Hexacopters with direct side force, tethered multirotor operation, UAV perching

 

We have a three targeted interests in the active field of drone design and operation:

  1. Optimal design for keeping a hexacopter drone on station, and its camera on target, without mounting gimbles to the camera.  By skewing its six rotors in a mathematically-optimized fashion, in addition to independent control of the four usual degrees of freedom in a quadcopter (pitch, roll, yaw, lift), we get two more degrees of freedom (direct sideforce in the two horizontal directions), which can then be used to keep the drone precisely on station, without the need to pitch or roll (even in windy conditions), at the penalty of a few percent loss of lift efficiency in calm conditions.  If the drone is being used actively as a (consumer- or security-grade) camera platform, this trade-off is worthwhile.

  2. Tethered operation of large multirotors at 200’ to 300’ altitude for forward observation (a problem which requires long duration and a lot of energy for electronic countermeasures, so power needs to be provided, at high voltage, over a substantial physical tether).  While expensive tethered drones have been operated from Humvees, we seek to develop a cost-effective autonomous tethered drone system that can take off and operate from a vehicle operating on the sea surface up to sea state 4 (4’ to 8’ waves), for operations off the coast of conflict areas, and autonomously land/submerge when necessary to avoid detection.

  3. UAV perching.  Our preliminary investigations on this fascinating bio-inspired problem, which combines a blend of dynamic modeling and learning, adaptive feedback control, and lightweight landing gear design (using cable-actuated soft materials) are quite promising.  It is motivated by surveillance applications in urban environments, in which the UAV should be quiet and bird-like (to be inconspicuous), and should spend most of its time perched on environmental features, as most targets of interest spend most of their time stationary. 

© 2017 by Thomas Bewley