imu_apps seems to be publishing in bursts

tanguy sagere

Hi! I'm working with a ModalAI Sentinel right now equipped with the VOXL2, and I've noticed after running a few test flights that the recorded imu_apps data is very patchy, with bursts of messages followed by entire seconds of silence. This puts alot of stress on my VIO. Am I missing something or is this a known issue, and if so how do I fix it?

my voxl-imu-server.conf params are the default.

Thank you in advance!

Moderator

Hi Tanguy,

That sounds like the CPU is being overloaded. Which version of SDK are you running (voxl-version) and can you show the output of voxl-inspect-cpu when you are seeing this issue?

tanguy sagere

@Moderator Hi! I'm using :

system-image: 1.5.5-M0054-14.1a-perf
kernel:       #1 SMP PREEMPT Fri Mar 24 00:48:55 UTC 2023 4.19.125
------------------------------------------------------------------------------
hw version:   M0054
------------------------------------------------------------------------------
voxl-suite:   0.9.5
------------------------------------------------------------------------------
Packages:
Repo:  http://voxl-packages.modalai.com/ ./dists/qrb5165/sdk-0.9/binary-arm64/
Last Updated: 2023-08-24 23:20:47

When experiencing the message dropout, this is the output of voxl-inspect-cpu :

tanguy sagere

I've solved the problem by setting the voxl-imu-server.conf to

"imu0_enable":  true,
"imu0_sample_rate_hz":  200,
"imu0_lp_cutoff_freq_hz":      92,
"imu0_rotate_common_frame":     true,
"imu0_fifo_poll_rate_hz":       200,
...

Tested on 2 different VOXL2 boards, this reduces the number of lost messages sequences from 60% to <0.5% of all messages. Information on why this is the case would be interesting, as it is stated here that the default config is optimized for VIO.

tom

@tanguy-sagere I wonder if you upgrade to SDK 1.0 if the issue resolves itself