blog; Motor Controller Options for 2015
 

Motor Controller Options for 2015
Blog Date:
Wednesday, August 20, 2014 - 08:50

Link to Blog

Please see the note below from FRC Kit of Parts Manager, Kate Pilotte, regarding motor controllers for 2015.

Hi all,

The Motor Controller landscape for the 2015 FRC season is going to be changing, and we’d like to share a few details in advance of Kickoff to give you a heads up. We normally only provide advance information on the upcoming season when necessary, but we think these details fall into that category.

Victor, Talon, and Jaguar Motor Controllers will be legal for the 2015 season and compatible with the new control system. A selection of these controllers will be available in the 2015 Kickoff Kits and/or through FIRST Choice.

The manufacturers of these motor controllers are, however, discontinuing them, and our understanding is the only ones available for purchase are those already in distribution.

Cross the Road Electronics and Innovation First International (IFI) have been working together on new motor controllers. They’ve published a joint press release about this collaboration and are sharing more information about the new products here.

We are sending new motor controllers to the Beta Teams for evaluation for legality in the 2015 season. While these two new controllers will not be in teams’ 2015 Kickoff Kits, we want to use the beta program to collect feedback on the new motor controllers that will enable us to decide if the new motor controllers will be listed as legal motor controllers for the 2015 FRC season. Based on initial testing results, we don’t believe there will be an issue with approving them for use in 2015, but teams should know the final decision has not yet been made.

The first controller is the Victor SP, a PWM motor controller. The second controller, the Talon SRX, is a CAN enabled motor controller with additional communication protocols and PID control. It is in development now, and will be shared with beta teams upon completion. Technical information for both devices is posted here.

Beta test tasks will be updated as needed to accommodate testing and evaluation of these devices. Meanwhile, questions about these devices can be posted to FIRST’s 2015 FRC Beta Test Forum, or emailed to CTRE or VEX.

Re: blog; Motor Controller Options for 2015
 

Here's a document with more info about the controllers. And WOW I like the size

And here's the VEX product page with some other specifics. And the product page for the Talon SRX

And one that sums up pretty much everything...

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Wow I really love how much smaller these are, hopefully everything works out and they're available this year.

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Stupid question. I don't see any screw terminals on the info sheet, how do leads connect to the motor controllers?

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One of the listed features is:

So the cables are embedded, similar to CIMs.

Not sure how I feel about this yet. On one hand, it will ensure that the cables don't come out of these controllers. On the other hand, it means we either have less reusability by permanently splicing the cables, or the same problem we currently have by using an intermediate connector.

I also have never had a big problem with cables getting jiggled loose from the existing controllers with a proper crimp.

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This is an interesting announcement. The old controllers are no longer made and the new controllers are not legal yet. Did I read that correctly?

David

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This might help visualize it.
This is the Victor SP the Beta teams received to test. The specs say the final will be black anodized, and the cooling fins are covered in this early version.

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The new controllers probably will be available, but it's not offical and will depend on results of beta testing (though it seems they most likely will end up being legal)

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Yeah, that struck me as weird, too. However, with FIRST opting to go into somewhat of a limbo, I think the fact that is not "approved" is only a formality at this point.

- Sunny G.

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I really love the embedded cables. It allows you to put the speed controllers in areas where you wouldn't have clearance for a screwdriver.

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Let's hope this doesn't result in a massive shortage of motor controllers in 2015.

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The controllers have integrated leads (e.g. 'pigtails') of 5.5 inches. This means you can put them near the PDB and then need to have an extra connection to get power to the motor or put them near the motor and have an extra connection to get to the PDB. Unless the motor is close enough to the PDB.

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I am curious to see what kind of connectors are on the CAN leads.

I hope it would be within the relaxed rules about repairing speed controllers to replace the cables if necessary. Many teams still have PWM cables getting eaten by drivetrains.

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I have lost count of the number of times I have helped teams debug their robots and found issues with how they had attached to their screw terminals, or had totally removed a screw and let debris fall in. The integrated pigtails are a great solution to this problem and will let teams find a connector that works for them while leaving all internal circuitry of the controller hermetically sealed.

Sure, some small percentage of speed controllers may have their leads compromised by being eaten by a mechanism (or being clipped by an overzealous freshman), but the cost reduction more than compensates for this.

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Removing the screws on most motor controllers creates debris within the motor controller as a consequence (i.e. it doesn't have to fall in, it is already there). If I recall correctly, both Jaguar and Victor (at least 884) use captive screw terminals. When the screws are removed, little bits of the removed screw are left behind. This was a bigger problem for Jaguar due to the lack of conformal coating (before VEX manufacture).

