IMU Bug Issue...!

flyingclint · Feb 23, 2015

I keep hearing about this IMU Bug issue that causes the I1 at motor spin up to suddenly lunge forward and crash!

issue here:
has this been fixed with recent updates or what???

My I1 will be here this Friday and I want to know what to expect, especially since I have a shoot with it that following Saturday. Is there anything you guys feel I should know about at this point, or have most of the issues been worked out since the I1 has now been on the market for about two months...???

Thanks!

-Clint

blade strike · Feb 23, 2015

This was fixed in .16 (current fw)

Now we just have a GPS degradation issue that happens when the compass starts to report errors. You are automatically switched into ATTI mode.

The sensitivity is really high currently and has been tuned much better in the new firmware that should be release shortly.

flyingclint · Feb 23, 2015

Ahhh... Ok, good to know! So there really isn't any other issues that you know of at this moment? Is this "GPS Degradation issue" serious, or is it something manageable in flight? Meaning is it something I should be worried about and it causes crazy, erratic, spontaneous behavior, or is it pretty tame and not much of a big deal??? If the ship is just going in and out of ATTI mode, that's not favorable, but isn't a big deal either! I can deal with that!

Thanks!

-Clint

Richard-Inspire · Feb 24, 2015

you certainly choose a nice safe spot for your first test flight!

RolandRSA · Feb 24, 2015

Until the new firmware is released i fly in ATTI mode. At least i know what mode i am in, i obviously pick the conditions i fly in carefully.
But i have not noticed any major issues in flight with the current firmware.

flyingclint · Feb 25, 2015

So, I am still a little nervous because i am not fully understanding what the IMU is and how it works and if I am supposed to be checking something with it every time I fly??? I just watched a video about the Pilot app and in there she showed an overview of the IMU section in the app and it talks about checking the IMU and also calibrating it in basic or advanced modes. So are things fine now that the IMU bug had been addressed and fixed from the last firmware update, or is this something I should still be checking before each flight and also needs to be calibrated before each flight??? I really want to get a firm understanding on all of this IMU stuff...! Thanks!

-Clint

Quadpilot · Feb 26, 2015

Clint,

The IMU is an inertial measurement unit that consists of an accelerometer and a 3-axis gyro that measures acceleration and movement in a 3 dimensional space. As such, it requires that it be calibrated to determine what is level, un-accelerated flight. To do that, it needs to be on a perfectly level surface, which is done on a flat surface that you've determined to be level. Once calibrated, the Inspire should be able to hold position without drifting. If the sensors for gyro are showing within .01 of .00 and 1.00 (in the About, Sensors section of the app), you are good to go, and don't need to keep doing the IMU calibration. if you suspect that the Inspire has been jarred in transport, or if the app prompts you to do an IMU calibration, then that is the only time you need to redo an IMU cal. OTOH, every time you change locations, you should do a Compass calibration, because the Inspire FC needs to sense the compass declination, which change with a change in location. As an aside, it is good to start the IMU cal with the craft at ambient temperature. Having the craft powered up for long tends to heat up the IMU, and will cause it to abort the calibration.

The latest firmware does not have basic and advanced calibration. There is only one option, which is the full advanced cal.

flyingclint · Feb 26, 2015

Quadpilot said:
Clint,

The IMU is an inertial measurement unit that consists of an accelerometer and a 3-axis gyro that measures acceleration and movement in a 3 dimensional space. As such, it requires that it be calibrated to determine what is level, un-accelerated flight. To do that, it needs to be on a perfectly level surface, which is done on a flat surface that you've determined to be level. Once calibrated, the Inspire should be able to hold position without drifting. If the sensors for gyro are showing within .01 of .00 and 1.00 (in the About, Sensors section of the app), you are good to go, and don't need to keep doing the IMU calibration. if you suspect that the Inspire has been jarred in transport, or if the app prompts you to do an IMU calibration, then that is the only time you need to redo an IMU cal. OTOH, every time you change locations, you should do a Compass calibration, because the Inspire FC needs to sense the compass declination, which change with a change in location. As an aside, it is good to start the IMU cal with the craft at ambient temperature. Having the craft powered up for long tends to heat up the IMU, and will cause it to abort the calibration.

The latest firmware does not have basic and advanced calibration. There is only one option, which is the full advanced cal.

Thank you so much quadpilot! Great detailed info! I guess I'm confused and concerned cause I never had to even think about this or do these calibrations on my Phantom vision plus quad, so why on a more advanced, $3000.00 quad am I needing to keep this step in my process and be aware of this being an issue? I just think for the money paid and how advanced this quad is supposed to be, this should be something that is set and doesn't need adjusting/calibrating unless a major change to the craft or problem has occurred and then it would make sense to worry about calibrating etc... Thanks for the info and I guess I need to do some more research or something. I'm just not sure how worried about this being an issue I should be! Am I making more of this than it is? Or are my concerns valid and necessary?
Thanks!
-Clint

Tahoe Ed · Feb 26, 2015

flyingclint said:
Thank you so much quadpilot! Great detailed info! I guess I'm confused and concerned cause I never had to even think about this or do these calibrations on my Phantom vision plus quad, so why on a more advanced, $3000.00 quad am I needing to keep this step in my process and be aware of this being an issue? I just think for the money paid and how advanced this quad is supposed to be, this should be something that is set and doesn't need adjusting/calibrating unless a major change to the craft or problem has occurred and then it would make sense to worry about calibrating etc... Thanks for the info and I guess I need to do some more research or something. I'm just not sure how worried about this being an issue I should be! Am I making more of this than it is? Or are my concerns valid and necessary?
Thanks!
-Clint

The Vision + also had IMU calibration and it should have been done at least after every update. That is what I do. The Inspire is a more complex machine and should be treated in a similar manner.

Quadpilot · Feb 26, 2015

flyingclint said:
Thank you so much quadpilot! Great detailed info! I guess I'm confused and concerned cause I never had to even think about this or do these calibrations on my Phantom vision plus quad, so why on a more advanced, $3000.00 quad am I needing to keep this step in my process and be aware of this being an issue? I just think for the money paid and how advanced this quad is supposed to be, this should be something that is set and doesn't need adjusting/calibrating unless a major change to the craft or problem has occurred and then it would make sense to worry about calibrating etc... Thanks for the info and I guess I need to do some more research or something. I'm just not sure how worried about this being an issue I should be! Am I making more of this than it is? Or are my concerns valid and necessary?
Thanks!
-Clint

IMU calibration, as Ed suggested, is only necessary when prompted by the app, or after a firmware (not app) upgrade. Other than that, unless you observe that is is having trouble holding position without stick input, there is no need to do a calibration (still need to do Compass cal when changing flying location, though!).
A quick way to verify is to check sensor data, as mentioned in my previous post. Stop worrying and start flying!