Jaguar VS Victor
 

Now that the season is over for us, we finally got around to deciding to what to do with our robot. Long story short, we have 1 jaguar and 1 victor left. We are planning to use mecanum wheels for our drivetrain and 1 window motor or an air cannon. We want this robot to last (since it will be our school toy for many years) but Im not sure whether to buy 4 victors or 4 jaguars. I know victors are way more durable than jaguars, but im wondering if 4 jaguars would be better for use with mecanum wheels. We are using PWM to signal all of your motors.

Re: Jaguar VS Victor
 

We used 4 victors to drive our four mecanum wheels. Don't have any problems with them.

Re: Jaguar VS Victor
 

That also depends on what type of feed back you want from your motors, Are you using can? Either way as far as efficiency they both are the same just a jag is smarter than a victor.

Re: Jaguar VS Victor
 

Started the season using Jaguars, CAN, and the 2CAN bus. The fatal CAN timeout error at start up got us and decided to swap to victors.

Re: Jaguar VS Victor
 

I am totally pro victor.
They weight less
They have smaller foot print
And oh yea you don't see thread after thread on them burning out.
I really like the fact first offers both for us to use. You can never go wrong with choice.

Re: Jaguar VS Victor
 

No, they don't chronically burn up, but I have seen a picture of a bunch of partially dissolved victors, I think it was due to loctite.

Victors, in my opinion, are the way to go if you want reliability and aren't to sure about CAN (I'm sure there is some special case in which a jaguar in pwm mode would have some advantages over a victor, ignoring the limit switch feature which is currently off-limits [pardon the pun] to pwm users) I also like the smaller size of the victors. Jaguars operating with can, on the other hand, can really streamline automation.

Re: Jaguar VS Victor
 

I use both.

Jags with CAN for anything that needs precise control (drive and arm). I prefer the linear output curve of the Jags and you have way more feedback and control mode options. I also like CAN bus daisy chain wiring, which is a lot cleaner and way easier to make custom length cables for. Jag are more vulnerable to swarf (metal bits) destroying them, but make sure you cover them during machining and you should be fine. Also, mounting them vertically (back to back) reduces the metal shaving vulnerability and reduces the footprint on the board. We have no problems with Black Jags when we keep them free from metal shavings. Don't use Grey Jags (they aren't made any more for many reasons) on a competition bot since their U6 gate driver chip is faulty (it took a failure at Philly to finally hammer the point home buy another Black Jag to run the arm).

I use Victor for things we are running at fixed speeds (roller claw) since they are lighter & smaller. Also for all Denso windows motors if I can't convince the team to use a better motor and can't run it at full speed with a relay (window motors are not meant to run off speed controllers and they don't work well with Jags). I have had about 6-8 Victors fail over the year due mostly to metal shaving (I think). Not coincidentally they were mounted in terrible places on the robot where all the metal shaving fall. This is an important consideration when locating and covering your electrical board.

Re: Jaguar VS Victor
 

We have have been use Victors only..
When our robots become 3 years old we remove the victors and use them on the new robot. Ya, they show a little wear, but functional there great.

Re: Jaguar VS Victor
 

I'm solidly in the Victor camp... At the end of the day, the winning robot is always a functional, running robot...

JMHO...

Re: Jaguar VS Victor
 

Many regionals have Jaguar support staff but Victors don't have the same issues that require support staff.

You can usually find teams with spare Jags or Victors but if they don't then spare parts only has Jags. Getting a Jag from spare parts requires either exchanging a broken one or paying for a new one. I'm sorry I don't remember which one it is exactly now and it could change in the future. It isn't really a big deal to switch between a Jag and Victor at a competition but the change in size and weight could make a difference.

Victors are normally a bit cheaper.

A Jaguar rep I spoke with said they would be coming out with a new version soon (hopefully for next year) that would be more durable and fix some of the problems. This would also make it slightly more expensive (like a dollar or two). If you were considering going with Jaguars I would recommend that you wait to see what they come up with.

I prefer Victors but I'm a mechanical person so that extra weight, size and lack of durability that comes with the Jaguar isn't worth the extra computing power which most teams don't even use.

Re: Jaguar VS Victor
 

Im on the victor train and probably always will be. They are liter and have a smaller footprint.

Jags are good if you use the feedback...but we have had too many problems with CAN.

Re: Jaguar VS Victor
 

The advantages that Jags have over Victors are CAN, and linearity of the output response.

The advantages that Victors have over Jags are a long history of reliability, reasonable robustness to metal shavings, lower size and weight, and the fact that for many veteran teams there are a lot of them lying around.

