What do you think of the jaguars?

[Billfred]

To my knowledge, neither 1618 nor 2815 burned out any Jaguars this season. (1618 used four on their robot, 2815 used four Jaguars on their manipulator and two Victors on the drivetrain.)

They're still a little big for my liking, but I'm intrigued by their potential.

[roboraven15]

what we have noticed, jaguars burn up before the motors do (in a situation of overstressing motors), which is pretty handy honestly rather change jag than motor.

[eugenebrooks]

To add two cents worth, we switched from Victors to Jaguars
on our drive in order to enable reliable operation of current sensed
traction control. The 120 hz chop rate of the victors was too low
to be smoothed out adequately with an RC fiter we put on the
current sensor. We did note that we lost a little top end speed
with this change, but the resulting traction control was worth
the trade.

The 40 amp current limit on the Jaguars was pretty aggressive
and we did hit that limit during testing with a gearbox that was
binding a bit. We did not have any Jaguars fail.

Eugene

[Mike Copioli]

We use two Jags. One for each side of the drive-train. Everywhere else we are using victors. We have had no failures of either the Jags or the Victors on either our comp bot or practice bot. I will say this, we mount all of our speed controllers vertically above our drive motors. This ensures the minimal amount of particulate to fall into the enclosure of the Jag. One key difference between the Jag and the Victor, the Jag does not have a conformal coating, the Victor does. I believe that this is a contributing factor to the number of failures seen.

[Jared Russell]

Originally Posted by Mike Copioli

We use two Jags. One for each side of the drive-train. Everywhere else we are using victors. We have had no failures of either the Jags or the Victors on either our comp bot or practice bot. I will say this, we mount all of our speed controllers vertically above our drive motors. This ensures the minimal amount of particulate to fall into the enclosure of the Jag. One key difference between the Jag and the Victor, the Jag does not have a conformal coating, the Victor does. I believe that this is a contributing factor to the number of failures seen.

We also mounted our Jags vertically, and have yet to lose a single one on either our main machine or our practice bot. I think that since particulate seems to be one of the single biggest factors in the failure of the Jags thus far, vertical mounting is (at the moment) the way to go.

[Gdeaver]

The higher frequency PWM drive of the Jags means they also will have higher switching losses. This means more heat to dispose of compared to a victor. The victors used IFR or Infineon FETS. Could the IFR FETS have better avalanche carrying ability? I Know that Luminary Micros has aligned with Fairchild but, could the IFR FETS be a better device for this application. Our robots are 12 volt devices cars are 12 volt nominal devices. Why not use automotive qualified and avalanche rated FETS ? Automotive motor controllers all seam to use 40 volt devices and our controllers are using 30 volt FETS. Does the jag have clamping diodes to take the Back EMF stress off of the FET intrinsic diode? Most hard switched motor controllers do. With the current loads we give the JAGS cooling is critical. Could the air flow not be evenly distributed across all the Fets? With the higher frequency PWM drive, there is more of a problem with ringing in the gate drive circuitry. Could this be causing the Fet and drive chip failure? The Jag is a step forward with capabilities we haven't even tapped yet, however there does SEAM to be an increased failure rate that needs to be addressed. Every year there will be a number of reverse polarity failures no matter which controller we use. This is just a given unless reverse battery protection is implemented.

[Mike AA]

We at first used 3 Jaguars on our robot, 2 on the drive and one in steering. I liked the larger response range and slower speeds capable of the Jaguars. After 2 regionals and 24? matches we have not had any problems and I will likely ask for more for next year. We primarily used them on the drive and steering for the more "detailed" capability. Our shooter and rock elevators didn't need precision and to save weight we used victors.

-Mike AA

[ay2b]

Originally Posted by roboraven15

what we have noticed, jaguars burn up before the motors do (in a situation of overstressing motors), which is pretty handy honestly rather change jag than motor.

I'd rather burn up a $28 CIM motor than a $75 speed controller. I think the other motors are also significantly cheaper than the Jaguar.