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I wonder if FRC would consider brushless motors & controllers in the future. Since the popularity of quadcopters exploded, there are tons of cheap options available

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If they run into a problem and these end up not being legal, I foresee a motor controller shortage next year. I'm glad we have about 20 talons, which should be enough for next year.

Also, not sure how I feel about the pigtails. Especially since they are only #12 gauge. I would have preferred to see #10 gauge, or a version with screw terminals for the teams that want to use them.

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The screw terminals would have dictated a larger packaging.

We were planning on leaving anderson pigtails on each end of EVERY speed controller going forward on 973, glad they made that decision for us essentially.

It's different, but I don't see it being a problem. If we had pigtails for 10+ years then switched to screw terminals people would be bothered in the other direction.

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I wouldn't be too worried. CIM motors come with even smaller #14 gauge wires, and teams have been fine with this. If you're very concerned with performance, you can trim the pigtails very short, and you'll end up with a very small voltage drop.

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We used andersons on the robot this year and were very happy with them. This change will be a good fit with our current wiring practice. Now the whole robot frame becomes the heat sink.

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It's a cool thought, but the contact resistance probably still ensures that natural convection dominates.

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I realize these things probably aren't supposed to be grounded to their frame, but in the event that they are, I personally would still screw them through a non-conductive piece of material like corrugated plastic or lexan.

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The documents linked state that they are electrically isolated.

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I'm fine with the removal of the screw terminals. Andersons end up on our motor ends anyway and for a lot of our speed controllers we'll probably go directly in to the PD panel with the leads for power.

I'm more worried about the PWM cables being attached. We've had far more PWM wires go bad over the years than 12AWG wire. It's going to be a little more annoying to troubleshoot since you can't just swap the PWM wires around at the speed controller. However I am glad that they all come with wires and I would hope they are nice high quality cable and connectors.

Overall these seem like huge improvements over where we were in the past. These will be much easier to mount in hidden places since you don't really need to access them and it will be easier to mount spares on the robot in case a speed controller drops out. 610 has done this in the past but since these take even less room and it's hard to change wires with them, I think more teams wills start following that practice.

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Fair enough.
Though I would still prefer using corrugated plastic. Not only because it is light, but you can punch mounting holes in it by simply shoving a screwdriver through it. To each his/her own of course.

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VersaFrame holes can easily be used to mount these. Holes are already drilled.

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My only question is what is the pinout for feedback pins on the SRX?

I only counted 10 pins on the feedback connector, but the Jag has 12 ( 5 - encoder, 3 Analog Input, 2x2 Limit Switches). I am sure a few pins are doubled up but I wonder which ones?

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You bring up a really good point about the PWM cables. It's surprising easy to damage one. We had a few issues with some PWM cables this year that took out one of our drivetrain motors. We had enough time to swap the cable during our 4 back to back matches, but if we had to take the controller out, it would have been much harder.

That said, our PWM cables were likely very low quality because after the incident, I was able to cause another PWM cable on our test board to fail by just bending it back a forth a few times.

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Great points Allen! Was thinking the same thing.

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I have to say... opening up the beta box and seeing these last week was pretty exciting! It's a nice, small, integrated component that hopefully is just as reliable and durable as the previous speed controllers we've had to work with. I'm definitely looking forward to trying these out once we put the beta hardware on last year's robot in a few weeks (the robot is unfortunately sequestered at the State Fair until then).

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Going to love using these. We used mostly Talon SRs on our competition bot this year because the Jaguars we were using were too big. These new ones make the Talon SRs look giant.

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Yeah, but of the 12 pins on the Jaguar, 4 of those were grounds. This was done to try to make each interface easy to wire. Using a unified connector accomplishes the same thing (and an interesting alternative).

Let's speculate.. that's fun. What I suspect is we'll find there is a certain amount of pin multiplexing (peripheral signals that share the same pins; the firmware connecting a single peripheral to a pin based on configured usage). Very common on MCUs.

Assuming that a connection can be established across either the CAN, USART, or SPI connection for control, that needs 6 of the 10 pins on the connector be distinct. Add 2 more for power and ground. That leaves 2 signals for a sensor.

End speculation.

However it ends up, it will be well thought out I'm sure.

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Well, this will certainly change the way we do wiring a little bit, but I'm sure we'll still come up with a way to make it look nice. I like that the mounting holes are in a line parallel with the case and a nice round 2.000" apart, rather than at opposite corners across a diagonal. I also like that we can pack a bajillion of these into a small area, and do not need to design our chassis around the width of a row of speed controls.

Also, I like that I don't have to practically write a whole grant just to put some speed controls on our robot.

