What do you think of the jaguars? [Archive]

Andrew Schreiber

31-03-2009, 10:41

I think part of it could be the fact that they are new.We have used the Victors for many years (as long as I have been in FIRST) and teams know how to use them. We know what they can take and what they can't. Give teams 5 years with the Jaguars we will probably not be blowing them that quick by then.

We did not use the Jaguars, I think during the off season I may play with them a little, the extra size worries me slightly but I think they have a lot more power than the Victors. Anyone have any ideas on how to analytically test this? I would be willing to help/do this testing if someone would help me write up requirements and design tests. (Not sure what people want to know about them)

JesseK

31-03-2009, 10:51

All we did was prevent the code from sending the two extremes of the pwm signal within N duty cycles of each other. More specifically, we try to ensure that only a maximum of 12V potential is seen across the motor outputs on the Jaguar. This keeps the motor from going full forward to full reverse in a split second, which has led to some teams seeing a 24V difference (from -12V to 12V) for a split second across the motor output terminals. This trips a fault circuit on the Jaguar, which takes 3 seconds to reset. I suspect that it also severely shortens the life of the Jaguar. Further discussion on this topic by some very highly reputable sources is here (http://www.chiefdelphi.com/forums/showthread.php?t=72144&highlight=jaguar+24v).

So I'd say you should blame software, not the hardware :rolleyes:.

Alex_2487

31-03-2009, 12:08

chris, most of the jaguars that were burning out at long island i hink was because teams mis wiring them. although i know team 870s jaguar was hooked up right and burt out.

Jared Russell

31-03-2009, 12:18

Assuming the reliability issues can be solved, the Jaguar is an improvement over the Victor. With twice the update frequency, more PWM output "steps", and improved linearity, you get better results out of feedback loops when the Jaguar is doing the speed controlling.

Tom Line

31-03-2009, 12:21

Unfortunately, all of our evidence is anecdotal rather than quantitative. However, I will point out a few things you can count on.

Victors were a proven product. As such, when something went wrong with a victor, it was very rare to see a team come here and complain about it.

In the same vein, the newness of the Jaguars tempts a lot of people to jump on Chief Delphi the second they have a problem and post about it. Chief Delphi is a very non-representative sample of the actual durability of the Jaguars.

I'm not sure how willing IFI or Micro-Luminary would be to share comparable failure rates, but that's the only way you're going to get a real answer to that question.

Regarding the power question, we hooked a Jaguar and a Victor up to the same motor, which was connected to an encoder. The Victor produced a 7% higher rate on the encoder, but the speed curves looked horrible compared to the Jag.

I'm not sure exactly how a change in free speed rate correlates to an actual power change - we didn't check the amperage output of both under load because we don't have a multimeter that runs that high.

Al Skierkiewicz

01-04-2009, 08:38

Before we get back into a full out war on Victor vs. Jaguar it is important to note a few things that are thrown about.
1. Both controllers at full throttle put out a constant voltage which is the battery less losses in the wiring, connectors and series resistance of the FETs in the controllers. The Jaguar FETs are a little lower but the Jaguar must switch to zero periodically to charge up the cap in the charge pump circuitry.
2. Linear? This varies with motor type and between motors of the same type. All works itself out with practice or some form of feedback.
3. Anecdotal or not, the Jaguars are seeing (at a higher rate) failures that were not seen with the Victors. They are working on it and in my opinion they are trying hard to give you a product that is reliable.
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.
5. The Jaguar has a current sense resistor in the negative side of the H bridge. Although low resistance (equivalent to 6" of #10 wire), it does effect the output voltage a little. This is the same resistor that the Jaguar uses for over current sense. Once reached, it takes a minimum of three seconds after the fault has been removed before the protection gives control back to the output.
6. Failures have occurred on all types of motors under all types of operation and Luminary is trying to get through all of the data and their own testing to determine where the problem is actually occurring. In spite of the years of electrical advice (mine and others), teams still manage to get conductive debris inside the controllers regardless of their manufacture. A few wayward strands of aluminum or a pile of filings will cause a FET to self destruct in a visible and noxious way. The result is usually a controller that is unrepairable.
7. At this point it seems that the greatest Jaguar failure is a controller that only produces output in one direction. If yours failed in another manner, Luminary needs to know.

