Our team is using 8 Talon SRX Motor controllers to drive our robot with a swerve drive drive train. there are quadrature encoders on the wheels for rotation, which are wired into breakout boards on the Talon SRX Controllers. This created an inconsistency in the drive as compared to when they are plugged directly into the RoboRIO, as the encoder values are 4 times higher than we would expect them to be, so we divided them by four to simply test if the system would work, but there is still some shakyness in the wheels.
According to the
Talon SRX software manual (Page 66):
Quote:
17.1. (Quadrature) Encoder Position
When measuring the position of a Quadrature Encoder, the position is measured in 4X encoder
edges. For example, if a US Digital Encoder with a 360 cycles per revolution (CPR) will count
1440 units per rotation when read using “Encoder Position” or “Sensor Position”.
The velocity units of a Quadrature Encoder is the change in Encoder Position per TvelMea
(TvelMeas=0.1sec). For example, if a US Digital Encoder (CPR=360) spins at 20 rotations per
second, this will result in a velocity of 2880 (28800 position units per second).
|
It was brought up that the Talons could be summing together four values, or the input could be lagging behind by four ticks, which would cause the issue we are seeing. If anyone knows how this functionality is implemented or if we could "turn it off" that would be very helpful, I cant seem to find anything in the talon documentation about this, other than the section i posted, i will check the roboRIO web interface as soon as i get to our robot to see if it is something about it there