Let's Make Robots!

$20 Robot platform

The Making of a Robot including Mcu for less than $20

This project was devised to show how easily it is to make a robot on limited funds.
It is a good "Starting Off" Robotic base as it can be easily changed and transformed.
This is just the start of the project and there are many additions planned for it.

It is a cross platform base, meaning that any micro computing unit (Brain) can be used ie. Propeller , Picaxe or Arduino (aka Atmega).
Due to its low cost i foresee me building a "Swarm" of them .....this one is already the second (first being a picaxe version).

The base uses Geared Stepper motors which means that it is very precise and repeatable in its movements. ( forget your  sloppy continuous servos )

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;-)...I can now confirm from the Google analytics that the Audience retention does not drop off at the aforementioned 1:56 point.....

In fact Audience retention increases throughout the video. (rapidly peaking when i put the wheels on for some strange reason).

Conclusion :- Hot_Glue Wheelie Rocks.

BTW .... i am open for any ideas on making this one more cost effective...  its designed with flexibity in mind.

Simple straight forward fast design.....leads to more people making them....

..regards Gareth :-)

I understand, flexibility is the enemy of the creativity :-)

Anyway, to save costs I would use cheaper gear motors (guess these steppers are not thbat cheapy) so you also get rid of one motor driver. Cheaper wheels and onlxy a half ping pong ball by reducing the ground clearance in the back. Maybe you still can save some cent by using a DIY board for µC and motor driver.

I know, $20 is already cheap but it's not the limit. It's easier for me than it's for you but I guess you could easy reduce the costs down to $15 included the sensor.

In my books aversion to HOTGLUE means lack of creativity/movement ..

..... Did you get the subliminal Freudian slip @ timescale 8:50

I dont always use HOTGLUE here is my latest way to attach sensors and in this case a UV LED (is a dead easy way to align)

3mm cubed Neo magnets...

Yes i have my eye on a $2 ultrasonic module....however still awaiting delivery. I have a simple rig i plan to use, 2iR emitters and 4 detectors to obstacle and cliff detect....

Yeah, hotglue is good but not good for everything.

@8:50 you were talking about solder ^_^

Your magnet attachment is just working if there is any magnetic metal nearby :-)

I would probably go for IR in this case. However, a $2 ultrasonic module is not much more expensive either...

In my setup they each have a running current of 200mA under load .... (Stall current 220mA).

If you compare that with a continuous servo then eyebrows will certainly rise......(i shiver at the thought of servo stall current x2)

My picaxe version is running off 2x3.7V Lipos rated @ 500mAHr and it runs for 1 hour continuous before the onboard voltage sniffer detects 6.2V and shuts the robot down (not to kill the Lipo ....however the low voltage cut off can be trimmed to trip @5.5V).

My Atmega 328 version is using 2x3.7V Lipos rated @4000mAHr so looks like a long life is destined.

If you want precision then these are very awesome motors, fast they are not however they have reasonable torque.

Cheap 28YBJ-48 stepper motors? I have 2 of them, I've thought about using them for a robot. But you need a lot of pins to drive 2 stepper motors and these little stepper motors draw quite a bit of current. Would like to hear more about your experience with them :)

Yep I bought 10 of these as they were so cheap.

But they are very slow at 5v with the reduction gearing (as seen in the video) I wonder if 12v helps with the speed any?

err...... if you can get them working @12V then i would like to be the first one to know.....

Seriously :- 12 Volts would burn the coils out - If you could "Very Short Pulse" them @12V then i guess the gear drive mech would not take the strain..

They are designed for lowspeed with good accuracy. I am still using mine (all 3 autonomous robots) and well pleased .

......Speed was not really a priority for my <$20 design.

My advise would be to set one up and ramp up the voltage up in stages - From my experiments the motor casing will get hot soon after 5V.