Air Data Computer Research Articles

Air data computer simulation and design credibility assessment considering ADC calculation model

Abstract Air data computer simulation system is a platform for studying aircraft air data system. It can also replace real air data computer and can be used in the experiment of ground integrated avionics system, which greatly reduces the cost and risk of the experiment. However, when the simulation system replaces the real system, whether its reliability, integrity and other indicators can meet the requirements becomes the key to the problem. Based on computer simulation theory and simulation credibility evaluation theory, this paper designs and implements two types of atmospheric data computer simulation systems and evaluates the credibility of the simulation systems. The basic theory of computer simulation and the general process of simulation are expounded, the evaluation theory of simulation credibility is introduced, and the evaluation calculation method of simulation credibility is given. The results show that the highest reliability of the reliability evaluation using the method in this paper reaches 90%, the highest error rate is 0.06%, and the average accuracy, efficiency and complexity of the hundred experiments are 97.31% and 97.00% and 0.154%. The highest reliability of the subjective comprehensive evaluation algorithm for reliability evaluation is 65%, the highest error rate is 0.27%, and the average accuracy, efficiency and complexity of the hundred experiments are 70.59% and 69.74%, and 0.502%. Therefore, the method in this paper not only has high reliability, low error rate, but also has strong comprehensive effectiveness.

Low Cost Avionics System for Ultralight Aircraft

Abstract The article presents a low cost avionics system for ultralight aircraft and paraplanes. The system contains Attitude and Heading Reference System, Air Data Computer and Primary Flight Display. Communication between units is via Wi-Fi. In the article design description was presented, as well as laboratory tests results. They are promising and the system is ready for in flight testing.

Verification of Air Data Computer Software using Formal Methods

With the rapid development of airborne system and software, the requirement of software’s robustness, adaptability and reliability improves continually. Failure of software function may cause severe property loss and personnel casualties. Formal methods are mathematically based techniques for the specification, development, and verification of software aspects of digital systems that have obvious advantages in improving safety and reliability of airborne software. This paper takes Air Data Computer software as an example for formal verification in the whole software development process including requirements process, design process, coding process and integration process to demonstrate a set of formal methods application in the airborne software verification process.

Formal Analysis and Verification of Airborne Software Based on DO-333

With rapid technological advances in airborne control systems, it has become imperative to ensure the reliability, robustness, and adaptability of airborne software since failure of these software could result in catastrophic loss of property and life. DO-333 is a supplement to the DO-178C standard, which is dedicated to guiding the application of formal methods in the review and analysis of airborne software development processes. However, DO-333 lacks theoretical guidance on how to choose appropriate formal methods and tools to achieve verification objectives at each stage of the verification process, thereby limiting their practical application. This paper is intended to illustrate the formal methods and tools available in the verification process to lay down a general guide for the formal development and verification of airborne software. We utilized the Air Data Computer (ADC) software as the research object and applied different formal methods to verify software lifecycle artifacts. This example explains how to apply formal methods in practical applications and proves the effectiveness of formal methods in the verification of airborne software.

An alternative neural airspeed computation method for aircrafts

PurposeThis paper aims to present an alternative airspeed computation method based on artificial neural networks (ANN) without requiring pitot-static system measurements.Design/methodology/approachThe data set used to train proposed neural model is obtained from the Digital Flight Data Acquisition Unit records of a Boeing 737 type commercial aircraft for real flight routes. The proposed method uses the flight parameters as inputs of the ANN. The Levenberg–Marquardt training algorithm was used to train the neural model.FindingsThe predicted airspeed values obtained with ANN are in good agreement with the measured airspeed values. The proposed neural model can be used as an alternative airspeed computation method.Practical implicationsThe proposed alternative airspeed computation method can be used when the air data computer or pitot-static system has failed.Originality/valueThe proposed method uses flight parameters as inputs for the ANN. As such, airspeed is calculated using flight parameters instead of the pitot-static system measurements.

