Motor issues when running ESC calibration
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@rdjarvis, so when you arm, the motors are spinning at idle rpm and rpms are not changing? Can you send me a short px4 log of this test?
Did you update px4 params for voxl esc min and max rpms?
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@Alex-Kushleyev yes motors spin when armed and respond appropriately to pitch, yaw and roll inputs (motors slowing and speeding up)
We have exhausted our efforts for this evening and will re-attack in the morning.
Thank you for all the help with hunting down these issues. We appreciate it and understand the frustration with these things.
Thank you,
RDJ -
@rdjarvis , based on your latest post, it seems the motors are spinning and responding to roll, pitch, yaw inputs, so i think the remaining issues may be in PX4 params.
By the way, I also wanted to mention, we have a fork of px4 flight review tool here : https://github.com/modalai/px4-flight-review . There is a quickstart guide in readme how to run this locally. Our version allows you to display ESC data such as commanded and actual RPMs, ESC temperatures, individual motor currents (where available) and total battery current.
By the way, since you are probably not using an APM for voltage/current monitoring, you should set (or double check) the
voxl_escpx4 driver to publish the voltage/current measurement, usingVOXL_ESC_PUB_BSTset to1.Then you will see the battery voltage and total current in battery status. (however if you are using APM, then you dont need that, set to 0)Alex
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@Alex-Kushleyev We are using the supplied PM from ModalAI C11 dev kit.
Tested this morning. All VOXL2 systems good.
Arm/Disarmed-Good
Arm/Motor Kill-GoodArm/Manual-Throttle Increase on RC Controller, UAV motors do not respond proportional to RC inputs. When throttle is increases, motors perform a very slow increase in RPM that does achieve flight. RPMs stay very low.
Could you point us to the PX4 params that we should be looking at to verify proper configuration?
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@rdjarvis , besides the PID tuning params, you need to make sure the min and max rpms in PX4 match what you have in esc params:
VOXL_ESC_RPM_MINandVOXL_ESC_RPM_MAX. did you set these PX4 params to 4000 and 40000? (btw in your test, was the motor able to reach 40K rpm? with my more aggressive prop, i think i had about 35K max).It is not a big deal if your ESC param in the ESC itself has maximum rpm that is higher than the motor can achieve. The ESC will just try to apply 100% power and will reach whatever rpm the motor can run at 100% power. But in PX4 params, you need to make sure that you set the maximum rpm that is actually achievable, otherwise PX4 will request the rpm that ESC cannot achieve and the drone will be less stable at maximum thrust.
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Yes, we confirmed the Params in PX4 QGC are identical to the Params in VOXL. Yes, Max RPM when performing calibration tests was 42k. I set it at 40k in both PX4 and VOXL-esc-params.
No response from throttle input when armed. We recalibrated the Radio and ensured RC Channel 3 was responding to Tx input.
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@rdjarvis , have you tried using actuator test to spin the motors (obviously be careful if props are on, or remove the props for the test). The actuator test should allow you to test the motors in the full range that you specified
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@Alex-Kushleyev Good morning.
Yes, Actuator tab in Vehicle Setup in QGC has VOXL ESC selected, motor directions are correct, and motor slider controls the motors.
Ch 3 RC Throttle Tx input does not apply actual throttle inputs when UAV is armed in any flight mode.
RC calibration was successful and RC Ch3 reacts correctly when Spektrum Tx mode 2 throttle stick is manipulated.
I will get you a log this morning when I'm clear of my meetings.
As always, thank you,
RDJ -
@rdjarvis, yes lets get a log where you are in manual flight mode (thrust, roll, pitch, yaw control) and you arm the drone and just move the thrust stick up and down a few times trying to take off. As a separate test, at idle throttle try to move roll and pitch stick to see the response from those inputs.
It looks like a px4 configuration issue but i am not sure what exactly.
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@Alex-Kushleyev Awesome, will do.
Thank you,
RDJ -
Also please check the value you use for the following param THR_MDL_FAC. Just curious about the current value, it should be close to one (0.7-0.8) for rpm control, but i can help you compute it exact value.
https://discuss.px4.io/t/thrust-curve-compensation-through-thr-mdl-fac/13207/3
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@Alex-Kushleyev How do I upload a log? The forum say I do not have permission.
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Upload it here and you can view results too. https://review.px4.io/ . The official flight review does not plot our custom esc data, but i will let you know how to view it later. I can download the log from the link above after you upload it and share a link
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@Alex-Kushleyev [mavlink] Event dropped (78, 65529)
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@rdjarvis said in Motor issues when running ESC calibration:
https://review.px4.io/plot_app?log=ae01b6f0-7910-43e4-a1c2-0d36ecc909d1
It seems you have something wrong with the thrust control (some filter?) the motors respond fine to roll / pitch but not thrust. see plots below showing RPMs. The ESC is tracking the desired RPMs well (actually a bit higher than desired at high rpm, but that is ok for now)
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(look at how desired motor outputs and desired rpms rise very slowly when you increase the desired thrust, never reaching enough rpms to hover)
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@Alex-Kushleyev Thank you. We understand that the desired inputs and actual input are not the same.
We have no filters. All ModalAI Hardware and Software are being used. ModalAI PX4 QGC Skin is used. Spektrum Rx/Tx DSMX as suggested by ModalAI is used.
We have purchased 2 ModalAI FPV 4n1 ESC and multiple VOXL and VOXL2 Dev kits to keep all hardware in the same ecosystem for easy integration and R&D for our product.
There is a disconnect between the FC/ESC comms on throttle Ch 3.
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I do appreciate your willingness to help. I have selected ModalAI products for our organization based off of current and future capabilities. I have even selected a motor that I know you are using to ensure stable testing and flight characteristics.
If the ModalAI DEV team cannot troubleshoot issues on known UAV setups that you have at your shop, then I need to have a conversation with a different department.
All web advertising, Documentation, and Videos produced by ModalAI have shown these capabilities working flawlessly and it feels we have been oversold the true capabilities of the system today.
At this point these products cant even take flight.
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I swapped the RC Channels for testing.
Throttle and yaw were swapped RC3 and RC4.
Same results with throttle not responding to inputs on RC4, instead of RC3.
