New Talon Speed Controller

[Camren]

Originally Posted by IndySam

We have been pushing around robots with Jags as long as they have been available and have never experienced this problem.

Interesting but in how long of increments like a few feet we have found that they would be fine. but a rookie pushing the robot down a hallway instead of using a cart was a problem. Also it could depend on if the robot is on or not.

[Jon Stratis]

Like IndySam, we've been doing this for years with no adverse affects on the Jaguars. This includes pushing it from one room to another (probably 100 ft). This is almost always with the robot off - we never push it long distances with it on... although just last night there was some small pushing going on to manually line the robot up for some testing while it was on (a few feet at a time).

[Camren]

Originally Posted by Jon Stratis

Like IndySam, we've been doing this for years with no adverse affects on the Jaguars. This includes pushing it from one room to another (probably 100 ft). This is almost always with the robot off - we never push it long distances with it on... although just last night there was some small pushing going on to manually line the robot up for some testing while it was on (a few feet at a time).

This lead me to think that it is when the robot is on it leads to adverse affects if pushed more then a few feet. I have noticed that when on the robot is harder to push but that could just be me.

[Ricky Q.]

Originally Posted by Jon Stratis

Awesome, I had no idea it did... I looked through the users manual and didn't find any mention of it... where is this sort of information documented?

It is currently documented only on the Product Web page. We'll make sure the manual for the Victor 888 includes this information.

Thanks,
Ricky

[Ether]

Originally Posted by Camren

Ok to clarify my above post...

From the scant technical detail so far available (if there's a schematic I haven't seen it), I can't see any reason why the Talon should be any different from the Jag when not powered, or when powered with a zero throttle command (in the deadband zone, you're either coasting or braking, not regenerating - someone please correct me if this in incorrect).

[Tom Line]

Originally Posted by Ether

Per the user manual, .9 to 2ms is the pulse width (duration of pulse).

50Hz is the frequency (max? or nominal?) of the pulses that can be processed.

Ether: So do you see anywhere where it gives us the actual response of the Talon? 5 ms like the Jag, or 17 like the Victor?

I'm curious because I know some teams switched to Jags for better shooter control this year specifically because of the 5 ms response over the 17.

[Ether]

Originally Posted by Tom Line

Ether: So do you see anywhere where it gives us the actual response of the Talon? 5 ms like the Jag, or 17 like the Victor?

Sorry Tom I haven't seen that anywhere. I assume Mike will provide that info the next time he visits this thread.

I'm guessing that the 50Hz number (20ms period) was given because it corresponds to the 20ms TeleOp period? The Talon may be capable of processing pulses coming in faster than that. But there's the driver issue. As I understand it, if you send commands at 10ms (100Hz) to the Victor driver, for example, you still get a 17ms period coming out of the driver.

[maddoctor90]

From the Talon User Manual "A Talon is a device used to control the rotational velocity (speed) of a brushed DC motor through modulating power over time. The Talon accomplishes this through an efficient form of rectification known as locked-antiphase rectification. This type of rectification returns current to the power source during the freewheeling period of the motor and during direction change."

From this quote and from what I perceived form talking to a guy from crosstheroadelectronics at IRI, I believe the Talon does have some regenerative capabilities. How they work and when they are active are two things I would love to have some clarification on.

[rachelholladay]

Well this is fairly exciting. I must confess that I would like to do a three way comparison of Victor vs Jaguar vs Talon. Last season we had issues with our gun for a while and were able to track that in part to what seemed to be the non-linear-ness of a Jaguar. We ended up swapping it for a Victor, which greatly improved the situation. Based on the supplied charts from the User Manual, the Talon seems to have pretty good linearity. That would certainly be an interesting series of tests for Beta Testing. (I am also wondering if the David Relay will be coming back for more testing, it was a neat little box of fun)

Although a rather minor point, I really like the lights feature, "The rate at which the led blinks is proportional to the percent throttle. The faster the LED blinks the closer the output is to 100% in either polarity." From the Jags and Victors I am very reliant on the color change for basic testing and while the blinking will probably serve more as a qualitative measure, it seems like a neat feature to have. (Although I'm sure that if I work with the Talon, a month later I'll have stared at blinking lights enough to go a little crazy).

I am a little surprised that there seems to be no CAN support, especially since this comes from Cross the Road Electronics, a vendor that supplies not only a lot of CAN equipment but 2CAN as well. There would have to be a major change in hardware to accommodate it, so I guess we should not be expecting CAN + Talon any time soon.

Looking ahead for the season my two logistics questions would be: what will come in the Kit (Rookie and Veteran)? If AndyMark is not selling Jaguars, who will?

[JohnSchneider]

Lack of CAN means we still have to use Jaguars :/

[connor.worley]

Originally Posted by animenerdjohn

Lack of CAN means we still have to use Jaguars :/

Why is PWM out of the question?

