Let's Make Robots!

Little 8

Very cheap but fun little beginners robot. It think' it has a brains within a Picaxe 8

 

Your browser is not able to display this multimedia content.

Your browser is not able to display this multimedia content.


Edit: Check out this nice clone: http://letsmakerobots.com/node/8386


From building big, nasty, with large shovel, 2 cores, multiple sensors, soundsystem etc, I got tired of that.. and decided to see what fun I could have with a little Picaxe 8 on a board ($16, total prize for robot is about $40).

Version II of this fella here: http://letsmakerobots.com/node/101

I have since recieved some interest in how to build this extremely easy and cheap robot, and so I hereby transform this post to a small and simple tutorial:


Shopping list:

Can be bought from Picaxe:

You can get this from anywhere:

  • 1 9V battery
  • Some sticks and something to cut them
  • Screwdriver
  • Soldering iron and led
  • Some pieces of wire and something to cut it with
  • Some different types of glue or tape etc
  • a table-tennis ball and a knife to cut it
- And then you need some motors with wheels. I recomend these, used in my robot.

 


I like the challenge of only having 8 pins and 128 bytes of code etc. But be aware; you get a funny robot, but it is blind, can only sense a bumper in front, and you really do not have much memory in it etc.

What I did after building this, was i set it up with Easy Radio serial wireless input on the only pin left for anything. This made it possible to control this little robot by another robot, which opens new windows etc.

Some friends and i in our local club also had a contest of making it draw the number 8 on a piece of paper with a marker glued to its back.. Good fun little fast and chep robot!

 

IMG_3399.jpg
A stick, some switches, and a sliced up table-tennis-sized ball for "the third wheel"

 

IMG_3397.jpg
To get the 9V down to 5V, I use a voltage regulator.

IMG_3400.jpg
I was just mounting with some glue, the strips just tohold things in place..

IMG_3401_0.jpg

IMG_3403.jpg
An angle grinder may look like an extreme tool for such a small job - but I use it quite often. Just turn it on, hold it steady against something, and anything you stick in there is just vanishing, nice and smooth - compared to cutting such small parts. I also use it for acrylic (Plexiglass), again it is perfect to make little cuts and markings.

IMG_3414.jpg

Just follow the instructions that comes with the board - it cannot be more simple, hook up the 2 motors.

The motors I recomend are incredible! Fast and strong, even though I only feed them 3.5V due to the 1.5V drop from the Motor Driver. So I actually had to make a "tale-bumper" (red square) as it was lifting the front a little too much :D With the bumper on it turned out quite cool, as it is just as capable of navigating on only the rear-wheels.. there is nothing else but a glider in front anyway.

IMG_3406.jpg

All needed now is some code and the battery.

TIP: Get rechargeable batteries (and a recharger) - Or you will soon have used as much on batteries as on the Robot itself!

REMEMBER: If you make anything like this, to take a picture and show me :)

Here is the code used in the robot on the video. Don't mind that the names of the sub-routines does not make sense to you. Fact is that nothing in this code makes much sense, it was just the fun I had at the time when I shoot the video :)

I will have a closer look at this soon, but on request, here the code from the video:


symbol fw = 20
symbol bc = 200

b0= 175

''''''

dav:
random w5

for w3 = 0 to w5
if pin3 = 1 then
gosub bum
end if
next w3


b0= b0 +1
random w5
if b0 < w5 then goto hest

random w5
if w5 > fw then
high 1 low 0'ForwardRight
endif

random w5
if w5 > fw then
high 4 low 2'ForwardLeft
endif

hest:

random w5
if w5 > bc then
high 2 low 4'ReverseLeft
endif

random w5
if w5 > bc then
high 0 low 1'ReverseRight
endif

goto dav

bum:
w4 = 32212
return

high 2 low 4 high 0 low 1'Reverse
pause 300
if b0 > 175 then
high 1 low 0'ForwardRight
high 2 low 4'ReverseLeft
else
high 4 low 2'ForwardLeft
high 0 low 1'ReverseRight
end if
pause 300

b0 = 175
return

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

Little 8 is a fast robot. I am starting to think about building that robot. I do have a quick question.

Does the switches from radio shack work?

SPDT Switch Without Roller<----
SPDT Switch with 3/4<----

Even though their not long whiskers like from your robot, but do they still work for the 8pin motor driver board?

I'mm trying to get to the link for the bumper switches, but these links aren't working. Can you help.
That link is an old e-bay sale. So it's expired by now. Did you try  google instead? These switches are very basic. Any robot-parts webshop sells them. Or any generic electronics store.

Does the  picaxe 8 boared has a motor driver built in it

 

There is a slot for a longer chip on the board. If it says l293d that is a motor driver. It MAY have a darlington which allows you to use 2 different voltages. See what is written on the chip and google it.
yes I can do my plan then
does it matter if u have a 5v regulator or not acording to your code
Code does not care what voltage is supplying the picaxe. The picaxe cares what the voltage is. Too low and it won't work, too high and POOF!
If i used diffrent type of motor could I still use this code
Code isnt really motor dependant. If you use different motors it will just make the robot move faster or slower.