Perancangan Siste Data Udara Menggunakan Media Tranmsisi Serat Optis

The use of optical fiber transmission media at the Air Data System is affected by the development of optical fiber technology. The system is able to present the data required by the flight crews quickly and accurately. Therefore, it supports the success of a certain mission. In addition, the air data system using the transmission medium optical fiber also has advantages other than the copper cables, i.e: immune to EMI (Electro Magnetic Interference), RFI (Radio Frequency Interference), EMP (Electro Magnetic Pulses), and will not experience any disruption caused by the occurrence of a short circuit.The fiber optic air data system is designed in consideration with the characteristics of it’s components i.e: the transmitter, optical fiber cable and the data receiver. The study also completely discusses the air data system, from the sensor, Air Data Computer (ADC), and the display of aircraft altitude and speed. .Kata kunci: Serat optis, sistem data udara, air data computer.

Research on Flight Altitude Information Fusion Method for ADS/INS/GPS Integrated Systems Based on Federated Filter

The precision of the altitude measurement system installed in some type airplane does not fulfill the need of the airborne equipment, this paper propose a method based on the federated filter which utilizes the data of the air data computer system (ADS), inertial navigation system (INS) and the GPS to improve the precision and stability of the altitude output. The results of simulation show that the algorithm takes full advantage of all of the sub-system, which reduces the error of the ADS and improves the altitude output precision. Meanwhile the method may separate some faulted sub-system (e.g. GPS) and reform the system, which renders the system better fault tolerant and real-time performance.

Algorithms of Measurement System for a Micro UAV

The article presents a measurement system for a micro UAV designed at the Department of Avionics and Control Systems of Rzeszów University of Technology. Since the project is based on earlier projects, e.g.[[[[1[[[1, the introduction begins with their short presentation [they are mentioned in the introduction firs. Then, the current project is discussed. The major objective of the project is to create a miniature autopilot cooperating with navigation units, data transmission units and measurement units. The system is based on Polish technological solutions. The autopilot is designed as a single unit, however the system is open and it allows you to use different elements. The system development is also possible. In-flight testing will be realized with the use of two unmanned flying platforms equipped with an electrical engine and a piston engine. The total mass of the platforms is 5 kg and 25 kg respectively. The article presents the structure of the control and navigation system and then, the structure of the measurement system. The measurement units consist of a GPS receiver, an attitude and heading reference system (AHRS) and an air data computer (ADC). Similar configuration is used in other micro UAV solutions, such as Micropilot or Kestrel. Then, algorithms of the measurement system are described. Navigation is based on GPS data with a DGPS (Differential GPS) advanced module. If the measurement information is complete, GPS data are used to correct measurements from other units. The system estimates wind disturbances and calculates accelerometers errors. In the case of missing GPS signals implementation of low-cost sensors may lead to significant measurement errors, and hence navigation only by means of the INS is impossible. In such a case, navigation is realized with the use of an inertial navigation system (INS), the magnetic heading measurement and ADC. AHRS unit algorithms use quaternion algebra for attitude calculation. For correction, complementary filtering is implemented [, [. The correction signal for the attitude (pitch and roll angles) is calculated with the use of acceleration measurements. Measurements of accelerations and yaw rates are used for the correction switching mechanism, since in dynamic states signals calculated from accelerations cannot be used for correction. Heading is corrected by means of magnetic heading measurement. ADC algorithms are based on typical aerodynamic dependences.

항공전자장비의 구조해석 및 설계에 대한 연구

This paper is about the analysis and design of avionics equipment`s housing and PCB(Printed Circuit Board) such as air data computer. Avionics equipment`s structural design as well as electrical properties is very critical and should be proved from design phase by analysis method. First, analyze the static load and vibration requirement for the installed equipment, and then proved it satisfy with its requirement using the computational structural analysis. Commercial tools were used for computation and the rib design of housing was verified and the placement of electrical component was proposed using the PCB`s local displacement information.

