Wheels spinning at different speeds program or electrical error?

[DFZXA]

Well our team has strafing working somewhat. The problem is that two wheels are spinning slower than the other two. For example if I push left (to strafe left) on the joystick the back left and front right wheels will spin slower than the other two. Then the opposite happens when pushed to the right. We took a voltmeter to the jaguars to see how much power they are getting when given the command. It read around 2 volts (yikes) so something is definitely up. When reading on the driver station the pwms to the jaguars show me that two are getting less than the other two. I don't know what else to list then, but here's the code we are using (except I changed from two joysticks to one logitech 3d). Oh and ignore that it says gyro dawg. Thanks for the help in advance.

[Grim Tuesday]

Do you have encoders on your gearboxes, or are they running in an open loop?

[Hawiian Cadder]

the cims are biased in one direction.

[DFZXA]

Originally Posted by Grim Tuesday

Do you have encoders on your gearboxes, or are they running in an open loop?

No encoders we only have 1 with a mount so I haven't programmed for them cause we can't mount them

Originally Posted by Hawiian Cadder

the cims are biased in one direction.

It seemed to work just fine when rotating and going back and forth with a slight curve though

[Chris is me]

Originally Posted by Hawiian Cadder

the cims are biased in one direction.

This is false.

Recalibrate your Victors.

[Tom Line]

Originally Posted by DFZXA

Well our team has strafing working somewhat. The problem is that two wheels are spinning slower than the other two. For example if I push left (to strafe left) on the joystick the back left and front right wheels will spin slower than the other two. Then the opposite happens when pushed to the right. We took a voltmeter to the jaguars to see how much power they are getting when given the command. It read around 2 volts (yikes) so something is definitely up. When reading on the driver station the pwms to the jaguars show me that two are getting less than the other two. I don't know what else to list then, but here's the code we are using (except I changed from two joysticks to one logitech 3d). Oh and ignore that it says gyro dawg. Thanks for the help in advance.

You have a couple clues.

2 volts on a jaguar output side? If the PWM's are showing different values, then they are telling the jag's to act differently. That also means that it's likely your controller is sending different values.

First, create 2 numeric controls in labview and hook THOSE up to your drive. See if you can get all full-speed values that way. I suspect you will be able to, and that this will point back at one of two things - you may not be calling out the axis' correctly on your new controller, or it may not be acting the way you expect.

Try going back to the logitech attacks and see if they function correctly. Remember - methodically narrow your problem down to one component: then you have the solution to your problem.

[Hawiian Cadder]

well, it depends, brand new fresh cims have no bias, but after a year they are about 3% or something and after two they have like 7% difference between forward and reverse.

[Chris is me]

Originally Posted by Hawiian Cadder

well, it depends, brand new fresh cims have no bias, but after a year they are about 3% or something and after two they have like 7% difference between forward and reverse.

What would cause that?

[DFZXA]

Yeah the wheels spin at full speed, but can't check the logitechs until school. Would an encoder even help? That would just read me how fast something is rotating wouldn't it? Also we have had our cims for two years I have never heard of them being biased. Otherwise if it is the joysticks is there some calibration on them?

Edit: Oh now that I think about it I think the pwms were reading higher than what the voltmeter said I don't remember, but the difference between the fast ones and slow ones was like 2 or something. I could tell a difference in the bars, but I don't think it was very drastic. Again I'll have to wait until tomorrow.

[Hawiian Cadder]

Originally Posted by Chris is me

What would cause that?

as they are used the rotor magnetizes, thus they gain a bias in which ever direction they are used the least.

[DFZXA]

Oh so I guess I have to check if I have anymore cims then. Hopefully we do or we're going to be behind.

[Hawiian Cadder]

Originally Posted by DFZXA

Oh so I guess I have to check if I have anymore cims then. Hopefully we do or we're going to be behind.

a better idea is to find out which cims are a little slow, and then program the other ones to go a little bit slower in that direction, this is what my team did last year and it worked pretty good.

[DFZXA]

They seem to all be slow in a certain direction cause like I said when I push left the rear left and front right will go slow and when I push right the rear right and front left will go slow.

[Hawiian Cadder]

Originally Posted by DFZXA

They seem to all be slow in a certain direction cause like I said when I push left the rear left and front right will go slow and when I push right the rear right and front left will go slow.

so find out which ones are slow and in what direction, and make them slow in the other direction too, so if motor 1 is 4 percent slow in counterclockwise, multiply all of its inputs clockwise by .96, then it will be the same both ways

[DFZXA]

Originally Posted by Grim Tuesday

Do you have encoders on your gearboxes, or are they running in an open loop?

I dunno what that means if you mean that in programming terms

Originally Posted by Hawiian Cadder

so find out which ones are slow and in what direction, and make them slow in the other direction too, so if motor 1 is 4 percent slow in counterclockwise, multiply all of its inputs clockwise by .96, then it will be the same both ways

Ok I'll try that too.