Avoidance System) is an airborne system designed to increase cockpit awareness of nearby aircraft and to service as a last defense against mid-air collisions between the aircrafts. In the existing system, four monopole stub elements are used as TCAS directional antenna and one blade type element is used as TCAS Omni-directional antenna. The transmission and reception frequencies of the TCAS antenna are 1.03G Hz and 1.09G Hz respectively. The existing TCAS antenna has some drawbacks such as low gain, large beamwidth, frequency and beam tuning/scanning issues etc. Antenna issues like unwanted signals reception may create difficulties in identifying the possible threats. In this paper, the focus is on the design and development of a novel Microstrip Antenna Array which can be used for TCAS/ACAS application. Two proposed antenna models are presented here – a Unit Element Dual Feed Microstrip Dual Patch Slotted Antenna and a Compact Microstrip Antenna Array. These are designed in CST tool to meet the current needs of aircraft Collision Avoidance System and to overcome the possible limitations associated with the existing techniques. The performance and other antenna characteristics have been explored from the simulation results followed by the antenna fabrication and measurement. A good Reflection Coefficient and VSWR with proper 50 Ω Impedance Matching, narrow Beamwidth, perfect Directional Radiation Pattern, high Gain and Directivity at the operating frequencies make this proposed antenna a good candidate for TCAS application. The proposed antenna would be expected to meet the requirements of the advanced avionics standards in terms of design simplicity, lightweight and high performance.     

基于TCASⅡ和ADS-B的组合监视防撞系统研究

为了有效地保持空中运行航空器的最小安全间隔和增加空域容量,急需发展独立可靠的空空监视和冲突检测与防撞系统.提出一种集合TCASⅡ和ADS-B技术的组合监视防撞系统,它以TCAsⅡ为基础,将ADS-B信息和TCASⅡ信息融合送入TCASⅡ决策单元,提供机栽监视、冲突检测和决策信息;同时以基于当前统计模型的卡尔曼滤波算法为...     

一种新的通用航空机载防撞逻辑设计方法

由于机载防撞系统(TCAS)是针对具有较大垂直高度变化率的大型飞机设计的,系统设定条件和与之相关的解脱建议并不能适用于通航飞机.针对通用航空的防撞问题,提出了一种基于马尔可夫决策过程(MDP)的防撞逻辑设计方法.首先,将飞机空中相遇过程的动态模型转换为离散转移函数;然后,基于防撞系统结果事件末端效用函数进行MDP建模,采用动态规划方法导出了最优防撞逻辑的迭代方程;最后,给出了通航飞机最优化防撞逻辑的设计流程并对最优防撞逻辑进行了计算机仿真.仿真结果表明,通过调整效用比参数可以在保证安全性能的同时有效降低系统告警率.在垂直相遇高度小于30 m的相遇过程占比高达18%的情况下,当告警率大于0.85时系统的碰撞概率仅为2.88×10-4左右.该设计方法对我国在低空空域通用飞机防撞系统的研究具有一定的参考价值.     

SMT-Based Symbolic Encoding and Formal Analysis of HML Models

Hybrid system is a dynamic system that involves continuous, discrete behaviors, and the interactions between continuous physical components and discrete controllers. In this paper a hybrid modeling language (called HML) for hybrid systems is extended with templates to achieve code reuse. For the formal analysis of the corresponding hybrid system models in this modeling language, these models are translated into SMT (satisfiability modulo theories) formulas as the input to an SMT solver dReal which retains the capability of bounded reachability analysis for non-linear hybrid systems. Moreover, dReal can produce data for potential traces of hybrid systems, thus it can be employed to simulate on hybrid systems. In this paper the simulation and reachability analysis are integrated in a prototype tool (open source). We present a case study for an inverted pendulum with PID (Proportional-Integral-Derivative) controllers and a rod reactor system for temperature control, both are verified to demonstrate the efficiency of the prototype tool. We conclude that, this modeling language is capable of modeling and verification of hybrid systems based on simulation and bounded reachability analysis.     

