While it is clear the Jaguars have a lot of new features, it seems we won’t be allowed to take advantage of them in the 2009 season. They have a few wire clips and a nice cover for the fan. Other than that, they are slightly heavier, considerably larger, and in much shorter supply than the victors. What advantages do they have over good ol’ victors, aside from being shiny and new?
Disclaimer: I am a mentor for Team 2468 by night, but a systems engineer at Luminary Micro by day. So, I am biased.
Pros:
- Jaguar costs less than a Victor 884, more than $40 less ($73.33 vs $114.99).
- Better output linearity (see http://www.chiefdelphi.com/forums/showpost.php?p=770666&postcount=86). If you want to see a demonstration of this, see http://www.youtube.com/watch?v=_X0_aFMpm9I.
- Integrated limit switch inputs (one forward, one reverse) [li].
[/li]- Controlled fan turns on only when H-bridge is generating a non-zero output voltage (8 fans amount to 0.5 A).
Cons:
- Bigger than the Victor 884.
- New kid on the block; teams have less experience with Jaguar compared to the Victor 884.
I am not sure how you determined the availability of one controller compared to the other. You can check the inventory at Digi-Key, but this doesn’t indicate how many are in the pipeline (only how many are currently in Digi-Key’s warehouse).
[*] The status of the limit switch can be made available to the cRIO with a small circuit that I will publish as a Jaguar application note after the holidays. This circuit is necessary in order to assure that additional ground paths are not created from the motor controller through the DSC.
As far as availability, I was referring to the fact that most teams probably have a few victors lying around, and many veteran teams definitely have a lot of victors lying around. I wasn’t aware of the lower price, however. Also, the output linearity tests you linked to were very definitive. I had no idea the victors were so poor :eek:.
At this point, I am much more impressed with the Jaguars than I was initially. Now we just need to find an efficient way to organize these.
The new Jags are also thermally and current limited. With the Victors we have been running open loop and things just kept going until something fried or a breaker tripped. In the real world companies that design motor controllers and use variable speed motor have to contend with something called a warranty. Protections are essential if a company doen’t want to go bankrupt from warranty claims.
Yep… and teams are free to choose what they want to use.
This constantly disturbs me. Luminary Micro is providing a price brealk for FRC teams, but you have to go to a specific Digi-Key web page. Otherwise, the cost to NON-FRC teams is $109, which is only a 6 advantage. Please use http://sales.digikey.com/dkes/FirstRoboticsCompetition.asp if you decide to order more Jaguars beyond those provided in the KoP. This link is also available at the bottom of the Jaguar web site at Luminary Micro (http://www.luminarymicro.com/jaguar).
One of our students came to the simple observation that if you stand on on its end (with the cable retention clips pointing up to the sky) you can put two of them back to back (fans facing in opposite directions) and take only a little more space than laying flat on a table. Our team will probably experiment with this orientation if space becomes tight.
Add to the list of Pros “the cool name”
In the future (2010 or beyond) the ability to run these on a CAN Bus will prove to be valuable to some teams.
The Jaguars have all of the features of the Victors - and much more, along with better linearity and range, plus they are less expensive to teams. A win-win-win all around.
One thing I’m worried about is the ability to clean them. With the victors, if we suspected a bit of wire or metal shaving accidentally got in there, we could clean it with compressed air easily. Does anyone know how the cover comes off a Jaguar for cleaning?
Don
One of the college students on 2815 was able to open one up and re-close it without incident. (Have to show the kids all the juicy innards, yes?)
I just hope their more robust then the victors. I don’t know how many wasted hours(in about 5-10min blocks) we spent trying to get the things to get a single. It would get it once, then the robot terns off and back on then all the sudden it doesn’t have a single…those little flashing red LEDs would give our team a collective a “sigh”.
But hey they were free, and they ran our robot straight through championships.
I don’t mean to pick on you, but I’ve seen a lot of posts like this.
The only failures we have EVER experienced with the IFI system and any of it’s components have been our own fault.
We have had only a couple incidents I can recall. One fried an entire RC, a couple other times we had connectors shear off of it because of our own stupidity.
My point is that if you experienced systematic problems with the IFI control system, it was probably something you were doing incorrectly, because when used properly all of IFI’s stuff just plain works. Do their products have things that could be better? Sure, everything does, but what they have is pretty darn good.
It’s also not fair to IFI, who has been a fantastic supporter of FIRST, to insinuate that their products are anything less than quality, which is clearly not the case.
First of all, yea i have to agree with this. Any team that has ever asked us for help with any of the IFI system components has explained their problem and then we found out that it was their own fault that made them have a system failure or a fried part.
Secondly, I know my POV on this subject, but do you guys think that the benefits outweigh the drawbacks? ie: weight (nto so much) but size?
The footprint is larger, yes, but it’s not bad at all. The future ability of using CAN far outweighs the size issue. I can’t wait to get rid of these PWM cables.
For 2009, I still see the victors as the clear choice due to their size. The jaguars really don’t have any features (legal for use in 2009) that outweigh their massive size.
How do we turn off this feature to run the fans constantly? Once hot, a FET wants to be cooled down even if it is not passing current. And I hope this doesn’t mean the fans are connected to the output of the H bridge.
Al,
This post seems to indicate that the conditions for the fans shutting off are that the motor is off, and 10 seconds have passed, *and *the temperature is below 38°C (roughly 100°F). I’d assume that’s a safe temperature for the Jaguars, since they set the number.
Bill beat me to it.
Al, They don’t turn off as soon as current is removed. In my experience, as soon as you ask the Jag to do something that fans turn on. Once you stop working the Jags, the fans stay on for a certain period of time (~ 1 minute). I’m not sure if it is time or temp dependent.
Scott and Bill
I guess the question then arises, is this an “or” function? The fan turns off after 10 seconds or the temp is below 38 degrees? Is the temperature sensor part of the circuit board or is it attached (thermally) to a FET? I am asking since we have not yet opened one and it will be a while before we get back into the shop.
Ditto here.
You mean aside from integrated end-limit switch inputs, a far more linear response curve and range, thermal and overcurrent protection, smart fans, clearer markings (can’t miss that red screw) and better cost, all of which the Jaguars have and Victors do not?
.
If you can’t make them fit on the robot, then those features don’t really add much value.
Actually, I’m going to have to vote against the screws.
If the screws were captured, that’s one thing. However, they’re not. And they’re very easy to completely unscrew. They’re also not error-proofed and can be put back in the wrong holes.
The result is that someone could accidently wire them backwards. I’d much rather they get rid of the colored screws and color something that can’t be reversed or removed.
I understand that a bit of caution prevent this issue most of the time. But I don’t think that anyone can argue that if it CAN happen, it WILL happen.
We’ve released the magic white smoke on a number of Victors in the past few years, and to our knowledge, we hadn’t done anything wrong, (aside from not being careful enough with metal shavings falling in). I am, however, more inclined to believe you. What could we have done wrong to burn them out? What happened to you guys?
Hopefully with this knowledge and some care, we won’t burn out any more victors, or jaguars if they are prone to the same weak points.