Papers by Florian Holzapfel
GPS Solutions, 2014
The Ground Based Augmentation System (GBAS) provides corrections for satellite navigation signals... more The Ground Based Augmentation System (GBAS) provides corrections for satellite navigation signals together with integrity parameters to aircraft and enables precision approach guidance. It will eventually replace the currently used Instrument Landing System (ILS). GBAS Approach Service Type (GAST) C stations supporting CAT-I operations have been fully developed and certified and first stations are operational. For the service type D, which is intended to support CAT-III operations including automatic approaches and landings, requirements have been drafted and are currently undergoing validation. One remaining issue is the requirement for monitoring of ionospheric anomalies in the ground subsystem. Large gradients in the concentration of free electrons in the ionosphere can lead to significant positioning errors when navigation is based on differential methods. We give a review of the derivation of currently proposed performance requirements for such a monitor. Next, we show that the required level of safety from an airworthiness perspective can be achieved even with relaxed monitoring requirements compared to the currently drafted standards. These relaxations result from satellite geometry assessments on the ground and actual approach characteristics towards a runway. We show that with this method it is sufficient to monitor for gradients in the range of about 450-550 mm/km while current standards require detection already from 300 mm/km. A remote monitoring receiver near the touchdown point can monitor the post-correction differential range error and use it as test statistic for GBAS performance monitoring and protection against ionospheric disturbances.
AIAA Guidance, Navigation, and Control Conference, 2012
An L1 control augmentation is developed based on a novel autopilot structure for a highly agile, ... more An L1 control augmentation is developed based on a novel autopilot structure for a highly agile, tail-controlled missile. The autopilot is designed to control the pitch and yaw accelerations in the body-fixed frame while maintaining a desired roll angle. In order to compensate for the undesirable effects of modeling uncertainty, an L1 adaptive controller with piece-wise constant adaptation laws is developed that explicitly takes into account the multi-loop dynamic structure of the autopilot. The benefits of the augmented design are demonstrated via Monte-Carlo simulations of a high-fidelity 6DOF missile model, in which a wide spectrum of uncertainty combinations is considered.
Modified Extended State Observer Control of Linear Systems
AIAA Guidance, Navigation, and Control Conference, 2016
Real-time simulation of nonlinear transmission behavior in electro-mechanical flight control systems
2014 Ieee International Conference on Aerospace Electronics and Remote Sensing Technology, Nov 1, 2014
ABSTRACT This work presents a modular MATLAB/Simulink1 block library to model electro-mechanical ... more ABSTRACT This work presents a modular MATLAB/Simulink1 block library to model electro-mechanical flight control actuation systems for high-fidelity simulations executed on real-time targets with limited computing capacity. The described design implements the most important nonlinear effects and introduces techniques allowing simplified parametrization of kinematics on basis of existing systems. The paper demonstrates a model for electro-mechanical actuators with regard to thermal behavior and accounts for stiff transitions e.g. in backlashes and clutches. The concept is proven by simulating a redundant drive train of an optionally-piloted aircraft and comparing it with an equivalent multi-body simulation.
Optimal trajectories for RPAS with discrete controls and discrete constraints
2014 Ieee International Conference on Aerospace Electronics and Remote Sensing Technology, Nov 1, 2014
ABSTRACT
Simulation and Adaptive Control of a High Agility Model Airplane in the Presence of Severe Structural Damage and Failures
AIAA Guidance, Navigation, and Control Conference, 2011
2009 IEEE Workshop on Signal Processing Systems, 2009
Cycle slips are a common error source in Global Navigation Satellite System (GNSS) carrier phase ... more Cycle slips are a common error source in Global Navigation Satellite System (GNSS) carrier phase measurements. In this paper, the cycle slip problem is approached using Receiver Autonomous Integrity Monitoring (RAIM) methodology. Carrier phase measurements are used here in a singlereceiver time-differential positioning method where integer ambiguities are canceled, but any cycle slips remain. The performance of the method was assessed by comparing the detection results to a Real-Time Kinematic (RTK) solution and by manual data examination. Postprocessing results obtained using authentic Global Positioning System (GPS) measurements logged by low-cost single-frequency receivers show that the method is able to reliably detect and identify single errors but fails in an exemplary multiple outlier scenario. As no reference receiver is needed, the method is a potential means to produce cycle-slip-corrected data usable in any postprocessing application.
Conception of an Efficient Computational Environment for Aircraft Dynamics and Control Research
ABSTRACT
Design and Implementation of an Integrated Wind-/Airdata- and Navigation System Based on Low-Cost Sensor Components
L1 fault tolerant adaptive control of a hexacopter with control degradation
2015 IEEE Conference on Control Applications (CCA), 2015
Nonlinear Flight-Path Control -- A Flight Dynamics Perspective
ABSTRACT
Entwicklung eines glqqTrack Planning Toolsgrqq für die Planung von Luftrennen
Low-Cost Sensor Based Integrated Airdata and Navigation System for General Aviation Aircraft
Realitätsgetreue Simulation eines Flugkörpers zur Fehlereffektanalyse und nichtlinearen adaptiven Regelung
ABSTRACT
The paper at hand provides a deep insight into the Flight Control System architecture of an exper... more The paper at hand provides a deep insight into the Flight Control System architecture of an experimental UAV. The main focus is laid on the safety features of the proposed architecture and the verification of intended functionality of the Flight Control System using the Hardware-in-the-Loop Simulation. Preliminary steps like flight dynamics modeling and verification by means of system identification are described to give the reader an idea of the required development steps that need to be performed before real flight tests can take place.
Optimal Scheduling of Fuel-Minimal Approach Trajectories
ABSTRACT
Berechnung lärmminimaler An- und Abflugrouten
AIAA Guidance, Navigation, and Control Conference, 2011
adaptive controller with piecewise-constant adaptation law augmenting a dynamic inversion PI erro... more adaptive controller with piecewise-constant adaptation law augmenting a dynamic inversion PI error controller for the FSD ExtremeStar, a high agility UAV with a large number of control devices. A three axis nonlinear dynamic inversion controller serves as the baseline controller for this architecture with roll-rate, pitch-rate and yaw-rate as inner loop command inputs. The outer loop of the controller is driven by the same type of commands, but it interposes a maneuver coordination and attitude correction before passing the signals to the inner loop. The state predictor of the architecture is modified in order to prevent the attempt of adaptive compensation of system inherent physical limitations. This paper first presents the baseline controller followed by a thorough description of the adaptive controller. Results are presented via a full-scale, nonlinear simulation of the FSD ExtremeStar under adverse conditions.
Similarities of Hedging and L1 Adaptive Control
ABSTRACT
Präzise Flugbahnrekonstruktion mittels miniaturisierter L1-GPS Empfänger durch ein Zeitdifferenzen-Verfahren
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Papers by Florian Holzapfel