VOXL2 calibrate ESCs

[Daniel Ryu]

Hello,

I have a VOXL2 drone with ESCs inside, and the only guides I could find on calibrating ESCs were either for voxl1 or with exposed ESCs. Is there a way I can calibrate the ESCs from QGC on my voxl2 drone without having to take it apart to access the ESCs physically?

[Alex Kushleyev]

Hello Daniel,

We are working on releasing an update to enable voxl-esc tools (https://gitlab.com/voxl-public/flight-core-px4/voxl-esc) running directly on VOXL2. We hope this will be ready sometime next week. However, right now, if you are able to access the ESC and plug in a cable with a serial-to-usb adapter, you could run the voxl-esc tools on linux/mac. If you need help with connecting to ESC directly and running voxl-esc tools on Linux, please let me know.

Alex

[Daniel Ryu]

@Alex-Kushleyev Is this the documentation for it? https://docs.modalai.com/modal-esc-px4-user-guide/. Or is it this documentation: https://docs.modalai.com/voxl2-esc-configs/

[Alex Kushleyev]

Let me take a step back and ask you.. Can you clarify what you mean by ESC Calibration?

[Daniel Ryu]

@Alex-Kushleyev We want to both adjust the parameters for the ESCs, and also calibrate the ESCs feed-forward curve. Would that be these tools? https://gitlab.com/voxl-public/flight-core-px4/voxl-esc/-/blob/master/tools/calibration.md https://docs.modalai.com/modal-esc-px4-user-guide/#px4-params

[Alex Kushleyev]

Hi Daniel,

Thank you for the clarification.

We do not plan to port the voxl-esc tools to be embedded into px4 itself, since that would be redundant. So you would either need to connect to the ESC directly and run existing voxl-esc tools on linux or wait a bit more for the release of the tools to run voxl-esc directly on VOXL2. The way that would work is the following: there will be a special bridge application which allows the VOXL2 CPU to talk to the serial port using the DSP. The CPU is not directly connected to the serial port (DSP is), so that is why the bridge app is required.

If this is time sensitive for you, please try to connect to the ESC directly and let me know if you need help with doing that.

As for the PX4 parameters, you should still be able to change them as before, this is not related to voxl-esc tools.

Alex

[Daniel Ryu]

@Alex-Kushleyev What power supply do you use for calibrating the ESCs? We want to calibrate ours for a 4S Li-Ion battery for these motors, and are unsure of what power supply we should get.
Motor specs:

• Motor Dimension:Φ24.7mm x 13.2mm
• KV2600
  https://gitlab.com/voxl-public/flight-core-px4/voxl-esc/-/blob/master/tools/calibration.md

[Alex Kushleyev]

In the calibration.md file, you will find the following statement:

set voltage to nominal battery voltage (7.5V for 2S, 11.3V for 3S, 15V for 4S) make sure the power supply can handle the maximum motor current. If not, you will see the voltage drop towards the end of the test (power supply limiting) and the calibration will be invalid

You should be able to determine the maximum motor current based on the motor specifications provided by the manufacturer. For 4S, you would set the power supply to about 15V (would need 16.8V if you wanted to see absolute maximum RPM achievable with a 4S battery)

Using a power supply is a suggestion, but you could just use a battery as well. You can monitor the current drawn by the ESC (the calibration script should print it on screen) and abort the test if you see or hear anything unusual.

Alex

[Jose Alfredo Rosas Cordova]

Hello, @Alex-Kushleyev:

Are the esc-tools already a part of the VOXL2 software or do I still need to get a UART to USB converter for the calibration?

[Alex Kushleyev]

Working on it as we speak, I hope to release a test version tomorrow.

[Alex Kushleyev]

Hi @Daniel-Ryu

Good news, we have a beta version that is ready for testing. Here are the details:

• use latest available VOXL2 system image
• python3 version of voxl-esc tools : https://gitlab.com/voxl-public/flight-core-px4/voxl-esc/-/tree/dev-python3
• this version works on PC and VOXL2 (we are moving away from python2.7)
• if pip3 is not installed, https://pip.pypa.io/en/stable/installation/#get-pip-py
• if numpy, pyserial are not installed : pip3 install --upgrade numpy pyserial
• installation on voxl2: https://gitlab.com/voxl-public/flight-core-px4/voxl-esc/-/tree/dev-python3/tools#installation-instructions-for-voxl2
• In summary, you will need to follow the steps below on voxl2. we will put it into a script soon.
• Please let me know if you run into any issues going through these steps

#clone the voxl-esc repo
cd /home/root
git clone https://gitlab.com/voxl-public/flight-core-px4/voxl-esc.git -b dev-python3`

#install voxl-esc-tools-bin version 1.1 into voxl-esc/tools directory
#see instructions https://gitlab.com/voxl-public/flight-core-px4/voxl-esc/-/tree/dev-python3/tools#accessing-the-esc-tools-software

#download and install slpi uart bridge package to VOXL2
cd /home/root
wget http://voxl-packages.modalai.com/dists/qrb5165/dev/binary-arm64/voxl-slpi-uart-bridge_1.0.0-202303021121_arm64.deb
dpkg -i voxl-slpi-uart-bridge_1.0.0-202303021121_arm64.deb

#stop and disable PX4 while using voxl-esc tools
systemctl stop voxl-px4 && systemctl disable voxl-px4

#temporarily move libpx4.so and create symlink for slpi bridge to libpx4.so
#this is required because currently the slpi application loader looks for libpx4.so (hardcoded)
cd /usr/lib/rfsa/adsp
mv libpx4.so libpx4.so.bak
ln -s ./libslpi_uart_bridge_slpi.so ./libpx4.so

#reboot VOXL2
reboot

#test voxl-esc tools
cd /home/root/voxl-esc/tools
./voxl-esc-scan.py

#perform ESC testing / calibration
#...

#when done, restore original libpx4.so
cd /usr/lib/rfsa/adsp
rm libpx4.so
cp libpx4.so.bak libpx4.so