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Rescue - pitch goes to zero and no attitude correction
https://www.spirit-system.com/phpBB3/viewtopic.php?f=20&t=5781		 Page 1 of 8
Author:  loctite [ Thu 10. Aug 2023 18:34:08 ]
Post subject:  Rescue - pitch goes to zero and no attitude correction
Resolution
Here's an update summarizing the root cause and what you can check if someone in the future believes they may have the same issue.

The problem was caused by a defect in the Spirit gyro. It had for unknown reasons lost it's factory sensor calibration data. This was diagnosed remotely by Spirit who could also recalibrate the sensor remotely through the configurator.
This was the very first such instance of this happening and the likelyhood of anyone else having the same issue is likely very low.

How to tell if you have the same issue:
If you are reliably able to trigger Rescue from the radio and the Spirit Configurator shows Rescue with blue lettering "Engaged" but the collective always goes to zero degree pitch you may be affected of this error.
To verify you can try to change Rescue collective pitch with the configurator or with an rc channel and the variable P:Rescue Collective Pitch with for instance a potmeter on your radio. If changing Rescue Collective Pitch does not change collective pitch during rescue but it stays locked at zero then you may have the same issue as I experienced.

If you have any other problems with servo movements, gyro compensation or the direction of pitch in Rescue mode you do not have the same issue and your problem is likely somewhere else in your setup.

PS.I've removed all the Youtube videos, they were useful during troubleshooting but I don't need my livingroom on permanent display.

Thanks to everyone for their feedback during the troubleshooting and to Tomas/Spirit for excellent customer service.

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Hi, I have a problem with my Spirit GT mounted in a Logo 600. The heli flies fine but Rescue does not work as expected. On the bench when Rescue is triggered the collective goes to zero degrees pitch. This happens if colletive is positive or negative when rescue is triggered. The same happens when the model is held inverted. Adjusting Rescue collective pitch makes no difference. In the air the heli makes no attempt to change orientation but decends at a good pace that would suggest collective pitch is at zero. Collective is locked when Rescue is activated but aileron and elevator can be controlled (as expected).

All the threads on here and Helifreak indicates that issues with Rescue originates with a faulty setup but I'm pretty sure I've done everything right. I made a thread on Helifreak earlier and made a video that shows my setup and the consensus is that the Spirit is correctly set up.

HF: thread: https://www.helifreak.com/showthread.php?t=935715
Video: https://www.youtube.com/watch?v=KrTPDLujluQ

Has anyone ever observed a similar issue, a heli that is apparently set up correct and flies fine but when Rescue normal i triggered just goes to zero pitch and does no attempt to correct attitude at all?

Things I've tried: Changing receiver, reflashing Spirit, starting from a factory reset, using a blank model with no curves etc, triggering rescue with channel 8 instead of 5, triggering rescue with Stabi function and Selected by channel, triggering Geolink Altitude limit instead of Rescue (same behaviour on ground and in the air). Activating Stabi Correction in Expert Settings.

There's nothing special in the logs and the altitude looks like it's measured correctly in the real time log as well.

To sum up up I'm fairly sure I've set the Spirit up correctly and flies fine BUT Rescue will not work as intended. Any help or suggestions will be greatly appreciated.

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Author:  franz88 [ Thu 10. Aug 2023 20:03:24 ]
Post subject:  Re: Rescue - pirch goes to zero and no attitude correction
first go in servo- subtrim (tuning) and put the blade as in the photo and spin the rotor 360 degrees
the two blade they always have to touch they must not have unlevel different at 360° in all position
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general- channel
f stabi function changhe in f:rescue normal

select stabi - function
and select select by channel

finally diagnostic - rescue the red writing
configured: channel when it is deactivated and written blue when active (is automatic)
Author:  loctite [ Thu 10. Aug 2023 22:02:26 ]
Post subject:  Re: Rescue - pitch goes to zero and no attitude correction
Thanks for helping me diagnose the issue.

I have check subtrim in all orientations and it is spot on, no discernable difference in the height of the blades in any orientation.

Rescue is also set up correctly, pictures below.

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Thanks for the suggestions of a possible root cause, I'm open to other ideas.
Author:  ExCCHP [ Thu 10. Aug 2023 23:43:25 ]
Post subject:  Re: Rescue - pitch goes to zero and no attitude correction
Copied and pasted from the Spirit Manual...


Rescue Duration:
Once specified duration period will pass the Rescue mode will end and model will start to hover. For this purpose Hovering Collective Pitch value is used. The period is counted from time the Rescue mode was engaged. The parameter is available for both Rescue (Normal) and Rescue (Acro). Transition from Rescue to Hovering is smooth and will happen only if Rescue mode is still engaged. Collective Pitch control is returned to the pilot as soon as a pitch stick movement is recognized.

