Averaging one side with Encoders or two wheeled drive?

[kinganu123]

So I was talking with the programmers, and being that we were doing six wheeled drive with 4 CIMS using 2 Victors, we figured we'd need 4 encoders. Now, my question is what would be the better approach?
1. One encoder on each shaft with only one channel wired. Then I'll direct the Encoder class towards the two Encoders on the same side and two for the other side.
2. Power only 2 motors for PID and have two fully wired Encoders on those shafts.

EDIT
This is for autonomous PID drive

[Alan Anderson]

Originally Posted by kinganu123

...4 CIMS using 2 Victors...

You'd better fix that before you do anything more fancy. Each motor requires its own speed controller.

Are both motors on each side connected to the same gearbox? Are all the wheels driven by the same gearbox output? You only need one encoder per gearbox.

[dellagd]

I believe that is a rule, correct?

[kinganu123]

All motors are mounted onto on of two nanotubes by andymark, which has a uniform gear ratio. But I was told that not all motors were created equal, which is why I figured 4 Encoders would be better
And R50 is a bit vague in my opinion. Not entirely sure if its legal or not...

[Ether]

Originally Posted by kinganu123

R50 is a bit vague in my opinion. Not entirely sure if its legal or not...

Look at rule [R46].

[artdutra04]

Originally Posted by kinganu123

All motors are mounted onto on of two nanotubes by andymark, which has a uniform gear ratio. But I was told that not all motors were created equal, which is why I figured 4 Encoders would be better
And R50 is a bit vague in my opinion. Not entirely sure if its legal or not...

If two motors are mechanically geared together, they will spin the same speed.

[Alan Anderson]

Originally Posted by artdutra04

If two motors are mechanically geared together, they will spin the same speed.

And if two motors are driving traction wheels on the same side of a robot, one can reasonably assume that they will be spinning the same speed...at least when driving straight or mostly straight. When one wheel is slipping more than another, it's not always easy to decide which one is the best wheel to use as a speed reference. I'd just use two encoders, connected to the section of the drivetrain having the wheels with the most weight on them.

[kinganu123]

they aren't
they are just housed in the same gearbox

[cgmv123]

Originally Posted by kinganu123

they aren't
they are just housed in the same gearbox

That's the definition of "mechanically geared together". The CIMple boxes in the kit have encoder shafts which are designed for the US Digital encoders which also happen to be in the kit. You only need two since you only have two output shafts. The encoder shaft is actually the same piece of metal as the output shaft, so you don't have to account for any gearing.

[PAR_WIG1350]

Originally Posted by cgmv123

That's the definition of "mechanically geared together". The CIMple boxes in the kit have encoder shafts which are designed for the US Digital encoders which also happen to be in the kit. You only need two since you only have two output shafts. The encoder shaft is actually the same piece of metal as the output shaft, so you don't have to account for any gearing.

I believe the OP is saying that they are in the same, physical box, but driving two distinct gear trains. Actually, I know this to be the case since the gearboxes used were listed as AM Nano Tubes, of which six stock variations exist, all of which only accept one motor per gear train.

[Tom Bottiglieri]

You don't need 4 encoders. Limit your acceleration and as Alan already said, put the encoders on the heavier side of the robot. Should be fine.