Re:Celestial Navigation for Drones
by plasticchris on Monday January 20, 2025 @09:16AM
(#42768953)
Or in short, the sensors are strapped down to the platform being measured - like your phone’s sensors for example.
Re:Celestial Navigation for Drones
by boscillator on Monday January 20, 2025 @09:25AM
(#42769035)
Yes! It's in contrast to gimbaled systems. Putting the measuring instrument on a gimbal simplifies the math and often improves accuracy, but at the expense that you need this large moving object that needs more power.
Gyros on gimbals have other drawbacks, such as drifting and gimbal lock.
Re:Celestial Navigation for Drones
by anothertroll456 on Tuesday January 21, 2025 @10:32AM
(#42781199)
Just gimbal lock. Drifting happens to all of them.
But also the gimbal mechanisms, gimbal low response time, etc.
The ultimate example of this is the incredibly accurate and expensive and complicated floating Advanced Inertial Reference Sphere used on the Peacekeeper ICBM.
https://en.wikipedia.org/wiki/Advanced_Inertial_Reference_Sp...
Re:Celestial Navigation for Drones
by sandworm101 on Monday January 20, 2025 @07:42PM
(#42774973)
Except that a gimbaled system, if enclosed in a single box/pod, can also be described as a strapdown system. The term speaks more to separate modularity than how the system functions internally.
I wonder if you could dangle the star tracker below the drone on a long string, decoupling its attitude from the attitude of the drone. A kevlar or spectra string capable of supporting 100 grams would be 20μm in diameter; 3 meters of it would weigh a milligram, which is significantly less than gimbals. A small weight a couple of meters below the star tracker on a carbon-fiber-composite rod would seem to be able to stabilize its attitude further except in yaw.
"Traditional, stable-platform navigation systems commonly involve separate accelerators and fibers or laser-based gyroscopes, with all the components mechanically and rigidly mounted on a stable platform that is isolated from the moving vehicle. This leads to the drawbacks of large size, poor reliability, and high cost. In contrast, in strapdown navigation systems, the inertial sensors are fastened directly to the vehicle’s body, which means the sensors rotate together with the vehicle. "
https://www.mdpi.com/2504-446X/8/11/652