Harrier Target Designation errors and autonomous shifting by its sensors.

[Fri13]

In a another thread is listed that INS drift is not implemented:

 

It is making me wonder would that explain the targeting points in DMT and TPOD radically shift around?

As I am having problems where designation can jump wildly.

Example I can have a TPOD suddenly designate point 50 nmi altitude and 90 degree another direction than ground where it originally was during turn.

 

The DMT can do similar things that it can drop a new designation from original target that is few nmi off, but new one can be floating in the air as well.

 

I have been looking for the technical reason why this happens. Like INS drift, but it doesn't make sense. As if the INS would drift so badly, then my location should go completely off. My attitude and targeting points and all should go just crazy if INS thinks suddenly that my position has shifted tens of miles or even just few miles. And as in GPS assisted INS mode, it shouldn't get drifted than tens of feets that is GPS accuracy (20 ft horizontal and 30-50 ft in vertical).

 

I thought that TPOD requires to have it targeting mode changed from Point/Area to INS mode (SSS Aft Long) before masking or performing even a gentle turn, but it happens regardless of that. And it doesn't explain why the system designation jumps as well around, not just the TPOD.

But if the INS drift is not modeled at all, then the cause can not be in INS... as it is the perfect system. Right?

 

In 1 min 10 s position I got confused about the TPOD designation jumping from a ground at about 3 clock at 9 nmi, to floating point up in the sky, 50 nmi above me.

 

 

 

 

 

Edited February 14, 2021 by Fri13

[Fri13]

Update: Seems that INS system is locked to the TPOD gimbal when TPOD is active sensor and Target Designator (TD). When you reach the TPOD gimbal limits, the INS system seems to behave like a TPOD gimbal and starts to rotate around aircraft with its speed. Then the INS system is lost and tries to "ground stabilize" itself anywhere around the aircraft and locks on the same original direction but to max range. The TPOD can designate only 50 nmi ranges why it sticks to that at the sky, as the TPOD was pointing before turn  to the right and low in angle (target at about 3'clock).

 

The error seems to be that TD is not stored to INS but to TPOD only.

This can be sometimes seen in INS slewing TD on MAP and when TPOD is slaved to it. The INS system is gimbal limited to TPOD, so when TD is moved around the aircraft at close range, the INS starts to quickly rotate around the aircraft and can not designate anything below the aircraft as TPOD gimbal denies it.

 

Assumption is that the TPOD should be the slave to INS and not otherway around. So if TD is moved somewhere using INS, then TPOD should try to point there regardless what is its gimbal limitation.

 

The oddity is that the TPOD gimbal roll axis should be only in boresight, not anywhere else. So unless you are flying straight toward the target, the TPOD should be able point directly at the target, but if you point TPOD across the boresight line then it needs to rotate around its axis and it can be seen as odd tipping when it rolls. But now the gimbal limit is reached other times as well.

 

The DMT has 420 degree gimbal limit in roll, and if you roll excessive over that 420 degrees, then the DMT will undesignate itself and cage itself.

But this is not done with TPOD to suffer from this new random TD and TPOD controlling INS stored TD.

 

 

 

Edited January 30, 2021 by Fri13

[Cunctator]

On 1/26/2021 at 5:03 PM, Fri13 said:

It is making me wonder would that explain the targeting points in DMT and TPOD radically shift around?

As I am having problems where designation can jump wildly.

Example I can have a TPOD suddenly designate point 50 nmi altitude and 90 degree another direction than ground where it originally was during turn.

 

The DMT can do similar things that it can drop a new designation from original target that is few nmi off, but new one can be floating in the air as well.

 

This was working very well (too well?) in the past. Perhaps a year or two ago. I could just turn around and re-attack the same target once it was designated with the DMT, maybe the new designation was maybe a dozen meters off, but it seemed reasonable. Now I mostly need to completely redesignate the target.

 

Maybe it would be be better to post your findings in the "Problems and Bugs" section. I doubt it will receive much notice here.

[Fri13]

9 minutes ago, Cunctator said:

 

This was working very well (too well?) in the past. Perhaps a year or two ago. I could just turn around and re-attack the same target once it was designated with the DMT, maybe the new designation was maybe a dozen meters off, but it seemed reasonable. Now I mostly need to completely redesignate the target.

 

Maybe it would be be better to post your findings in the "Problems and Bugs" section. I doubt it will receive much notice here.

