Chan-Hong Yeom

Orbit Ephemeris Failure Detection in a GNSS Regional Application

To satisfy civil aviation requirements using the Global Navigation Satellite System (GNSS), it is important to guarantee system integrity. In this work, we propose a fault detection algorithm for GNSS ephemeris anomalies. The basic principle concerns baseline length estimation with GNSS measurements (pseudorange, broadcasted ephemerides). The estimated baseline length is subtracted from the true baseline length, computed using the exact surveyed ground antenna positions. If this subtracted value differs by more than a given threshold, this indicates that an ephemeris anomaly has been detected. This algorithm is suitable for detecting Type A ephemeris failure, and more advantageous for use with multiple stations with various long baseline vectors. The principles of the algorithm, sensitivity analysis, minimum detectable error (MDE), and protection level derivation are described and we verify the sensitivity analysis and algorithm availability based on real GPS data in Korea. Consequently, this algorithm is appropriate for GNSS regional implementation.

Comparison Study on Take-Off and Landing Flight Test Using Ground Observation and DGPS Method

The flight test is last means of compliance to satisfy airworthiness standards and important to evaluate the performance and safety of the developed aircraft. The flight test technologies are obtained from great numbers of experiences and know-hows and protected. In addition, flight test should be conducted efficiently since its various test conditions and items. Therefore, it is requisite to secure efficient flight test methods. This paper discusses the flight test methods for take-off and landing performance and two kinds of techniques are proposed. By performing real flight tests, they are compared with each other and analyzed through the flight analysis.

Nonlinear aircraft tracking filter utilizing a point mass flight dynamics model

A nonlinear aircraft tracking filter using a point mass flight dynamics model with three degrees of freedom is presented. While the models used by conventional air traffic control tracking filters are based on simple kinematics, the model for the present filter is based not only on kinematic relations but also on three-dimensional aircraft translational force equations and control variables. This allows for practical and sophisticated implementation of the attitude effects on translational acceleration. The control variables, which consist of the angle of attack, roll angle, and thrust setting, are treated as states with random processes. Tracking with simulation data indicates that the present filter is superior to other single and multiple model-based filters in terms of position and course accuracy, and the model associated with it is insensitive to flight motion types and design parameters. The results of tracking with real flight data also correspond well with those found by tracking with the simulation data.

Research on Algorithm and Operation Boundary for Fault Detection of Onboard GNSS Receiver

In this paper, we proposed a algorithm and an operation boundary for fault detection of a onboard GNSS receiver. After aircraft exchange corrections computed by an aircraft receiver, a faulty aircraft receiver is detected by checking consistency of correction. For this purpose, PRC residual is used as the test statistic for fault detection of the onboard GNSS receiver. And operation boundaries are set by using DGPS position error increase with respect to the distance from a reference station. If the fault detection is performed by using aircraft only in operation boundary, the more accurate fault detection can be possible.

Flight Simulation and Control System Design Software for Prototype Development

Flight simulation and control system design (FS&CSD) software to be used for a prototype development is presented. This software is developed in environment in that all inputs and outputs of complex aircraft motion and its systems are represented by simple block diagram models. The software includes typical linear models as well as a full six degree-of-freedom nonlinear model for the entire flight envelope including the motion on the ground. Using these block models with standard features and various toolboxes of , the software can be used to design and test stability ana control augmentation system by various methodologies. An iterative numerical procedure is described, which computes initial conditions for practical cases of steady-state airplane motion. Also designed is an easy to use graphical user interface to make the software amenable to the procedures of simulation tasks as well as visualizing and analyzing the simulation results.

MULTI-SENSOR DATA PROCESSING FOR AIR TRAFFIC CONTROL SYSTEM

Multi-sensor data processing (MSDP) software is developed as a core module of the surveillance data processing system (SDPS) for air traffic control. MSDP processes not only radar input but also data from ADS-B and multilateration (MLAT), allowing it to produce system tracks for other applications in the air traffic control system. The multiple plot variable update (MPVU) and the interacting multiple model (IMM) are adopted in the MSDP in order to process data from multiple sensors and to support multiple flight modes. Tracking performance test results based on EUROCONTROL surveillance standards indicate that the MSDP meets EUROCONTROL requirements.

Performance Improvement of Maneuvering Target Tracking with Radar Measurement Noise Estimation

Measurement noise variance of the radar is one of the main inputs of a state estimator of surveillance data processing system for air traffic control and has influences on the accuracy performance of maneuvering target tracking. A method is presented of estimating measurement noise variances every frame of target tracking using likelihood functions of multiple IMM filter. The results by running of Monte Carlo simulation show that variances are estimated within 5% of errors compared with true values and the tracking accuracy performance is improved.

Nonlinear Analysis of Inflatable Membrane Structures with Wrinkling Effect

The large deformation of inflatable membrane structure is numerically and experimentally considered in this paper. The numerical algorithm of wrinkling based on Miller and Hedgepeth membrane theory is developed using user material(UMAT) subroutine written by FORTRAN. Wrinkled area and deformed shapes of inflatable membrane structures are investigated by using ABAQUS with UMAT subroutine of wrinkling algorithm.

Analysis of Airship Gust Response Using Low Mach Number Preconditioning

In the present study, a numerical method has been developed for the calculation of the gust response of an airship using unstructured meshes. A preconditioning method is incorporated for accurate and efficient computations of the Euler equations at the low Mach number range. A simple sharp-edged gust is used as a gust model. The accuracy of the present method is demonstrated through comparisons with an exact line theory. The numerical results show that the variation of lift is relatively larger than that of moment. It is also shown that the static stability of the airship is enhanced with the use of control fins. 缀Ѐ㘰〻ሀ䝥湥牡氠瑥捨湯汯杹