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.
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.
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?
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.
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.
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.
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.
Calibration of motor controllers is a pretty standard practice in RC (especially in the quad rotor world). If the controllers aren’t calibrated, the motors will not be in sync (i.e. receive the same power input) – which could be an issue for motors that are mechanically linked. In quadrotors, the motors are linked via software PID for stability purposes, meaning uncalibrated motor controllers will cause a quadrotor to crash almost immediately.
Greetings, a new season has begun! and we seem to have a new speed controller that looks like a Vic!
A quick look at the Jag schematic says that when the robot is pushed, the generated current will try to flow in such a way to charge the battery. But if the battery is not connected the voltage to the PDB will keep rizing… Is there something in the PDB that will shunt this current - or something will blow!
The type of locked antiphase PWM modulation that is used in the Talon is simply the method that used to turn on the FETs that provide motor currents. The FETs in the Talon, Victor and Jaguar all have diodes that provide a path back to the power supply while the motors are coasting or being pushed. This diode is a result of manufacture as I understand.
Rickie and Jon, not to mislead, the conformal coatings on the Victors protect the circuit board components, but the leads of the FETs are still sometimes exposed. Metal swarf still can kill a Victor but they are far more immune to this than the current TI/Luminary production Jaguars. I am going to guess (highly recommend) that the IFI production runs will contain the same conformal coatings as current Victor products. The really difficult component in the Jag to coat is the current sense resistor since this can dissipate large amounts of power/heat. However, if metal falls across it, there isn’t likely to be any catastrophic failure since the value is so small.