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Mechanics and Construction / Re: Anybody make their own wheels?
« Last post by mklrobo on September 08, 2016, 01:25:04 PM »
 :) Hello!

In reference to your wheels, I would try Tractor Supply. American Science and Surplus (online)
has some wild items, that may help.
        Insofaras your Raspberry Pi, the problem with that will be integrating RPIO library into
your kernel. The main language I have seen for the Pi is Python, which I like a lot.
(another C++ library extension) I bought Wheezy for my Pi, and still can not figure out
how to load the RPIO module into it. (You must have RPIO to control your inputs/outputs.)
  :'(  I am so unhappy!
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Mechanics and Construction / Anybody make their own wheels?
« Last post by JustANerd on September 07, 2016, 03:09:31 PM »
Hey folks!

First time on the site, and first post.

I've been pretty mechanical my entire life, and as a kid I used to try to build robots all the time. Now that I am an old man and pretty much disabled, (hips and back are shot due to an old injury) I have a lot of time to kill. Picked up a book on how to build a raspberry pi robot. He uses some parts that are just really impractical for me. One is the wheels. I can't find the powerwheels parts in the right size no matter where I look. So, I am considering trying to make my own.

I am thinking plywood and hardboard. Pluwood for the hub, and hardboard for the "tire". Hardboard can be bent easily with a heat gun, so that part is no problem at all. Found some traction strips that are rubber from my local hardware store, so slippage won't be a problem either. Only issue I might see is deformation of the hardboard from moisture outside, but I think I can seal it well enough to keep that from happening.

This ends up being a pretty large bot, so I was wanting some opinions. 3/4 ply for the hubs, spoked and/or holes to lighten it up without losing integrity is my preference. Any other ideas?

book I bought:  https://www.amazon.com/Make-Raspberry-Pi-Controlled-Robot-Building/dp/1457186039/ref=sr_1_1?s=books&ie=UTF8&qid=1473284119&sr=1-1&keywords=raspberry+pi+robot
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Mechanics and Construction / wheelchair motor : removal of wheel hub
« Last post by anilkumar15 on September 06, 2016, 07:03:43 PM »
Hi

I need help. I have invacare wheel-chair motor with wheelhub .
How do you remove the wheel hub from the motor?
There is a mounting bolt at the center of the wheel-mounting hub . Does it need to be rotated clock-wise or anti-clockwise to remove it ?
Is there any trick for it ?

Thanks
Anil K.
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Misc / Mechanical vs optical/software shape recognition - need some guidance
« Last post by Loz on September 02, 2016, 06:30:13 PM »
Hi all,

I've spent the last few days doing research and am hoping someone can provide some guidance on which path I should take.

End goal: a sorting machine that can sort hundreds, potentially thousands of different small parts based on shape and colour. shape and colour would both be from a list that could be defined, think lego :)

I've been doing research for the last few days on how to do this and I've come to two possible solutions.
1. a system that takes up an impractical amount of space, to mechanically sort based on parts going down a conveyor and being passed over different profiles to match pieces. there would then need to be a 2nd smaller device to sort based on colour. the only way I see this working is if I have "cards" that have the profiles laser cut/machined and based on my needs at the time, I slot the cards I need into place in the sorter and everything else drops into a "misc/unsorted" bin at the end.

2. shape detection. in my mind, I imagine:
 a very small conveyor with a bin at the beginning (parts in) -> a detector section which would have a camera top and side to detect the appropriate profile -> colour sensor -> to what would then be a series of paddles that would flip left/right and guide the part off the side of the conveyor at the appropriate point.
my idea also has this in a "learning mode" of sorts each time its powered up. lets say there's 20 bins that items can be sorted into none of which are allocated to any part. the first part that goes through we'll call it "A", doesnt match anything the system allocates bin 1. the second part, lets call it "C" goes through and the system allocates bin 2. now any subsequent time part A or C go through it will detect a match and flick it off into bin 1 or 2. now after 30 odd parts going through a new part shows up, and it does the same process again. any parts over the bin limit get shuffled into a final "bin 21" that is the un-sortable stuff.
While I understand the mechanical platform and I could build that no worries, it would be huge and time consuming to be swapping out the cards by hand. I'd also have to make and store potentially thousands of different cards which would be painful, especially when I need to find that 1 in 5000.

now the research I've done on shape detection, it seems quite complicated software wise. either that or simply my lack of knowledge on the subject means I perceive it as extremely complicated. OpenCV is what I see to be the most likely candidate, there's no way I can afford any of the paid products for a hobby project :). I did also wonder if a Pixy & arduino would do the job, but training the pixy each time would probably be just as arduous as sorting parts by hand.

I'm stuck on deciding to try something new, and go down the software shape recognition path or going with what I know would be expensive, limited by space, and time consuming to build (mechanical).

Thanks in advance all!
 
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Mechanics and Construction / Re: DC motor
« Last post by Parethe on September 02, 2016, 02:43:31 AM »
The Gear is used to make project compact. Instead of using four dc motors you can use 1 dc motor with gears.
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Misc / MeccaNoid Super Servo Mod (more torque)
« Last post by MeccaNoid Madness on August 27, 2016, 06:06:26 PM »
This is how I made a servo with more torque:

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Robot Videos / NXROBO BIG-i: The first personalized family robot
« Last post by nusi.elwes on August 27, 2016, 09:32:10 AM »
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Software / Help needed for algorithm
« Last post by msavazzi on August 26, 2016, 11:56:40 AM »
Team,
I'm new to this forum, so first of all I wish to say hello to everyone!

Second here is the reason why I subscribed: it's quite some time I'm trying to solve this challenge but I'm not able to. I want to build a robot that put in an area will cover all of it.
The area should be random and could include some "black spots".
simple forward and bounce will not work.

I've tried to search but I was not able to find anything... can you help me? can you provide me some guidance or help on what to search?

On the robot side I have no issue with motors, wheels, sensors, etc...

To make it simple assume that I have a bumper in front of the robot and I just use that to detect ostacles.

Thank you for your help!
M
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Mechanics and Construction / Fluidic Based Actuators
« Last post by joeedh on August 24, 2016, 04:58:25 PM »
Hi all.  I'm a computer graphics engineer, and for years I've dreamed of building a small, compact robot with dozens (at least 24) of actuators (mostly for research).  Recently I've been trying fluidics out (with compressed air), and I was wondering if anyone else has ever done that.

The basic idea I had is to attach a mini solenoid valve (like from blood pressure monitors) to a fluidic valve.  The solenoid valve takes an air stream of, safe, 4-5 PSI, and uses the fluidic valve to amplify it to 20-30.  That then drives a pneumatic actuator.  I have a 3d printer, and I've managed to get a fluidic valve that seems to work (it works the way I want it too. . .but, not the way my books on fluidics say it should, heh), and I've ordered a little solenoid valve.

The fluidic valve, including the solenoid, works out to about 25mm x 55mm x 20mm tall, so about 1'' by 2'' by 1''.  I haven't decided what to do about the actuator yet (air muscles?  Disney's pneumatic rack and pinion setup? a pneumatic stepper motor?), but I'm planning to start with simple air muscles (because they are easy).

Anyway, thanks for any replies.
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 :) Hello!  :)

     There are vendors advertising on the right hand side of your web - screen that may be of help.
I have looked at Lego - mindstorms at Toys are us; Mechanoid Madness posts, where you have a
cute robot to assemble. If you visit Youtube for Mechanoid Madness, you can find a slew of suggestions!
Good Luck, and have fun!!   ;) :) :D ;D
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