飞机着陆时的容错导航

研究了飞机在微波着陆环境中的传感器容错系统。该系统的主要目的是检测辅助导航设备和机载传感器的故障,并在这些传感器可能发生故障时提供可靠的飞机状态估计值。自动导航和控制系统利用这些状态估计控制和引导飞机按预定路线降落。     

A new approach to robust fault detection and identification

A methodology for instrument fault detection and identification (FDI) in linear dynamical systems subject to plant parameter variations or uncertainties is presented. At the heart of this approach is a robust estimator for which the necessary and sufficient conditions to its existence are outlined. The robust estimator can simultaneously estimate the unmeasurable state variables of the system for the purpose of control and provide necessary information for FDI purposes. A novel feature of this approach is that it can actually identify the shape and magnitude of the failures. The scheme allows for fast and accurate FDI, and can account for structural uncertainties and variations in the parameters of the dynamical model of the system. The overall fault tolerant control system strategy proposed is verified through simulation studies performed on the control of a vertical takeoff and landing (VTOL) aircraft in the vertical plane     

An adaptive array detector with mismatched signal rejection

An adaptive detection algorithm with a sensibility parameter for rejecting unwanted signals is presented. This algorithm is a simple modification of the generalized likelihood ratio (GLR) detector (or test) for detecting a signal in zero mean Gaussian noise with unknown correlation matrix. Specifically, the adaptive detection algorithm is obtained by introducing an arbitrary positive scalar, which is called the sensitivity parameter, into the GLR detector as a multiplier of an already existing quadratic term. The GLR detector then becomes a special case of this detector for the unity sensitivity parameter. It is shown that the sensitivity parameter controls the degree to which unwanted signals are rejected. From numerical examples, it is demonstrated how the sensitivity parameter can be chosen such that unwanted signals, can be rejected while maintaining acceptable detection loss for slightly mismatched signals. Further insight into previous work on adaptive detection is also given     

Instrument Fault Detection

The dedicated observer scheme (DOS) for detecting incipient instrument faults by functional redundancy is applied to a simulation of the lateral axis control system of a hydrofoil boat. Observer designs and detection logic are found for which 14 separate instrument faults are detected without false alarms. The scheme is shown to be robust with respect to variations in two significant physical parameters.     

Minimum Sensitivity Controllers with Application to VTOL Aircraft

A technique is described for the design of a fixed-gain feedback controlier for a vertical takeoff and landing (VTOL) aircraft, which minimizes the effect of arbitrary variations in the aircraft dynamics on aircraft performance over varying flight conditions. The design method involves the assignment of the eigenvalues of the aircraft model to prescribed locations in the complex plane and the minimization of their sensitivities to model parameter variations. This controller is shown to possess better tracking and regulating capabilities than another fixed-gain controller designed merely for assignment of eigenvalues using nominal parameter values, without any consideration of their sensitivity to plant parameter variations.     

某型号空气压缩机的常见故障及排除方法

目的正确分析、准确判断空气压缩机的常见故障。方法通过观察、测量、试验等方法判断故障部位和类型。结果故障主要是活塞环严重磨损、活门密封性降低、偏心轮扭断、润滑油路堵塞和活门严重故障等。结论迅速快捷地排除空压机故障。     

Planetary Radio Astronomy Receiver

Voyager (Mariner Jupiter/Saturn 1977) spacecraft will carry the first experiment specifically designed to measure low-frequency nonthermal planetary radio emissions. The technical aspects of the planetary radio astronomy instrument are described here. Signals from 10-m orthogonal monopoles are processed to measure polarization and for either maximum sensitivity or observation of rapid temporal variations. The 0.3-?V/?kHz (i.e., -117 dBm/kHz with a 50-12 source) sensitivity and the 140-dB dynamic range achieved allow signals to be observed from near earth through planetary encounter. Stepped-or fixed-frequency operation is commandable over a range of 1.2 kHz to 40.5 MHz with internal calibration for absolute amplitude measurement.     

