A Small-Scale Prototype to Study the Takeoff of Tethered Rigid Aircrafts for Airborne Wind Energy

Fagiano, Lorenzo; Nguyen-Van, Eric; Rager, F.; Schnez, Stephan; Ohler, C.

doi:10.1109/tmech.2017.2698405

Cited by 12 publications

(13 citation statements)

References 29 publications

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“…For the sake of brevity, only the main characteristics of the glider are shown in Table 1, while the full details on the employed hardware, sensors, actuators etc. are reported in [22].…”

Section: Aircraftmentioning

confidence: 99%

“…As anticipated in the introduction, the details of the ground station design and control are outside the scope of this paper and can be found in [22]. However, we recall here the principle of operation of the winch control system, since this is instrumental to understand one of the main assumptions that we consider when modeling the aircraft and designing its onboard controller.…”

Section: Ground Station Controlmentioning

confidence: 99%

“…A standard proportional controller in an inner control loop is then in charge of tracking such a reference speed by adjusting the motor current, which is subject to saturation (hence imposing a saturation on the motor torque). The full details of the ground station controller and more in general of the ground station design are described in [22]. However, for the sake of completeness we include here a short description of the feedback control strategy that computes the reference winch speed.…”

Section: Ground Station Controlmentioning

confidence: 99%

“…pulled). As shown in [22], a sensible choice for the involved design parameters isθ The actual winch control strategy is slightly more complex, since it involves also a feed-forward term during the take-off transient, in order to latch the winch speed to the slide speed, see [22] for details.…”

Section: Ground Station Controlmentioning

confidence: 99%

“…Rather, the ground station controller exploits a local, indirect measurement of the tether force to adjust the reeling speed. For the sake of brevity, this control algorithm is only briefly described here; the full details are presented in [22]. Instead, the focus of the present paper is on the design of the onboard control system and on the results of the autonomous take-off tests.…”

Section: Introductionmentioning

confidence: 99%

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Autonomous Takeoff and Flight of a Tethered Aircraft for Airborne Wind Energy

Fagiano

Nguyen-Van

Rager

et al. 2018

IEEE Trans. Contr. Syst. Technol.

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A control design approach to achieve fully autonomous take-off and flight maneuvers with a tethered aircraft is presented and demonstrated in real-world flight tests with a small-scale prototype. A ground station equipped with a controlled winch and a linear motion system accelerates the aircraft to take-off speed and controls the tether reeling in order to limit the pulling force. This setup corresponds to airborne wind energy systems with ground-based energy generation and rigid aircrafts. A simple model of the aircraft's dynamics is introduced and its parameters are identified from experimental data. A model-based, hierarchical feedback controller is then designed, whose aim is to manipulate the elevator, aileron and propeller inputs in order to stabilize the aircraft during the take-off and to achieve figure-of-eight flight patterns parallel to the ground. The controller operates in a fully decoupled mode with respect to the ground station. Parameter tuning and stability/robustness aspect are discussed, too. The experimental results indicate that the controller is able to achieve satisfactory performance and robustness, notwithstanding its simplicity, and confirm that the considered take-off approach is technically viable and solves the issue of launching this kind of airborne wind energy systems in a compact space and at low additional cost.

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“…For the sake of brevity, only the main characteristics of the glider are shown in Table 1, while the full details on the employed hardware, sensors, actuators etc. are reported in [22].…”

Section: Aircraftmentioning

confidence: 99%

Section: Ground Station Controlmentioning

confidence: 99%

Section: Ground Station Controlmentioning

confidence: 99%

Section: Ground Station Controlmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Autonomous Takeoff and Flight of a Tethered Aircraft for Airborne Wind Energy

Fagiano

Nguyen-Van

Rager

et al. 2018

IEEE Trans. Contr. Syst. Technol.

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Automatic testbed with a visual motion tracking system for airborne wind energy applications

et al. 2023

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The architecture and a flight test campaign of a small‐scale testbed aimed at aerodynamic and dynamic characterization of airborne wind energy systems are presented. The testbed involves a two‐line rigid‐framed delta kite and an automatic ground station for the lateral control of the kite and reel‐in/reel‐out of the two tethers. The environment, and the states of the kite, the tethers and the actuators are measured by a set of on‐ground and onboard sensors that include, among others, an inertial measurement unit, GNSS receivers, load cells, actuator encoders, a wind station, and a visual motion tracking (VMT) system based on three cameras and an artificial neural network (YOLOv2). The results of a 5‐min flight, including the take‐off, cross‐wind flight, and landing, were used to analyze the capabilities of the testbed. It was shown that the time derivative of the kite course angle exhibits a linear correlation with both the delayed steering input and the delayed differential tether tension, being the dispersion lower for the latter. The intrinsic and extrinsic calibrations proposed for the VMT system led to a good agreement between the estimation of the kite position and course angle provided by the VMT system and the onboard computer. Moreover, although the YOLOv2 algorithm failed in the detection of the kite within around 5% of the images, the simultaneous non‐detection from the three cameras was below 0.1% during the full flight. Such a reliability suggests that a VMT system can be used as a redundant or backup sensor for the GNSS.

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