[jason701802]

Originally Posted by IndySam

We have been pushing around robots with Jags as long as they have been available and have never experienced this problem.

We have killed at least one Jag this way (I think two), as well as another my hooking the output to power (which is almost the same thing) (all the Jags were tan). The one (or two) we killed, died when the robot was pushed fairly quickly. Since then, we try to avoid pushing the robot or at least push it slowly. We've never killed a Victor this way and have pushed these robots around much more aggressively.

[Gdeaver]

The .9 to 2.0 ms with a 0 output at 1.5 ms asymmetric response confuses me. Why did they do this? This is going to lead teams to terrible out of the box experience. If the Talon is hooked up to the controller and the present Victor motor drive routines are used, then a team will not get full power in 1 direction. This will require calibration. One more step for teams to screw up. Which will lead to rants and support issues. The pulse timing is listed as 10 bit or 1024 buckets. With calibration there will be less settings in one direction than the other. Does it matter? probably no. The question this year will be " Did you calibrate your Talon." Response - "I don't know." "You have to calibrate your Talon." "How do you do that?" and on and on. Cross the roads - It's time for a firmware up grade before you let this thing out in the wild. Your life will be better if you correct this now before the Chief Delphi Flamming starts. Why was this done? Is it a clock counter timer issue? Asymmetric I don't like it. I don't remember ever seeing a commercial speed control with asymmetric response.

[Mike Copioli]

Originally Posted by Ether

Sorry Tom I haven't seen that anywhere. I assume Mike will provide that info the next time he visits this thread.

I'm guessing that the 50Hz number (20ms period) was given because it corresponds to the 20ms TeleOp period? The Talon may be capable of processing pulses coming in faster than that. But there's the driver issue. As I understand it, if you send commands at 10ms (100Hz) to the Victor driver, for example, you still get a 17ms period coming out of the driver.

This was a typo in the User Manual. The actual refresh rate is 333Hz or (3 ms). The input capture is driven by an interrupt so as long as there is some space between the edges of the input pulse, the output will update correctly.
If your pulse spacing is 3 ms or greater you should have no problem.

[Mike Copioli]

Originally Posted by Gdeaver

The .9 to 2.0 ms with a 0 output at 1.5 ms asymmetric response confuses me. Why did they do this? This is going to lead teams to terrible out of the box experience. If the Talon is hooked up to the controller and the present Victor motor drive routines are used, then a team will not get full power in 1 direction. This will require calibration. One more step for teams to screw up. Which will lead to rants and support issues. The pulse timing is listed as 10 bit or 1024 buckets. With calibration there will be less settings in one direction than the other. Does it matter? probably no. The question this year will be " Did you calibrate your Talon." Response - "I don't know." "You have to calibrate your Talon." "How do you do that?" and on and on. Cross the roads - It's time for a firmware up grade before you let this thing out in the wild. Your life will be better if you correct this now before the Chief Delphi Flamming starts. Why was this done? Is it a clock counter timer issue? Asymmetric I don't like it. I don't remember ever seeing a commercial speed control with asymmetric response.

Ok,

Sit down, relax...I assure you the sky is not falling.

There were a couple typos in the user manual, the ACTUAL expected pulse width is 1.0-2.0 ms with the center = 1.5 ms. The user manual should have read .990-2.010ms. The reason for the 10 us gap is to over drive the pulse to ensure that any error in the input pulse does not cause the output to transition between full on and chopped. Let me make something perfectly clear; This is not necessary for the Talon to function smoothly or symmetrically, just a recommendation. On top of that the Talons firmware has 10 us(2%) of padding on each extreme of the input pulse.

Screwing up calibration is not really possible. The calibration values are checked against bounding values. If the cal values are outside of those boundaries the Talon will simply use the last "good" calibration values. The worst that could happen is truncation of the output.(full throttle is obtained at a lesser input value) But even then all you are really changing is granularity or resolution. Remember the Talon is 10 bit, the Victor uses 8 bit(which BTW is more than enough resolution)

Also to assume that you would only have two speed controller classes as before would be presumptuous. The Victor and Jaguar classes both use different timing parameters for full forward, full reverse and center. The Victor class uses 2.035ms = MAX, CEN = 1.526ms, MIN 1.032ms, this is also asymmetrical. If the Talon is deemed legal a Talon Class would most likely exist.

As far as calibration is concerned, if you are not already calibrating your PMW based motor controllers, you should be. Calibration not only corrects for pulse timing discrepancies, it also scales the out put MIN, MAX, and CEN to your joystick MIN, MAX and CEN.

So you can relax there is no need to upgrade your firmware, or flame the thread(although from my experience this will happen anyway). It was simply a mistake in the user manual.