Thank you VEX and CTRE!

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I like it. I hope these are the controllers for a nice string of years so we can stock up and reuse them for multiple years.

It will be a tough call when we decide what controllers to buy this year and how many. Cost of new stuff vs space savings.

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The only thing I'm slightly worried about on these is the heat dissipation: I'm not exactly the most knowledgeable on the subject, but looking at the size, I'm a bit worried whether or not there will be enough surface area on the controllers to adequately cool them down. In the documentation, it states that the fins will take care of passive cooling, but we've traditionally put fans on our speed controllers, even the Talons (we had a bunch of extra fans of that size, so we figured why not). Would like to talk to some teams early in the season after they've started working with them, see what their findings are. Active cooling for these might be a challenge, aside from putting a big computer fan over a network just for a little cooling, I don't see an extremely efficient way of doing it.

However, I'm still really excited, as these seem to be pretty well suited for FIRST in terms of price point, size (haven't used Jaguars in years specifically for that reason) and reliability during competition. Not working with screw terminals will be great as well, I always seem to lose those screws, and they're really hard to find once they roll away on the shop floor.

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I trust the parties involved when they say they are fine as is.

The talon worked fine without a fan and the thermal mass on it appeared to be much smaller for reference.

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The body is made of aluminum, and it is isolated from the electronics inside. If you're concerned about cooling, rub some thermal paste on it and bolt it to an aluminum plate.

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Or don't risk violating the rule against modifying electronics and add a fan instead.

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What rule did you have in mind, that prohibits mounting a motor controller using the provided mounting holes?

The thermal paste could be omitted, if that is the concern.

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Yes, that would be the concern.

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One of my concerns is that the PWM/CAN wires enters the enclosure within a mm or two of one of the input power wires in both the Talon SRX and the Victor SP. It will likely lead a lot of people to route the PWM/CAN wires adjacent to the input power wires for some distance. This arrangement makes it much more likely that the PWM/CAN wires pick up the noise from the switching action of the output transistors. It is likely that they have been able to use a smaller enclosure by using newer MOSFETs that have lower on-resistance (for lower conduction losses) and/or shorter rise and fall times (for lower switching losses). Shorter rise and fall times are likely to cause stronger inductive coupling of the switching noise into signal wires running in parallel with the power wires.

The integrated PWM wires will probably mean that more teams will have to purchase the pins and crimpers to replace/repair the connectors when they inevitably wear out or get damaged.

I am hoping that the power wires are truly a "high strand count" type (28 or 30 AWG strands instead of 25 AWG strands) with the soft silicone insulation. It would make it so much easier to do a neat job of running the power wires (VEXPro, are you listening?)

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The SRX interface drawing lists the CAN leads as being twisted pair, which should help some (though I'm not sure how much).

---

I hope there's an allowance in the rules for year-to-year reuse of motor controllers that have had connectors attached to them.

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What rule disallows thermal paste? Sticking chemicals on the outside of electronics is modification? Would the same rule disallow Velcro attachment, or labels being applied to speed controllers? Both of those use chemical compounds applied to the heat sink causing different operating conditions.
Your post reminds me of the bumper pool noodle tape issue from last year.

Some things don't need regulating IMHO.

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Or cut an PWM extension in half and solder a new connector on. All teams should have soldering supplies.

Integrated PWM wires are very very common on RC multi-rotors, planes, cars .etc that experience quite a lot of wear. Multi-rotors particularly depend on high speed control loops where noise would be noticeable.

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This. Given the price point, size, and the availability of other options, these things will be in truely massive demand once the season starts. I wouldn't be suprised if they sold 10,000 in the first month they're on sale. I also wouldn't be surprised if they sold out within the first day. So, basically, there will be massive problems if there aren't enough of these controllers to go around.

I trust Vex and CTRE to learn from their mistakes and do this launch right, but then again, I've been wrong before about trusting companies to have enough stock in time for the season. I hope we won't see any problems with inventpy come January (or even better, come November).

On the other hand, these things look amazing. I'm so jealous of the students that will get to use these things. I remember that it seemed that motor controllers just got 2x better when the origional Talon came out, and somehow they've don't it again. This is a huge leap forward in FRC motor controller technology.

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Personally, I doubt any inspector would even notice thermal paste between a speed controller and an aluminum mount - you would have to take the controller off to see it! And as an LRI, it's something I've never actually considered before. R64 from 2014 does state that they "shall not be tampered with, modified, or adjusted in any way"... so the question comes down to whether thermal paste would be considered a modification or adjustment to the speed controller. I think most people would say no, but someone wanting to be strict may draw a parallel between R64 and R76, which states "All pneumatic COMPONENTS must be used in their original, unaltered condition", and has a blue box that specifically mentions items like painting...

