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mit-aera / FlightGoggles

A framework for photorealistic hardware-in-the-loop agile flight simulation using Unity3D and ROS. Developed by MIT AERA group.
http://flightgoggles.mit.edu
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Strange quaternion issue #145

Closed juanmed closed 4 years ago

juanmed commented 4 years ago

Hello,

I used flightgoogles in the past for the AlphaPilot Challenge and tried it again this week for other simulations. I am having an issue which an strange error message I did not face before: 

[ERROR] [1578553914.709314675]: Ignoring transform for child_frame_id "uav/imu" from authority "unknown_publisher" because of an invalid quaternion in the transform (-nan -nan -nan -nan)

         at line 257 in /tmp/binarydeb/ros-kinetic-tf2-0.5.20/src/buffer_core.cpp
Error:   TF_NAN_INPUT: Ignoring transform for child_frame_id "uav/imu" from authority "unknown_publisher" because of a nan value in the transform (-nan -nan nan) (nan nan -nan -nan)
         at line 244 in /tmp/binarydeb/ros-kinetic-tf2-0.5.20/src/buffer_core.cpp
Error:   TF_DENORMALIZED_QUATERNION: Ignoring transform for child_frame_id "uav/imu" from authority "unknown_publisher" because of an invalid quaternion in the transform (nan nan -nan -nan)
         at line 257 in /tmp/binarydeb/ros-kinetic-tf2-0.5.20/src/buffer_core.cpp

This simulator starts correctly using roslaunch flightgoogles core.launch but right at the moment I sent the arming message to the /uav/input/arm topic, the issue above gets printed repeatedly at a high rate. This issue does not happen all the time, sometimes I am able to fly (using the keyboard or by sending control messages to /uav/input/rateThrust/) the vehicle without issues.

I will appreciate any help you could provide. Thank you.

My system is: OS: Ubuntu 16.04 64bit CPU: Intel® Core™ i5-8400 CPU @ 2.80GHz × 6 Graphics: GeForce GTX 1050 Ti/PCIe/SSE2 RAM: 8Gb

eatal commented 4 years ago

Hi @juanmed ,

I have not seen this issue myself. Can you make sure that all control messages on /uav/input/rateThrust/ are in order? For example, can you recreate the issue while sending constant numeric values as commanded angular rates and thrust?

After that, a good starting point for debugging may be to add some diagnostics in the block starting here to find out the origin of the NaNs.

juanmed commented 4 years ago

Thanks, I will try out your suggestions and let you know.

eatal commented 4 years ago

I'll close this for lack of new information. Feel free to reopen in case of any updates.