robostangs548

01-04-2009, 08:43

I like them, they are pretty cheap, double update frequency, and work pretty well... The only issue that I have is the quality... They arn't the best quality wise, but they do work pretty good... The on off fan is pretty sweet, and yeah, they work great... I would happily use them from now on....

mtaman02

01-04-2009, 09:10

If better documentation is provided to all teams then we should see less wiring faults and better coding tactics. Thankfully we had an NI Tech AND Luminary Tech running around assisting with both wiring troublehsooting and coding help which greatly reduced the amount of Jag's given out at the event... (as a matter of fact I DIDN"T GIVE OUT ANY Jag's at NJ b/c of them). If any were given out it was by Luminary b/c they were doing on site RMA for "real" failures. It's sad how not every venue had the same kind of service =[.

Mark McLeod

01-04-2009, 10:25

Andrew Schreiber

01-04-2009, 10:28

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.

mtaman02

01-04-2009, 16:07

Richard.Varone

01-04-2009, 16:20

I only had to authorize one Jaguar from Spare Parts at SBPLI, but teams had spares of their own to draw from, so it's harder to track all the failures. The one I did authorize was for Bay Shore, 271, and they burned out a bunch on their practice 'bot before the regional, so they didn't have any spares of their own.

If anyone is curious a bunch = 5 in 1 week, they all came from the same order (Our Spares) so we are assuming it was just a bad batch, because on our real bot we've had only 1 failure out of 9.

Edit: Other then that I love the jags, they've given us to have alot finer control over our bot ( mainly our head )

Al Skierkiewicz

01-04-2009, 19:19

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

01-04-2009, 20:44

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

01-04-2009, 22:53

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

01-04-2009, 23:34

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

02-04-2009, 07:57

Jared Russell

02-04-2009, 08:32

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

02-04-2009, 09:04

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

02-04-2009, 11:59

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

02-04-2009, 15:00

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

02-04-2009, 15:25

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

03-04-2009, 08:04

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

03-04-2009, 09:08

MrForbes

03-04-2009, 11:53

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

03-04-2009, 12:03

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

03-04-2009, 12:08

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

03-04-2009, 12:09

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

03-04-2009, 12:16

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

03-04-2009, 12:23

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?

mtaman02

03-04-2009, 12:27

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?

I wasn't sure if the Jags had the same type of labeling since I didn't really look at them when I had the chance *note to self* look at Jags.

They could color code it better Red/Black since MOST of the wiring in the robot should be standard I know it doesn't end up that way but color coding might be best and then do a burn in label or just label on the sides with a much larger + or - with M or B next to it either way I'm all for making it easier, it's just getting the respective comp. attention to do it. Maybe E-Mailing them would be best???

Al Skierkiewicz

03-04-2009, 13:23

Mike and Jim,
Although the Red Black color coding is OK for the US it is not in other parts of the world. The best suggestion, now that you own the device, it take a nice, big, colored sharpie and write "POS IN", "NEG IN", "MOT +" and "MOT -" right on the cover. While you are at it, mark the Black side of the PWM cable as well. Your inspector will give you extra Brownie points.
One thing we should all be teaching is that there are documents that exist for our benefit. They come from First in the form of Manuals, Team Updates, spec sheets and KOP list. Most of the KOP suppliers have great websites that contain operating manuals and sometime service manuals and schematics.

MrForbes

03-04-2009, 13:28

Ok, I give up....

MikeE

04-04-2009, 16:09

It would be nice if Luminary put better markings on the controllers, but I agree that the DIY Sharpie solution solves the problems faster.