You could, if you wanted, draw a parallel between R64 and R76 as both say you can't modify a part, and then a parallel between paint and thermal paste, as they are both topical coatings for a part. It's a bit of a stretch (and not anything I personally would call at an event unless otherwise instructed by the GDC), but it seems like a good question for the Q&A to me.

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"Onboard closed-loop PID control" for the Talon SRX? What exactly does this mean? Can you tell it to move to a certain position like a servo, or something like that?

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I personally think the integrated pigtails are great. No more soldering crimp connectors (even though you shouldn't need to, better safe than sorry) to 2 sets of wires. I don't foresee reuse to be an issue if you invest in anderson powerpoles or similar connectors. We look forward to being able to beta test these awesome devices

and I'm liking the more standard measurements of the new victor

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That's exactly the dilemma: FIRST presumably doesn't want you to douse it in toluene (because you might dissolve something important), but they probably don't care if you write on it using a marker. And yet both chemicals' effects are governed only by the rather unspecific rule against modifications.

The typical compromise is to adopt an ad hoc interpretation of the term modification that is as loose as the circumstances will allow, in order to approximate a just outcome. It's a mess and an inefficient use of everyone's time to have to design with this nebulous constraint in mind.

A clear rule predicated on the functional effects of the modification would be more equitable, but it would also be harder to enforce with consistency and rigour, because of differences in officials' ability to identify and evaluate failure modes. A narrower rule that permits more freedom in design choices, but which also exposes some additional failure modes would also be more equitable, but less safe.

In this case, I vote for the latter: the catch-all safety rule is so strong that the additional safety afforded by the no modifications rule is sometimes negligible. Where that's the case, allow modifications, and focus attention on the teams that do something unsafe, rather than dividing attention among the teams that make mundane modifications safely.

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PID stands for proportional-integral-derivative. This three dollar phrase means that for a speed control loop you can tell the speed controller to go to 2500 RPM and expect it to command the motor to go to 2500 RPM quickly, smoothly and precisely (assuming you have a rotary encoder to measure the speed at the shaft). I may not have the details quite right in this case but that's the general idea of PID for speed control.

For more on PID enter PID Controller in Wikipedia.

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I know what PID is, but I'm wondering what specifically an onboard PID on the motor controller entails and how you could use it. My last post was pretty unclear, sorry.
For example, could you just send an error, output range, and gains to the motor controller and would it calculate the PID itself?

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Oops sorry if I sounded condescending. It would be kinda cool if it could automagically compute the PID coefficients but I suspect life wouldn't be that easy.

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Could someone post some examples of the Anderson powerpoles they have used with success in the past?

The only types that I have used (excluding the battery connectors) have been very shoddy; wires falling out, plastic crumbling, etc. Admittedly, this was years ago so I am hoping that newer versions are much better.

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Has anyone been able to find any details about the algorithm used for the built-in PID in the Talon SRX? Is it strict PID, or does it have, for example, user-selectable feedforward etc.

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We use these as well as the 15A/45A versions when appropriate. The trick to them is that you really need the correct crimper, we've used that one for the past three years, and I can't recall anything really going wrong. We've found that generally the contact gets pulled out of the housing before the crimp fails.

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It means you can plug a sensor like an encoder or potentiometer into the speed controller, then, with CAN, you tell the speed controller you want to enable PID control and what your PID gains are, and it will do the PID control logic on the speed controller itself.

The advantage is that you don't have to waste cRIO processing power on PID loops and you can run them much faster. The disadvantage used to be that the only controller you could use for it, the Jaguar, was big, expensive, and not as reliable as the Victor.

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And the CAN bus was a ticking time bomb on your robot. If one device dropped out the whole bus was screwed due to CAN Timeout exceptions.

Sincerely hope that's been fixed.

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The original blog says they will be in hands of the Beta testers soon. Hopefully they will post their experiences.

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I would love to see a velocity PID loop with:

Selectable Frequency (though a fixed rate would be fine if it is fast enough)
User tunable P, I, D gains
User tunable Feedforward gain
User tunable Forward/reverse stiction compensation
User tunable Maximum output cap
User tunable Maximum integrator output
VERY IMPORTANT: Slave mode so that a single sensor can be used to control a multi-motor, multi-Talon mechanism (like the drivetrain). It was never really clear how to do this with Jaguars.

I do not think I would ever run a position control loop on the speed controller, but I can envision making heavy use of velocity control.

