Random Engineering, Physics, ..., Concepts and Ideas

[Windy_Skies]

Some landing+tether search results:

A Survey of Autonomous Landing Techniques for UAVs | Archive link

Abstract—Landing an aerial vehicle is a very challenging problem. Pilots spend numerous hours practicing touchdowns because of the risk involved during landing phase. Developing autonomous landing technologies have been an active area of research over the past decade. This paper presents a review of landing techniques ranging from GPS based landing to vision based landing techniques; from basic nonlinear to intelligent, hybrid and robust control. It is aimed at providing a broad
perspective on the status of the landing control problem and controller design. The paper provides a comparison based on parameters such as type of the vehicle, assumptions made in the problem design, techniques used and efficacy of the algorithm in real world conditions.

https://repository.tudelft.nl/islandora/object/uuid:58616891-5447-446b-86e5-f190dbc9ede9 | Archive link | AWES forum link

Vertical Takeoff and Landing of Flexible Wing Kite Power Systems

Abstract

In this work, a novel vertical takeoff and landing methodology for flexible wing kite power systems is presented. Starting from a basic mast-based launching and landing concept, the operational envelope will be enlarged using the external assistance of a multicopter. The multicopter is used to drag the kite along a specified launching path until the operational altitude is reached, where the kite is detached and steered to its characteristic parking position while the multicopter lands. The landing of the kite will be conducted without multicopter assistance, and solely the winch will be used to pull the kite toward the ground station. For all maneuvers, flight control algorithms are presented, and the feasibility of the proposed methodology is analyzed using a developed simulation environment incorporating models for the kite, multicopter, ground station, and the tethers that connect the individual subsystems.

Guideline for Preliminary Sizing of a Vertical Take-Off and Landing System for
Rigid-Wing Airborne Wind Energy | Archive link

Abstract
Autonomous launching and landing of a tethered aircraft is one of the main challenges for an Airborne Wind Energy (AWE) system. A promising approach is Vertikal Take-Off and Landing (VTOL) with multiple rotors and many AWE startups rely on this take-off technique.

In this work the launching method VTOL is described using a mathematical model. This model can be used for a preliminary design regarding the size of the launching structure for a given AWE drone. In order to do so, important aircraft parameters are needed as an input and the required on-board power as well as the capacity of the energy storage are determined.

A critical requirement for an efficient power generation is a light-weight aircraft. Therefore, minimizing the weight of the VTOL system should be considered as one of the main objectives when designing the aircraft. In this work it is proposed to utilize the aerodynamic force to reduce the needed propeller thrust and hence minimize the required power for launching. Based on relevant equations describing the take-off procedure, a guideline for the design of such a VTOL system is presented.

To describe the launching sequence more accurately and investigate the effect of different flight paths on the needed thrust, a dynamic model is introduced and simulations on different start and landing sequences are carried out. Thereby, two control approaches are compared to each other focusing on the ability to optimally use the aerodynamic force to reduce the required propeller action. This leads to a recommendation of how the launch should be executed in order to be realizable with a light-weight VTOL system.

In this thesis it could be shown, that maximizing the aerodynamic force has a great potential regarding the reduction of the needed rotor thrust. This effect has not yet been investigated in the literature and should be considered when dealing with take-off and landing systems. Furthermore, it offers possibilities to novel control approaches, which optimally uses the aerodynamic force. The proposed control structure leaks in generality since it can only be applied in 2D models. Nonetheless, it gives an insight into the potential of using the aerodynamic force for control purposes.

Take-off and landing of an AWE system using a multicopter | Archive link

Abstract— In this paper, the problem of take-off and landing of an airborne wind energy system is addressed. The solution explored is to equipe the airborne wing of the system with a multicopter drone in order to perform the take-off and land maneuvers, even in the absence of wind. The proposed model with the proposed control strategy is implemented and tested in a numerical environment. The results show efficiency of the proposed control law and its robustness with respect to modelling errors and wind gusts.