Timeline for How can a Mars helicopter be autonomous if there isn't a Martian GPS?
Current License: CC BY-SA 4.0
14 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Oct 25, 2018 at 2:26 | comment | added | uhoh | @ceejayoz excellent point! That would be good to note in answer itself. Both would accumulate error as they go, though vision-based would only accumulate absolute error; you could always use your terrain map to return to your power source and recharge (if that's the way it works). | |
| Oct 25, 2018 at 0:32 | comment | added | ceejayoz | @uhoh It wouldn't be much use for real-time navigation, but if the helicopter makes short, planned hops it'd be good for fixing current position before embarking on one. Might be a handy supplement for inertial/vision-based real-time guidance. | |
| Oct 24, 2018 at 23:53 | comment | added | uhoh | The Δ-DOR antennas on Earth receive a signal from the helicopter on Mars, process and calculate a position, then transmit that position back to the helicopter. The round trip light time is roughly between 9 and 40 minutes, depending on the orientation of the two planets in their orbit. With such a huge latency like that, I can not see how this could be used in a practical way for self-navigation of a helicopter. | |
| Oct 24, 2018 at 22:18 | comment | added | Rich | There were a number of accurate radio-navigation techniques in use pre-GPS. These included: active radio ranging (measure distance from vehicle to fixed point), radio bearing (measure solid angle from vehicle to fixed point), passive hyperbolic (measure time difference between signal from two stations), doppler (measure velocity of a single satellite). These could be used in conjunction [although as below, they've gone with optical terrain based]. | |
| Oct 24, 2018 at 18:06 | comment | added | OnoSendai | @ceejayoz Precisely - added a reference image for TERCOM, thanks for bringing that up. | |
| Oct 24, 2018 at 18:05 | comment | added | OnoSendai | @uhoh My original post wasn't exactly clear about that, thanks for pointing that out. Edited for clarification. | |
| Oct 24, 2018 at 18:04 | history | edited | OnoSendai | CC BY-SA 4.0 |
added 756 characters in body
|
| Oct 24, 2018 at 17:31 | history | edited | OnoSendai | CC BY-SA 4.0 |
Expanding on possible techniques.
|
| Oct 24, 2018 at 16:47 | comment | added | ceejayoz | Surface mapping is, incidentally, how cruise missiles used to operate. It's well tested, and very functional, as various US-targeted regimes can attest to. (GPS has supplanted it, but it'd likely work quite well for Mars.) | |
| Oct 24, 2018 at 15:46 | comment | added | uhoh | How does an autonomous helicopter use Δ-DOR? Radio signals from the spacecraft are received by two widely separated deep-space ground stations on Earth, and... | |
| Oct 24, 2018 at 15:35 | comment | added | OnoSendai | @Uwe You're completely right. In my defense, I wanted to keep it short and to the point. Adding to your comment, even general relativity is used to compensate for time dilation-related error analysis by the ground stations, as described here: en.wikipedia.org/wiki/… | |
| Oct 24, 2018 at 15:23 | comment | added | Uwe | GPD needs not only a flotilla of satellites around our planet to work, it also needs several ground stations for precise orbit measurement of each satellite. There is no precise position determination if you got no precise orbit data for all satellites used to determine position. | |
| Oct 24, 2018 at 14:45 | history | edited | OnoSendai | CC BY-SA 4.0 |
added 10 characters in body
|
| Oct 24, 2018 at 14:40 | history | answered | OnoSendai | CC BY-SA 4.0 |