The cheap air data computer for aviation applications

PurposeTo present both the construction and sample applications of the small, low‐cost air data computer (ADC) with CAN interface, which has been designed at Avionics Department of Rzeszow Technical University.Design/methodology/approachThe ADC has been developed as a partial task during realization of few aviation projects. It uses cheap piesoresistive pressure sensors with digital temperature compensation to calculate following flight data: altitude, airspeed computed in two ways as instrumental airspeed and true airspeed, altitude rate, and atmosphere parameters: pressure, temperature and air density. This device is small and lightweight then it can be used on boards of both small aircraft and unmanned flying vehicles.FindingsThis paper provides information about designed ADC's measurements accuracy. Also it informs about possibilities of the presented device uses.Practical implicationsThe lightweight low‐cost ADC can reduce both price and weight of complete control systems different types of flying vehicles are equipped with.Originality/valueThis paper presets original the construction of the ADC equipped with CAN 2B interface and working with CAN Aerospace protocol.

Simple virtual attitude sensors for general aviation aircraft

PurposeThis paper aims to present a proposal of a simple analytical redundancy method using for virtual attitude reference system design. The main idea of the project is applied typical on‐board general aviation aircraft equipment for solving pitch and bank angles.Design/methodology/approachThe presented solution is based on satellite navigation and air data computer signals, which are independent from basic attitude and heading reference system. The concept described is related to the kinematics relations and aerodynamic forces formulas.FindingsThe paper shows that the virtual attitude sensors are used by failure detection and reconfiguration subsystem and as a standby attitude reference system for general aviation aircraft equipped with augmentation control system applied for improving safety and efficiency handling qualities of aircraft.Originality/valueThis solution allows improvements in operating properties of already existing and newly designed executive aircraft, as well as establishing a higher level of flight safety.

Fodias Project: An Overview and the Development Status

The navigation segment of the FO-DIAS avionics system and test results from a mobile test-rig are presented.The Aerospace Laboratories of the Forll (FO) branch of the University of Bologna, in collaboration with Italian Public Authorities and Industry, are developing a DGNSS Instrument Approach System (called FO-DIAS) following the MASPS of RTCA/DO-217 and RTCA/DO-245.In particular, FO-DIAS is devoted to General Aviation (GA) which, in the near future, is also supposed to comply, as Commercial Aviation does, with the Required Navigation Performance (RNP) of the DIAS MASPS.On the other hand, even if Inertial Reference Systems could easily augment the RNP continuity parameter of the System, nevertheless their cost for G.A. suggests to implement a cheaper Avionics Dead Reckoning Computer (ADR-C) with inputs from the onboard Air Data Computer (ADC) and the Attitude and Heading Reference System (AHRS).Since the vertical channel is the most critical one for accuracy integrity and continuity, an accurate baro-inertial channel have to be synthesized so that its altitude information can augment the DGNSS pseudorange information.As to the horizontal channel of the ADR, it is continuously updated, whenever the DGNSS solution is available, but it guaranties the continuity of the accuracy, in case the signal of some satellites or of DIAS ground station fails, by means of the True Airspeed Data (TAS) from the ADC.First test data show promising results. Obviously, before validating the whole concept further work is to be done to define the Airplane Integrity Monitoring (AIM) function.

Writing Practical RTOS for Small Real-Time Embedded System

In this paper, the design of a practical real time operating system for small-embedded system is discussed. The RTOS discussed here was implemented in an airdata computer for use in a low-cost helicopter. Different types of real time tasks are identified. How the embedded system software handles these real time tasks is discussed. Topics covered include how critical tasks are implemented using interrupts, how just-in-time tasks are scheduled to execute by the system timers, and how time-controllable tasks are implemented in system software. The paper presented here was part of the research and development work that the author did when he worked in the aerospace industries in Singapore.

In-flight demonstration of a real-time flush airdata sensing system

A prototype real-time flush airdata sensing system has been developed and flight tested at the NASA Dryden Flight Research Center. This system uses a matrix of pressure orifices on the vehicle nose to estimate airdata parameters in real time using nonlinear regression. The algorithm is robust to sensor failures and noise in the measured pressures. The real-time flush airdata sensing (FADS) system has been calibrated using inertial trajectory measurements that were bootstrapped for atmospheric conditions using meteorological data. Mach numbers as high as 1.6 and angles of attack greater than 45 deg have been tested. The system performance has been evaluated by comparing the real-time FADS to the ship system airdata computer measurements to give a quantitative evaluation relative to an accepted measurement standard. Nominal agreements of approximately 0.003 in Mach number and 0.20 deg in angle of attack and angle of sideslip have been achieved.

