pic: MVRE-109, high-recision shafted encoder



Presenting the MVRE-109, a compact, shafted encoder with high-precision incremental and absolute outputs. I went through several revisions of this model, including one that used a mini-HDMI cable for data transmission. Overall I’m very happy with it, and I think I’ll sell a few of these to FRC teams. I’m looking at $21 shipped, which includes 2 6-pin cables so you can interface the absolute and incremental portions at the same time. Link to Ebay listing here: http://www.ebay.com/itm/-/122123469731?

Picture shows the MVRE-109 between an US Digital S4 and a US Digital MA3.

Features:
-14-bit (16384-position) absolute position via SPI
-1000CPR (4000PPR) incremental with index
-28,000 rpm max
-3/8"-32 mounting thread (same as Grayhills, potentiometers, and US Digital Encoders)
-Same volume as an MA3 encoder (shorter, but larger diameter)
-Magnetic encoder for robustness
-Uses 6-pin JST SR-series cables
-1/4" shaft by default, but can be made to suit any size from 0.157"/4mm to 1/2"+

If you’re attending CC or CCC I can give these to you in person.

Now this is cool! What kind of testing have you done on these to ensure robustness in FRC-type applications?

Thank you! I’ve worked with both custom shafted encoders pretty much identical to this one and the AS5047P chips fairly extensively at this point. I’ve found that the former is very robust as long as your prints have sufficient wall thickness (which they do) and that the threads are undersized. Although I haven’t made this particular model yet, I think I’ve developed a sufficiently strong formula for design that should make this far stronger than your typical Us Digital encoder, from my experience. I would run an order before selling normally, but I wanted to get them to teams at CC in a couple weeks, and I don’t have time for 2 runs in that time.

The shaft assembly feels stronger than that of the S4s and MA3s, although I haven’t purposefully tried to physically break one yet. If anybody is interested, I could make a video showing me destroying one of those. :stuck_out_tongue:

Because the AS5047 is a contactless magnetic encoder like the Talon SRX encoder, it’s incredibly robust. You may remember this baby: https://www.chiefdelphi.com/media/photos/43840
A few of them have been used in a mimicry robotic arm with great success. I’ll see if I can post a pic here later, but essentially it’s a sketchily made wooden arm that uses potentiometers as shafts, with the sensor magnet glued onto the tip. Despite being handled by kids who apparently have no idea how wiring works (I’ve been working with them on this for a year and they still don’t know how to keep 5V and GND where they’re supposed to be) and dropped and mangled numerous times, the encoders have lived on.
With this newest encoder, I’m hoping that this batch will face much heavier testing from teams.

The absolute positioning appears to flucuate around +/-5 counts (0.03%), although that may be just from the vibration of the hands.

I’m a bit confused, are you custom making these or did you just find your own connection to a supplier? If you are just making them I’m not sure how these would be legal to use in FRC.

Looks really interesting. I might want to get a few to play around with. Would you be willing to ship these to Canada? I’m sure there are a number of teams up hear that could find a use for these.

I’ve already PMed about this. As long as he can meet all the requirements for a VENDOR according to the FRC rules (may change, but haven’t in a while) then he is able to sell them and they would be FRC legal. Weather or not the VENDOR definition should be updated is another discussion.

I am making my own, although I wouldn’t be opposed to getting an FRC vendor to make them. I also received a PM about this, so I’ll go into detail about how I’m fine for this.
Relevant image:

A: should be covered under Ebay. I know many teams buy from Ebay and AliExpress each year, and a mentor for 115 sold breakouts through Ebay a couple years back as well.
B: I’m independent of 115 now, as I graduated last year.
C: Given the low quantity of orders I get, I’ll have a stockpile of these proportional to the number of teams that want them before January. “Higher-than-normal” order rates are basically more than 10 for me.
D: I can maintain stock (10+) very easily. I’ll also have access to a PCB CNC soon, so even if I run behind it should be easy to get parts to teams in under a week. Right now, it takes around 10 days to get the PCBs because I’m ordering from OSHPark.
E. I’m posting it here, aren’t I? :stuck_out_tongue:

Sure. I’ll need to see if the magnet can be shipped across international lines, and if they can I’d be more than happy to get you a few.

I forgot to mention that I’ll have the design files up eventually too.

I think it is a massive stretch to argue that the federal tax ID number for Ebay.com somehow qualifies you as a vendor. Literally anyone can setup an Ebay account.

You’re essentially redefining these rules to do what you want, when you at this point clearly don’t meet the intent of them. Saying 10 parts in stock is a “normal” amount?

This looks like great work and all that, but I don’t think you can consider yourself an FRC legal vendor because you have an Ebay account and made a dozen of something. This seems like the exact situation the rule was written for.

I would also wonder about any certifications or testing that would need to be done due to it being an electrical device. I know when we were working on custom slip rings, we thought one part of being able to sell them as a vendor, we were worried we had to have them tested and rated, UL, etc.

If FIRST is willing to count an account on ebay then count be as surprised. I never got the impression that counted.

I will say I do not understand why FIRST feels it necessary to include section B. Not sure how that helps either party, the supplier or consumer both.

If it does, the policy is sort of meaningless, methinks.

Honestly, if you’re only going to have a stock of 10 or so, I have a hard time buying that as meeting the requirements of the policy, at least in any way that’s consistent with the policy’s intent. If an off-the-shelf resource is available to one team, it ought to be available to every team - a stock that limited really isn’t, in practice, available to every team.

Else, what’s preventing any team that wants to pre-machine parts from spinning off a handful of spares, opening an ebay account, and calling it a COTS product?

