How to Log More Data (Flight Dynamics and Simulation)

[otaviozordan]

Dear all,

I am developing a neural network to model the dynamics of the Crazyflie and predict the drone’s response to each command. To achieve this, I need to log the following data:

Inertial data: acceleration (acc) and gyroscope (gyro);

Drone state: estimated position;

Control signals: motor commands.

Currently, I am sending control commands using cflib in Python, generating flight trajectories, and I use the Lighthouse system for position estimation with two base stations. From what I understand, the Crazyflie logging system has a byte limit on the data that can be transmitted at once, which may restrict the number of variables I can log simultaneously.

With that in mind, I have a few questions:

1. What exactly is the byte limit of the logging system, and is there a way to optimize it to log more variables?

2. How can I directly access the motor control commands or the controller’s reference signal? Is there an existing log for this?

3. Would modifying the Crazyflie firmware be necessary to efficiently obtain this data?

If anyone has faced a similar challenge or has suggestions on the best approach, I would greatly appreciate your guidance.

Thank you in advance for your time and help!

Best regards,
Otávio Zordan

[ArisMorgens]

Hello Otávio!

Your project sounds really fun!
If you already haven't, I would recommend to start from the step-by-step: Connecting, logging and parameters tutorial and then move to the step-by-step: Motion commander tutorial, where in Step 4, logging while flying is well explained.

1. The limitation of the log subsystem is that one log block must be contained in one radio packet and the radio packets are 32bytes long. If the variables that you want to log exceed the 32bytes, you can add more log blocks (more LogConfigs in Step 4 of the step-by-step: Motion commander tutorial).

2. You can check all the existing logging variables here or by connecting your Crazyflie to the cfclient and look at the log TOC tab.

3. Modifying the firmware is not needed when trying the above.

Let us know if you face any further difficulties. Have fun flying!