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The entire CAN subsystem has been re-written for the RoboRio... We've been doing some testing with a CAN robot (6 Jags, PDP and PCM), but we haven't yet tried to drop a jag to see what happens. I'll see if we can give that a try on Saturday.

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According to CRE in St Louis, that is something they were/are working on. Granted, I don't work for them and we have minimal contact with them but this is one of the things we would like to see as well.

900 makes great use of CAN. We've been using it rather successfully (we think) for the last 4 years (ok, 3 but running Java in between was our own fault and we won't be doing that again). LabView was a lot easier to work with for CAN than Java was.

If we have the opportunity to beta test any of this then we most definitely will. We're eager to get started with our testing this Saturday (We're a residential high school and this week has been the first week back for the students).

Also, we've used both position and velocity control. Position is a lot more temperamental about having the correct values so tuning PID is more important, at least from our experience with it.

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http://2014.discobots.org/node/94

http://lh5.ggpht.com/-4l8yI7w_YQg/Uw...0/P2126448.JPG

The Talon motor controllers all had Anderson connectors on their outputs. This allowed the electronics panel to be built up outside of the robot then "dropped in" and connected to the eight drive motors and the collector motor. There was also a set of Anderson connectors at the end of the collector arm so that the collector motor could be swapped out without having to pull the wiring out of the collector arm. Anderson connectors were also used at bot ends of the wiring for the Spike relay controlling the compressor so that the compressor could be swapped out. They gave absolutely no trouble throughout the severe punishment of two regionals plus 3 off-season events. The polycarb panel only had to be removed for the Inspectors.

Absolutely! Doing a pull test on all crimps immediately after making the crimp will decrease the failure rate dramatically. That is what the assembly people at work are taught to do.

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You must have been using something else, or counterfeit ones.

We've used Anderson's forever, and they are awesome. The housings are very durable.

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We've had issues with the Anderson connectors, both with the casings melting and with the terminals falling out of the casings. We use the correct crimping tool and the solder them, any idea what we might be doing wrong?

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We use them at work in some of our industrial UPS' and have never seen them break down like that either.

It is likely that you may be getting too much heating from the contact resistance and/or sustained high currents. If the terminals are bent, the contact resistance may be high. I have also seen terminals where the silver coating was worn off, possibly leading to higher contact resistance.

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Perhaps an EE could help me out, but why go to 15kHz for the switching frequency? Is the 1kHz used on the Victor 888 not smooth enough?

From my small knowledge of EMI, the effective interference from the motors is proportional to switching frequency and current, both of which are very high in this application. Putting so much circuitry right next to the controller (like the CAN bus) makes me a little nervous.

The motors also generate really strong fields and though they drop off quickly, they still have an effect on our control system. Now that our main controller is no longer in a big heavy metal grounded enclosure, I'm slightly concerned about this.

That said, I am not an EE, but I dislike anything that increases electrical interference on the robots.

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I had the pleasure of sitting beside an APP employee (Rich, if I recall correctly-I'm bad with names) at one of the Supplier Summit dinners. He was the guy who created the battery wires+SB50 for the KoP. I mentioned my team that year was crimping and soldering the connections. He discouraged soldering, indicating the potential to damage the terminal if soldered poorly. Since then I've just taken him at his word and my team just crimps with one of their tools. We've never had an issue with the housings deforming, either the ones we've crimped ourselves, the ones we've bought from AM (crimped), or the ones we receive in the KoP (crimped).

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First off, I'm delurking after several months of down-time/new baby/work specifically to note that I drooled a little when I saw the tech-specs of these new controllers. We've always been attached to CAN, so we never went with the Talon SRs, and suffered mightily on mounting space for it. I'm really looking forward to packing 4-ish Talon SRXs into the footprint of a single Jaguar in 2015, and I will be sorely disappointed if I'm not allowed to do so. Also, I'm dearly hoping that CTRE will make the source for the controllers a little more open than it was for the Jags. The only thing available for the Jags was the very original non-FRC source, which made it troublesome to figure out what they were doing, why speed feedback wasn't reliable/available, etc.

If we're using this thread to put in feature requests, my request for the Talon SRX is for sensor feedback output regardless of what control mode you're in. One of the problems on the Jag was that you could only get certain feedback if you were in that particular mode. So speed feedback was only available in speed PID control. So no using the Jag as a sensor input for your nicer C++ PID code.

Magnets,
I think the number of teams using Jags/Talon SRs with no EMI problems is testament to the notion that PWM frequency isn't a huge EMI source on the bots. Since the new controllers will use the same sign-magnitude/synchronous rectification control as the Jag/Talon SR, it shouldn't be a problem. Sign-magnitude control toggles between the high/low FETs on the switched leg to switch between driving/recirculating the current. This makes for smaller current ripples and less EMI. You're probably going to get more noise from the brush commutation than the PWM switching, especially on high-speed 550-can motors.