发动机故障方程的最少故障整体优化解

 发动机故障诊断是根据有限的发动机性能参数的测量值在众多的可能发生但不一定发生的故障之中确定出故障的类别和程度。测量参数与故障参数之间的关系通常表示为亚定的线性方程组△y=A△x,式中△y为测量参数向量而△x为故障参数向量。引入最少故障原理可以对亚定的故障方程组求解。求解方法可分为整体优化解法和组合优化解法两大类。本文给出两种基于最少故障原理的约束整体优化解法。最少故障原理和约束条件的引入可以有效地保证最优解的确定性和合理性。文中还给出了利用整体优化解法进行发动机故障诊断的实例。     

On the Sensitivity of a Fixed-Point Smoothing Algorithm

This paper presents a simple approach to the derivation of sensitivity measures of smoothing algorithms. It is proposed that the known sensitivity results of the Kalman filtering algorithm be utilized along with the state augmentation approach for this purpose. The sensitivity measures so obtained are easier to compute than the ones available in the literature. It is then shown that the fixed-point smoothing algorithm, derived recently by Biswas and Mahalanabis [1], [2], is less sensitive to model parameter variations than the algorithm studied by Griffin and Sage [7], [8]. The case of a satellite tracking problem is presented by way of illustrating the results.     

System sensitivity to parametric variations in the problem of lateral motion flight vehicle control

The results of investigation of dynamic system sensitivity to parametric variations in the channel of flight vehicle lateral motion are presented using the notion of infinitesimal transformation. The exact relationships establishing a link between the structure of parameter deviation and that of system phase coordinate deviation are obtained.     

波音737飞机主起落架安装部位故障、原因与应对措施

对波音737飞机主起落架安装部位结构进行了简要介绍;基于30余年来波音737系列飞机运营主起落架安装部位的相关服务通报,概括了737系列飞机主起落架安装部位曾出现过的故障;进而分析了这些故障出现的原因,列举了波音公司实践中针对这些故障而采取的应对措施。本文工作对我国大型客机的设计具有现实的参考价值。     

Fine Resolution Epithermal Neutron Detector (FREND) Onboard the ExoMars Trace Gas Orbiter

ExoMars is a two-launch mission undertaken by Roscosmos and European Space Agency. Trace Gas Orbiter, a satellite part of the 2016 launch carries the Fine Resolution Neutron Detector instrument as part of its payload. The instrument aims at mapping hydrogen content in the upper meter of Martian soil with spatial resolution between 60 and 200 km diameter spot. This resolution is achieved by a collimation module that limits the field of view of the instruments detectors. A dosimetry module that surveys the radiation environment in cruise to Mars and on orbit around it is another part of the instrument.This paper describes the mission and the instrument, its measurement principles and technical characteristics. We perform an initial assessment of our sensitivity and time required to achieve the mission goal. The Martian atmosphere is a parameter that needs to be considered in data analysis of a collimated neutron instrument. This factor is described in a section of this paper. Finally, the first data accumulated during cruise to Mars is presented.     

异型螺杆铣削刀具监控仪的研究

针对异形螺杆铣削加工特点,阐述了异型螺杆铣削刀具磨损/破损监控原理,采用振动信号和功率信号特征值作为检测刀具磨损的参量,利用自适应神经--模糊推理系统(ANFIS)算法和哈默斯坦非线性系统的辨识,建立刀具状态监控模型,并基于模型进行了监控仪的设计,并对监控系统的设计做了详细的论述.经试验验证,该系统满足了对刀具监控的要求.     

VTOL Aircraft Control Output Tracking Sensitivity Design

A method is presented for reducing trajectory sensitivity and achieving robust asymptotic tracking for linear feedback systems when there are parameter perturbations and disturbance inputs. The controller consists of a servocompensator containing the modes of the reference signals and disturbance inputs, a stabilizing feedback loop, and a feedforward compensator. Application of the method to the design of a vertical takeoff and landing (VTOL) aircraft flight control system is discussed. The use of a precompensator allows performance maneuvers such that the aircraft tracks desired trajectories and the feedforward and feedback signals aid in reducing the trajectory sensitivity to variations of parameters due to change in airspeed and to wind gust. Simulation results are presented to show the robust tracking, disturbance rejection, and sensitivity reduction capabilities of the flight control system.     

