Jaguars

[MrBasse]

How can everyone claim that Talons are tougher than another speed controller. We have been using the same Victors for four years straight and haven't had a failure yet. Talons have only been around for a year, so time will tell. Jaguars on the other hand...We've cooked 9 of those (one with actual flame coming out of the vents) and avoid them as much as possible unless we run out of Victors. I'm fairly sure that I can get smoke to come out of one just by looking at it, but it might also have something to do with our shop environment...

In my view, availability of the Talon during season has been the biggest issue with it, so we have yet to get to play with one. I'm excited to get one, but we don't have the funds to pick up enough to use without mixing speed controllers.

[MichaelBick]

While we wouldn't use jaguars on the comp bot, I've heard they are really good for protos because of they build in PID and current sensing.

[Anupam Goli]

You can purchase additional jaguars here: http://www.vexrobotics.com/217-3367.html

I always thought the CAN bus capabilities of the jaguar were very interesting and if the hardware was more reliable, I'd use the jaguar more often.

[MechEng83]

We ended up using all 3 controllers at various points on our 2013 robot. (Though only 2 at any one time.)

Jaguars are great because of following reasons (and we utilize each one):

Current sensing
Internal PID control
Forward/Reverse Limit Switches
CAN

Jaguars have the following drawbacks (each of which we've experienced):
Relatively low current limits (Though it seems to have been raised with the latest firmware update)
Poor CAN (physical) connection robustness
Highly sensitive to swarf (metal debris) -- though the new ones have a conformal coating.

[Pault]

Originally Posted by MechEng83

Jaguars have the following drawbacks (each of which we've experienced):
Relatively low current limits (Though it seems to have been raised with the latest firmware update)
Poor CAN (physical) connection robustness
Highly sensitive to swarf (metal debris) -- though the new ones have a conformal coating.

Don't forget about a giant footprint.

And all those extra features can be a disadvantage too, because you now have the temptation to use them when often you would be better off without them.

In 2012 (rookie year) my team used Jaguars with CAN. I will just say that even the word CAN now instills fear into the hearts of our veteran students. In 2013 we wanted to use Talons, but the sold out, so instead we used Victor 888s, and had no complaints. This year we have bought 4 talons to put on the electronics test bed we are building, and if they really are as good as everyone says they are we will put them on our 2014 robot.

[yash101]

We used Victors last year, and kept cooking them, (because our motors kept shorting out, damaging their FETs. We haven't been having those problems anymore, because our shooter is disabled so we barely use it. Victors, themselves, are quite nice. They were lightweight last year, compared to jaguars, and they work nicely. I do not have too much experience with Jaguars, but it seems though the feature set is quite great. The CAN interface is nice, along with the PWM interface. These can be networked through an RS232 interface too! There are a lot more features that I won't list, but here's the manual: http://content.vexrobotics.com/docs/...e_20130215.pdf. As mentioned before, a big problem in these motor controllers is their maximum continuous current. In the product page (http://www.vexrobotics.com/217-3367.html), here is the specs table:

Never Limit Progressive Limit Immediate Limit
Pre v107 40A 50A 60A
v107 40A 50A 92A


Here are the Talon specs:
Page: http://www.andymark.com/Talon-p/am-2505.htm

Input voltage: 6-28 VDC
Continuous current: 60 A (above 40A continuous we recommend adding this fan)
Peak current: 100 A
Input PWM signal: 0.9-2 ms @ 333 Hz
Input resolution: 10-bit (1024 steps)
Output resolution: 10-bit (1024 steps)
Output switching frequency: 15 kHz
Talon SR: Synchronous sign-magnitude rectification
Smart LED, blinks proportional to throttle, now with obvious change from 99% throttle to 100%
Simple calibration
User selectable brake/coast
4% neutral dead band
Linear throttle response

I hope this helped. This is a comparison between Talons and Jaguars.

[Jared]

The two most important features of a speed controller are reliability and cost. We don't want to worry about swapping out controllers after a match, and we really want to avoid failures during the match. Reliability is also important because we use previous years speed controllers on the practice robot. This year, our practice bot had victors from 2003 and 2004 that have already been used on at least two robots. Victors are the only controller with this type of reliability. They are also the cheapest.

As for the extra features, I think they're a waste. We end up wrapping the speed controller class to add a few utilities, so it's easy to add a pidcontroller and and the function to make the output linear. The jaguars don't really have any features that can't be done on the crio.