We use only Victors for all of the reasons listed.

Re: Jaguar VS Victor
 

We were burned by jags multiple times this year.

It makes troubleshooting a really hard task when jags are always susceptible to failure. The Victors in our drive never had a single issue (and the Victors we've used on the years of robots prior also had no issues). I watched a black jag go up in smoke this year for what seemed to be no apparent reason, amongst many other issues.

I think Victors will be what we use on everything from here on out.

-Brando

Re: Jaguar VS Victor
 

We have been using 4 jaguars leftover from 2009 and 2010 and this year after our first game we have noticed that they are going bad gradually. Luckily we had 4 brand new replacements in our crate but i am seriously wondering if i am not interested in using CAN bus at all, would victors be a better choice?
I will start a serious debate about this issue next year with my team.

Re: Jaguar VS Victor
 

this is our second year using jags exclusively, last year we had one fail this year we've had two.
all three times we opened them up and it was pretty obvious that metal had gotten inside somehow and shorted things out. but we have since found ways to address the problem
we've had good results with Jaguars, and aside from the few that fail for obvious reasons we have almost no issues with them, and i would recommend them.

Re: Jaguar VS Victor
 

From the discussion in this and other threads, it seems the consenses is that the Jags are beneficial only because of the CAN bus functionality and the more linear power curve. What I am interested in knowing is how many teams actually found these benefits indispensable and under what circumstances? We have been using Victors all these years and don't see the need to go with the Jags. I know CAN bus offers a lot of new nice functionalities but how many teams are actually using them in software and if they absolutely cannot do without these functionalities? Every year we had a discussion on switching to Jags but when doing cost and benefit analysis, Jags always lose out for us.

Re: Jaguar VS Victor
 

We used CAN for Breakaway to control a kicker. To get it in position, we used current mode control to move backwards until it felt a force from a hardstop. To fire, we used an intentionally under-damped PID looped around position on an encoder. This made it easy to reliably control the rest positions and contact speed.

I do have to admit that we had a slight advantage - 3 of the mentors were involved in the design of some aspect of the CAN system.

Re: Jaguar VS Victor
 

So if I understand you correctly, using CAN to control the kicker basically saved you a limit switch. And what does an under-damped PID loop has to do with CAN? I don't quite see it probably because I don't know your kicker's design.

Re: Jaguar VS Victor
 

It was a rotary kicker direct driven by a motor: the boot would rush 120ish degrees to kick the ball, return to 90ish degrees to get back within the envelope, and then slowly return to 0ish degrees to reset.

The kick (0 -> 120 ->90) was handled in a single CAN command of "Travel to 90 with constants P,I,D". Since those constants were under-damped, it would reliably "over-travel" to 120. It was surprisingly easy to tune.

The return was just a "apply amperage -A". Yes, we could have done this with a limit-switch, but it was just as easy to do it this way. One benefit was that it made it really easy to hold it in the ready position against gravity. Not enough reason to move to CAN, but since it was already there...

I've used this as an example with a few students, and I think it is a very interesting teachable moment. Plot the desired response on a torque/speed chart, and then compare it to voltage, current and speed modes. For kicker return, current mode is pretty darn close to optimal.

I really don't think that CAN should be used for every motor on every robot. It isn't a blanket replacement for PWM (though it can be used as one), and it isn't a silver bullet - it enables access to new control modes that can provide significant benefit when applied correctly in the appropriate situations.

I'm glad your team has the discussion, and I'm glad they are coming to a conclusion that works for them.

Re: Jaguar VS Victor
 

If jags weren't that fragile (i.e. get fried easily compared to victors and get cut-outs during competition), it could have easily won the cost benefit analysis. So our conclusion is that unless our robot design calls for a certain feature that jags can easily provide through CAN and cost too much to implement using Victors, we would avoid them. Hopefully, the next generation of jags will improve the reliability enough that will swing our opinion the other way.

Re: Jaguar VS Victor
 

The one problem we have had with both would be pwm cables falling out. We plan on trying the CAN system to clean up the wiring and add functionality. I didn't know that jaguars burned out so easily though. We have had one very old one go out, but that is all.

Re: Jaguar VS Victor
 

Personally, I find it really surprising to see everyone slamming Jags on reliability. Least year, we used 7 of them on the robot. The year before, we used 4. Year before that, we used 2. We've only had 1 issue with them between 7 different official competitions (and who knows how many off season events) competition, and that was due to the limit switch input on one getting screwed up (it worked if we jiggled our inputs for the limit switch, but replacing the Jag fixed it entirely). That Jag still works with jumpers. We've never burned out a Jag or a Victor in 6 years of competing.

