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Picture of Large Dancing Robot
Build a large dancing robot. This was supposed to be a walking robot, but it more kinda beebopped around.

video on last step.


 
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Step 1: Build a Prototype

Picture of Build a Prototype
First, The _Prototype_:

Before you make a large, high power robot, it's good to make a smaller scale prototype. I made a simple walking robot using

= Brains: PIC16f877A,
= Actuators: two small geared pager motors (http://www.solarbotics.com/products/gm10/)
= Actuator Control: an L293 H-bridge,
= Body: I used one of those thin metal things that cover your unused card slots at the back of your PC.
= Fasteners: Everything was kept together by double sided tape and twist ties and some small screws from an old computer case.

Info on how to use the PIC and the L293 h bridge motor controller are covered in my previous instructables:
PIC: http://www.instructables.com/id/Intro-to-PIC-Microcontrollers/
H-Bridge: http://www.instructables.com/id/EHL7TR9A61ETVPKL4D/

--Notes--:
you can download the code I used (LWalker.bas).
The gears on the motors are important because they add torque (needed for a walking robot since it has lift its own weight).

http://www.youtube.com/watch?v=VyqcOvQ5BhQ


Step 2: Hardware(1): Stuff You'll Need

Picture of Hardware(1): Stuff You'll Need
Now I started building the larger scale version. I used:

= two 24 volt wheelchair motors I had bought a while ago (to make a bot for the battlebots tv show, didn't happen) (from Ebay)
= two victor 883 24volt motor speed controllers (from ebay, originally sold by IFI robotics)
four 12v 5ah batteries (two in series for each motor) (from allelectronics.com)
= two planks of wood stolen from a contruction site
= two 10 foot pieces of EMT electrical conduit (from Lowes)
= a conduit bending tool (Lowes)
= bicycle inner tubes (go to a local bike shop and ask for popped tubes from the trash)
= u bolts, screws, locking nuts, locking washers, a ratchet wrench, hack saw, power drill
= friction feet thingees (you slide them onto table legs for friction) (from a local hardware store)

Step 3: Hardware(2): Bend the Legs

Picture of Hardware(2): Bend the Legs
MySnap1.jpg
(1) using the wood as a body screw on one motor so that the shaft is pointing upwards at approximately a 45 degree angle. Screw on the other motor so that the shaft is horizontal.

(2) bend the legs using the conduit bending tool into whatever shape you think will work (I had to try a couple different angle bends before it wort of worked).
One thing about shaping the legs, don't make them flare out too far foreward and back. If the legs flare out too much as the robot walks they will get further and further apart and the robot will sag in the middle.
Also, don't flare the legs out to the left and right of the robot, this makes it more stable but also a LOT harder for the robot to move the legs up and down. Flaring them inwards towards the robots body axis made a huge beneficial difference on my robot.

--Note--:
In my experience it is very hard to do double bends with steel conduit (see S shaped bend in diagram below). A big part of conduit bending is making sure you have enough weight distributed in the right places (to hold down different parts of the conduit, etc). So it's goo to have very heavy objects around, like a radiator, or big people.

Step 4: Hardware(3): Leg Attachment

Picture of Hardware(3): Leg Attachment
MySnap1.jpg
(3) See the diagram below to reinforce the legs so they can be attached very securely to the motors. To make sure that they were attached well I used a right angled peice of steel to hold the conduit from two sides. Use locking nuts and locking washers here.

--Note--:
try to make it so the legs can be somewhat easily detached from the motors so that you can modify the leg bends if needed after later testing (after you finish the electronics)

Step 5: Electronics(1): PIC micro and the PAK VIII

Picture of Electronics(1): PIC micro and the PAK VIII
pak8 circuit.gif
Refer to my previous instructables on using the PIC, or you can use another type of microcontroller, or you can just use switches to control power to the motors and skip the whole digital electronics part.

I used a PIC microcontroller because my original intention was to put the batteries, controller, etc all on the robot to make it autonomous, but I had to rush to complete it because I was building it for an event (nyc idiotarod), so I just used long extension cords to supply power to the robot from an external power source.

To allow the PIC to control the motors while also doing other stuff (like listening for your commands, or whatever), you'll want to use a pulse width modulation (PWM) coprocessor such as the PAK VIII. This chip takes in a clocked in value from the PIC and takes care of sending the correct pulse width commands to the Victor 885 speed controller. Figuring out how to interface to it from the PIC via software was a bit of a pain, you can download the code I used (LBigWalk.bas).

The circuit diagram for how to connect everything together is below.
TO SEE THE CIRCUIT IMAGE FULL FOLLOW THE LINK BELOW:
http://www.instructables.com/files/orig/FEO/FOH6/FC0Z01U6/FEOFOH6FC0Z01U6.jpg

Step 6: Electronics(2): Make the Control Switches

Picture of Electronics(2): Make the Control Switches
I hooked up four tiny pushbutton switched to manually send commands to the PIC. Two buttons for each motor (clockwise/counterclockwise rotation). These were connected to the PIC as seen in the diagram below. You can also see how they were connected on the circuit diagram on the previous page.