The intent of the rule is to ensure that any team that wants to buy something can do so, and from a legitimate vendor. Ebay works through Paypal, offers a return service, and has various guarantees and restrictions on what people can sell. Many businesses, especially eastern Asian ones, sell almost exclusively on Ebay, Ali Express, and Alibaba. As a legitimate question (because I’m in the dark about this), what wouldn’t qualify Ebay?
I know that teams buy and sell on Ebay and Aliexpress often, so if it is illegal as you say a lot of teams have unintentionally broken rules in the past. In particular, MVRT actually sold around 150 breakout boards for the Talon SRX back in 2015 through a mentor. 115 also used those for 2015 and 2016, and will probably continue using them for 2017 and onwards. Oddly enough, nobody brought up anything about Ebay not being a legitimate seller window back then, maybe because it was a team selling them rather than just an alumni.

I wish that keeping 10 in stock was very low, although I’m flattered that you think that I sell more than just a few of anything. :smiley: In all seriousness, I think you’re way overestimating how many people are interested in custom electronics. Even my cheapo PWM generator only sold about six (6) units, and that was my most useful device.
The bottom line is that very, very few teams have a marked interest in custom encoders, even (especially?) ones as cheap as this. Although it’s true that I’m selling next to nothing, nothing is stopping you from buying one right now and letting me expand my stock for the season. My goal is to sell enough to start giving these away for free at competitions, and for every ~4 of these I can sell that’s 1 more freebie that I can give away. If you don’t think that I sell enough right now, please buy one so I can expand my stock to something that you think is normal. Don’t just complain about the problem, do something about it. :wink:

I loved your slip ring project, it was very well executed.
As far as testing and electrical stuff goes, this is nowhere near the power of a custom slip ring. I know that teams use custom breakouts all the time; in terms of power or usage, this isn’t much different. It just has a fancy plastic case and a couple bearings. It poses as much risk as a bad crimp to your robot.
I’m not too clear on B either. Perhaps it’s to prevent fake “teams” registered by vendors from selling en masse at competitions?

As a side note, I do want to open up a storefront for these kinds of things at some point. I’m thinking of selling MVRE-109s, hex bore encoders, and cheap PWM generators among a few other things. Does anybody know of a good platform that I could use to set up a website and process payments through Paypal with?

See above. If I sell 10 of these, I’m breaking a record for “profit made” and I might even be able to recoup my development investment. :expressionless: Right now, they are definitely available to every team that wants them, and that number is very low. I believe I have 6 or 8 people right now that have expressed an interest in purchasing a couple.

I’m not trying to impugn your motives here - I’m sure your intentions are good. But, you haven’t addressed my point - if your setup satisfied the rule, what’s stopping any team that wants to use parts they’ve developed outside of build season from making a few spares and starting an ebay account and calling it a COTS product?

I think we just found out why the “B” clause is there. :stuck_out_tongue: The operations of the team and vendor should be separate.

Assuming you get around that, nothing, as long as they make it available to all teams and can get a turnaround of less than a week. For example if a team wanted to sell pneumatic wheels this year like WCPs, I’m sure a solid CNC could pull off making quite a few of those, especially early in the build season. I see your point though; the rule is clearly meant to prevent a team from just making a few and selling them. My argument is that I am meeting and exceeding the low demand for these products.

I’m curious as to what parts teams would sell this way. I’ve discussed selling custom wheels with someone before, but past that I can’t imagine what a team would sell that would actually given them a considerable edge without having such a high demand that nobody would buy them.

I suppose it does come down to that clause - so long as you’re making these without any resources from your former team, that’s less-worrisome, though I still feel it might be a bit too close to something that could be used as an easy end-run around the fabricated parts restrictions.

I don’t think what’s going on here is by any means a stretch. EBay has a tax id, and asid61 is no longer affiliated with his team. He’s fine.

That being said, let’s consider a scenario that I don’t think anyone would be opposed to. When 775pros were out of stock, I saw lots of teams selling them to each other. Would you consider this in violation of section A or B? I wouldn’t.

All asid61 is doing is taking a custom (so technically fabricated) part, and selling it with a bunch of COTS parts attached. Worst case, it’s a fabricated item, rather than a COTS item, per

A VENDER is a legitimate business source for COTS items that satisfies all of the following criteria.

(emphasis mine)

Just my 2¢.

The fact that ebay has or does not have a Federal Tax ID number is irrelevant to this discussion. Ebay is nothing more than a market place or transaction facilitator if you will. The do not own nor sell the products that are sold through them. The same thing goes for the Amazon market place, they facilitate transactions for sellers of products that they don’t own. That is why each listing will state “sold and shipped by Amazon” for inventory they own and “sold and shipped by xxx” for products that they do not own.

That by no means indicates that you can not buy products from ebay or Amazon just that their respective Tax ID numbers are not transitive and thus do not mean that the seller qualifies as a Vendor under FRC rules.

On the other hand legitimate businesses that are organized as sole proprietorships are nor required to have a Federal Tax ID number that business will report its income under the sole proprietor’s SSN. However having a SSN does not mean that a person would meet the definition of a Vendor under past FRC rules, they would need what ever licenses businesses are required in their locality to actually be a business.

-snip- I can’t read. Please disregard

Thank you for the information, that all makes sense.
I tried to fill out the form for running a small business out of my garage for Cupertino. It doesn’t look like there are any particular fees to pay (yet), so I might as well just register for a license and get some form of business ID.
In any case, anybody who would have bought one has already been scared off by the possibility of not being able to use it during competition, so it’s not even worth doing at this point. Kind of a shame, but getting the license is a good idea in the long run anyway.

Why not go the other route and just ask FIRST HQ if you are a vendor or what you would need to do to become one.

I’m sure HQ wants people making products for FRC teams. You may not be able to meet their terms now (or maybe you are) but you might be able to in the near future.

I emailed HQ a few hours ago asking what I can do. It shouldn’t be too hard, hopefully.