[WIP] Fixed-wing performance model docs #2842

RomanBapst · 2023-11-02T09:33:38Z

Docs for

Added PerformanceModel for fixed wing PX4-Autopilot#22091
mention that some compensations apply only for propellers (e..g maximum climbrate would be different for jet engine)
document procedure when user does initial tuning in conditions very different from sea level standard atmospheric conditions

RomanBapst · 2023-11-02T09:59:00Z

@github-actions Could you please post a couple more times, I don't understand yet.

hamishwillee · 2023-11-02T10:30:29Z

@github-actions Could you please post a couple more times, I don't understand yet.

FW_S_CEILING is not in https://docs.px4.io/main/en/advanced_config/parameter_reference.html but your doc links to that. Probably because PR not yet merged?

And you need to add this to SUMMARY.md.

It will whinge on every commit until those are fixed.

hamishwillee · 2023-11-02T10:38:36Z

en/releases/main.md

@@ -1,6 +1,6 @@
 # PX4-Autopilot Main Release Notes

-This contains changes to PX4 since the last major release (v1.14).
+This contains changes to PX4 since the last major release (v1.14). 


@RomanBapst When you're done, can you add a release note in this doc for the change following the pattern in https://docs.px4.io/main/en/releases/1.14.html

I'm trying to make sure that we don't have to come back and think about what we did and why when we get to the release.

@RomanBapst ^^^^

hamishwillee · 2023-11-22T01:23:40Z

@RomanBapst Let me know when this is ready for review (I see corresponding PR went in).

en/config_fw/weight_and_altitude_tuning.md

Signed-off-by: RomanBapst <[email protected]>

en/config_fw/weight_and_altitude_tuning.md

Co-authored-by: Hamish Willee <[email protected]>

en/config_fw/weight_and_altitude_tuning.md

Signed-off-by: RomanBapst <[email protected]>

RomanBapst · 2024-01-08T08:21:30Z

@hamishwillee I am not sure what the issue with the formula rendering is. They render fine in vscode, but that might not say anything.
Is this the right place to look for what's supported?
https://docs.mathjax.org/en/latest/input/tex/macros/index.html

I might also need to start using chatGPT...

hamishwillee · 2024-01-09T07:01:55Z

Formulas fixed - the markers can't have whitespace. See commit

hamishwillee · 2024-01-09T07:30:12Z

@RomanBapst OK, fixed rendering and subedit. You should have another look and add info in a release note if this is a new feature (?). If it is docs on older features, from what version is this all true?

sfuhrer

Maybe you could split the docs a bit more into sections that explain what PX4 is doing in the background (the parts with the formulas basically), and what the user has to do to enable the auto adaptions (set the WEIGHT_GROSS, set the CEILING, ..anything else if I forgot about it).

en/config_fw/weight_and_altitude_tuning.md

sfuhrer · 2024-01-09T10:23:19Z

en/config_fw/weight_and_altitude_tuning.md

+
+rearranging this equation for airspeed gives:
+
+$$V = \\sqrt{\\frac{2mg}{\\rho c_A F}}$$


Suggested change

$$V = \\sqrt{\\frac{2mg}{\\rho c_A F}}$$

$$V = \sqrt{\frac{2mg}{\rho c_A F}}$$

hamishwillee · 2024-01-09T23:16:51Z

@RomanBapst @sfuhrer I'm away for two weeks, so won't be commenting on this further for a bit.

Maybe you could split the docs a bit more into sections that explain what PX4 is doing in the background (the parts with the formulas basically), and what the user has to do to enable the auto adaptions (set the WEIGHT_GROSS, set the CEILING, ..anything else if I forgot about it).

I agree with this - the 80% of users just need to know what you set, while the rest are interested in what PX4 does.

You've somewhat done this by having the top section of weight compensation "this is what you do" and then the subsections "this is how things are scaled", but it isn't obvious when you're reading the docs. In the compensating for air density section you've mixed what the user has to do and what PX4 does in each of the subsections.

So as @sfuhrer indicates I'd have a top section covering everything that the user actually does - such as set WEIGHT_BASE and WEIGHT_GROSS, FW_SERVICE_CEIL and so on, indicating what they tune, and possibly linking down from that information to where the information what PX4 does to use this information.