Design and development of a unit element microstrip antenna for aircraft collision avoidance system

Aircraft/traffic alert and collision avoidance system (ACAS/TCAS) is an airborne system which is designed to provide the service as a last defense equipment for avoiding mid-air collisions between the aircraft. In the existing system, four monopole stub-elements are used as ACAS directional antenna and one blade type element is used as ACAS omnidirectional antenna. The existing ACAS antenna has some drawbacks such as low gain, large beamwidth, frequency and beam tuning/scanning issues etc. Antenna issues like unwanted signals reception may create difficulties to identify the possible threats. In this paper, the focus is on the design and development of a unit element microstrip antenna which can be used for ACAS application and to overcome the possible limitations associated with the existing techniques. Two proposed antenna models are presented here, which are single feed and dual feed microstrip dual patch slotted antenna. These are designed and simulated in CST Microwave Studio tool. The performance and other antenna characteristics have been explored from the simulation results followed by the antenna fabrication and measurement. A good reflection coefficient, Voltage Standing Wave Ratio (VSWR), narrow beamwidth, perfect directional radiation pattern, high gain and directivity make this proposed antenna a good candidate for this application.     

民机空中交通警戒与防撞系统目标跟踪算法

空中交通警戒与防撞系统(TCAS)是航空电子综合环境监视系统的一个重要组成部分,它能有效降低空中飞行器间的碰撞威胁,对于提高飞行安全有着非常重要的意义。TCAS是一种不依赖地面设备的空中交通防撞系统。它能够探测在其领域内装有空中交通管制应答机的飞机,向驾驶员报告潜在的相撞目标。目标跟踪是TCAS的一个重要模块,能提供目标的飞行状态信息,并对目标的未来飞行状态进行预测。对空中目标进行稳定、高精确度的跟踪是目标跟踪模块的重要任务。本文介绍了基于扩展卡尔曼和交互式多模型(IMM-EKF)的目标跟踪算法,实现对目标的精确跟踪。通过仿真验证,证明算法能实现精确的目标跟踪,对防止空中相撞起到了积极作用。     

A game theoretic approach to controller design for hybrid systems

We present a method to design controllers for safety specifications in hybrid systems. The hybrid system combines discrete event dynamics with nonlinear continuous dynamics: the discrete event dynamics model linguistic and qualitative information and naturally accommodate mode switching logic, and the continuous dynamics model the physical processes themselves, such as the continuous response of an aircraft to the forces of aileron and throttle. Input variables model both continuous and discrete control and disturbance parameters. We translate safety specifications into restrictions on the system's reachable sets of states. Then, using analysis based on optimal control and game theory for automata and continuous dynamical systems, we derive Hamilton-Jacobi equations whose solutions describe the boundaries of reachable sets. These equations are the heart of our general controller synthesis technique for hybrid systems, in which we calculate feedback control laws for the continuous and discrete variables, which guarantee that the hybrid system remains in the “safe subset” of the reachable set. We discuss issues related to computing solutions to Hamilton-Jacobi equations. Throughout, we demonstrate out techniques on examples of hybrid automata modeling aircraft conflict resolution, autopilot flight mode switching, and vehicle collision avoidance     

Hybrid control system design using a fuzzy logic interface

A hybrid control system is proposed for regulating an unknown nonlinear plant. The interface between the continuous-state plant and the discrete-event supervisor is designed using a fuzzy logic approach. The fuzzy logic interface partitions the continuous-state space into a finite number of regions. In each region, the original unknown nonlinear plant is approximated by a fuzzy logic-based linear model, then state-feedback controllers are designed for each linear model. A high-level supervisor coordinates (mode switching) the set of closed-loop systems in a stable and safe manner. The stability of the system is studied using nonsmooth Lyapunov functions. For illustration and verification purposes, this technique has been applied to the well-known inverted pendulum balancing problem.     

基于机动目标威胁和粒子群算法的航路规划

执行飞行作战任务前对飞行航路进行合理规划十分重要,而环境/威胁建模是航路规划需要解决的首要问题。根据飞行过程中可能遇到的各种威胁源的特点,建立了山体障碍、恶劣气候及导弹、高炮固定阵地等各种静态威胁源的威胁概率函数模型,并进一步构建了机动导弹、高炮等动态威胁源的威胁概率函数模型;针对粒子群算法全局搜索能力强、收敛性好的特点,将粒子群算法运用到航路规划中,并进行了仿真实验,仿真结果证明了模型及算法的有效性。