Cleanup and improve sim battery

[hunt0r]

Description

This PR prepares for every simulated vehicle to implement battery consumption (#10050).

It causes minimal (no?) changes in observed behavior. A follow-up PR will switch vehicles to actually using these improvements. (If you're interested, preview that PR here.)

Summary of significant changes:

• Reword the SIM_BATT_VOLTAGE and SIM_BATT_CAP_AH parameter descriptions for clarity & completeness. These define the user-facing behavior.
• Improve SITL::Battery class to support that behavior.
• Disentangle SITL::Battery from SITL::Frame.

Testing (your PR may be summarily closed without these)

Side-by-side of EvaluateBatteryModel shows no changes (figures below).
Simple MultiCopter (--model x) in SITL: arm, takeoff, hover, land.

• Tested via example
• Tested in SITL
• Tested on hardware
• Autotest included
• Not AI slop
• logs attached
• logs available on request

Recommendations

Reviewers: Please start with the descriptions of SIM_BATT_VOLTAGE and SIM_BATT_CAP_AH parameters. In case I interpreted these incorrectly, we must sort that first! (They're in the last commit.)

After that, I recommend skimming commit-by-commit to understand the individual steps being taken.

Testing images from example

Observe that before-and-after are the same.

After this PR:

Reference image (from here in repo):

[hunt0r]

I looked at removing this, but it looks like ~20 children also have it because this does. 🙁

I'm happy to do that in a separate cleanup PR, but it would distract too much from the focus of this one.

[hunt0r]

I don't love how every Aircraft has a SITL::Battery but many ignore it. That's a slightly smelly design. But its consistent with the current state of the code. Hence me merely adding a comment here to alert folks about that.

I welcome a spin-off discussion about the future of simulated batteries. I'd prefer that every aircraft (every instantiated child of SITL::Aircraft) either have a SITL::Battery and use it, or do something custom and not have a SITL::Battery inside at all.

As an example, an alternate design would be for "the sim" to own "the simulated battery" as a stand-alone object. While that's nonphysical, its consistent with SITL::Sim containing stuff like a SITL::Sprayer, SITL::Parachute, SITL::Buzzer, etc. which I presume would be physically carried by the aircraft.

[hunt0r]

TIL that ./waf all does not in fact build everything. I will fix the failure...

(In case anyone is interested, there are targets which are only valid for --board=linux.)

Update: Fixed.

[IamPete1]

This is a surprisingly big change, the commits also need a squash. Rather than a larger rework it would be easyer to review if you could make the minimum change to get the new functionality.

[hunt0r]

I'm not yet understanding the feedback, can you provide more detail?

the commits also need a squash.

Sure! I am happy to squash them together after the content is approved. (I assumed it is helpful to parse the changes step-by-step, but of course if a reviewer prefers not, just review the final outcome.)

Rather than a larger rework it would be easyer to review if you could make the minimum change to get the new functionality.

What "new functionality" are you referring to?

This is a surprisingly big change

Which step(s) should not be done?

[hunt0r]

Rebasing on master to see if the tests now pass. (At least the most significant-looking one did for us locally yesterday...)

[hunt0r]

I have repro'ed the failure locally. Converting to draft while I fix it.

[hunt0r]

Closing this, because it's contribution is being landed incrementally via various PRs such as #32561, #32538, and #32637