I would suspect it is as simple as ticking the box for Rescue Duration. Maybe set it to 5 sec for the bench test. In real life that might be too long tho. I use 1.5sec but its personal preference. From there adjust your hovering pitch to whatever your model hovers at out of ground effect. If unsure Suggest starting around +60%.

Also change the acro delay to 0.3 sec. 0.1 is too fast IMO

As a side note, your cyclic ring tuning should not be more that your collective pitch. You said you have the collective pitch set to +/- 10°. So you cyclic pitch should be no more or a little less than 10°, without any binding of the servos of course.
Author:  loctite [ Fri 11. Aug 2023 7:33:45 ]
Post subject:  Re: Rescue - pitch goes to zero and no attitude correction
Looks like we end up having paralell conversations here and on Helifread, sorry about that.

I've tried activating Rescue Duration and increasing hovering pitch but it makes no difference. Also the manual is very specific that rescue is active as long as the switch is kept engaged. Rescue duration seems mostly to be a method to disengage rescue automatically if one is not using a spring loaded switch.

Another interesting point is that the model behaves exactly the same when Geolink Altitude Hold is engaged, zero pitch and a rapid decent. The barometer seems to work according to the log though.
Author:  ZeXx86 [ Fri 11. Aug 2023 7:38:40 ]
Post subject:  Re: Rescue - pitch goes to zero and no attitude correction
Hello,

it is possible your servo centering is not correct. For this reason your model does not ascend at configured Rescue Collective Pitch.

Please check this:
1. activate Servos/Subtrim (tuning)
2. check that all servo arms are in the center of their travel - servo arms should be level
3. check that swashplate is horizontal - no deflection should be visible
4. check that there is 0° between main blades

If some of these are wrong, Rescue and other features will not work correctly.
Author:  loctite [ Fri 11. Aug 2023 8:17:53 ]
Post subject:  Re: Rescue - pitch goes to zero and no attitude correction
I've set the heli up with a swash gauge and it's very close if not perfect. Servo horns are as dead center at I can get eyeballing it. I had a little less thanone degree more positive than negative pitch which I corrected in the Servo Travel Correction settings.

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Perhaps I could try a factory reset and not adjust anything at all other than travel direction of the servos. On the bench then I should see positive pitch being applied when rescue is activated?
That should take any configuration issue out of the equation? As it is now I think the unit does not go into the rescue "state" at all, it goes to some other mode where pitch is zero. It would be very strange for a problem like this not to be caused by a configuration issue but I feel I've really tried pretty much everything.
Author:  ZeXx86 [ Fri 11. Aug 2023 8:37:18 ]
Post subject:  Re: Rescue - pitch goes to zero and no attitude correction
Please make sure that you are measuring all these angles while Subtrim (tuning) menu is enabled.

You can check if Rescue Collective Pitch is changing the angle.

Also I recommend to not enable Rescue Duration, because this will move to collective pitch to Hovering Collective Pitch percentage, which is close to 0° and might look like it does not work, while it works as programmed.
Author:  franz88 [ Fri 11. Aug 2023 9:25:08 ]
Post subject:  Re: Rescue - pitch goes to zero and no attitude correction
https://youtu.be/YM6Caw9GZh0
see my video and you have to understand what you did different.
use automatic Italian subtitles and then click automatic English translation
Author:  loctite [ Fri 11. Aug 2023 9:49:01 ]
Post subject:  Re: Rescue - pitch goes to zero and no attitude correction
Excellent video, however I don't see any mistakes I've made. All travel directions are correct, orientation of the Spirit is correct etc.

The earlier pitctures were taken with subtrim tuning enabled. There's maybe about a degree difference around the circumference of the rotor disc measured by a digital pitch gauge. But even if there is a very small difference here, how can the Spirit be aware of that on the ground?
Changing the Rescue Collective Pitch has absolutely no impact on the behavour. If it's at 10%, 60% or 90% the results are the same, the pitch just goes to zero. Also in Altitude hold the same thing happens, the heli decents rapidly as if the pitch is zeroed. Surely there should be feedback to add collective if the barometer measures declining altitude when it's in Altitude hold?
There is no difference in behavour with Rescue Duration turned off or on either.

Is there any way of logging the state of the control loop, which mode it is in? It does not look like rescue is activated properly and i looks like the unit is stuck in some other state. I have reflashed the firmware and started from a factory reset a few times as well. What I would expect to see upon activating rescue is an amount of positive pitch goverened by the amount of Rescue Collective Pitch configured.
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