Step 7: Electronics(3): Motor Speed Controller and Batteries

Picture of Electronics(3): Motor Speed Controller and Batteries
For the Victor 885 to know what speed to set the motors to, you have to send it +5v pulses with widths between 1ms (minimum power) and 2ms (max power). Sending it pulses with a width of 1.5ms puts the motor in neutral. The time between each pulse sent to the Victor 885 must be at least 27ms. Because you're sending it variable width pulses, this type of control is called "Pulse Width Modulation" or PWM for short.

These pulses are sent to the two Victor 885s from the PAK VIII described previously. Datasheets and other information on using the Victor 885 is included below. I also attached a datasheet of the batteries I used.

The Victor 885's LED will turn red when it's running the motors full reverse, green for full forward, and orange for neutral. The LED will blink if it's not receiving any pulse width modulation (PWM) commands.

Step 8: Run It

Picture of Run It
If it works or not, have fun

http://www.youtube.com/watch?v=vUCTpNb8Bug


Nicapizza3 years ago
Hey, i know its been a long time scence this was posted, but what is the song? it sounds a lot like arctic monkeys and i really like it.
vicky6664 years ago
By the way i think this robot walks and it does not dance and i think you should change the name to 'large walking robot' as many people thinking it's a dancing robot, and get confused like i did!!!!!!!!!!!!!!1
calm down!!!!!!!!!!!
andross525 years ago
Did anyone else notice the url?
me! Giggles....
waffleman5 years ago
im sorry but i dont really see how one can be very excited about this? it just shakes around a bit, nothing special........
leevonk (author)  waffleman5 years ago
I agree with the second part of your statement but not the first and third. It is in fact quite special compared to most things that 'just shake around a bit'    :)
robo35 years ago
nice build!!!!!!!!!!!!!
erobot6 years ago
u rocked yar..well i'm interested to design a dancing robo..please help me ofcourse, this protocol will help me up!! thanks and regards eRobot madhu@bvrit.ac.in
nice one i love bro!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Unit0426 years ago
Nice stuff here! I've been thinking about making a walker myself (not quite as big, but still). Looking at your diagram, the 45 degree tilted up end is supposed to be forward, the horizontal motor end is the butt.
The front motor is activated in any given direction, rapidly followed by the rear legs, rotating in the opposite direction. After that, both motors reverse, starting with the front motor.

see:
solarbotics.net
leevonk (author)  Unit0426 years ago
yeah, I know, but I tried it that way and ran into a problem that is specific to larger robots, the metal conduit I was using for the legs couldn't hold up the robot body when the legs were at 45 degree angles, the metal bent and the whole body sagged, so I had to bend them more inwards. Also, when I made a smaller version (first video shown in the instructions) it actually ended up moving in the opositie direction with the 45 degree angle legs at the front. given all of that and the fact that I was trying to build the large version in one long 24 hour session and you see the not so great result.
Unit042 leevonk6 years ago
Mmmm... bummer. Back to wheels! :D
crankola6 years ago
Heyyyy- I remember this! in fact im standing in the background in a red jumpsuit with the rest of COBRA, Idiotarod organizers. I really liked the robot and I thought it was a great interpretation of the "contest". Just sorry you didnt win anything... :( But keep doing this and maybe they will have a "Best animatronic dancer", or best "jiggy terminator" award!!
leevonk (author)  crankola6 years ago
not sure if I'll have time to build another one for this years idiotarod, and I lent out my motors for another project, so we'll see
elixeo7 years ago
Great instructable. Liked the Video but I have to admit I found the girl a bit irritating.
leevonk (author)  elixeo7 years ago
she's a really good friend of mine, she's a lot of fun, I find you irritating.
leevonk (author)  leevonk7 years ago
by the way, how can you like the video while finding her irritating, she's in all but 5 seconds of it! I think that you just like her so much that your brain is confused
The girl in the blue helmet is cute ! Around 59 seconds into the second video I forgot there was even a robot there . Shes hot !
Hi, guys, The robot works! But perhaps the body seems so weigh to move. That's right, the girl is irritating. I can hardly focused on the robot while the girl appears!!!
Clayton H.7 years ago
So this is really just a giant Vibrobot?
theRIAA7 years ago
need more POWER!
No sir , what this needs is more cowbell.....
I GOTTA have more cowbell.
SWV17877 years ago
Honestly the girl in the blue hard-hat was more entertaining than the large dancing robot but it was a cool idea
leevonk (author)  SWV17877 years ago
I agree, the robot needs more spunk, I'm working on it, but that's as good as I could get it at the time. I'm going to try putting all four batteries on one motor to see if that makes a difference, also I have to buy some more emt conduit to bend into some new front legs, i'll put an update video here if it any of that works.
Nice! Especially loved the warning 54 seconds into the movie :P
...Awesome! Looks really hard to make, but it's awesome!