This research addresses the vehicle design problem for industry class tethered hexarotor development project. Hexarotors are unmanned aerial vehicles of resent research interest due to their capability of vertical take offs, landings and hovering at specific locations. Tethered vehicles has the advantage over battery operated flights for not having the flight time restrictions. In existing tethered hexarotors the payloads are lower than 20kg due to the design and the weight of power conversion devices. This paper presents vehicle design and automated cable winding structure of new prototype of heavy payload type tethered hexarotor which is capable of carrying user specified data acquisition device mounted on vehicle weighing more than 30kgs and has capability to provide about extra 1kw power to operate in field operations where reliability is the key factor. The proposed vehicle design is compact, light weighted, aerodynamically and mechanically optimum to proceed to the actual vehicle assembly. The proposed automated cable winding structure makes the tethered system efficient and safe.
This paper address recent developments on auxiliary power unit for dual supply unmanned aerial vehicles. The proposed APU is designed and developed as a scalable backup power solution to tethered UAV systems. The APU addressed in this paper consist of off-line battery power supply and a high speed fault detection and switching unit, to control the proposed APU. Target operation of APU is to switch the battery power whenever the primary cable power is unavailable and switch back to cable power whenever the cable power is available during the UAV flight mission. The switching speed of newly developed prototype in this research with high speed logic ICs and n-channel MOSFETs is proved to be within milliseconds range and therefore could be considered fast enough for low altitude hovering missions. The outcome of the proposed design is also compact and light weighted, hence making the proposed prototype applicable in many existing battery powered UAVs for hybrid use.
This research paper addresses the designing of high speed free fall detection and primary trigger generation problem as a part of an in-flight emergency technology developments for unmanned aerial vehicles. The primary trigger is the very first to be detected and to be generated with high speed and accuracy in designing protection mechanism. This trigger indicates that UAV started falling. Sequences of resulting mechanism such as airbag inflation comes secondly. Speed requirement is a deterministic factor when the flight altitude is low. In this paper a high speed analog module is proposed to achieve the primary trigger and performed relevant validation tests on linear free fall and rotational free fall which covers the majority of free fall patterns. The positive test results verify the design as a primary trigger generation module for linear and rotational free fall detection in low altitude UAV missions or which could be enhanced with additional features to form more complex system of airbag inflation in UAV in-flight emergency technology development.
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