Re: What do you think of the jaguars?
 

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.

Re: What do you think of the jaguars?
 

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)

Re: What do you think of the jaguars?
 

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

(sorry.....)

Re: What do you think of the jaguars?
 

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.

Re: What do you think of the jaguars?
 

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

Re: What do you think of the 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:

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

Re: What do you think of the jaguars?
 

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

Re: What do you think of the jaguars?
 

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.

Re: What do you think of the jaguars?
 

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.

Re: What do you think of the jaguars?
 

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

Re: What do you think of the jaguars?
 

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.

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

Re: What do you think of the jaguars?
 

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*

Re: What do you think of the jaguars?
 

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.

Re: What do you think of the jaguars?
 

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.

Re: What do you think of the jaguars?
 

Neither the Victor or the Jaguar have reverse polarity protection. From the Victor user guide: 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.