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Jags and Talons have always been 15KHz output.

The higher switching frequency reduces ripple current in the motor and motor wires. Ripple current contributes to motor heating and electrical noise.

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I also am not an EE, but have a lot of experience with this sort of stuff. In short, you're right, the higher frequency is proportional to higher interference. That said, I checked the spec sheets, and the old Talons are operating at 15kHz, and people have been fine.

I don't understand the reason to go up to 15kHz for the controllers. Switching up to 100 amps at 15kHz is not something to be taken lightly, as the high current and frequency causes parasitic capacitance to ground. This results in an effect called common mode coupling, which ends up "contaminating" your ground plane. Anything else that uses this ground can be affected by it.

Switching to a higher frequency also makes the system less efficient. Although the more efficient sign-magnitude switching could make up for this loss, you'd see higher efficiency if it switched at 10kHz than 15kHz. The reason is that the faster you switch the FETs, the more time they'll end up spending in their switching state. The transition is not instantaneous, and as you increase frequency, they'll spend more time in between, which is inefficient.

Also, I can't really think of a great reason for them to go this high. The 1kHz frequency was audible, and so will the 15kHz frequency (close to the frequency your CRT television's transformer makes). The talon is 15kHz and the Victor 888 is 1kHz. You really can't tell the difference between the two frequencies, other than the noise they make.

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While I agree that in theory faster switching will decrease efficiency, I'm not sure that it'll be that large of an effect in practice.

At 15 kHz, a MOSFET would switch on and off twice every 1/(15 kHz), which is a switch about every 30,000 ns at 50% duty cycle. The MOSFETs I've seen on the market nowadays all switch faster than 10 ns, and some even faster than 5 ns IIRC. That's about .03% of each state at 50% duty cycle. Of course, as switch your FETs at closer to 0% or 100% duty cycle, the effect you're describing will be more important, but I don't think it'll significantly decrease the efficiency of the controller.

EDIT: For what it's worth, I'm not an EE either. But that could change in the future.

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I do not remember this ever being an issue with the old IFI controllers and they were a similar form factor.

Re: blog; Motor Controller Options for 2015
 

My biggest concern regarding the integrated leads is that installing connectors on the ends of the wires constitutes a modification away from COTS state. This means that use of a particular motor controller on a competition bot will (under current rules) only be legal during the year in which the connectors were attached. Currently, we utilize previously purchased Talons as spares. In a pinch, we have even raided previous year's robots for motor controllers (not at an event). With these new ones, unless the rules change, they have a built in expiration date. If you've already attached connectors, you can't use them on a competition bot after the next kickoff day. And cutting off the connectors and putting on new ones isn't legal because just cutting off the connectors doesn't return the wires to their original length. I think now is a good time to revisit the rules regarding reuse of parts. It was bad enough that we couldn't reuse CIMS, but CIMS are fairly cheap, and don't require swapping out very often. Not being able to reuse motor controllers is going to hurt our pocketbook.

Re: blog; Motor Controller Options for 2015
 

I'm really torn about this. I'm thrilled with the new form factors and functionality in both of the new controllers. Both VexPro and CTRE build high quality, reasonably priced components that have brought competition to another level. But after being burned by the Talon shortage in 2013 and hearing about the Versachassis shortages in 2014, I have honest concerns with either company's ability to meet the demands of introducing a new product line. I don't have many choices - we can stock up on Talons now and miss an opportunity, try to stock up on new controllers (whenever they're available, it appears I can't even pre-order them yet) and gamble on them being legal, or just hang out and hope for the best.
Anyone at either company want to try to give me a warm fuzzy feeling about being able to buy speed controllers week 1? I'm not a business person but I get the difficulty in estimating demand and controlling supply of specific items. Convince me you've figured it out.

Re: blog; Motor Controller Options for 2015
 

Was this ruled on officially by FIRST that teams could not reuse CIMs after crimping on a connector? I don't know that I've ever seen that in the Q&A. I'm not going to throw any teams under the bus but lets face it, teams re-use CIMs.

You are definitely right about this given a pure legal reading of the rules though. I'd just like to know if FIRST has ruled on it.

Re: blog; Motor Controller Options for 2015
 

I can't imagine that FIRST would rule in a way like this. It would be counter to the way teams have operated for years.

Re: blog; Motor Controller Options for 2015
 

Todd,
What rule would not allow CIM reuse?