Back to the Jaguars...
We use 6 Jaguars in our drive system and through development, 22 matches at two Regionals (and an obscene number of practice rounds at NASA/VCU), we haven't had a single problem with them. They are mounted horizontally but under covers large enough to allow air cooling.
Due to some early design decisions we've had to rely more than we intended on the low speed characteristics of the Jaguars, and I have been very impressed with how controllable they allow the drive system to be.

Matt Howard

06-04-2009, 13:15

We use 6 Jaguars in our drive system and through development, 22 matches at two Regionals (and an obscene number of practice rounds at NASA/VCU), we haven't had a single problem with them.

That may be true, however on the flipside of that there are teams using the same amount of Victors and have not had any problems with those either. Since our rookie year in 05' out of the 22 victors we've used, we've had a failure with 1. Which was due to carelessness. (Metal Shavings)

As much as some people like to put faith into the Jaguars, there have been too many mishaps over such a short period for them to be trustworthy in my book.

The combination of the large footprint, and less than reliable track record is what will be keeping Jaguars off of our robots until the eventual phasing out of the IFI products.

MikeE

07-04-2009, 12:58

That may be true, however on the flipside of that there are teams using the same amount of Victors and have not had any problems with those either. Since our rookie year in 05' out of the 22 victors we've used, we've had a failure with 1. Which was due to carelessness. (Metal Shavings)

As much as some people like to put faith into the Jaguars, there have been too many mishaps over such a short period for them to be trustworthy in my book.

The combination of the large footprint, and less than reliable track record is what will be keeping Jaguars off of our robots until the eventual phasing out of the IFI products.

One anecdote isn't a statistically significant result in either direction. However there is an understandable tendency for problems to be reported at a far higher rate than good experiences, so I wanted to throw our positive experience into the mix.
Reading all of the threads, there do seem to be some very specific issues with the Jaguars, but I suspect that a large percentage of the problems reported are due to inexperience with the controllers, not system design or manufacturing problems.

Time and careful analysis of the returns should yield a more comprehensive understanding.

Matt Howard

07-04-2009, 13:10

One anecdote isn't a statistically significant result in either direction. ....I suspect that a large percentage of the problems reported are due to inexperience with the controllers, not system design or manufacturing problems.

I don't recall saying that it was.

As for the controllers, if the majority of problems caused really are due to user error, wouldn't we see the same types of failures with the victors in rookie teams? I can think of at least 3 rookie teams off hand that have didn't have any problems with Victors this year, and none of the students or mentors had ever used one.

The Jaguars have some neat features, but for the scale of what we are working on (HS Competition Robots) why replace something that's tried and true?

Alan Anderson

07-04-2009, 13:29

The Jaguars have some neat features, but for the scale of what we are working on (HS Competition Robots) why replace something that's tried and true?

Budget: A Jaguar costs less for a team to buy than a Victor.
Technical: A Jaguar has additional capabilities over a Victor. Some are usable without additional cost (though the limit switch input was disallowed by the rules this year). Others the cRIO will be able to take advantage of with a simple communication module.
I won't speculate on other reasons.

MrForbes

07-04-2009, 13:50

Budget: A Jaguar costs less for a team to buy than a Victor.

This year we did the "budget" thing....we got 4 new Jaguars and one new Victor in the kit, we had a few used Victors to swipe off old robots, so that's what we used--4 Jags, 3 Victors

Matt Howard

07-04-2009, 14:23

Technical: A Jaguar has additional capabilities over a Victor. Some are usable without additional cost (though the limit switch input was disallowed by the rules this year). Others the cRIO will be able to take advantage of with a simple communication module.
I won't speculate on other reasons.

Additional capabilities that we are unable to use, combined with a larger footprint and a less than reliable track record is what turns me off.

Alan Anderson

07-04-2009, 16:12

Additional capabilities that we are unable to use,...

