Robot Characterization

[bigchuy]

Hello Everyone, I’m a mentor with FRC1296 and I had a couple of questions about the Robot Characterization Tool…

Our drivetrain consists of 4 TalonFX motors, standard differential drive and six wheels.
Project Type: drivetrain
Control Type: CTRE

The auto-generated template has an entry for “encoderEPR” (Encoder edges-per-revolution). Should this value be 2048? I have seen some discussion that this needs to account for the gear ratio but there appears to be an attribute in the template for that named “gearing”.

The comment in the template says…
# For the CTRE Mag Encoder, use 16384 (4 * 4096 = 16384)

Why are they multiplying by 4?

Any help would be greatly appreciated.

[Vinay_Pan]

Hey!

So as far as I’m aware, edges-per-revolution account for a quarter-turn of a revolution (Encoders - Hardware — FIRST Robotics Competition documentation). This is why the comment indicates that they multiply by 4 since the encoder itself is a quadrature encoder.

I’m fairly sure that you should be using 2048 for the encoder EPR. This has somewhat been talked about in this thread as well so check it out!

Finding Edges per revolution for Falcon 500 with Talon FX

Hello @ozrien , I’m trying to build a shooter with 2 falcon 500s with talon fx built-in. I am currently characterizing the motors but I ran into the problem when I was finding the edges per revolution of the flywheel. I know that the ratio to turn the flywheel is 1 rotation of the motor: 1 rotation of the flywheel. I hope you can help me with this additional information. Thank you so much! hfrughfg

[bigchuy]

OK, that makes sense to me. Thank you for the quick response!

[Weldingrod1]

Edges per revolution is the total number of signal transitions per rev. So, up and down are separate, as are A and B. So, a 100 pulses per rev quadrature encoder is 100 pulses x two channels x two states.

The reason for this is that is the highest possible positional information without interpolation and guessing the speed.