[yash101]

I agree. Victors will take a lot of abuse before failing. The only failures we had were because of a shorted motor. If they added temperature sensors to the MOSFETS, they could allow it to do an emergency shutdown before damage!

[MechEng83]

Originally Posted by Jared

The jaguars don't really have any features that can't be done on the crio.

Please let me know where the current sensing feature is on the cRIO. My team has been unaware of this feature.

[techhelpbb]

Originally Posted by MechEng83

Please let me know where the current sensing feature is on the cRIO. My team has been unaware of this feature.

With minimal hardware the feature could exist but I doubt it would be legal under the FRC rules as it would require measuring the voltage drop over a specific length of wire using the analog bumper or some other analog accessory. It can be done with a series resistor like in the Jaguar but in doing so you'd be in the path of the current with more than wire. I doubt it would be legal on the output side of an electronic motor control as it would make a connection between the bridge in the electronic motor control and the motor back to the control system. It might not be legal on the power input side of an FRC electronic motor control either. Course on the power input is both the current to the motor and the electronics in the motor control (which are small in comparison to the motor). There's also the issue that the current at the power input point will have aspects not conforming to the current at the output to the motor (the bypass diodes, various features, the resistance of the MOSFETS).

Don't think of trying this trick unless you understand the difference between a single ended and differential A/D input.

[MechEng83]

Originally Posted by techhelpbb

With minimal hardware the feature could exist but I doubt it would be legal under the FRC rules as it would require measuring the voltage drop over a specific length of wire using the analog bumper or some other analog accessory. It can be done with a series resistor like in the Jaguar but in doing so you'd be in the path of the current with more than wire. I doubt it would be legal on the output side of an electronic motor control as it would make a connection between the bridge in the electronic motor control and the motor back to the control system. It might not be legal on the power input side of an FRC electronic motor control either. Course on the power input is both the current to the motor and the electronics in the motor control (which are small in comparison to the motor). There's also the issue that the current at the power input point will have aspects not conforming to the current at the output to the motor (the bypass diodes, various features, the resistance of the MOSFETS).

Don't think of trying this trick unless you understand the difference between a single ended and differential A/D input.

That wasn't actually a serious question, but thanks for the answer! For the Talons we used on our drive train, we experimented with using a wire coiled around one of the wire leads and got some values in a custom circuit. I'm not sure of all the details, our electrical mentors worked on it.

[Munchskull]

As was wondering, at the rick of sounding ignorant, what is the performance difference between Spikes, Jaguars, and Talons? I know the Jaguars have CAN but what that does is a little of a mystery to me.

[Ether]

Originally Posted by Munchskull

what is the performance difference between Spikes, Jaguars, and Talons?

A Spike is simply a couple of relays, whereas Jag and Talon are speed controllers.

Performance curves for Jag, Talon, and Vic may be found here:

http://www.chiefdelphi.com/media/papers/2720

I know the Jaguars have CAN but what that does is a little of a mystery to me.

In order to help you, it would help to know if it is a mystery because you've read and don't understand the documentation, or because you can't find the documents.

[techhelpbb]

Originally Posted by MechEng83

That wasn't actually a serious question, but thanks for the answer! For the Talons we used on our drive train, we experimented with using a wire coiled around one of the wire leads and got some values in a custom circuit. I'm not sure of all the details, our electrical mentors worked on it.

It sounds like your team measured the electromagnetic field around the wire with a circuit that works like a current sense transformer. It doesn't actually connect to the circuit it merely robs some of the magnetic field around the wire (which is generally there as long as current flows) and converts it to something you can measure. That might let you skate on the FRC rules about getting in the circuit path between the electronic speed control and the motor. Plus when done with a current sense transformer you bypass the grounding issues as one leg of the output can be tied to that electronics ground with little impact on the electronic motor control or the motor. Using a current sense transformer it's important to note that measuring AC and DC currents require different considerations.

There are Allegro hall effect sensors that can measure circuit current if you dig around they were recommended up on ChiefDelphi before (oddly almost precisely 3 years ago):
http://www.chiefdelphi.com/forums/ar...p/t-87568.html

I am interested if these are legal in FRC in competition. However that might be a side track for this topic.

[Ether]

Originally Posted by techhelpbb

It doesn't actually connect to the circuit it merely robs some of the magnetic field around the wire

Well, it actually is connected to the circuit, albeit inductively via the transformer formed by the lead wire and the coil wrapped around it.

Since the current to the motor may contain a large ripple under various operating conditions due to the interaction of the speed controller PWM switching, the motor inductance, and the motor commutation, there may be some issues involved in interpreting the measurements.