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Misc / Definition of robot?
« Last post by IvyW on September 16, 2016, 10:09:57 AM »
I'm an editor on WhatIs.com. We cover definitions of robotics terms and I'm looking for clarification on the basic definition of robot. Here's our current definition of robot: http://whatis.techtarget.com/definition/robot-insect-robot-autonomous-robot.

I have always considered a robot to be a physical system but I'm increasingly seeing references to software -- expert systems, for example -- as robots. I've also seen "robot" defined as "any system that replicates a human capability," which seems pretty broad.

Can anyone help me clarify this issue or point me towards a good source?

Electronics / Some explanations on Temperature controlled LEDs
« Last post by Banart on September 16, 2016, 12:59:15 AM »

This is one of the hobby circuits that we can build by our own in our home.The function of this circuit is to indicate the temperature levels using a simple LED.Moreover this temperature controlled led circuit can be used as an indicator to denote the increase in temperature.This circuit uses two LEDs (D1 & D2), IC 7805(IC 1) which is the 5v regulator, IC LM35(IC 2) which is the temperature sensor, IC CA3130(IC 3) is the opamp,Transistors Q1&Q2 and finally resistors R1,R2,R3,R4,R5.Now lets move into the working explanation of this circuit.
Here in the above circuit 9v DC supply is used to operate the circuit.Then the 9v is given into the  5v regulator(IC 1).You can also use 5v voltage supply if you have it with you.Then the temperature sensor (IC 2) is connected to it.The output of the LM35 increases by 10mv per degree rise in temperature.Output of the LM35 is given to the non inverting terminal of the Opamp.The inverting input of the same Opamp can be given with any reference voltage using any resistor R2.And the output of the Opamp is connected to the base of the transistor Q1 and the collector of the transistor Q1 is coupled to the base of the Transistor Q2.And red colored LED is connected to the collector of Q1 and green to the collector of Q2.
The circuit is nothing but two LEDs (D1 and D2), whose status are controlled by the temperature of the surroundings. The famous IC LM35 is used as the temperature sensor here. Output of LM35 increases by 10mV per degree rise in temperature. Output of LM35 is connected to the non inverting input of the opamp CA3130.The inverting input of the same opamp can be given with the required reference voltage using POT R2. If the reference voltage is 0.8V, then the voltage at the non inverting input (output of LM35) becomes 0.8V when the temperature is 80 degree Celsius. At this point the output of IC3 goes to positive saturation. This makes the transistor Q1 On and LED D1 glows. Since the base of Q2 is connected to the collector of Q1, Q2 will be switched OFF and LED D2 remains OFF. When the temperature is below 80 degree Celsius the reverse happens.IC1 produces a stable 5V DC working voltage from the available9V DC supply. If you already have a 5V DC supply then you can use it directly.


The circuit can be assembled on a Vero board.
IC3 must be mounted on a holder.
The temperature trip point can be set by adjusting POTR2.
Type no of Q1 and Q2 are not very critical. Any general purpose NPN transistors will do it.

If the reference voltage is 0.5v then the voltage at the non inverting input becomes 0.5v when the temperature raises to 50 degree celsius. So that both of the voltages get into the comparator as a result the output of the Opamp (IC 3) enters into the positive saturation.This trigger the transistor Q1 on and as a result the LED glows indicating the rise in temperature above 50 degree celsius.Since the base of the transistor Q2 is connected to the collector of the Q1 it remains in off state.When the temperature is below 50 degree celsius the reverse process happens making the LED 2 is light up indicating that the temperature is below 50 degree celsius.The temperature limiting range can be modified by adjusting POT R2.Now your all new homemade temperature controlled LED is ready.
Mechanics and Construction / Re: Anybody make their own wheels?
« Last post by JustANerd on September 08, 2016, 02:26:21 PM »
Hmmm, never messed with that OS. I'm still using raspbian. My main problem is with wheels is that the only 14" diameter I can find are either way too heavy, or too narrow to keep from sinking because of weight. This sucker is going to have some mass to it. Aslo, I'm not willing to spend over a  hundred bucks on cheap plastic. lol
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!
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
Mechanics and Construction / wheelchair motor : removal of wheel hub
« Last post by anilkumar15 on September 06, 2016, 07:03:43 PM »

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 ?

Anil K.
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!
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.
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:

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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