Don't ignore what you were able to use:
built-in overcurrent protection
integrated pwm cable retension hook
status/diagnostic indicator (telling more than a Victor does)
high-temperature detection and shutdown

Whether any of that is beneficial (or indeed if it was detrimental to a team's intended design) is another issue.

Matt Howard

07-04-2009, 22:55

Whether any of that is beneficial (or indeed if it was detrimental to a team's intended design) is another issue.

Which is exactly the issue at hand. Nobody is saying that the added features are a bad thing. However the product simply has a dubious track record at this point.

I'm sure all the problems people have been reporting will be cleared up between now and next season.

chessking132

07-04-2009, 23:18

Team 75 is using all jaguars this year and we have had only one problem. Knock on wood. In the Quarter finials of New Jersey it stooped working in the forward direction but it would go in reverse. We sent it back to Luminary Micro but they never go back to us on the cause of the problem. Other then that my only complaint is their size.

Matthew Simpson

Team 75 Driver

utlinebacker

15-04-2009, 23:41

I'm not sure how willing IFI or Micro-Luminary would be to share comparable failure rates, but that's the only way you're going to get a real answer to that question.

It has been a few weeks since I have checked in on CD. We have been busy visiting various regional events and ensuring that teams have a great experience with their Jaguars. I figured this was as good a place as any to post this - since it is precisely where someone asked for it! We have provided this document to FIRST - and we will soon distribute it to each and every team that returned a Jaguar to us for failure analysis.

If you are going to Atlanta - and you happen to have a failure, let me know. We'll be there in force to keep you in the competition! Good luck!

Luminary Micro people to look for in Atlanta (wearing Luminary Micro apparel):
Jonathan Guy - Director of Systems and Software
Brian Kircher - Sr. Software Engineer
Scott McMahon - Sr. Systems Engineer
Kyle Norman - Applications Engineer
Jean Anne Booth - Founder, Chief Marketing Officer
Scott Emley - Product Marketing Manager

Regards,
Scott

Vikesrock

16-04-2009, 00:53

Thank you for posting this detailed report Scott. LM has done an excellent job throughout the season of answering our questions on this forum and provided the requested transparency and in many cases seems to have gone well above and beyond the call of duty.

I have seen numerous mentions to the possibility of swarf creation through the use of ring terminals. Is there any plan to fix this in future revisions. I know that at least for my team, we much prefer ring terminals to spade terminals for increased security of the connection. In a competition environment I just don't trust spade terminals even with proper strain relief.

s1900ahon

16-04-2009, 06:36

I know that at least for my team, we much prefer ring terminals to spade terminals for increased security of the connection. In a competition environment I just don't trust spade terminals even with proper strain relief.

Is the security you seek is to avoid the situation where a screw terminal loosens due to vibration and you think that a spade terminal might then become detached, because of gravity and the mounting orientation or spring force in the wire?

If so, you might consider starting with a ring terminal and cutting a small slot in the ring in a direction that isn't in line with the disconnecting force. For example, if I were to mount a motor controller on a vertical surface with the terminals up and down (up=M+/M-, down=V+/V-) I would cut the down rings at the 5 or 7 o'clock position so that I could slide the ring on knowing that if the V+/V- screw terminal loosened somewhat the wire won't disconnect due to the wire being pulled down.

Just a thought in an attempt to avoid removing the terminal screw while also avoiding the effects of vibration on a terminal screw.

XXShadowXX

16-04-2009, 08:37

I here bad thing after bad thing about jags, and every meeting and event i waited for them to fail, screw up, or release the magical smoke that makes them run. It never happened, so I am happy to report that we have had no issue with the jagaurs this year.

