[REPORTED]INS New Implementation Wrong

[hein22]

So as the title says, the new INS implementation appears to be either bugged or not simulated at all. I started cold and dark and without touching the INS knob I moved the plane quite a lot to a different position. Then I did a GND alignment and it knew exactly the new coordinates of my plane and aligned perfectly. If I had put the knob in IFA then GPS alignment would have started and it would have made sense, but in GND the alignment should not have known my new position. Track attached.

ins new implementation wrong.trk

[squid509]

wouldst the INS get its initial potion form the GPS?

the only sim i fly that has a detailed INS sys is the PMDG 747 and you could punch in what ever you want for initial potion or copy paste the GPS potion

 

are you saying in ground alignment in the F18 should not be using the GPS as initial potion?

[Tholozor]

According to the NATOPS, the aircraft first uses waypoint 0 as the aircraft's initial position. I think what he's saying is that waypoint 0 should be set to the aircraft's spawning position, and that moving the INS switch to GND shouldn't change waypoint 0 to the aircraft's current location when the alignment begins.

[hein22]

wouldst the INS get its initial potion form the GPS?

the only sim i fly that has a detailed INS sys is the PMDG 747 and you could punch in what ever you want for initial potion or copy paste the GPS potion

 

are you saying in ground alignment in the F18 should not be using the GPS as initial potion?

 

No, the INS aligns on its own, once IFA is selected then the GPS keeps the INS aligned. If you align with IFA then the alignment is done with GPS. But what I am describing is about GND.

[hein22]

According to the NATOPS, the aircraft first uses waypoint 0 as the aircraft's initial position. I think what he's saying is that waypoint 0 should be set to the aircraft's spawning position, and that moving the INS switch to GND shouldn't change waypoint 0 to the aircraft's current location when the alignment begins.

 

INS aligns with waypoint 0, just like Santi explained in the sticky. If you move from that waypoint then the INS would not know where you are and would align incorrectly. But in DCS it is all magically done.

[hein22]

Nice to see the investigating tag. Look forward to seeing comments from ED. Thanks.

[Frederf]

INS can discover latitude automatically during alignment, longitude it can't. If you align an airplane with wrong latitude the convergence will take longer or may even fail. Longitude INS has no clue and must trust the given information.

 

Presumably if you taxi away from "0" before alignment to another part of the airbase then it should eventually settle on new correct latitude but be wrong on longitude. When set to IFA the GPS input would filter the position back to correct over time. I can't see how F-18 can discover longitude during alignment unless it is sneaky getting GPS data somehow.

[hein22]

INS can discover latitude automatically during alignment, longitude it can't. If you align an airplane with wrong latitude the convergence will take longer or may even fail. Longitude INS has no clue and must trust the given information.

 

Presumably if you taxi away from "0" before alignment to another part of the airbase then it should eventually settle on new correct latitude but be wrong on longitude. When set to IFA the GPS input would filter the position back to correct over time. I can't see how F-18 can discover longitude during alignment unless it is sneaky getting GPS data somehow.

 

Exactly! Just out of curiosity: how does an INS discover latitude and why cannot it do the same with longitude? THanks.

[Meyomyx]

Heading and earth rotation. but that resultant movement could be replicated at any longitude.

 

Imagine 3 aircraft all pointing due North. One at the North pole, one at the Equator and one at the South pole. The gyros on the one at the north pole would experience "yaw left" with no heading change. The one at the equator would experience"roll right" with no heading change and the one at the South pole "yaw right" with no heading change. So there is only one point of latitude that will give a certain combination of gyro inputs. BUT, if you think about it, that could happen on any line of longitude.

 

Maybe it would be quicker with a clock and a sextant ;D

[hein22]

Heading and earth rotation. but that resultant movement could be replicated at any longitude.

 

Imagine 3 aircraft all pointing due North. One at the North pole, one at the Equator and one at the South pole. The gyros on the one at the north pole would experience "yaw left" with no heading change. The one at the equator would experience"roll right" with no heading change and the one at the South pole "yaw right" with no heading change. So there is only one point of latitude that will give a certain combination of gyro inputs. BUT, if you think about it, that could happen on any line of longitude.

 

Maybe it would be quicker with a clock and a sextant ;D

 

I didn't really catch anything of that. Can you elaborate for me please?

[randomTOTEN]

These videos apply to primarily civilian units, and of the older design which use mechanical gyros and accelerometers. They should inform on the theory of modern military units, with laser gyros and accelerometers. Topics such as alignment, the importance of True North, and the problems caused by motion during alignment are addressed.

 

 

Here's laser gyros,

Edited August 22, 2020 by randomTOTEN

[Frederf]

Exactly! Just out of curiosity: how does an INS discover latitude and why cannot it do the same with longitude? Thanks.

Simplest way I can describe it is imagine standing on a ball in space, maybe 10m in diameter. There is no gravity. Someone nails your space suit boots down and you close your eyes. Then someone spins the ball.

 

If you are at the north pole you will feel yourself spinning like a ballerina. If you are at the equator you will feel yourself doing a flip every rotation. If you're half way you're feel a mixture of these sensations. If your sensations are accurate you can guess how far between equator and pole you are even with your eyes closed

 

Gyroscopes can do this sort of sensation accurately even after 1/360th of the Earth turning once.

 

But you will never guess which "time zone" you are on the ball just by feel with your eyes closed. Being at longitude X and longitude Y feels the exact same if your latitude is the same. Gyroscopes can't tell that either.

[Hammer1-1]

I just tried starting the hornet up for the first time since the latest release and I keep getting an INS ATT degd message on the display. What am I doing wrong here?

 

 

edit: nvm, found something I should have looked for in the beginning...

Edited August 22, 2020 by Hammer1-1

[BIGNEWY]

Reported to the team,

 

thank you