Airspeed measurement: Add accurate models for dynamic pressure

[LorenzMeier]

This allows to get very accurate readings from the SDP3x sensor series from Sensirion using a complete sensor model.

@AndreasAntener Another set of test flights with this in would be great. I've left the unfiltered value uncompensated so that we can compare efficiently.

[dagar]

We could have the drivers themselves report the model.

[LorenzMeier]

Indeed, good idea.

[dagar]

There also seems to be a desire for supporting multiple airspeed sensors (even for only this kind of testing). Getting some kind identifier in place for extending the calibration is the first step. I suppose we'd still need a completely separate dev id and model enum though.

[LorenzMeier]

First step would be to add uint32 device_id # unique device ID for the sensor that does not change between power cycles and then decode that struct to extract the sensor type ID. But I'll do that separately to not clutter this PR.

[LorenzMeier]

@dagar I added all this here now. No more params required by default.

[dagar]

Thanks!

[priseborough]

Where do we include the correction for positional error scale factor which is installation (not sensor) dependent? That can be up to +-20% depending in sensor location.

[dagar]

There's a field for it here. https://github.com/PX4/Firmware/blob/master/src/drivers/drv_airspeed.h#L71

Then we'll need appropriate parameters and to glue it all together.

[priseborough]

As a separate PR, I could implement a simple 3-state filter enabling the scale factor to be adjusted on-line during fight testing. In my experience, most users don't understand the difference between TAS and IAS/EAS and as a result calibrate the system incorrectly.

Edit: I'd forgotten that this has already been done here: #7424

[AndreasAntener]

I ran the correction over the data from my last test and it looks pretty good:

[AndreasAntener]

I found some negative values that cause problems during the correction calculation and found a mistake in the C version, will add a commit and test.

[LorenzMeier]

Great. My main concern are issues in the C version.

[AndreasAntener]

I ran out of office time to run another test with the firmware (long meeting..) but the compensation on the data looks good. I'm not around for another test until next Tuesday though.. Who else has a setup?

[LorenzMeier]

I should have one tomorrow to validate against ground speed.

[LorenzMeier]

Very low speed bench test:

[LorenzMeier]

Similar test without compensation:

[LorenzMeier]

@AndreasAntener This should be good to go for testing.

[dagar]

Rebased on master for logging all differential pressure sensors and device ids.