Using predicted movement to maintain optical-communication lock with nearby balloon
View Patent ↗A balloon may include an optical-communication component, which may have a pointing axis. A pointing mechanism could be configured to adjust the pointing axis. The optical-communication component could be operable to communicate with a correspondent balloon via a free-space optical link. For example, the optical-communication component could include an optical receiver, transmitter, or transceiver. A controller could be configured to determine a predicted relative location of the correspondent balloon. The controller may control the pointing mechanism to adjust the pointing axis of the optical-communication component based on the predicted relative location so as to maintain the free-space optical link with the correspondent balloon.
1. A balloon, comprising:
an optical-communication component having a pointing axis, wherein the optical-communication component comprises an optical receiver configured to receive free-space optical signals along the pointing axis, wherein the optical-communication component is operable to communicate with a correspondent balloon via a free-space optical link, and wherein the optical receiver comprises a multiple element detector system configured to detect changes in an optical beam location;
a pointing mechanism configured to adjust the pointing axis;
a controller, wherein the controller is configured to determine a predicted relative location of the correspondent balloon and control the pointing mechanism to adjust the pointing axis based on the predicted relative location, to maintain the free-space optical link with the correspondent balloon.
2. The balloon of claim 1 , wherein the balloon is a high-altitude balloon in a high-altitude balloon mesh network.
3. The balloon of claim 1 , wherein the optical receiver comprises a photodiode.
4. The balloon of claim 1 , wherein the controller is configured to determine the predicted relative location of the correspondent balloon based on free-space optical signals from the correspondent balloon received by the optical receiver.
5. The balloon of claim 1 , wherein the optical-communication component further comprises an optical transmitter configured to transmit free-space optical signals along the pointing axis.
6. The balloon of claim 1 , wherein the optical transmitter comprises a light-emitting diode.
7. The balloon of claim 1 , wherein the optical transmitter comprises a laser.
8. The balloon of claim 1 , wherein the optical transmitter comprises a modulator, wherein the modulator is configured to modulate light to form the free-space optical signals.
9. The balloon of claim 8 , wherein the modulator comprises a spatial light modulator.
10. The balloon of claim 8 , wherein the modulator comprises a polarization modulator.
11. The balloon of claim 8 , wherein the modulator comprises a liquid-crystal modulator.
12. The balloon of claim 1 , wherein the controller is configured to determine the predicted relative location of the correspondent balloon based on a Kalman filter method.
13. The balloon of claim 12 , wherein the predicted relative location of the correspondent balloon is determined using a last known location of the correspondent balloon as an input to the Kalman filter method.
14. The balloon of claim 12 , wherein the predicted relative location of the correspondent balloon is determined using a last known location and a last known motion vector of the correspondent balloon as inputs to the Kalman filter method.
15. The balloon of claim 1 , wherein the controller is configured to determine the predicted relative location of the correspondent balloon based on a linear-quadratic estimation method.
16. The balloon of claim 1 , further comprising a camera configured to acquire images of the correspondent balloon, wherein the controller is configured to determine the predicted relative location of the correspondent balloon based on the images.
17. The balloon of claim 1 , further comprising a radio transceiver configured to acquire radio signals from the correspondent balloon, wherein the controller is configured to determine the predicted relative location of the correspondent balloon based on the radio signals.
18. The balloon of claim 1 , further comprising a global positioning system configured to acquire global positioning system data, wherein the controller is configured to determine the predicted relative location of the correspondent balloon based on the global positioning system data.
19. The balloon of claim 1 , further comprising an inertial guidance system configured to acquire inertial guidance system data, wherein the controller is configured to determine the predicted relative location of the correspondent balloon based on the inertial guidance system data.
20. A method, comprising:
determining a location of a first balloon, wherein the first balloon comprises an optical-communication component having a pointing axis, wherein the optical communication component is configured to communicate with a second balloon via a free-space optical link, wherein the optical communication component comprises an optical receiver configured to receive free-space optical signals along the pointing axis, and wherein the optical receiver comprises a multiple element detector system configured to detect changes in an optical beam location;
determining a predicted location of the second balloon relative to the location of the first balloon based on a last known location and a last known motion vector of the second balloon; and
controlling a pointing mechanism to adjust the pointing axis of the optical-communication component in the first balloon based on the predicted location, to maintain the free-space optical link with the second balloon.
21. The method of claim 20 , wherein determining the predicted location of the second balloon comprises using a Kalman filter method.
22. The method of claim 21 , wherein determining the predicted location of the second balloon comprises using the last known location of the second balloon as an input to the Kalman filter method.
23. The method of claim 21 , wherein determining the predicted location of the second balloon comprises using the last known location and the last known motion vector of the second balloon as inputs to the Kalman filter method.
24. The method of claim 20 , wherein determining the predicted location of the second balloon comprises using a linear-quadratic estimation method.
25. The method of claim 20 , wherein the optical-communication component further comprises an optical transmitter configured to transmit free-space optical signals along the pointing axis.
26. A non-transitory computer readable medium having stored therein instructions executable by a computing device to cause the computing device to perform functions comprising:
determining a location of a first balloon, wherein the first balloon comprises an optical communication component having a pointing axis, wherein the optical communication component is configured to communicate with a second balloon via a free-space optical link, wherein the optical communication component comprises an optical receiver configured to receive free-space optical signals along the pointing axis, and wherein the optical receiver comprises a multiple element detector system configured to detect changes in an optical beam location;
determining a predicted location of the second balloon relative to the location of the first balloon based on a last known location and a last known motion vector of the second balloon; and
controlling a pointing mechanism to adjust the pointing axis of an optical-communication component in the first balloon based on the predicted location, to maintain the free-space optical link with the second balloon.
27. The non-transitory computer readable medium of claim 26 , wherein determining the predicted location of the second balloon comprises using a Kalman filter method.
28. The non-transitory computer readable medium of claim 27 , wherein determining the predicted location of the second balloon comprises using the last known location and the last known motion vector of the second balloon as inputs to the Kalman filter method.
29. The non-transitory computer readable medium of claim 26 , wherein determining the predicted location of the second balloon comprises using a linear-quadratic estimation method.