All-digital jets are taking off: Aboard developmental commercial and military aircraft, digital electronics score high in compactness, control flexibility, and reliability

The key attributes of second-generation digital avionics systems are discussed. These are: increased integration, allowing more functions in less space; increased reliability through redundancy of components and systems and augmented fault-tolerance capabilities; and an improved man-machine interface, including such features as flat panels and voice controls. Examples of increased integration include more efficient data buses that cut down on wiring and connectors, and an inertial reference system and an air-data computer combined into one line-replacement unit. The author describes several commercial and military aircraft with emphasis on the European Airbus Industrie A-320, which will be the first commercial aircraft to use second-generation digital avionics. This 150-passenger, medium-range airliner is schedule to enter service in the spring of 1988. Issues in fault tolerance and improved aircraft control are included.

Contracts

An order worth in excess of £100,000 for absolute air pressure transducers has been received by the Aerospace Department, Farnborough Division of Solartron Transducers, from Smiths Industries in Cheltenham. These transducers will be the primary sensors in air data computers being manufactured for Sea Harrier aircraft of the Royal Navy.

A Functionally Redundant Altimeter

A scheme to provide redundant sensor data in an automatic control system using the principle of functional redundancy is described. Normally there are three redundant radar altimeters used in the terminal phase of automatic landing of jet transport airplanes. This scheme replaces one of these altimeters with a data processing scheme based on a Kalman filter. The filter is driven by altitude rate and acceleration signals from the air data computer and vertical accelerometer. A special initialization technique employs the two altimeter signals. The feasibility of this scheme is indicated by tests in which data obtained from these several sensors during flight tests are used to drive the functionally redundant altimeter.

Digital Computation Makes AFCS More Reliable

In airline service the reliability of a system is more than the confirmed failures for the system; it is the total removal experience of the system. Thus, the reliability of a system lies not only in the piece part failure rates, but also in the capability to verify and isolate failures. The application of digital technology brings several significant reliability improvements to automatic flight control systems (AFCS) when compared to contemporary analog systems. These advantages are demonstrated by the experience of the digital air data computer (DADC) of the DC-10 and the digital AFCS of the JA-37 Viggen. Experience with this equipment is reviewed, and the results are interpreted in terms of projections for airline DAFCS reliability. The digital system built-in test implemented by a stored program and the central processor gives a system integrity and dispatch reliability unequaled by analog systems. This high-integrity self-test reduces removal rates by giving line personnel a trustworthy tool and more complete automatic test processes for verifying maintenance actions. Digital circuit technology is directly suitable to largescale integrated circuits (LSIC) which reduce piece part counts and improve LRU reliability. Digital circuits are less subject to drift and the attendant difficulty to detect failures. These factors, coupled with the inherent high-integrity self-test, provide the basis for a significant improvement in reliability by the use of a digital automatic flight control system.

Reliability Case History of an Airborne Air Data Computer

The life of an airborne Air Data computer and some of its components have been observed in the field and in the laboratory. This paper treats 3 aspects of the reliability. Part 1 shows the relationship of predicted to actual MTBF and explains some seasonal fluctuations in actual MTBF. Monthly and yearly fluctuations are also explored. Part 2 shows some effects of workmanship-in-repair on reliability growth. The repair procedure was changed and the reliability gradually improved over a long period of time. Part 3 treats one of the components, a wirewound potentiometer, in some detail. A failure analysis and an improvement program are described.

Reliability case history of an airborne air data computer : T. Murata, IEEE Trans. Reliab.R-24. (2) 98 1975

Reliability case history of an airborne air data computer : T. Murata, IEEE Trans. Reliab.R-24. (2) 98 1975