David

Re: blog; Motor Controller Options for 2015
 

The rule Todd is referring to is (from 2014):
This is clarified in a blue box,
along with the definition found in the glossary:
So, from a strict reading of the rule, crimping or soldering connectors to the ends of leads or even cutting the leads is an alteration, and makes an item (a CIM motor, one of these new controllers, etc) illegal in future years.

Now, I ask all of you two questions. First, do you think it's the intent of the rules to make a CIM motor illegal because you spent 30 seconds adding a pair of 50 cent connectors on it? Second, do you think your inspector, LRI, or any team at your event is going to know or care?

When I read the rule, two possible intents come to mind (note that I'm not the GDC, so I could be wrong about either/both of these):

The first is fair play - we don't want veteran teams having an advantage over rookie teams by being able to pull out a robot from 7 years ago that can already play the game, and instead of spending 6 weeks build one get to spend it improving and driving one. Veterans already have enough of an advantage through their experience with FIRST and through having people (mentors, upper classmen or graduates) with first hand experience in games similar to those we're playing now (for example, the similarities between Arial Assist and Over Drive).

The second is educational - we want the students on the team this year to have the experience of designing and building a robot, not just using what someone else built before them. I've heard before (on here? In LRI training? Not sure) that reusing an assembled gear box (which ships from the supplier unassembled) is illegal... but taking that gear box, breaking it down and then reassembling it during the build season makes it legal because you returned it to the form it arrived in. That strongly implies that the educational experience of assembling a gearbox and seeing how it works is important with this rule.

As an LRI, even if I was 100% certain that a team reused a CIM motor or speed controller and the connectors they had on it from the previous year, I wouldn't say anything or hassle them in any way. On the other hand, if a team comes in with a shooter on it I recognize, and I can verify that it came from a previous robot, they'll be in trouble. When we went with the new sizing rules, there were several teams that had to be lectured, as their re-use was obvious - they used the previous years frame and (assuming) drive train without modification. In that case, the modifications made to make it fit within the sizing parameters was enough of a penalty and lesson for the teams in question, and we could let them play once they got it fixed (which took the entire practice day, and afterwards their mechanisms had issues due to the changes).

Re: blog; Motor Controller Options for 2015
 

R13 ROBOT elements created before Kickoff are not permitted. If you crimp on a connector you've created an element. A specific exception in R13 allowed using battery assemblies from prior years, so if there was a concern with something as simple as charging a battery being a modification it seems that crimping a connector would have the same concern.

Re: blog; Motor Controller Options for 2015
 

CIMS with crimps fall under the rule that makes any COTS part plus an added connector a non-COTS fabricated "assembly". Battery assemblies got an explicit exception a few years ago, so there is precedent for removing some restrictions on reuse.

Re: blog; Motor Controller Options for 2015
 

Interesting. I never thought of it this way. Definitely one for the Q&A.

By that logic, I could reuse a CIM (and the new Talons) if I used wirenuts and avoided a crimped connector.

David

Re: blog; Motor Controller Options for 2015
 

By the letter of the rule connectors on a motor make it not longer COTS/Reusable, but by the intent of the rule, this entire conversation is beating a dead horse with a level that is unfortunately consistent with all things on ChiefDelphi lately.

I personally commend VEXpro and CTRE on their joint effort to produce this product, and am excited at the form factor and apparent quality, it should have a very positive impact on our wiring layout.

Perhaps they can just have connectors mounted to the motor controllers from the factory or push for a reasonable rule change (about motor leads and connectors on all motors and control hardware).

Re: blog; Motor Controller Options for 2015
 

I agree it's not the intent of the rule but if some teams are following it to that level. There should be official clarification that they shouldn't be. They are at a disadvantage by holding themselves to a standard that I don't believe FIRST expects for them.

Re: blog; Motor Controller Options for 2015
 

Agreed. They really need to publish a list that tells you what rules you don't need to follow.

For newer teams, it gets confusing.

Re: blog; Motor Controller Options for 2015
 

It's not a question about "what rules you don't need to follow"... it's about reading the rules for both the letter and intent of the law and using common sense in interpreting them.

Re: blog; Motor Controller Options for 2015
 

The issue is my view of intent is very different than your view of intent. But you can issue a red card retroactively if you find I viewed intent differently.

Rules should require intent to follow.

Re: blog; Motor Controller Options for 2015
 

Exactly, my interpretation of the intent can differ than yours. Just like the issue with the withholding allowance and robots in the parking lot this past season.

Re: blog; Motor Controller Options for 2015
 

Using common sense as a guiding principle, would it be permissible to apply a thin film of non-curing thermal grease to the mounting surface of the new Victor SP (or Talon SRX) before bolting it to the robot?

