ULTRA - Unmanned Low-cost Testing Research Aircraft

Krings, Matthias; Annighofer, Bjorn; Thieleckey, Frank

doi:10.1109/acc.2013.6580044

Cited by 7 publications

(2 citation statements)

References 6 publications

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“…In such case, a more directed sensitivity analysis might help to uncover the local characteristics. To evaluate the overall performance of the para-metervarying, model-predictive envelope protection system virtual flight tests are performed utilizing the ULTRA laboratory infrastructure and simulation environment [12].…”

Section: Sensitivity Analysismentioning

confidence: 99%

A predictive envelope protection system using linear, parameter-varying models

Krings

Thielecke

2014

CEAS Aeronaut J

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A parameter-varying, model-predictive envelope protection system is developed simplifying the controller structures required to keep the aircraft within a safe angle-of-attack and normal load factor envelope. The idea of a quasi-steady flight condition is used to map the flight envelope limits onto the setpoint values of a single flight control law. Since no mode switching is required, the selected level of automation, i.e., autopilot and flight management functionalities, is independent from the proximity to any angle-of-attack and normal load factor limit. In contrast to previous approaches, the proposed algorithm makes use of a quasi-linear, parameter-varying control loop model to adapt to the true nonlinear aircraft behavior. A variance-based sensitivity analysis highlights the most significant scheduling variables within this control loop model and, therefore, indicates the option of model reduction and improvement in efficiency, respectively. The proposed envelope protection system is evaluated throughout virtual flight tests with the unmanned flight test platform ULTRA-Dimona showing promising overall performance also in the presence of wind and turbulence. Keywords Envelope protection system Á Fixed-wing aircraft Á Linear, parameter-varying modeling Á Dynamic trim method Abbreviations ANOVA Analysis of variances CG Center of gravity DOE Design of experiments DT Dynamic trim LPV Linear, parameter-varying LTI Linear, time-invariant LTV Linear, time-varying MITL Model-in-the-loop q-LPV Quasi-linear, parameter-varying ULTRA Unmanned low-cost testing research aircraft

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Section: Sensitivity Analysismentioning

confidence: 99%

A predictive envelope protection system using linear, parameter-varying models

Krings

Thielecke

2014

CEAS Aeronaut J

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“…By using flight simulators to run virtual flight tests at the early stages of the design, this could provide the evidence to verify the feasibility of the plane before moving into preliminary and detailed stages of the design. Indeed, various researchers have used flight simulators to minimize cost and time consumed for flight tests (Krings et al , 2013; Krings and Thielecke, 2015; Jung and Tsiotras, 2007; Xiao et al , 2015; Nie et al , 2014; Lee et al , 2013; Park et al , 2015). Flight simulators can also be used to somewhat certify the aircraft, or a part of the aircraft (Gutierrez et al , 2014).…”

Section: Introductionmentioning

confidence: 99%

Application of virtual flight test framework with derivative design optimization

Park

Chung

Kwon

2018

AEAT

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Purpose The purpose of this paper is a development of a virtual flight test framework with derivative design optimization. Aircraft manufactures and engineers have been putting significant effort into the design process to lower the cost of development and time to a minimum. In terms of flight tests and aircraft certification, implementing simulation and virtual test techniques may be a sufficient method in achieving these goals. In addition to simulation and virtual test, a derivative design can be implemented to satisfy different market demands and technical changes while reducing development cost and time. Design/methodology/approach In this paper, a derivative design optimization was applied to Expedition 350, a small piston engine powered aircraft developed by Found Aircraft in Canada. A derivative that changes the manned aircraft to an Unmanned Aerial Vehicle for payload delivery was considered. An optimum configuration was obtained while enhancing the endurance of the UAV. The multidisciplinary design optimization module of the framework represents the optimized configuration and additional parameters for the simulator. These values were implemented in the simulator and generated the aircraft model for simulation. Two aircraft models were generated for the flight test. Findings The optimization process delivered the UAV derivative of Expedition E350, and it had increased endurance up to 21.7 hours. The original and optimized models were implemented into virtual flight test. The cruise performance exhibited less than 10 per cent error on cruise performance between the original model and Pilots Operating Handbook (POH). The dynamic stability of original and optimized models was tested by checking Phugoid, short period, Dutch roll and spiral roll modes. Both models exhibited stable dynamic stability characteristics. Practical implications The original Expedition 350 was generated to verify the accuracy of the simulation data by comparing its result with actual flight test data. The optimized model was generated to evaluate the optimization results. Ultimately, the virtual flight test framework with an aircraft derivative design was proposed in this research. The additional module for derivative design optimization was developed and its results were implemented to commercial off-the-shelf simulators. Originality/value This paper proposed the application of UAV derivative design optimization for the virtual flight test framework. The methodology included the optimization of UAV derivative utilizing MDO and virtual flight testing of an optimized result with a flight simulator.

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Nonlinear system identification of a UAV model with distributed aerodynamics and flexible structure

Herrmann¹,

Theis²,

Thielecke³

2023

CEAS Aeronaut J

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This paper presents the nonlinear system identification of a slightly flexible 25 kg fixed-wing UAV in the time-domain using a computationally efficient distributed aerodynamics model and a linear structural dynamics representation. The equations of motion are formed by making use of the free vibration modes of the structure and the mean axes formulation. The structural modes and mode shapes are determined from ground vibration tests. The distributed aerodynamics, accounting for elastic deformations, are modeled using a quasi-steady stability and control derivative approach and by applying strip theory. Initial distributions for the derivatives are obtained from vortex-lattice-method calculations. For matching the model response to the measured response, parameters for scaling the initial derivative distributions are introduced. The flexible model is subsequently identified based on flight test data using the output error method in the time-domain and maximum-likelihood estimation. A good overall identification result is achieved with a close match of the fast aircraft dynamics. Finally, an evaluation is given on the suitability of the identified model for real-time simulation, loads’ estimation, and active load control law design.

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ULTRA - Unmanned Low-cost Testing Research Aircraft

Cited by 7 publications

References 6 publications

A predictive envelope protection system using linear, parameter-varying models

A predictive envelope protection system using linear, parameter-varying models

Application of virtual flight test framework with derivative design optimization

Nonlinear system identification of a UAV model with distributed aerodynamics and flexible structure

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