Ice-cream stick robot
In preparation for the School Education Expo in September 2011 (www.edexpo.com) in Sydney/Australia we at RoboteShop (www.roboteshop.com) wanted a robot that would inspire students, teachers and parents into robotics. So we wanted something that was affordable and easy to make.
I started with the electronics from Innovati's RQ-5 Paper robot kit for two reasons;
- The kit is cheap
- The electronics included 1 servo, IR sensors, buzzer and more importantly an interface board that included 3 servo ports.
I didn't exactly know what I could do with the servos, but the more the better. Then I saw Karl Williams book called Insectronics which featured a hexapod that only used three servos to move 6 legs. All I needed now was two more servos and something to make the body.
With absolutely no skill when it comes to metal sheet working, I wanted a robot made of something that I couldn't hurt myself with. I was going to try and make it out of paper, but I'm no good at origami (and I might get a paper cut). However, since I know how to accidently glue my fingers together, I felt confident I could glue other things together as well.
So I got a bag of colored ice-cream sticks and split-pins from a craft shop. I was looking for the plain gold split-pins, but all they had were the colored flower ones (my mother in law gave me a funny look when I told her I'm going to use them to build a robot). Instead of using nuts and bolts for the pivot points I was confident I could do this with simple split-pins.
My design process ran in parallel with by build and my unit of measure was ice-cream sticks. The body, as you can see in the photo is 1x1 stick in size and everything else is 1/2, 1/4 sticks. None of that fancy stuff like measure twice, cut once.
Everything was hot glued together, servos to frame, legs to servo. I did make one major error. The legs were originally 1 stick high, but the center of gravity was so high that it would always fall over after a couple of steps. This is because the walking gait had the robot shuffle back and forth.
To fix this, I lowered the robot as much as possible, as you can see the middle legs are stumpy and the rest have been chopped. Luckily I had a heat gun laying around (for renovating) and I was able to use this to re-melt the glue (without burning the wood) which allowed me to remove the legs and chop them.
Although the EV8 is pre-programmed in the RQ-5 Paper Robot, there is an EV8 writer available that allows users to load new programs. I used the writer to create a small program to use the IR sensors to avoid objects. Originally the sensors were both facing forward and the robot wasn't behaving properly, but when I angled them slightly to the sides, the results were much better.
I've included a text file that contains the program used in the video. As you can see in the main loop, the light sensor on the robot has been commented out. But I wrote it so that the robot would activate in light and stop in the dark. You can imagine a beam from a hand light hitting the robot in a dark room, the robot would suddenly start to move! If you have any questions about this project let me know.