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200,000 orders and new Zumo robot preview
- 4 March 2015This one looks much better and more convenient than the previous versions.
New products: Magnetic quadrature encoders for micro metal gearmotors
- 19 February 2015Hi, in the meanwhile we developed our own encoder based on AS5040 and the original idea of the one found on Tindie (it seems it has disappeared):
https://dl.dropboxusercontent.com/u/14855888/eRobot.cat/IMG-20150215-WA0024.jpg
First prototype in the right (black pcb) works but had some mistakes on pcb, we had to "dremel" solve it.
Second prototype in the left (blue pcb) problems addressed and size shrinked a little bit.
Both use the same pin configuration as your pololu optical and magnetic versions, so they are compatible and direct-replace (except for the longer size due to use of two pcbs instead of one). They fit the Pololu motor exact size so they are smd like solderable (you do not need to use wires or cut pcb. I got the idea from your original optical encoder pads, but those broke easy (they were half cut), these are full pads and more resistant.
On losing my baby
- 12 February 2015This is a very sad story. My condolences.
New product: A-Star 32U4 Prime LV
- 19 December 2014You are right Jon, the zumo is designed only to have the Arduino (or like) upside-down, so there is no way to come across this. The LCD would requiere an adaptor or similar to be usable in that way. Pins confict with LCD and Zumo? That's a big problem then to what I was planning (use this board for zumos).
New product: A-Star 32U4 Prime LV
- 16 December 2014That's the problem, John. If you upside-down the board then the lcd is useless.
At least, you should provide an extended pinhead version instead of the normal version, so it should be possible to solder female pinheads in zumo robot and use them both together in its natural side (not upside-down).
New product: A-Star 32U4 Prime LV
- 14 December 2014This is a very interesting board!
One thing I'm not sure if you obviated: to include female pins in the bottom side so we can use it directly attached to zumo robot.
New products: Magnetic quadrature encoders for micro metal gearmotors
- 18 October 2014Jan, here you have another way for an encoder:
http://www.melexis.com/Position--Speed-Sensors/Speed-Sensors/Cam-Sensor-3.aspx
Yo do not need a complex multipole magnet, but a metallic tooth gear and a simple magnet. I do not know the maximum cpr number you can obtain in this way (for sure it can't go as high as an AMS sensor), but it looks like it can overcome that 12 cpr.
Some calculus for the robotics people. If you are trying to control the motor speed (the same for acceleration), you are going to get a conclusion: you need lots of cprs. Fast robots run easily at 3 m/s and they can peak near double. A loop control time of 1 ms (some do it faster) gives you an error of 3mm (affordable in a linefollower, bad in a micromouse). If motor is spinning at 15000 rpm (250 revolutions per second, 0,25 revolution per millisecond). With a 12 cpr encoder attached, at that speed you will only have 3 cpr per millisecond. If you lower the speed (say to 1 m/s) then you have only 1 cpr per millisecond. That is totally useless in speed control. We have two options: reduce loop period (say 100 ms) but that gives an error of 300 mm (dissaster) or increment encoder pulses per revolution (complex/expensive).
At this time, Pololu encoders are very nice to mesure distance (also dead-reckoning), but not for speed control.
New products: Magnetic quadrature encoders for micro metal gearmotors
- 8 October 2014Hi Jan, thanks to answer.
In micromouse they (me not yet) use 1:5, 1:4 gear ratios. 99% of them use 32 bit micros with integrated encoder peripheral inputs. They need a very fine speed and acceleration control over each motor. They also use it for dead reckoning combined with giros. They need high cpr counts on their encoders to accomplish all of that. You can take a look at a nice blog from the USA at: http://micromouseusa.com/
In linefollowers we use from 1:10 down to 1:5, 1:4, 1:3 gear ratios. We do not yet need the exact same power nor the so high cpr count as Micromousers, but as per year the robots are evolving very fast, they for sure will need soon.
Top of the art, maxxon, motors are really expensive. But hobbysts cannot afford a +$200 per motor to mount their robot. Pololu, like Sparkfun and a very few others, is a reference for all of us hobby robotics. Sensor itself is not so expensive: Price (1k)* $ 4.21 http://ams.com/eng/Products/Position-Sensors/Magnetic-Rotary-Position-Sensors/AS5047D.
Anyway, that 28 cpr does sound nice. Can you tell me when are you going to have them in stock?
New products: Magnetic quadrature encoders for micro metal gearmotors
- 6 October 2014Hi Sean,
Speaking about micromouse motors, most top robot builders use motors from quality (and very expensive) brands (maxxon, faulhaber, portescap, ...). In those motors the encoder is set to the motor shaft, so 1024 crp compares directly to 12 cpr, and thats independent of the wheel reduction gear.
In the event that your application does not need that such a resolution, those sensors are programmable and you can reduce the output resolution.
As I pointed in the link from Tindie, there are ways tu use Pololu micro metal gear motors with encoders and obtain a very decent encoded motors. In fact that is the same the big brands do, of course, they do it in an upper level of finishes and refinement.
Jan, do you think Pololu can do something similar to that? That will rock the market in hobby encoder motors.
New products: Magnetic quadrature encoders for micro metal gearmotors
- 4 October 2014I have bought some optical encóders from you. The ones for the special wheel and the newer back shaft optical. If I tell you truth I am dissapointed with them. The "half cut holes" was a very clever idea, but also a bad mecannical idea. They broke very easily if you use with cables, unless you have a very-very soft/flexible cables, or if you unsolder/desolder a few times.
And now you release this magnetic encoder with only 12cpr... I am more dissapointed. I expected much more from you, One of the top robot contests in world is micromouse, they usually use 256 to 1024 cpr encoders. I expected you released some kind of magnetic encoder, but a full sensor, not some hall effect sensors. Something like Austria Microsystems sensors (AS5040, AS5047 for example). And for the pcb disposition, take a look at this:
https://www.tindie.com/products/EmbeddedArea/a-rotary-magnetic-encoder-for-your-gear-motor-assembled-as5040-magnet/
I think that idea is near to perfection: self portable on motor, only one cable for encoder+motor, small size, great resolution. Let's do some encoders similar to that. Today's robotics need a more sophisticated encoder than a 12/16 cpr.