Voxl2 reboot due to what it seems a power limitation

Riccardo Franceschini

I'm currently facing a challenge with my VoXL2 Flight Deck (with power module v3), where it seems to reboot due to a power limitation issue. I'm running SDK version 1.1.2 and trying to execute a segmentation model converted to TFLite. The model runs successfully at 5Hz, but the problem arises when I observe a significant increase in power consumption, particularly the current, when I try to run anything else.

Here are the power metrics before and after starting the model:

Before Starting Model:

Voltage | Charge | Current
14.70V  | 100%   | 0.63A

After Starting Model:

Voltage | Charge | Current
14.70V  | 100%   | 0.91A

The current spikes to 0.8A, with peaks of 0.9A. When I also run the voxl-mpa-to-ros node and another custom node, the power change is significant enough to trigger a reboot of the drone. I've experimented with the skip_n_frames parameter to achieve a more stable result, but the board seems to be operating at its limit. Any attempt to surpass 1.0A, easily triggered by subscribing to ROS topics or running basic logging scripts, results in a reboot, rendering it unsuitable for flying.

Key observations:

GPU usage is at its limit.
CPU and temperature are within acceptable ranges.
I'm seeking guidance on how to address this power limitation. Are there specific parameters that can be configured or ways to modify the power limit of the board to handle the increased load without triggering reboots?

Any insights or suggestions would be greatly appreciated. Thank you in advance!

Alex Kushleyev

@Riccardo-Franceschini , what device are you using to measure voltage and current?

I would recommend a few simple things to try next:

if you have another power module v3, just swap it out and test again
try swapping the 4-wire power cable that connects the power module and voxl2. Perhaps there is poor contact on the power pins

If the issue still persists, we can try to diagnose it by logging the current draw from battery and also 5V output (power module v3 has current sensing of both)

Vinny

@Alex-Kushleyev @Riccardo-Franceschini
This is most certainly not a power network or power module limitation.
We have extensively stressed the power module for it's 6A rating many many times, including over the full industrial temp range. Every unit also undergoes a "DUT Test" of 3A load during manufacturing testing.
The power module can certainly deliver a full 30W of Continuous power. 1A will barely make it sweat.

The more likely culprits can be either the power cable, which often get stressed easily by pulling on the cables during extraction/removal instead of the cable shroud. This will over time shred the cable junction at the pin contacts. We have a standing rule at HQ to replace the main power cable every few months.
Or, it might be some GPU linked trigger due to a 100% load, especially if you are not seeing any CPU issues.

If you wish to share a photo of your setup, we can help further.
Thanks!

Riccardo Franceschini

Hi,

after experimenting, we found that the problem was a RealSense external camera that we plugged in.

It was connected through USB via the 5G module. Probably, this was causing a short circuit or overload of the board. Anyway, modifying the connection cable so that only the data goes through the board while it is powered separately seems to solve the problem.

Alex Kushleyev

Great to hear you got it figured out!

Vinny

Hi @Riccardo-Franceschini
Our USB hubs have a smart power switch with a message feature that relays back to the host if there is an error/over-current condition on VBUS.
It might be that is what was causing the reset.
But yeah, glad you figured it out!!
Nice work!

Vinny

@Riccardo-Franceschini For future note, this page here lists all the VBUS capabilities in our designs so you know which port (if any) can support your high current use cases:
https://docs.modalai.com/expansion-design-guide/#usb-expansion-over-j3--j5