The problem is, you seldom hear about teams using Jags successfully. It's the teams that have problems with them that come and post, so it looks like there's a much larger problem than there actually is.

Re: Jaguar VS Victor
 

One special case I can think of: When operating at stall, a Jaguar tends to heat up the motor a bit less than a Vic, for the same torque output.

Re: Jaguar VS Victor
 

This year, we are trying Jaguars and CAN bus because we are quickly running out of digital I/O channels with all the encoders (encoders can directly connect to the Jags). It sure does clean up our wiring. See my pictures on this thread (http://chiefdelphi.com/forums/showth...t=99554&page=2).
However, while making the Jags to work with the code, one of the brand new Jag is already malfunctioning. I don't know what happened. Here is the sequence of events:
- We have 4 Black Jaguars driving a mecanum wheel set.
- Flashed the latest firmware to all the Jags and the 2CAN.
- Successfully assigning IDs and running each individual motors by using the bdc-comm tool.
- We have four encoders (one for each motor), but for some reasons all the encoders are not working (could be because of the new way we connect them). We are still investigating it.
- While testing different modes of the Jags, one of them died. The status LED goes dark even though I have power to it. After replacing the dead jag and some tweaking around with the code, the robot now runs teleop fine.

Since this is a brand new Jag, is it under warranty? How would I send it back for repair?

Re: Jaguar VS Victor
 

There is a link to RMA information at http://www.ti.com/jaguar

Re: Jaguar VS Victor
 

I just want to throw this into the mix:

Pro Jag (black)

The 2Can controller is awesome. Nothing beats remotely a remote user panel to debug/modify. And it saves wiring space by having the the 2can-crio connection over Ethernet.

Re: Jaguar VS Victor
 

If your using PWM, Victors are your best bet. I've used both for years, and based on what you've said, Victors seem to be right for you. Jaguars only advantage is that they can run Can. Can will give you better feedback (Voltage/current/other), but are bigger, and less durable. Based on you saying "School TOY", I'm assuming this robot is in for a long life full of those autonomous mishaps that send your robot full speed into a wall. Victors will be able to take that abuse, while jags will not (Trust me, after testing, we used victors in our 120lbs battlebot). Hope this helps

Re: Jaguar VS Victor
 

I'd be all over the 2CAN interface, but I just can't justify the $200 item (PER ROBOT if you keep them around) when there is a $2 option that just happens to run 4 times slower. I haven't run into a situation where we've been limited by the bandwidth (yet).

While CAN is a nice interface that simplifies wiring, that's only one small benefit for the Jags. The BIGGEST improvement is minor loop control capabilities. Imagine driving to speed during the competition and then switching over to position mode to give you the ability to accurately traverse a specific distance.

While the Jags are fairly rugged, we had some issues last year with a couple of them. I'm of the opinion however, that the mechanical guys killed them with aluminum filings... If you're careful though, they work just fine.

- Bryce

Re: Jaguar VS Victor
 

My opinions on the topic:

-The serial bridge is ~1/8th the speed of the 2can, yes (115,200baud serial vs 1M?) - That's fairly significant if you update the Jaguars fast enough

-We have yet to use a CAN jaguar, or have any features we cannot do with purely a Victor and some software on our end. We like it this way for some things, as we can modify the control loop to fit our robot (a PID loop isn't great for everything), or add multiple control loops and add the output (e.g. control to distance + control to heading over the two sides).

-We will never use a Jaguar in drivetrains because of their high-current shutdown. We had a lot of issues on our Lunacy bot post-season, because after 5 minutes of driving (with super low cof wheels, remember) the shooter could randomly (predictably after a few minutes) shut down due to the extended current draw of forward-reverse slams.

-I've heard the black jags are far more reliable than the grey ones. We are willing to use a black jag if it gives us an advantage, but we haven't found an advantage yet. They are functionally the same over PWM, but if you only use PWM control, the Jaguars are physically bigger and can't handle the extended high-current draw that the Victors can.

-In my time on 33, I've only seen 1 Victor die, ever. We have some of the really old Victor 883's which we still use for practice and mock up robots, and they still work after many years of use. The Jaguars don't yet have that kind of track record, especially after the really bad grey jags.

Re: Jaguar VS Victor
 

Yep, you'd be right. However, we've run at least 6 Jaguars in CAN mode on a robot for the last couple of years now, and the serial to CAN interface has not been considered slow. How often do you plan on updating a Jaguar anyway? To give you an idea, the Jaguar messages that are sent are only 32-bits long. The therefore theoretical maximum bandwidth of messages is 3600 commands PER SECOND. In PWM mode, the Jags can be updated every 5ms or so and the Victors every 10ms. So that's only 200 and 100 commands per second, respectively. Assuming 10 Jaguars and a 60% efficiency, you still get about 200 updates per second per Jaguar. And with fewer, the update rate is higher. My point was that I can't justify the $200 cost for update speeds that I already get.