Galileo Probe Mass Spectrometer experiment

The Galileo Probe Mass Spectrometer (GPMS) is a Probe instrument designed to measure the chemical and isotopic composition including vertical variations of the constituents in the atmosphere of Jupiter. The measurement will be performed by in situ sampling of the ambient atmosphere in the pressure range from approximately 150 mbar to 20 bar. In addition batch sampling will be performed for noble gas composition measurement and isotopic ratio determination and for sensitivity enhancement of non-reactive trace gases.The instrument consists of a gas sampling system which is connected to a quadrupole mass analyzer for molecular weight analysis. In addition two sample enrichment cells and one noble gas analysis cell are part of the sampling system. The mass range of the quadrupole analyzer is from 2 amu to 150 amu. The maximum dynamic range is 10⁸. The detector threshold ranges from 10 ppmv for H₂O to 1 ppbv for Kr and Xe. It is dependent on instrument background and ambient gas composition because of spectral interference. The threshold values are lowered through sample enrichment by a factor of 100 to 500 for stable hydrocarbons and by a factor of 10 for noble gases. The gas sampling system and the mass analyzer are sealed and evacuated until the measurement sequence is initiated after the Probe enters into the atmosphere of Jupiter. The instrument weighs 13.2 kg and the average power consumption is 13 W.The instrument follows a sampling sequence of 8192 steps and a sampling rate of two steps per second. The measurement period lasts appropriately 60 min through the nominal pressure and altitude range.     

Fault Detection and Diagnosis of Aircraft Actuators using Fuzzy-Tuning IMM Filter

This paper proposes a new interacting multiple model (IMM) filter for actuator fault detection. Since each individual filter of the IMM filter uses the combined information of the estimation values from all the operating filters, it can effectively estimate system parameter variations, thereby it can diagnose the actuator damage with an unknown magnitude. In this study, to diagnose the actuator failure fast and accurately, fuzzy logic is used to tune a transition probability among multiple models. This makes the fault detection process smooth and reduces the possibility of false fault detection. Also, a discrete fault tolerant command tracker is derived to cope with actuator damages. To validate the performance of the proposed fault detection and diagnosis (FDD) algorithm, numerical simulations are performed for a high performance aircraft system.     

Instrument Failure Detection in Partially Observable Systems

Instrument failure detection using the dedicated observer scheme (DOS) depends on partial state observability through each instrument which is monitored. For instrument fault detection by the DOS technique, a quantitative measure of partial state observability is established for each instrument and used to determine a necessary condition on the output structure of the system. This measure, called the internal redundancy of the instrument, indicates the complexity of the logic required for failure detection, and it also indicates where some hardware redundancy can be introduced into the system to improve the fault detection capability of the DOS. The principles developed are applied to a simulation of the pitch axis autopilot of the A7 jet aircraft.     

737-300机务维护模拟机技术探讨

在分析系统硬件和软件的基础上,简要地分析了系统模拟故障的方法,同时分析了在系统中加入新故障的可能性,提出了加入新故障的基本方法。     

基于Fuzzy数学的飞机自动停车故障诊断

飞机本身是一个复杂的系统.因此,系统及分系统的故障也是纷繁复杂的,反映在故障征兆(表象)与原因上,同一故障征兆可能是多种原因所引起的,而同一故障原因又往往产生多种故障征兆.对于故障征兆与故障原因间的复杂隶属关系,如果使用传统的经典数学模型来处理往往不能准确的解决问题.本文将模糊数学方法引入到飞机故障诊断中,建立了某型飞机自动停车故障诊断的数学模型,解决了针对一种或数种故障征兆,如何准确、快速地找到引起故障的真正原因,并且针对最大隶属度原则的缺陷,改进了该原则,此诊断方法可以按飞机系统功能分解推广到对任一分系统(如液压系统,燃料系统,冷气系统,着陆装置系统等)的故障诊断.