Blue Raven Calibration Frustrations

[ihbarddx]

I have found the BR calibration experience to be consistently exasperating.

Suggested improvements:

There should be feedback when the instrument successfully calibrates an axis. As of now, you find out at the end if all your calibrations were accepted. If even one was missed, you start the torture all over again. It would be nice if the display told the user which axes are completed. (Or maybe I'm doing something wrong...) (EDIT: A solid green light comes on once the axis has been accepted. I missed this because I do the procedure once a month, because the virtual buttons on my phone are so insensitive that they rarely respond to being pressed, and I don't get the green light at the end of the last axis.)

The Record Axis (virtual) button is too close to other virtual buttons, any of which will restart the calibration. This fat fingers effect is especially frustrating, since one is normally in some haste to smash the record Axis button before it turns off. (EDIT: My wife lent me her button pushing style.)

Please understand that I normally perform the procedure at night, before a launch, and my neighbors object to being awakened by my screams.

(EDIT: If the device knows when everything is aligned, why can't it automatically accept the calibration without my button-pushing intervention?)

 

[Adrian A]

Thank you for the feedback!

I have found the BR calibration experience to be consistently exasperating.

Suggested improvements:

There should be feedback when the instrument successfully calibrates an axis. As of now, you find out at the end if all your calibrations were accepted. If even one was missed, you start the torture all over again. It would be nice if the display told the user which axes are completed. (Or maybe I'm doing something wrong...) (EDIT: A solid green light comes on once the axis has been accepted. I missed this because I do the procedure once a month, because the virtual buttons on my phone are so insensitive that they rarely respond to being pressed, and I don't get the green light at the end of the last axis.)

When each axis is successfully recorded, the app shows it in green text below that orientation. In the example below, only the -Z up position was successfully recorded so far. Maybe that text should be brighter? Or maybe we could change the color of the sketch to green to show when it's done?

The Record Axis (virtual) button is too close to other virtual buttons, any of which will restart the calibration. This fat fingers effect is especially frustrating, since one is normally in some haste to smash the record Axis button before it turns off. (EDIT: My wife lent me her button pushing style.)

I agree. It doesn't help that not everything is fitting on one screen for most devices so you have to scroll a little. I think I'll have my developer shrink down the diagrams to make more room, so the buttons at the bottom have some space above the bottom tab buttons.

Please understand that I normally perform the procedure at night, before a launch, and my neighbors object to being awakened by my screams.

(EDIT: If the device knows when everything is aligned, why can't it automatically accept the calibration without my button-pushing intervention?)

After spending years doing calibrations with the iFIP, which was completely automatic, I really prefer being able to control when I think the positioning is done and the reading stable. YMMV.

 

[kjhambrick]

Thanks for the reminder, Larry.

I wanted to recalibrate my oldest Blue Raven but forgot all about it.

It is a little tricky as you noted, especially since the instructions were written for the FIPs interface.

I was able to get it done but only by re-reading Adrian's instructions here on TRF: Featherweight Blue Raven Development Thread: Ground tests ( Post #28 ) which remimded me I needed to tilt the Blue Raven a tad so that off-axis readings are small.

Even though my Blue Raven is mounted on a 'calibration block' I still have to tilt it slightly so that the other axes are +/- 0.025 G before the [Record Axis] button lites up.

It does almost take three hands

Anyhow, below are one sim before and two sims after recalibration for my oldest Blue Raven, S/N 0236 ...

Note that the two after sims show slightly different offsets ...

Now it's time to reinstall S/N 0236 in my 38mm Av-Bay and refly T'Pring's P'Toy on an H180 ( see Rough Accelerometer Data from a Blue Raven in a 38mm Av-Bay -- Is the noise for real ? )

Good Luck Larry !

-- kjh

Before Racalibration. Note the Hi-G y-axis offset and pad accel:



After first recalibration:



And after the 2nd recalibration:

 

[ihbarddx]

Thank you for the feedback!




When each axis is successfully recorded, the app shows it in green text below that orientation. In the example below, only the -Z up position was successfully recorded so far. Maybe that text should be brighter? Or maybe we could change the color of the sketch to green to show when it's done?
View attachment 642798


I agree. It doesn't help that not everything is fitting on one screen for most devices so you have to scroll a little. I think I'll have my developer shrink down the diagrams to make more room, so the buttons at the bottom have some space above the bottom tab buttons.

After spending years doing calibrations with the iFIP, which was completely automatic, I really prefer being able to control when I think the positioning is done and the reading stable. YMMV.

Thanks, Adrian
Sorry for the tone. It was the exasperation talking.

 

[Neutronium95]

Thank you for the feedback!




When each axis is successfully recorded, the app shows it in green text below that orientation. In the example below, only the -Z up position was successfully recorded so far. Maybe that text should be brighter? Or maybe we could change the color of the sketch to green to show when it's done?
View attachment 642798


I agree. It doesn't help that not everything is fitting on one screen for most devices so you have to scroll a little. I think I'll have my developer shrink down the diagrams to make more room, so the buttons at the bottom have some space above the bottom tab buttons.

After spending years doing calibrations with the iFIP, which was completely automatic, I really prefer being able to control when I think the positioning is done and the reading stable. YMMV.

Is it possible to calibrate the accelerometers on the 29mm Bulkhead Blue Raven? It would probably require some sort of 3D printed fixture to calibrate with any accuracy.

 

[Adrian A]

Is it possible to calibrate the accelerometers on the 29mm Bulkhead Blue Raven? It would probably require some sort of 3D printed fixture to calibrate with any accuracy.

Yes, it's quite possible, though the diagrams of the orientations obviously have to be ignored. The nice thing about the calibrations is that it tells you when it's aligned well enough to record the axis. If you keep your eye on the 3 real-time numbers you can adjust to zero out the cross-axis measurements It's not too hard. Just roll the board until the X or Y is close to zero, and tilt until the Z is close to zero, then record the axis. And the other nice thing is that at each calibration orientation, only the 1-G axis is getting recorded, and any misalignment errors just introduce cosine errors, which are very small for small angles.