 

First querying that are there others who are facing the same problem. As I have experienced this since like 2017 of the release.

The TD jumps around at random manners.

There is as well the bug that you can redesignate without undesignating first. So you can just press TDC Down when INS is on and you have TPOD DES active and the VV doesn't show the dot center of it to mark it is designation mode etc. But this is not about pressing designation or any button, just to fly and suddenly TD jumps somewhere elsewhere.

 

And it can't be INS drift related as if that is not modeled. And if there is a INS drift, then it can't be happening at such cases that it suddenly drifts tens of miles.

 

With the TPOD I can understand that you need to change it from a Area or Spot tracking modes to INS mode by SSS Aft Long (the INS at bottom is boxed in the TPOD screen) so now you can mask the TPOD and perform some maneuvers.

[DmitriKozlowsky]

After initial grnd alignment, set NAV to IFA, and forget about it. If it clunks out during mission, revert to manual navigation, and mkI sensor for tgt aquisition and defense.

[Fri13]

It is on the IFA (INS tightly coupled with GPS), and this is not about navigation but about targeting pod and INS overall with drifting.

 

It can happen odd ways, like example here the TPOD designates itself again while turning.

 

If we do not have INS drifting modeled etc, then TPOD should still maintain its position regardless it is in the AREA track instead INR mode (SSS Aft Long).

It shouldn't either start tracking a some random point in the air when it is already magical by always knowing the ground altitude and tracks it.

 

So do we have the INS/INR drifting modeled or not?

 

Comparing to example Wags F-16 tutorial about TPOD, you should park it to INS mode before masking so the system enters the memory mode and stays where it was before masking, but I can't see this to happen normally in the Harrier as it is random.

 

[Fri13]

Made a quick test mission just to test the TPOD drifting and I think I got the problem solved. It is the TPOD gimbal backwards. When the TPOD gimbal reaches the rear side so that the point of view marker moves top of the screen, then the TPOD gets locked in place and moves to maximum range and some random position. You can even catch it with the boresight position and drag the designator around as you please and release it by simply rolling around. I just spent time just flying around trying to find out when and how does the designator jump.

 

It doesn't matter do you have TPOD in PT, AR or INR modes, it will always go crazy when the crescent moves to proper position.

I think I got the trackfile from it but it is now over 7 MB so can't paste here. Tomorrow I try to find time to make a proper bug report about it, as the whole INS and targeting system in the Harrier seems to be completely broken.

 

[Fri13]

 

There is the trackfile for the behavior.

 

It is the TPOD gimbal that is causing the trouble.

The TPOD gimbal is the cause that the Target Designation is shifted even to ridiculous 54 nmi distances.

The TPOD gimbal has rotation in its boresight axis, and Razbam has programmed the TPOD to have a wide cone shaped gimbal limit in both sides, and seems to be wider at the aft than front.

 

 

When then TPOD target point reaches those zones, it will shift as it tries to "avoid" the area and is pushed around like a small ball would be pushed by a larger ball, but target point "flow" around the gimbal axis, performing a circle, but it gets then locked to random new location because of that.

 

The problem is as well that the TPOD target point can be grabbed by those zones, and you can drag the target point around, almost as much as you want as it is stuck to it.

In some scenarios the aircraft turning rate (speed) acts like a golf club, and it will swing the target point further when it is going up in the sky. And the problem seems to be that the target point is ground stabilized artificially, so it will stick to something close on the ground, but when it gets direction to go upward in the sky, its only limitation is the skybox at artificial 54 nmi range. And this makes it float and be even dragged behind the aircraft at the same speed, like a tractor beam pulling it, until you turn enough to stabilize it in the air.

 

This is a core problem in the Harrier targeting system.

Based to the NATOPS, the INS designation should happen only inside the HUD. So when the system Target Designation (TD) is done with INS, it happens inside the HUD using the FPM, and then it is symbolized with a dot inside it. The designation happens only by TDC ACTION and it will be movable when it is inside HUD field of view, the pilot is required to "sweeten" the TD position when flying and wait between movements to let the targeting system to calculate the new position that pilot will correct visually by moving the TD diamond. Once the TD is outside of the HUD field of view, it shouldn't be anymore to be slewed in INS mode but is locked in the INS memory, now it is possible be slewed in INS mode. The INS mode shouldn't have a instant lock on the ground, but likely be either locked to infinity or aircraft radar altimeter, meaning it is floating in the air, and then pilot is required to correct its position by moving it over the target and stopping, waiting to system calculate the new position and then continue doing so that system can get the idea of the slant range based pilot corrections.