I suppose the only case where you might prefer to replace the speed controller is if you're pressed for time (eg between matches) and the speed controller is easier to access than the motor. In general though, I'd rather have a cheaper part fail than a more expensive part.

[ebmonon36]

We used 7 Jaguars and 1 Victor on our robot and 2 on our test robot back at the shop. The Jaguars went into Fault mode once, not resulting in failure, before we shipped the robot, but I think it was caused by a low battery. No Jaguars were lost on our team. From our team's standpoint, I think we like the Jaguars and are very eagerly awaiting news on the CAN bus and the other features on the Jaguar.

[Al Skierkiewicz]

Originally Posted by eugenebrooks

The 120 hz chop rate of the victors was too low
to be smoothed out adequately with an RC fiter we put on the
current sensor.

Eugene

Doc,
What were you using for a current sensor? The KOP supplied or something else.

[lynca]

Originally Posted by Mike Copioli

We use two Jags. One for each side of the drive-train. Everywhere else we are using victors. We have had no failures of either the Jags or the Victors on either our comp bot or practice bot.

We do the exact same thing ! The Jags are the best for drive related functions.

[MrForbes]

We haven't had any trouble with the Jaguars. We have four of them, driving all the motors that need precise speed control, plus a few Victors driving the rest of the motors. Ours are mounted vertically in a covered wooden box that opens away from the rest of the robot, so it would be very difficult for stray particles to get into them. also none of our motors are heavily loaded, by design.

LM (and IFI for that matter) could do a much better job of marking the terminals, it would not take too much effort for them to put big, legible warning lables stating which side goes to the motor, and which to the battery, and warning about polarity. This could save teams a lot of heartache...we all know that everyone should know how to wire things properly, but reality is that a lot of people who work on the robots are still learning about electricity, and taking extra steps to reduce expensive mistakes is warranted.

[mtaman02]

Originally Posted by squirrel

LM (and IFI for that matter) could do a much better job of marking the terminals, it would not take too much effort for them to put big, legible warning lables stating which side goes to the motor, and which to the battery, and warning about polarity. This could save teams a lot of heartache...we all know that everyone should know how to wire things properly, but reality is that a lot of people who work on the robots are still learning about electricity, and taking extra steps to reduce expensive mistakes is warranted.

I hate to say this and I don't wanna sound mean but if you have new kids doing robot related work that can easily get messed up by just having the wires reversed then it should be the job of the Alumni, Mentors, Coaches and other sources to instruct the kids during build season how how things should properly be wired AND supv. them as they're doing it to ensure it's done right. Don't just tell them how to do it and walk away or leave it to them to research it... While self teaching is good, doing it during build season is not the time for that to happen. Each committee should be well trained before build season in what they have to do to have a successful team showing.

[Alan Anderson]

Originally Posted by squirrel

LM (and IFI for that matter) could do a much better job of marking the terminals, it would not take too much effort for them to put big, legible warning lables stating which side goes to the motor, and which to the battery, and warning about polarity.

A small but easily-seen stripe from an appropriate-colored sharpie has been marked on the plastic next to each terminal on ours.

Using colored screws is a half-baked solution. They come out. It only takes a small error in putting them in to practically ensure that the next person to try to follow the color code will introduce a wiring fault that can destroy the part.

[MrForbes]

Originally Posted by mtaman02

I hate to say this and I don't wanna sound mean but if you have new kids doing robot related work that can easily get messed up by just having the wires reversed then it should be the job of the Alumni, Mentors, Coaches and other sources to instruct the kids during build season how how things should properly be wired AND supv. them as they're doing it to ensure it's done right. Don't just tell them how to do it and walk away or leave it to them to research it... While self teaching is good, doing it during build season is not the time for that to happen. Each committee should be well trained before build season in what they have to do to have a successful team showing.

That is a great answer for those teams that have knowlegable mentors, coaches, and alumni. There are many young teams who don't have anyone who knows this stuff well, why not make things a bit easier for them?