I’m going to setup the Pixhawk now, but I continue to receive errors of "Bad Accel Health" or “inconsistent compass”. I'm doing the setup indoor.
I already updated the Firmware (with Craft and Theory build for the telemetry cable, but the issue was the same before this flashing), and I also already re-calibrated the accels, but the issue is still present.
Do you have any idea about what could be the problem? Could it be a hardware problem?

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I'm looking for the IMU parameters, but I cannot find it. How is it listed under the "Advanced Parameters List" on APM Planner for Mac?

I also looked for it under the graph tab, but I just found the RAW_IMU and SCALED_IMU2


If it's broken....fix it.  If it ain't broke......I'll soon fix that too.  Not my original quote, but thought I'd share ( :

Tony K, thanks for all your insightful suggestions.  I'm hoping I don't have to go back down that rabbit hole as I have found myself.....finally.....spending less time on the bench and more time in the air. 

One last question.  I have a second (Pixhawk based) quad, she's about 2 yrs old now, that has been rock solid for me running V3.2.1.  Would you update it to 3.3.3?

You see 3.3.3 might expose some vibration issues that 3.2.1 does not. If that quad has very good vibration isolation i would say upgrade if you are not sure id say dont do it.  So it all depends on what size quad it is and how good your vibration damping is, otherwise you should not have any issues. 3.3.3 is more sensitive to vibration issues from what i understand. See here 


Copter 3.3-rc1 11-Apr-2015
Changes from 3.2.1
1) Only support fast CPUs boards (Pixhawk, VRBrain, etc) and drop support for APM1, APM2 (sorry!)
2) AutoTune for yaw
3) Smooth throttle curve which should reduce wobbles during fast climbs and descents
4) ch7/ch8 aux switches expanded to ch9 ~ ch12 (see CH9_OPT ~ CH12_OPT params)
5) PX4Flow support in Loiter mode (still somewhat experimental)
6) Safety features:
a) EKF on by default replacing DCM/InertialNav which should improve robustness
b) increased accelerometer range from 8G to 16G to reduce chance of climb due to high vibrations (requires accel calibration)
7) Landing features:
a) improved landing on slopes
b) retractable landing gear (see LGR_ parameters)
8) Camera Gimbal features:
a) SToRM32 gimbal support (using MAVLink)
b) AlexMos gimbal support (using AlexMos serial interface)
c) do-mount-control commands supported in missions (allows controlling gimbal angle in missions)
9) Battery related features:
a) PID scaling for battery voltage (disabled by default, see MOT_THST_BAT_ parameters)
b) smart battery support
10) Other:
a) support do-set-home command (allows return-to-me and locked home position once GCS enhancements are completed)
b) performance improvements for Pixhawk reduce CPU load from 80% to 15%
c) firmware string name changed from ArduCopter to APM:Copter

Its this : 

INS_USE: 0 or 1 

INS_USE2 : 0 or 1

3rd IMU does not exist on pixhawk as you probably know 

Thanks Tony,

very helpful. Meanwhile I found those parameters but anyway I needed your confirmations.

I will try to arm it outdoors with pre-arm checks, then with one and the other IMUs inactive.

Will let you know. Thanks again.

At first I admit that BAD_ACCEL_HELATH / INCONSITENT_ACCELORMETERS and the compass error are two different problems.

I also encounter theBAD_ACCEL_HELATH / INCONSITENT_ACCELORMETERS problems only on cold days. Which seems to come from values from IMU2 differing to much from IMU1 (I looked at the log) And for me it seems to be the IMU2 issue as described within the linked by Tony K:


(Thanks for this interesting analysis!)

If the error occurs, it helps for me to let the pixhawk warm up for view minutes and than to move it around all axes until the warning disappears.


I also had the inconsistent compass warning during setup. You did not indicate if you are using an external GPS and compass, If you are it may indicate the internal Pixhawk compass and the external compass don,t agree. After much time trying to solve my compass issue I simply disabled the internal Pixhawk compass in Mission planner. Had not problems after this. In any case the external compass performs much better.

The craft and Theory option works great. You would be aware that you need to down load a special version of pixhawk software until the next version of pixhawk release catches up, also Opentx version 2.1.7 has some issue which will be fixed in 2.1.8

Cheers Henny


I attach to this post the screenshot of the graphics. Looks like the IMUs have different values.


1. do I have to setup in some way the external Ublox Neo8 GPS antenna?

2. from the screenshot, do you think I may have HW issues?



Hey guys, an update since I'm still stuck... maybe because APM Planner for Mac cannot calibrate properly the sensors?

Some details:

  • Pixhawk with APM:Copter V3.3.3
  • Macbook Pro 13" early 2015 with OS 10.11.3
  • APM Planner software 0b4ab402-2.0.20
  • external GPS uBlox Neo M8N connected to GPS and I2C ports (I2C expansion bay)

Besides that I cannot connect the SIK V2 telemetry radios (they can see each other, they have solid green LED, they can download settings to APM Planner SW correctly, but if I choose the radio serial port at 56k BAUD rate, they connect to each other but do not show the connection to the Pixhawk) using the Telem1 Port...

I still have several errors while trying to arm the copter, they are all related to the sensors.

The errors shown in the info view page are:

  • FAILURE: Failed CMD: 241 (trying to calibrate the compass)
  • PreArm: EKF compass variance
  • BAD accel health
  • inconsistent compasses
  • accelerometers not healthy

I attach some screenshots. As you can see in one of the screenshots, the map shows a moving copter, which obviously was not moving at all. I was indoor in that moment, but yesterday in outdoor the copter was still showing movements while it was on the ground.

Attaching more screenshot in the following posts.

Please help gurus, I'm stuck here and I must fly this bird. Thanks.



Here some older screenshots. I'm going to take something newer today.




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