Re: blog; Motor Controller Options for 2015
 

It was asked in Q&A for 2014. Q454 and Q445.

Highlights:
"Installation of connectors would make the resulting assembly a FABRICATED ITEM."

"Some additional work must have been done to the part (e.g. trimming leads, adding connectors) after the 2014 Kickoff for the part to be legal per R13."

It was asked in the context of the rule that 45 lbs fabricated components (including spares) must be brought into first day of competition and inspected and that additional non-COTS items could not be stored outside the pits and used on the robot, hence the reference to the 45 lbs limit. The implication was that spare motors must be brand new in box motors with no connectors and they would be exempt from the limit.

Hopefully they straighten this out this year. Or we're going to need more motors.

Re: blog; Motor Controller Options for 2015
 

I've seen statements like this in several places, but it appears to me that they are essentially the same price as existing speed controller options. What am I missing that everyone else has noticed?

Re: blog; Motor Controller Options for 2015
 

I've already posted my opinion on that.

Re: blog; Motor Controller Options for 2015
 

Regardless of what somebody tells you is okay on the internet, any common sense interpretation of a rule is not guaranteed to be enforced equally between events.

Common sense to an engineer who designs speed controller would dictate that thermal compound is just fine.

Common sense to an inexperienced robot inspector who has no background in this matter might say that this is illegal.

Unfortunately, I do not know the intent of the rule. I'd like to think that FIRST encourages teams to reuse parts from previous years, but in the past FIRST has required use to be wasteful with certain aspects of robot development.

Also, that's not a good enough answer for a team paying $5,000 to compete. An official who is in a bad mood can say "nope, you're wrong" and because they are the highest authority, there is nothing that you can do about it. It also makes things unfair, as different events will have different rules, as not everybody interprets things the same way, especially confusing. For example, nobody can describe the difference between defensive and offensive possession in words, so there will always be disagreements based on interpretation.

Putting in the clarifying sentence (not in a blue box, those things are evil) "Trimming or stripping wires on speed controllers or motors is not considered a modification for the purposes of G-(??)" takes under a minute to write, and helps everybody.

Re: blog; Motor Controller Options for 2015
 

Exactly. Your common sense says thermal paste is OK. cgmv123's common sense says it's not OK.

Re: blog; Motor Controller Options for 2015
 

This should be expanded to pneumatics such as solenoid wires and compressors as well.

In general I think the reuse clause of the rules needs to be rewritten. I have had teams claim to me that if they cut off a section of 4'x8' polycarb in one season they couldn't use any of the rest of that sheet in another season. In my mind that is clearly not the case. The rest of the sheet is not in it's final configuration to go on the robot and is completely legal raw stock material to be cut and used on their robot. However the rule is still confusing teams and we should strive to have as clear rules as possible.

Re: blog; Motor Controller Options for 2015
 

Point of reference. I am with Jon. When inspecting I would not consider terminals or leads on a motor/controller to change it from COTs to Fabricated. (Unless the LRI said different, I am a worker bee inspector.) But this in 2014 in came up in terms of the weight allowance for fabricated parts as a grey area. Generally If you look at the definition of "fabricated" in the rules & Q&A, it tends to be strictly defined. For instance using magic on a COTS item makes it Fabricated. I have seen several instances of letter of the rule verses intent of the rule cause headaches. It would be nice to have a blue box exception or similar.

Re: blog; Motor Controller Options for 2015
 

Common sense tells me that applying passive grease to a part is not a modification, but I can respect the opinion of others whose common sense tells them otherwise. However, I can also get all laywer-y and decide to apply the thermal grease instead to the spot on the robot where I'm going to mount the speed controller, and I don't see anything in recent rules that would make doing it a problem.

Actually, I'd probably avoid the messiness of grease and use a flexible thermally conductive pad.

Re: blog; Motor Controller Options for 2015
 

I'm leaning toward Wago Lever Nuts, myself. They're definitely easier to install than a set of PowerPole connectors. The continuous current rating isn't as high as I'd like, but intermittent operation on a 40A circuit ought to be okay.

Re: blog; Motor Controller Options for 2015
 

I've been interpreting these statements as "It's really nice we won't have to buy ~$1000 of new speed controllers because our old ones are still legal." I don't have any background with a situation where teams had to replace all their speed controllers in one year, but then I've only been in FRC since 2011, so maybe someone who has been around longer can shed a historical light on this.

Re: blog; Motor Controller Options for 2015
 

If I recall correctly, speed controllers used to be more expensive, but when the Talon came out there was a special introductory price that triggered big discounts on all of the speed controllers that pretty much never went away.