Mrpresident1776

17-04-2009, 00:00

They worked okay for 1507 (the Warlocks) at both Finger Lakes and Philadelphia. However, we fried our first Jaguar today in our last practice match. It took out our right drive train and rendered us a sitting duck for the match.
When I saw we weren't moving, my first though was a fried drive motor gearbox (happened once at FLR and once at PHL). Luckily, the Jaguar was a quicker fix (5m vs 15m) and we got a replacement from Luminary Micro.
I guess it's an okay piece of equipment although the PWM slot should be improved.

pyr0b0y

17-04-2009, 12:02

Our team had the same problem as mrpresident, half way through competition one of our jaguars totally stopped responding in one direction....plus they are a lot bigger that the victors. Although the jaguars are pretty straightforward to install, it doesnt mean they are as good as the victors. I used victors for 4 years in high school and never had one problem with them!

,4lex S.

17-04-2009, 20:21

Despite the supposed better reliability of the Vic's, we couldn't drag our programmers off of the Jaguars once they realized they had more linear output.

We only lost one, and it was promptly replaced by a Luminary Micro rep. I think the static problems of the regolith may have amplified the related failure rate this year. As long as you read the instructions, and it isn't a defective unit, they seem to work quite well.

coalhot

18-04-2009, 18:20

This year 304 only had one Jag fail, and that was because I put the voltage in in the motor out :( . (happens)...

One upside i will mention is that after blowing up the jag, it was very easy to get the technical data, and get the replacement parts. One night at the soldering iron, and the Jag was fixed. Especially after researching Victors(never had to service one, always had enough spares), the tech data came in so usefull.

--Philip

artdutra04

18-04-2009, 23:24

Maybe to counter some of the bias that appears in these threads (people with negative experiences tend to speak up more often), that apart from the increased real estate the Jaguars eat up, we've had absolutely no operational issues with them on both our competition and practice robots. Since we still have a bunch of Victor 884s around, we only used the four Jaguars that came in the KoP, two on the drive train of each robot.

Once our supply of Victors runs out (or as soon as they allow us to use the CAN bus and the advanced features of the Jaguars), we'll be using Jaguars for most functions on our robots except in locations where space is an issue. *cough* smaller Jaguars would be awesome *cough*

lynca

19-04-2009, 11:33

we've had absolutely no operational issues with them on both our competition and practice robots.

Same here, we have driven the Jags for hours of Regional and Championship play without any issue the entire season.

shgshgshgshg

19-04-2009, 13:39

As far as speed control they are much better than the victors, but My team had some problems with them too. One of them came to us broken, and it took a while to get back to us with a good one. I think that it has a lot of potential, but if the manufacture can increase the durability of the controller a little bit it could be a great replacement for the victor...

Steigerwald

19-04-2009, 16:42

We managed to kill 4 the same way on out test bot. Basically, you need to make sure that it is not getting power from the motor when there is no power from the battery. We had our gearboxes set up with 2 cims each. When we wanted to test with only one cim per side, we just removed the power from the jaguar and not the motor. The unpowered motor acted like a generator and put a current back into the speed controller. It killed a tiny resistor at R5.

Barak Shelef

25-04-2009, 15:16

We had no problems during our build season or regional but at the second to last game in the championship we blew 2 jags at the same time... but there's a solution!

From what I understood from the guys from micro-whatever's booth in the pits, the driver gate was destroyed most likely due to static electricity backlash from the driving motors to the speed controller. caused probably because of the playing field (plastic wheels and plastic flooring) - because the robots weren't grounded to the floor, during a collision between a statically charged robot and an uncharged robot, the current might have gone back to the jaguar melting the drive gate.

If that really is the problem (supported by the statistics from utlinebacker's posted report), it can be easily fixed by adding a grounding rework from the robot. i.e. get a small wire, exposed on both ends, attach a connector to one side, bolt the connector to your chassis and let the exposed end be dragged on the field - similar to most cars. (even a small gauge wire would do the trick) And all the static charge will be immediately grounded.

