Andreas Klöckner
German Aerospace Center
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Publication
Featured researches published by Andreas Klöckner.
AIAA Guidance, Navigation, and Control (GNC) Conference | 2013
Andreas Klöckner
In order to rigorously analyze mission plans, they have to be translated into a tractable formalism. This paper proposes to use the description logic Attributive Language with Complements and concrete Domains ALC(D) as the input formalism for a mission plan based on behavior trees. The interface is described using the safety circuit of an exemplary unmanned aerial vehicle. The system is executed using a three-degree-of-freedom simulation model. Results indicate that the system can be used as a first step towards verification of mission plans with formal methods. In a more efficient variant, the behavior tree mission plan executes sufficiently fast to be deployed in actual flight computers.
Archive | 2013
Andreas Klöckner; Martin Leitner; Daniel Schlabe; Gertjan Looye
Solar-powered high-altitude unmanned platforms are highly optimized and integrated aircraft. In order to account for the complex, multi-physical interactions between their systems, we propose using integrated simulation models throughout the aircraft’s life cycle. Especially small teams with limited ressources should benefit from this approach. In this paper, we describe our approach to an integrated model of the Electric High-Altitude Solar-Powered Aircraft ELHASPA. It includes aspects of the environment, flight mechanics, energy system, and aeroelasticity. Model variants can be derived easily. The relevant parts of the model are described and the model’s application is demonstrated.
american control conference | 2013
Maximilian Laiacker; Andreas Klöckner; Konstantin Kondak; Marc Schwarzbach; Gertjan Looye; Dominik Sommer; Ingo Kossyk
In this paper we present a system for operation and testing of different UAVs. The system allows easy development and modification of control and mission software. The system is composed of hard- and software modules with a standardized interface. We have been using the system with rotary and fixed wing UAVs with a take-off mass between 10 and 100 kg. For larger platforms the system can be used in a redundant setup. The software modules are integrated in a special real-time framework, which supports execution, scheduling, communication and system monitoring. A modular simulation and control infrastructure allows for flexible, integrated design and analysis of control laws. The code for the computational part of the modules can be generated from Matlab/Simulink-models or from Modelica-models. The system supports debugging, soft- and hardware in the loop simulations, operator training as well as real flight experiments. The main design concepts are explained at hand of our solar powered high altitude platform ELHASPA and the 10 years experience in development and operation will be summarized.
AIAA Modeling and Simulation Technologies (MST) Conference | 2013
Andreas Klöckner
This paper presents estimation algorithms for flight dynamics of small unmanned aircraft. The estimates are mainly based on geometric information. Optional information taken into account are airfoil polars, a few mass characteristics and static thrust measurements. The aerodynamics dataset is estimated using the Vortex Lattice Method. Weight-and-balance estimates are driven by assuming constant mass per surface. Propulsion is estimated based on typical characteristics. The model is compared to higher-fidelity models, namely wind-tunnel measurements and inertia measurements. The differences to the reference are typically below 20% of the aerodynamic coefficients and below 10% of the reference inertia.
AIAA Modeling and Simulation Technologies Conference | 2012
Andreas Klöckner; Daniel Schlabe; Gertjan Looye
In recent years, there has been much research towards fixed-wing high-altitude solar- powered aircraft. Accurate knowledge about the behavior of the aircraft and its energy system is needed in order to plan and execute these aircrafts’ missions. To this end, an integrated simulation model has been derived. It contains six-degrees-of-freedom flight dynamics, an energy system with solar cells, batteries, motors, and the effect of the en- vironment on the solar radiation. A continuous day-and-night flight has been simulated and results are presented. The model represents all relevant effects for solar-powered air- craft including dynamic interaction between flight dynamics and energy system. The same model is used for pilot training and control design of the aircraft.
equation based object oriented modeling languages and tools | 2016
Alexander Pollok; Andreas Klöckner
From the perspective of a practitioner, the development of perfect equation-based models is limited by language, hardware, and ones own mind. While the first two aspects are covered extensively in literature, only little attention has been given to the third one. We make a case for simple models, with a focus on two aspects: use of inheritance and creation of flexible models. Both can have adverse side-effects if used without restriction. To exemplify this discussion, two versions of a library as used in the aerospace industry are compared. The old version made heavy use of inheritance and tried to conduct everything with a minimal number of components. It was completely redesigned after maintenance efforts became too high. A psychological experiment was performed, where the effect of inheritance on the ability of participants to understand a model was analyzed. Results showed that each level of hierarchy significantly increases the time to understand a model by 26.65 s, when correcting for total model length. This supports our hypothesis that flat models are easier to understand than deeply nested models.
equation based object oriented modeling languages and tools | 2017
Alexander Pollok; Andreas Klöckner; Dirk Zimmer
For equation-based modelling languages, modelling experts have many degrees of freedom when building a model from scratch. One of the most basic choices the expert faces is the mode of representation. The same system can be represented for instance as a block-diagram, by writing down the physical equations, by writing an algorithm, or by graphically connecting ready-made subcomponents. To give some guidance in this aspect, an experiment was conducted to measure the effects of different representations on various tasks. Participants had to identify models and predict their transient response. Both the time to execute the task and the correctness of the answer were measured. Participants also had to rate their confidence regarding the models. Results showed that tasks were executed much faster for graphical representations than for block-digrams. Equation-based and algorithm-based models can be grouped in the middle. The same results hold for rated confidence. Interestingly, the amount of errors was similar for all representations. Apparently, modelling experts largely compensate for difficulty by taking their time.
Experiments in Fluids | 2007
Sebastian Große; Wolfgang Schröder; Michael Klaas; Andreas Klöckner; J. Roggenkamp
international modelica conference | 2014
Andreas Klöckner
GI-Jahrestagung | 2013
Andreas Klöckner