Re: Speed Controllers: Which is best?
 

The cause is almost certainly the fact that Jaguars and Talons use different ranges of control. With the same PWM signal, a motor connected to a Jaguar will run slower than one connected to a Talon. If the same program is used, then either the Talon will reach full output before full power is commanded, or the Jaguar will never reach full output.

The software needs to respect the different speed controller hardware requirements.

Re: Speed Controllers: Which is best?
 

Mounting wouldn't be too much of an issue as they are all held on with 3M Duallock, but not a bad idea never the less.

Re: Speed Controllers: Which is best?
 

Don't forget the various speed controllers have varying abilities to keep their signal cables in. And as they age, the springiness decreases and cables are more prone to fall out.

Talons have the clear advantage of being able to securely hold PWM cables in. Or if you use CAN with the Jaguars, the RJ connectors click in too.

We had some issues keeping PWMs in our spikes which were mounted upside down, which cost us some climb points. We put some tape on the PWM heads (to make it about 0.02mm thicker) and it fit snugly into Jaguars, and was better (but not perfect) with spikes. Other than that, we put an abundance of tape around it to hold it in, but not an ideal solution.

Also, I dislike spikes because there is a small gap between the casing and the the pins to slip in and get severely bent if pressing it in too hard (as was kind of required with the added tape). Also they'd fall apart because they're just held together with a simple plastic snap thing. Buuut they're small and are great if you just need on/off.

I haven't played with Victors in this regard though, so I don't know how well they hold their cables.

Re: Speed Controllers: Which is best?
 

Victors aren't the greatest at holding PWM cables, we typically put a dab of hot glue where the cable connector meets the housing. If a swap is necessary a knife or flathead screwdriver can remove the glue rather quickly.

Re: Speed Controllers: Which is best?
 

We used talons for the drivetrain and victor 888s for our shooter wheels. Last year we had problems with CAN, so the talons' PWM security is greatly appreciated. Though its something of an art to put them in quickly.
We are using victor 884s as backups for the talons at competition.

Re: Speed Controllers: Which is best?
 

It was time for us to purchase some new speed controllers this year.

We didn't purchase any Jags because of reliability issues and not wanting to invest in a basically dead product.

We got a bunch of Tallons with our AM voucher and purchased a couple more.
We use these mostly on our drive and they have behaved flawlessly even with us pushing the speed envelope and working them hard.

We also got 888's with the Vex voucher and also purchased additional units. We use these with other motors and (like the 884's before them) and they also performed flawlessly.

We have been very happy with both products.

Re: Speed Controllers: Which is best?
 

We used Talons this year and were very happy with the small footprint, great response time, and linear output. They are very robust and do not break at all. We used Jags for the past three years, and I was never a fan of them. They constantly broke from metal shavings and had numerous errors throughout the years. It was nice to be able to use CAN, but I found that there were more problems with that than anything else. I have worked a little with Victors on old robots, and they were fine, but they took up more space and had a less linear response curve. If I were to pick any, though, I would go with Talons--they don't break!

Re: Speed Controllers: Which is best?
 

Assuming (as I did, perhaps incorrectly) that Team 3997 changed the code to use the proper WPILib driver for each motor controller, and calibrated the motor controllers appropriately, is there any other reason to expect "the big difference in the speed of the drivetrain" they noticed? For example, is there any reason to think that the difference between the Jag and Talon switching designs might interact with a CIM to produce such an effect? Have any other teams noticed a difference (or no difference) in top-end motor speed with Jag vs Talon?

Re: Speed Controllers: Which is best?
 

Regarding cable retention, Jaguars have a tab below the PWM connector that you should run the cable through. I'd recommend having a tie down nearby for controllers that are purely friction fit for PWM connections, to lower the chance that things wiggle loose. A bit of black electrical tape doesn't hurt either.

There's per-controller tuning in WPILib; don't know whether the same tuning is present for LabVIEW. This means that, for the most accurate response, you want to create speed controller instances that match the controller in use. Having a different controller will function, but with a curve that will seem nonlinear.

Pro tip for WPILib users: declare your speed controllers as SpeedControllers in your header:

but create instances that match your controllers in use:

This makes it easier to switch controllers by making changes only where you construct the instances.

Re: Speed Controllers: Which is best?
 

Jaguars are the only ones that support closed loop (i.e. not through the cRIO) PID, are they not?

Re: Speed Controllers: Which is best?
 

Correct

Re: Speed Controllers: Which is best?
 

This might be a topic for a new thread, but how do you actually accomplish that? Is it built into the hardware (CAN specific I assume?)?

Re: Speed Controllers: Which is best?
 

Look at the CANJaguar class in WPILib.

Re: Speed Controllers: Which is best?
 

All motor controllers have basically the same structure. This applies to Jaguars, Talons, Victors, and even the VEX Motor Controller 29s. Each has a small microcontroller, a motor interface, and some way of communicating with it. The microcontroller is a system-on-a-chip (SoC) that contains a CPU, memory (flash and SRAM), timers, etc.

In the case of Jaguar, the microcontroller contains a CAN interface that is capable of receiving packets (messages) sent by the cRIO that contain commands. The software takes the packets and interprets them. So there is no specific hardware (logic gates) that are specifically wired together to do the PID, it is just software.

Re: Speed Controllers: Which is best?
 

This is incorrect. See chapter 7 in the Jaguar guide: http://content.vexrobotics.com/docs/...e_20130215.pdf

The Jaguar will accept position, speed or current values over the CAN network, and then utilizes its own internal PID controller to hit the desired target.