What do you think of the jaguars?

[Andrew Schreiber]

Originally Posted by Al Skierkiewicz

4. The output frequency of the Jaguar is 15kHz while the Victor is 150Hz. I suspect that this difference with the KOP motors is the big difference teams are seeing with output speeds.

Out of curiosity (and forgive the stupid question) what exactly does this mean from a real world standpoint? I mean more is usually better but there comes a point where you just don't need it. (Not saying that we don't need the extra output frequency, just a general statement)

And I too would like to see more documentation as well. I was severely disappointed when I saw how little there was.

[Al Skierkiewicz]

Originally Posted by Andrew Schreiber

Out of curiosity (and forgive the stupid question) what exactly does this mean from a real world standpoint? I mean more is usually better but there comes a point where you just don't need it. (Not saying that we don't need the extra output frequency, just a general statement)

And I too would like to see more documentation as well. I was severely disappointed when I saw how little there was.

Andrew,
There was quite a bit more documentation on the Jaguars including schematics available on the Luminary website.
As to the output frequency vs response. The brush/commutator length converts into a repetitive frequency calculation dependent on speed for each motor. All KOP motors are not the same brush/commutator design. The FP is significantly different than the CIM. The difference in output frequency of the controller determines how effectively the controller can make current changes in the winding it is connected to, through the brush assy. The higher frequency may interact differently on a particular motor due to winding inductance or the number of voltage transitions it would make while connected to one particular winding. The mass of the armature also comes into play when comparing motors as does the mechanical load on said motor. While the Jaguar may be more "linear" on one type of motor than the Victor, it might not be on another. Take a close look at the motor curves and then try to interpolate different loads into the response.

[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

[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.

[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?

[mtaman02]

Originally Posted by squirrel

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?

I agree but someone still should have a basic knowledge of what M+ and M- and + - means. If I'm not mistaken the 883's and 884's were marked as such and I with no problems and no background got it right. I'm not trying to be tough even though it is coming off like that just saying there's documentation on it and if not or it's hard to find then YOU CAN ALWAYS ASK SOMEONE ON HERE @ CD!!!!! There are thousands of us here, hundreds of us on at a time so it's not like there's no ones around. There's nothing wrong with saying I need help like so many have said in the past... There is plenty of Alumni Mentors Coaches (Like Al S, Mark M and various others) that are constantly on here coaching teams through tech. specs.

So rookie teams if you need help PLEASE ASK!!! Yes it's cool to do it on your own, but it's even cooler to say I don't know please help... CDs open 24/7

[MrForbes]

Originally Posted by mtaman02

I agree but someone still should have a basic knowledge of what M+ and M- and + - means.

First you have to actually notice that there is an M on one end of the device...then you have to realize that it's important...then you might realize it means Motor. I've been in the pits on Thursday at rookie heavy regionals....

It can't hurt to mark the connections in an obvious way. How about it LM and IFI?