Sometimes it's just nice to tell a Jaguar to go to a position using a Set() command rather than having to write or use a PID in your code for it. :)

This year, rate limiting (built-in) will solve most of those issues. However, we have run Jaguars on the drive train for the last couple years and we could not make them reset when using a joystick to thrash the motors back and forth. We only run into those issues when the command for full forward is immediately followed by full reverse. And even THEN we only had that issue because we were doing that with five motors simultaneously. (It was a swerve drive train without completely rotating modules). Even THEN the issue was a voltage dip because of the HUGE current spike of 5 CIM motors reversing direction immediately. Rate limiting solved that issue nicely. It's typically considered unnecessary to slam them back and forth since even a quick rate limit will be imperceptible to humans.

I think that probably has to do with people removing the screws on the Grey Jags even though they aren't meant to be removed - and thus leaving metal shards in the case.

Now that, I'd agree with. Jags just need some babying and there are a few fundamental rules that have to be followed to have success. They have their problems, but they're pretty great at the same time.

- Bryce

Re: Jaguar VS Victor
 

It would be nice if you could do the same thing with speed (in the drivetrain).

Re: Jaguar VS Victor
 

Is there some reason one can't?

- Bryce

Re: Jaguar VS Victor
 

Have you ever successfully done it?

http://www.chiefdelphi.com/forums/sh...d.php?t=100135

Re: Jaguar VS Victor
 

No, we've only used position mode on two different occasions (with some funky coding it worked pretty well for the dynamic system of a two jointed arm and for module orientation on a swerve drive system).

We WERE however, planning on using speed control for the shooter. I guess we'll have to take a good hard look at that one. I didn't realize the background of this...thanks for the heads up.

- Bryce

Re: Jaguar VS Victor
 

On the other hand, Jaguars have been proven to be notoriously more unreliable, as evidenced by the high frequency of hardware and software updates. Jaguars also have a much shorter track record than Victors. What's more is that this problem isn't exactly as exaggerated as you see it to be - yes, the bulk of Jaguar posts are about problems/failures, but can you say the same about Victors?

Re: Jaguar VS Victor
 

Yes, the majority of victor posts are people who don't get the PWM cable plugged in properly.

Re: Jaguar VS Victor
 

I have a similar question regarding these...

I am a new mentor on a rookie team and I've only ever really worked with Victors. We could really use the smaller footprint/size/durability of the victors, BUT we got 4 Jags and only 1 Victor in our kit and can't afford to buy many more speed controllers (definitely can't buy 7 victors, maybe barely 3).

If our team has 4 Jaguars and 4 Victors, can we use them all on the robot with minimal headaches?
How much additional difficulty would it be programming/wiring/any other considerations to have such a mixed set?

Re: Jaguar VS Victor
 

If you are using the Jaguars with PWM, it is no different from the Victors in terms of programming. Instead of instantiating a Victor object, you just instantiate a Jaguar object. It would be a little more involve if you operate the Jaguars with CAN bus but the upside is simpler wiring and more functionality (e.g. Can use built-in PID control on position and speed mode, can read the voltage, current, speed and position from the Jaguars etc). Our team has been using Victors in the previous years. We are trying the Jaguar the first time this year. We were afraid of the reliability issue. That's why we hesitated for so long. But eventually we knew we must jump over at a certain point, so might as well now. Hopefully, the added functionalities of the Jaguars are well worth it. If you want to play it on the safe side, you can use a mix of the controllers. We definitely want to use the Jaguars for the shooter because it can potentially do speed control (if we can tune the built-in PID to give us a stable speed). We also plan the code such that we can easily switch back to Victors if we have to (e.g. Jags failing during competition).

Re: Jaguar VS Victor
 

Until Jaguars are demonstrated to be as reliable as Victors in intensive applications such as drivetrains, there won't be an eventually for me :)

Our team is employing the exact same strategy. We anticipate that, because our shooter will only ever run in one direction and will not rapidly change speed, there is not much chance that these Jaguars will actually fail. But we are also developing a Victor-based speed controller in code as well, to hedge against the risk of Jaguar failure.

Re: Jaguar VS Victor
 

There's a recent thread about using the Jag's built-in speed control:
http://www.chiefdelphi.com/forums/sh...d.php?t=100135