[Communication Constraints Violation] Error Occur While Playing Examples

[Park0328]

Hello,

I am currently conducting experiments using the Franka Research 3 robot.
During the experiments, an error occurred, and I am reaching out to ask for your assistance in finding a solution.

Development Environment:

Ubuntu 22.04

Linux 6.8.1 rt-8 (RT kernel)

libfranka: 0.15.0

ROS: ROS2 Humble

PC: ASUS NUC Pro 13

I have set up the recommended development environment as outlined in the FCI documentation. However, while running the example programs, I am encountering an unexpected [Communication Constraints Violation] error.

Referring to previously closed issues on other Franka GitHub repositories, I investigated where the exception is triggered.
It turns out that the error occurs during the robot state update process in the franka_hardware_interface.cpp file, specifically at the line:

'hw_franka_robot_state_ = robot_->readOnce();'

I have already tried all the suggested solutions provided in the official troubleshooting guide (https://frankaemika.github.io/docs/troubleshooting.html), and I am compiling with optimization using -DCMAKE_BUILD_TYPE=Release.

I also ran a communication test, and the results indicate that the network condition is good.

Starting communication test.
#100 Current success rate: 1.00
#200 Current success rate: 1.00
#300 Current success rate: 1.00
#400 Current success rate: 1.00
#500 Current success rate: 1.00
#600 Current success rate: 1.00
#700 Current success rate: 1.00
#800 Current success rate: 1.00
#900 Current success rate: 1.00
#1000 Current success rate: 1.00
#1100 Current success rate: 1.00
#1200 Current success rate: 1.00
#1300 Current success rate: 1.00
#1400 Current success rate: 1.00
#1500 Current success rate: 1.00
#1600 Current success rate: 1.00
#1700 Current success rate: 1.00
#1800 Current success rate: 1.00
#1900 Current success rate: 1.00
#2000 Current success rate: 1.00
#2100 Current success rate: 1.00
#2200 Current success rate: 1.00
#2300 Current success rate: 1.00
#2400 Current success rate: 1.00
#2500 Current success rate: 1.00
#2600 Current success rate: 1.00
#2700 Current success rate: 1.00
#2800 Current success rate: 1.00
#2900 Current success rate: 1.00
#3000 Current success rate: 1.00
#3100 Current success rate: 1.00
#3200 Current success rate: 1.00
#3300 Current success rate: 1.00
#3400 Current success rate: 1.00
#3500 Current success rate: 1.00
#3600 Current success rate: 1.00
#3700 Current success rate: 1.00
#3800 Current success rate: 1.00
#3900 Current success rate: 1.00
#4000 Current success rate: 1.00
#4100 Current success rate: 1.00
#4200 Current success rate: 1.00
#4300 Current success rate: 1.00
#4400 Current success rate: 1.00
#4500 Current success rate: 1.00
#4600 Current success rate: 1.00
#4700 Current success rate: 1.00
#4800 Current success rate: 1.00
#4900 Current success rate: 1.00
#5000 Current success rate: 1.00
#5100 Current success rate: 1.00
#5200 Current success rate: 1.00
#5300 Current success rate: 1.00
#5400 Current success rate: 1.00
#5500 Current success rate: 1.00
#5600 Current success rate: 1.00
#5700 Current success rate: 1.00
#5800 Current success rate: 1.00
#5900 Current success rate: 1.00
#6000 Current success rate: 1.00
#6100 Current success rate: 1.00
#6200 Current success rate: 1.00
#6300 Current success rate: 1.00
#6400 Current success rate: 1.00
#6500 Current success rate: 1.00
#6600 Current success rate: 1.00
#6700 Current success rate: 1.00
#6800 Current success rate: 1.00
#6900 Current success rate: 1.00
#7000 Current success rate: 1.00
#7100 Current success rate: 1.00
#7200 Current success rate: 1.00
#7300 Current success rate: 1.00
#7400 Current success rate: 1.00
#7500 Current success rate: 1.00
#7600 Current success rate: 1.00
#7700 Current success rate: 1.00
#7800 Current success rate: 1.00
#7900 Current success rate: 1.00
#8000 Current success rate: 1.00
#8100 Current success rate: 1.00
#8200 Current success rate: 1.00
#8300 Current success rate: 1.00
#8400 Current success rate: 1.00
#8500 Current success rate: 1.00
#8600 Current success rate: 1.00
#8700 Current success rate: 1.00
#8800 Current success rate: 1.00
#8900 Current success rate: 1.00
#9000 Current success rate: 1.00
#9100 Current success rate: 1.00
#9200 Current success rate: 1.00
#9300 Current success rate: 1.00
#9400 Current success rate: 1.00
#9500 Current success rate: 1.00
#9600 Current success rate: 1.00
#9700 Current success rate: 1.00
#9800 Current success rate: 1.00
#9900 Current success rate: 1.00
#10000 Current success rate: 1.00

Finished test, shutting down example

#######################################################
Control command success rate of 10000 samples:
Max: 1.00
Avg: 1.00
Min: 1.00
#######################################################

Could you please advise on how I might resolve this issue?

[AndreasKuhner]

Hi @Park0328

A communication constraint violation means that the connection between your notebook and master controller was shortly delayed (could be some other computational spikes, network traffic, ...)

If it happens more often, you might need to investigate your hardware setup.

Cheers,
Andreas

[JoshSmithSkild]

I fixed this issue after trying all options by downgrading to 5.7.2 on the arms and 14.1 for libfranka. However, I was using Polymetis not franka_ros2 but looks similar. Some people had similar issue here:

facebookresearch/fairo#1426

[AndreasKuhner]

Hi @JoshSmithSkild ,
that would be a surprise if downgrading to 5.7.2 would have resolved communication_constraint issues :) Our internal tests showed that 5.7.2 ~= 5.8.0. And both of them are worse than 5.6.0.

However, the 5.8.1 release improved everything by a lot and should be comparable (thou still not the same) as 5.6.0. Hence, I would recommend to give 5.8.1 a shot.