However, for this to work, ALL teams must use that, otherwise even a grounded robot could be shocked by an ungrounded, charged robot. And although I find it hard to believe regolith is gonna be used next year as well, it's a good idea to do that anyways. just as a safe measure. ::safety::

galewind

25-04-2009, 15:39

Hazmatt

25-04-2009, 16:17

We used the jaguars for the main drive. Every jaguar we used failed.

Al Skierkiewicz

25-04-2009, 22:33

Barak,
Starting in at least week 3, the field was sprayed with a staticide. This had been discussed on several other fora and the conclusion has been that dragging a wire does very little. The trailers have had a chain on them since week 3 as well even though there is no discharge path through the fiberglass flooring. I had no reports of static crashes during the Championship. There is still a chance for robots with large belts to build up static within the robot but those seem to have been also non-existent during the humid Atlanta weather. We have two large and fast moving belts and experienced no static that we know of during the Champs.

gorrilla

25-04-2009, 22:36

I like them...

never had a problem with them untill in Atlanta when we absolutely filled one with metal shavings and it still worked in one direction;)

we de-tached it and dumped the shavings out and replaced it with a new one to be safe(still worked)

MrForbes

25-04-2009, 22:47

We used the jaguars for the main drive. Every jaguar we used failed.

I wonder if it's your team's name?

(sorry.....)

animus_nero

25-04-2009, 23:07

We actually did not have any trouble with them.

Well...that was until one of our drivers covered a jag with a rag and then tried to drive the robot :rolleyes:

Following the future technology showcase workshop in Atlanta, I think the built-in PID controls, voltage, and amperage sensors will be quite useful.

Bertman

25-04-2009, 23:25

We used six on our bot. Two regionals and Atlanta. No failures.

Barak Shelef

27-04-2009, 17:31

Wait, let me get this straight...does this effectively mean that you can't roll around the robot on the floor when you don't have the bot turned on? Turning wheels = turning motors, turning motors = generating power through the motor... generating power = fried jaguars?

No... problem is the static discharge goes through the induction circuit of the jag. the low voltage PWM module and FET array is the delicate part. HOWEVER:

Barak,
Starting in at least week 3, the field was sprayed with a staticide. This had been discussed on several other fora and the conclusion has been that dragging a wire does very little. The trailers have had a chain on them since week 3 as well even though there is no discharge path through the fiberglass flooring. I had no reports of static crashes during the Championship. There is still a chance for robots with large belts to build up static within the robot but those seem to have been also non-existent during the humid Atlanta weather. We have two large and fast moving belts and experienced no static that we know of during the Champs.

We'll i guess it's something more fundamental with the jaguars themselves. Thanks for the info (Y)

Only other thing I can think that could mess up in such an odd way the electronics was maybe a strong magnetic field. I remember some problems with polarity changes with the victors as well when they were close to large motors and such, but it seems a stretch considering our jags had a good 2 feet away from our CIMs

Sarah H

27-04-2009, 22:40

I personally think that the victors are much more reliable, we lost more matches than we even know due to Jag issues. I do agree that since they are new there are many glitches that have not been worked out yet, and next year improvements will be made to make them better, and more over the next few years, but I personally would not advise on using them net year. Being a senior on the team, I have talked to our engineers regarding these complaints, and they tend to agree with me for the most part. Jags are much cheaper and we do not particularly like reusing speed controllers, but for the number of problems the Jags have caused, I think its almost worth it to reuse or spend the extra cash for a more reliable controller.

Just my personal opinion as a driver

Al Skierkiewicz

27-04-2009, 23:28

Barak,
There is no 'induction' circuitry in the speed controllers. As to interference, the only thing that might cause a problem is a large and changing magnetic field. Static fields do not induce any currents in nearby conductors. What you may be thinking of is the noise induced in servo PWM cables that are sensed as data in the servos. In the case of cameras, the servos produced unexpected results. The PWM circuitry and power FETs in both controller designs are well protected and robust.