Then all the rest on what PX4 does could be in its own section PX4 Scaling Algorithms. The notation bit would go under there too.

Further, consider this section:

If you read this out of context looks like this is something you have to do "Scale the Maximum Climb Rate" and "The maximum climb rate (FW_T_CLMB_MAX) must be scaled as a function of the weight ratio.". Actually this is what PX4 does. So I'd rewrite that section (and similar) as "TECS scales the maximum climb rate (FW_T_CLMB_MAX) as a function of the weight ratio."

Hope that makes sense. I can help with this in two weeks if it isn't clear.

…eds to tune and the theory behind the various compensations Signed-off-by: RomanBapst <[email protected]>

Signed-off-by: RomanBapst <[email protected]>

RomanBapst · 2024-01-31T12:42:24Z

@hamishwillee @sfuhrer I tried to restructure the text according to your input, please let me know what you think.

github-actions · 2024-01-31T12:42:34Z

No flaws found

hamishwillee · 2024-02-01T02:36:17Z

en/config_fw/weight_and_altitude_tuning.md

+
+### Effect of Density on Trim Throttle
+
+TODO: Add derivation here.


ETA? I.e. is it worth merging the rest first and doing this as a post process?

hamishwillee · 2024-02-01T02:52:11Z

@sfuhrer @RomanBapst I just pressed the wrong button and merged this rather than updated :-(.

Let's build on the docs now published. I did a subedit to my taste in #3029 - I think the new structure is better but this can be made a bit tidier.

@RomanBapst We may need answers/fixes from these (I'll merge my fixup PR but questions are against it):

release note as per [WIP] Fixed-wing performance model docs #2842 (review)
Suggested correction by @sfuhrer [WIP] Fixed-wing performance model docs #2842 (comment)
Air pressure questions https://github.com/PX4/PX4-user_guide/pull/3029/files#r1473787467
Service ceiling question https://github.com/PX4/PX4-user_guide/pull/3029/files#r1473785868

DronecodeBot · 2024-08-03T04:57:43Z

This pull request has been mentioned on Discussion Forum for PX4, Pixhawk, QGroundControl, MAVSDK, MAVLink. There might be relevant details there:

https://discuss.px4.io/t/px4-v1-15-public-changes-what-needs-docs/39850/7

hamishwillee force-pushed the weight_altitude_tuning branch from 9610535 to 3233be6 Compare November 2, 2023 10:27

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Added PerformanceModel for fixed wing PX4/PX4-Autopilot#22091

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sfuhrer changed the title ~~WIP: Docs for https://github.com/PX4/PX4-Autopilot/pull/22091~~ [WIP] Fixed-wing performance model docs Nov 21, 2023

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RomanBapst and others added 11 commits December 13, 2023 09:46

initial docs for weight & altitude tuning

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fixed some typos

4794f93

Signed-off-by: RomanBapst <[email protected]>

Update main.md

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added entry to summary.md

b3829b8

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try another summary.md

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added more formulas to docs

676ba21

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fixed formula

dd781ab

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try to fix formula

2667f62

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progress

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small fix

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Prettier/heading fixes

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Update en/config_fw/weight_and_altitude_tuning.md

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Co-authored-by: Hamish Willee <[email protected]>

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fixed parameter naming

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Fix up all the calculations

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Subedit a bit

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restructuring to create a better distinction between what the user ne…

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…eds to tune and the theory behind the various compensations Signed-off-by: RomanBapst <[email protected]>

fixed link

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Fixed-wing performance model docs - update #3029

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[WIP] Fixed-wing performance model docs #2842

[WIP] Fixed-wing performance model docs #2842

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DronecodeBot commented Aug 3, 2024


		rearranging this equation for airspeed gives:

		$$V = \\sqrt{\\frac{2mg}{\\rho c_A F}}$$

	$$V = \\sqrt{\\frac{2mg}{\\rho c_A F}}$$
	$$V = \sqrt{\frac{2mg}{\rho c_A F}}$$


		### Effect of Density on Trim Throttle

		TODO: Add derivation here.

[WIP] Fixed-wing performance model docs #2842

[WIP] Fixed-wing performance model docs #2842

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