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Unread 07-05-2011, 15:20
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Re: Victors verses Jaguars?

First off, there have been a couple of recent threads about this, so while you're waiting for others to reply, you might try a search.

I'm going to make the assumption that your team used PWM cables (most teams use PWM for controlling Jaguar speed controllers) There is just a 1-way data flow, and that's from the Compact RIO (or digital side car (DSC), depending on how technical you want to get) to the speed controller of your choice with PWM control.

PWM, or Pulse Width Modulation sends a square wave over the signal (typically white wire) to the speed controller. The black wire is the negative, and the red wire is 6V positive (from the DSC PWM outputs). Another note to make is that the 6V positive is normally disabled unless you have the jumper in place to use the 6V line (usually only needed with servos).

So...
White - Signal, PWM Square Wave Signal
Red - Positive, 6V+ (normally disabled and open)
Black - Negative, 0V reference
1 way communication from Compact RIO to Speed Controller

So now that I have that cleared up, now on to Jaguars vs. Victors

Jaguars:
Pros:
  • More linear control
  • Better protected
  • Quieter (fan noise)
  • Quieter (motor control whine)
  • Over-current protection
  • Over-temperature protection
  • CAN-bus (more on this in a bit)
  • Cheaper

Cons:
  • Large, weird shape
  • Over-zealous over-current protection (trips too quickly)
  • Defects (especially with Gray Jaguars [NO LONGER PRODUCED])


Victors:
Pros:
  • Small
  • Reliable (with care)
  • CIMple (Just the basics, power, motor output, and PWM-in)
  • Tried and trusted for many years (884 since I believe 2004, correct me if needed, and 883 before)

Cons:
  • More expensive
  • Open air design is prone to magically attracting the metal shavings
  • No CAN-bus support
  • No Over-Current Protection
  • No Over-Temperature Protection
  • Non-linear control curve

My opinion:
For drive motors, you can just stick with Victors. They'll be able to better provide the pushing power needed for those brief instances when you need it, and the auto-resetting snap action breakers will take care of the over-current problem. They're smaller, the fans run constantly, and there is less to go wrong inside of them.

For high-precision control, I would use Jaguars. The better linear control, plus the support for the CAN-bus will ultimately let you have better control of the motor. By high-precision, I speak of any motor used in a closed-loop control scheme with a sensor. There is nothing wrong with using them for the drive motors, and your team may want to use them for drive motors to have better control if using sensors such as the gyro or encoders for precise positioning.

We had cut-out problems with the Black Jaguars at the Championship this year. We believe it was just over-current protection on the field as we discovered we could trip the Jaguars if it came into a pushing match in high gear. No design flaw with the Jaguars or the robot, just a design limitation.

The CAN-bus is something your team may want to look into in the near future . It allows for 2-way communication, just like you mentioned. It offers some neat features for motor control too. You can control it like normal from 0-100%, current mode, voltage mode, faults, and more. It also allows you to get data from the Jaguars including temperature, voltage in, voltage out, and current. The programming will be a bit more complicated, and you will add a single point of failure to the robot. If you're willing to live with that, then use it. The single point of failure is the CAN-network itself. Instead of having a cable go to each speed controller in a star network configuration, you'll be using a piggy-back network, where there is only one control line, then a connection between each Jaguar with a termination connector on the last node (basically just a resistor between two pins).

Hopefully this will help you. Could you be a little more descriptive about what you mean the the rest of the robot shut down? What is working, what is not working?
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Last edited by RyanN : 07-05-2011 at 20:46.
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