Jon Jack

16-05-2009, 20:53

I've mentioned this in another post, but we've used 8 Jaguars over this year.

The four jaguars we used on our competition robot went through our pre-ship scrimmage (12+ hours of run time), San Diego (50 minutes of run time), Las Vegas (60+ minutes of run time) and the Championship (40+ minutes of run time). This a combined run time of 14.5 hours.

The other four jaguars we used on our early release test bed (6 hours of run time) and our practice robot (100+ hours of run time). This is a combined run time of 106 hours.

We have close to 120 hours of run time between 8 jaguars and have had zero failures to date.

Yes, their footprint is huge relative to the Victors. However, with the added features coming to this control system over the next few years the Jaguars should open up a lot of capability that Victors won't be able to provide.

ZInventor

16-05-2009, 21:56

we had one jag fail, driving a globe motor!!!

darn diodes (that's what the LM guy said at champs...)

apparently, quite a few jags had bad input diodes in the bridge rectifier (idk why they have a bridge...), and had to replace quite a few jags (the pile of bad ones at champs was pretty impressive)

-Z

blhenze

22-05-2009, 22:36

Vikesrock

22-05-2009, 22:40

I'm now working on devising a circuit to place between the PDB and the controller to prevent this from every happening again.

If anyone has had experience with MOSFET as a solution, I'd sure appreciate hearing about it. You can contact me offline at

bhenze@sapulpa.k12.ok.us

If you are planning this for a competition robot I wouldn't put too much effort into it. For the three years I have been in FRC the rules have prohibited custom devices placed in the power pathway for the motor controllers.

*Disclaimer: The rules change every year*

EricVanWyk

27-05-2009, 00:39

If anyone has had experience with MOSFET as a solution, I'd sure appreciate hearing about it. You can contact me offline at

bhenze@sapulpa.k12.ok.us

I used a circuit similar to what I think you are thinking of on the PD, DSC and Solenoid Breakout. http://usfirst.org/community/frc/content.aspx?id=11838

It'll be a honker of a FET, and most likely not legal for competition.

Gdeaver

27-05-2009, 07:43

Infineon makes a P Fet just for reverse battery protection. Rated at 100 amps. One would not be enough since it would see the full load of the jag all the time.

Joe Ross

27-05-2009, 10:11

In the Jaguar vs Victor debate we made an expensive mistake. A battery was wired incorrectly. When it was connected to the robot all 4 Jaguars fried instantly, the three Victors did not. I'm now working on devising a circuit to place between the PDB and the controller to prevent this from every happening again.

Neither the Victor or the Jaguar have reverse polarity protection. From the Victor user guide: WARNING: BEFORE APPLYING POWER:
1. Ensure the input connections are not reversed.
Connecting 12V and GND backwards will
destroy the unit.
2. Ensure that there is not a short circuit on the
output. A short circuit will destroy the unit.
3. Ensure there is a circuit breaker either inline
with the 12V power input to the speed controller,
or inline with the motor. Use an appropriate
circuit breaker for your application to ensure
that long term exposure to a stalled motor (high
currents) will not overheat the Victor.

You may have just gotten lucky that the Victors didn't blow. I heard of another team this year that reversed their battery and blew both Victors and Jaguars.

Al Skierkiewicz

27-05-2009, 10:45

Neither the Victor nor the Jaguar have reverse polarity protection. There is several checks that every team should make before using batteries. Have the electrical team members check over every battery. At least one team member should catch a wiring error. Then line up all the wired batteries and compare. If there are batteries that don't match, determine which ones are wired correctly and fix the others. The Anderson Power Products connectors are clearly marked with a "+" and "-" symbol. A simple check with a voltmeter will indicate the correct wiring of the battery. Follow this with a check of voltage polarity at the power distro with all circuit breakers removed. Then only insert one breaker at a time and check for correct operation. Only when you are sure that the entire system is correctly wired, insert all breakers and reapply power.