“AHRS: Needs position estimate” when arming in Loiter + Compass calibration never completes

ArduCopter Copter 4.6
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1

Hi everyone,

I’m having trouble arming my drone in Loiter mode on ArduCopter 4.6.0.
Even with 12 satellites and HDOP ~0.8, I get the following error every time I try to arm:

AHRS: Needs position estimate
I also have Fence disabled, so it’s not a fence-related issue.

Compass Calibration Problem

While calibrating the compass in Mission Planner, the green progress bar never finishes. It keeps going indefinitely. Eventually, I clicked “Accept” manually to save the values because the calibration would not end on its own. I’m suspecting this might be related.

System Info

  • Firmware: ArduCopter 4.6.0
  • GPS: 12 satellites, HDOP 0.8
  • Modes:
    • Stabilize → arms fine
    • AltHold → arms fine
    • Loiter → fails with “Needs position estimate”
  • Compass calibration: Never finishes → forced Accept
2

Try with different mission planner version. Also use ardupilot methodic configurator.

3

This is normal, Loiter mode needs a GPS position update at 5Hz or higher, I bet your GPS receiver is delivering less than that.

And you need to fully calibrate your compass while having a GPS fixed signal, that is also a requirement for correct loiter operation.

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4

Hi @ompatil,

For the compass calibration, try setting the “Fitness” to “Relaxed”. No big deal but it’s mentioned on the wiki in the Onboard calibration section. Perhaps it should be more obvious though

5

Hello,

Sure ill try that and let you know. Thank you for your replay!

6

Hello,

Understood ill try this.

Thank You ! :smiley:

1 Like