Systems and methods for automated, lighter-than-air airborne platform
Embodiments disclosed herein enable routine autonomous execution of at least some major phases of aerostat operation in response to commands from human or automated external operators, a built-in decision-making capacity, or both. Various embodiments combine one or more actively controlled tethers, aerodynamic aerostat control surfaces, mechanical assistive devices (e.g., jointed arms attached to a ground station), and/or active propulsors attached to the aerostat to govern aerostat behavior during launch, flight, and landing phases of operation. Some embodiments enable automatic autonomous performance of all phases of routine post-commissioning aerostat operation, including launch, flight, and landing, without any routine need for availability of a human crew.
1. A method of controlling landing of an aerostat with a computerized flight controller, the aerostat being attached to a ground station with one or more tethers, the method comprising:
(a) retracting the one or more tethers to bring the aerostat toward the ground station during a descend phase;
(b) upon sensing that the aerostat has descended to a distance above the ground station, automatically transitioning the flight controller to a capture mode until an initial physical contact between the ground station and the aerostat and/or bridles attached to the aerostat is sensed;
(c) after sensing the initial physical contact of the ground station with the aerostat and/or bridles attached to the aerostat, automatically transitioning the flight controller to a dock mode during which the aerostat is moved from an initial ground station contact position to a docked position on a cradle of the ground station.
2. A method as in claim 1 , further comprising:
(d) after the aerostat is in the docked position, latching the aerostat to the ground station.
3. A method as in claim 1 , further comprising the bridles, and wherein (d) comprises catching the bridles and pulling the bridles away from one another and/or downward to bring the aerostat from the initial ground station contact position to the docked position on the cradle.
4. A method as in claim 1 , wherein no bridles are attached to the aerostat, the one or more tethers comprise a plurality of tethers, and (c) comprises moving the aerostat to the initial ground station contact position to the docked position on the cradle.
5. A method as in claim 1 , wherein the ground station includes a rotatable platform, and further comprising rotating the rotatable platform.
6. A method as in claim 5 , wherein the ground station includes one or more winches to retract the one or more tethers, and further comprising initiating retraction of the one or more tethers with a controller.
7. A method as in claim 1 , further comprising:
prior to (c), verifying physical contact of the ground station with the aerostat and/or bridles attached to the aerostat.
8. A method as in claim 1 , further comprising:
(d) using an automated dispatch controller to determine the suitability of launching of the aerostat; and
(e) using the flight controller to launch the aerostat.
9. A method as in claim 1 , further comprising:
(d) autonomously controlling the aerostat to bring the aerostat to an attitude set point.
10. A method as in claim 9 , wherein the attitude set point is adjusted during flight of the aerostat.
11. A method as in claim 9 , wherein (d) comprises controlling a bridle spreader to control for attitude of the aerostat.
12. A method as in claim 1 , wherein sensing initial contact of the ground station with the aerostat and/or bridles attached to the aerostat comprises sensing a proximity between an orientation tag attached to the aerostat and a sensor installed in the ground station.
13. A method as in claim 12 , wherein sensing initial contact of the g round station with the aerostat and/or bridles attached to the aerostat further comprises sensing whether a bridle block attached to the aerostat is aligned with a capture port of the ground station based in part on sensing of one or more sensors around a perimeter of the capture port.
14. A method as in claim 13 , in response to sensing that the aerostat is misaligned with the captured port of the ground station, retracting at least one of the tethers with an amount of force to cause a rotation of the bridle block to align with the capture port.
15. A method as in claim 1 , further comprising:
during the descend phase, determining whether a position of the aerostat is outside a low-risk zone;
in response to determining that the position of the aerostat is outside the low-risk zone, automatically making one or more responses to maintain the position of the aerostat inside the low-risk zone.
16. A method as in claim 15 , wherein making one or more responses comprises performing one or more operations to decrease oscillations of the aerostat.
17. A method as in claim 16 , wherein the one or more operations to decrease oscillations of the aerostat comprise:
pausing descending of the aerostat to decrease oscillations of the aerostat to an acceptable magnitude;
adjusting the one or more tethers to decrease an oscillation magnitude of the aerostat;
differentially adjusting the one or more tethers to decrease oscillations of the aerostat; or
activating one or more propulsors or control surfaces on the aerostat to decrease oscillations of the aerostat.
18. A method as in claim 15 , wherein the low-risk zone is defined by a shape of a cone.