 

The MAP mode is likely something else where pilot could move the TD around map in the display polar coordinates. So in MAP mode the TD cursor moves Up/Down/Left/Right by the TDC. The TD position likely is then stored based the TAMMAC map altitude, but it shouldn't be locked to real terrain altitude like it is now in Harrier. So pilot needs to turn around and get the TD inside HUD to use INS mode to "sweeten" the TD position by correcting it visually. Again a very unreliable targeting system with large inaccuracy.

 

Then there is the ARBS/TV and ARBS/LST modes, that requires a contrast (a visible light contrast like strong shadow from vehicle, or laser spot) where they get locked. And then the ARBS system will calculate the slant range as long it gets enough angle rate (that pilot was required to perform by shifting TD around while flying to correct it) and time to calculate it. The pilot benefits two ways with the ARBS/TV and ARBS/LTS modes:

 

1) 6x magnification with the ARBS/TV and capability to easily lock on contrasty targets/areas.

2) Easy target lock with third party laser designation by using various laser search scan modes for areas.

 

Both modes does generate the TD to the targeting system and it is memorized by using INS position of the aircraft. So as long the navigation system works with INS properly with accurate knowledge where aircraft is, so long the TD stays properly on the target as its coordinates doesn't move, unless pilot purposely starts to move it around.

 

Then comes the TPOD. The TPOD gets the control of the target designation automatically, it receives instant ground altitude position and locking, it has instant target designation where ever it is pointing. So where TPOD looks, there goes the TD regardless how it was created.

 

As the TPOD has its gimbal limitations, it will affect to all systems - including even MAP and INS designations. The gimbal can affect map deignation so that when slewing the TD in map using current INS mode, the TD might not be possible be moved through the aircraft but it will rotate around the aircraft like the aircraft would be the gimbal axis (vertically) so TD jumps from one side of the aircraft to another side by going around invisible gimbal circle.

 

 

So far I have got that to happen only when I have had the TPOD mounted, but it might happen as well without TPOD. But the MAP MODE should allow to move TD even through the aircraft instead just around it. But this might have something to do with the "polar coordinates" slewing system where the TDC inputs are related to the coordinates instead the MAP position. Meaning TDC UP/DOWN moves TD closer or further from the aircraft, and TDC LEFT/RIGHT moves TD around the aircraft.

 

Then there is mixture with the EHSD MAP mode, where TD movement speed in INS/MAP mode is locked to ground speed, so TD diamond will move on the map at same 5 nmi scale speed regardless is the scale 13 nmi, 25 nmi or larget scale. Meaning that to get TD moved long distances, it will take long time as it is moving at very slow speed meant for 5 nmi map scale.

 

And this is problematic when the TPOD "captures" the whole system, it captures its TD with its gimbal and then it will shift that TD all around places, and it can happen as well by MAP doing the shifting when overflying the target as the aircraft gimbal axis "pushes" the TD around its path.

 

This cause odd behaviors where the stored Target Designation is not where it is suppose to be. It is not registered to the system as coordinates relative to INS position, but it is pushed around without pilot actions by the TPOD and MAP.

The INS drifting would mean that as the aircraft position is not anymore known, then anything related to that is shifted as much as the INS drift error is. So if example INS drift error becomes 0.2 nmi to north and 0.1 nmi to east, then the stored Target Designation should be shifted as much as that is the error in aircraft position from where the INS target designation is calculated (the error should be only the amount between creation of the Target Designation to real time moment).

 

When the INS system is assisted with the digital coordinates, where the aircraft can store the target coordinates, it should know where the target is as long it knows its own position. And this is where the GPS becomes very handy and the IFA mode with tightly coupled mode where the TPOD shouldn't be capable autonomously shift the target position because TPOD gimbal just happens to rotate around its boresight axis in Front/Aft. The TD should stay in the coordinates that were stored, and the TPOD should return after possible gimbal limit to those coordinates that pilot designated. As the GPS assist the INS system to maintain aircraft accurate position in space, the error in accuracy is very small, couple meters. And so on target error should be very minimal as long the target can be designated accurately by angle and range.

 

And that is where the lack of contrast detection and locking, lack of proper INS HUD designation and its corrections etc comes to play, as some of those systems (ARBS/TV and ARBS/LST) properly used can allow to get very accurate target coordinates, while some are inaccurate (INS HUD/MAP) and some are between (TPOD) depending their use.

 

 

TPOD dragging.trk

Edited February 14, 2021 by Fri13

[Fri13]

 

Here is a key position from that track (in track position 3 min 15 seconds):

 

 

The target point designated with the TPOD is at the grass at right side of the aircraft when flying pass. After passing, the TPOD gets triggered to jump 54 nmi distance at the rear, from where it will be drag automatically to boresight position and it stays there until a little harder roll is performed that will release the TPOD designator on that position (in the air or on the ground). In the video it is visible as well how the target designation can be dragged around by using the boresight position to "capture" the designation and move it where wanted.

 

@RAZBAM_ELMO Time to move this thread to the Bugs and Problems section as a bug report now when it has the track file and cause is found.

[Honey]

Flew the harrier for a couple of days and it's still full of bugs. Targeting with TPOD was extremely frustrating though. I put up a quick night mission, placed targets at a location without any known to me visual references, put up a waypoint onto them and off I went to rely on EHSD DESG to do its trick. I flew around for maybe an hour before by some miracle TPOD actually was pointing to the waypoint and showed the units on the ground. It was pointing at anything at random, including points outside the map, and the sky. Eventually, I just decided to cycle waypoints with wink, while map desg was on, and once in a blue moon the tpod actually pointed at the waypoints.

 

Will the harrier ever actually function?

[Ramsay]

27 minutes ago, Honey said:

Will the harrier ever actually function?

The TPOD should function pretty well by now outside of INS designation/slewing and the TPOD's direction cue on the MPCD i.e. a 12 o'clock "dot" doesn't always mean the TPOD sensor is looking forward.

Which mode was the TPOD in (SSS or TPOD HOTAS) as IIRC it's designation/undesignation slave/unslave logic changes depending on mode

Do you have a short track or video of the behaviour that's causing problems ?

50 minutes ago, Honey said:

I put up a quick night mission ...

How did the mission/TPOD logic behave when flown during the day - it's what I would do to confirm there's bug rather than pilot error/ loss of SA ?

[BIGNEWY]

please stay on topic here, post deleted.

thank you

[Honey]

Ramsay,

 

That's the point, sometimes TPOD won't look at the point you're telling it to. But, nonetheless, I just flew a good sortie in mp in this aircraft, and stumbled upon the same weird behavior. I had 4 TPs created on the map, and one of them the TPOD wouldn't turn at. I was in INS, pressing MAP DESG pointed the TPOD entirely at random. I switched to T2 and that worked. Unfortunately, that was in MP, so no track. I think this erratic behavior is related to the op.

 

BIGNEWY, sorry, the bugs are just really annoying.

[JackHammer89]

I've definitely noticed the TPOD getting "lost" when obscured and at gimbal limits and then when it returns to the "target" location, which seems to usually be the wrong place. 

[AlphaJuliet]

Yeah It's a known bug, annoying as hell.
Has been there almost since the beginning.

We're working on it.

Cheers.

A.J.

[Vorlon]

Just purchased the AV8B and I'm experiencing issues like above.  When the Maverick is slaved to the VV I can roughly designate the target, then refine the target lock and kill it without any problems. In the attached short mission video you can see the issues only when I use waypoint target designations. I "paused" the simulation so I would have time to demonstrate the issue. The TPOD does not ground stabilize nor does it stay locked on the waypoint. In the second clip, I increment the waypoints and it snaps to it, but the drifts to the west.  Using the slew TDC will bring it back but continues west.  I unbound all TDC bindings to make sure it was not a hardware issue, still drifts, undesignate causes the TPOD to center above the VV.  Once in this mode I can't slave the seeker to the VV to lock the target in a way I know works.

 

Edited December 18, 2023 by Vorlon

[Vakarian]

1. Add a bit of a deadzone to ensure it's not your hardware (sensors can not center correctly, especially on cheaper equipment and original TM Warthogs)

2. Ensure you don't have any double binds and that you got your switchology correct. You were slewing in INS mode couple of times and while there might be time to do it, I really doubt you were trying to do that while looking through the TPOD and finding the target

[Vorlon]

I'm using the WW O2 Throttle and JS.  I have dead zones added in both.  No double binds, actually, still does it when nothing is bound to SSS and TDC.

[Vakarian]

Well, post a track so someone can see what exactly are you doing