DumpsterBot (AKA DumbsterBot ) was the result of a plan to make a simple first pass low cost robot. By keeping my expectations low and using easy to fabricate materials (cardboard and hot-glue) I was able to give myself a greater likelihood of success. Plus I find running and gunning design can be rather fun for early development. The primary goal of this robot is to be a table survival robot, a robot that can explore the surface of a clean table without falling off. It is powered by two servo motors, reads the table edge with two micro rocker switches and is controlled by an arduino uno hooked up to a rechargeable battery. The body was built around the parts using scrap cardboard and a hot glue gun. With DumpsterBot complete I now have a platform for future club challenge competitions.
The first part of DumpsterBot was acquiring materials. The Robot Group was sponsoring a free Arduino class that came with a parts lists of supplies included on the list was two servos, Ardunio Uno, battery pack, edge sonic sensor and a breadboard with wires. I used all of these items on my build except for the sonic sensor. The Arduino class was where I actually started and the idea for the robot and it all came together pretty quickly after this first class. DumpsterBot is my first robot after working with an Arduino for less than a month. With that in mind I felt really inspired to show others (and myself) just how easy Arduino robots can be. Early Robot Group meetings had given me the idea of making a table robot for our challenge in April. The servos I bought were not continuous rotation, this means you can’t use them as drive wheels without further modification. Continuous rotation servos are a bit more expensive and harder to find, but worth the effort if you have the time. I was in a rush so I found an article online for modifying the servos and got them ready to go.The rest of my parts were ready to go as is. I started with a 6”x6” footprint limit per our competition guidelines, all other construction was done on the fly. I just folded up cardboard into little box shapes and glued them together. I started cutting cardboard wheels out when one of the members of The Robot Group took pity on me and ran off to the laser to make me some wooden wheels complete with servo splines. These wheels are now the crown jewel of my robot. To mount the servos I traced the shape of the base on the sides with a marker and cut out a window on each side to mount the motor. I went for center mounted wheels as they seems to turn more predictably. I glued on bits of scrap wood to act as sliders in the front and back. I put one micro switch on each side of the robot, ensuring that the switch is engaged when the bot is rolling and only triggers when it goes off the edge of the table. The addition of a few cardboard rails made a great holder for my Arduino demo board kit.
I was now ready to test my code which did not work. After lots of research I realized that my 6 volt battery pack was not enough voltage to run the Arduino chip and the servos. For this setup a 7 volt supply is recommended. I looked around the house and saw my rechargeable camera battery, read 7.2 volts on the side. Encouraged I glued together a cardboard battery box. I stabbed some jumper wires through the end to line up with the battery contacts inside the box and included a piece of white packing foam to act as a spring to hold the battery terminals in place. Tried my code again and it worked!
Coding the robot took me a while as I am new to this and wanted more than basic edge avoidance. I wrote a code that has a number of flags that helps to determine which corner has fallen off before straightening out just off the edge to realign itself to the table edge before backing up and turning in a new direction, which for now is defaulted at left of the edge. This code is not enough to enter finish our challenge in April, but it is a great start.
I always had a lot of fun in my early tech classes and summer engineering programs that had quick design competitions utilizing glue guns and cheap materials for builds. This is one of the fastest ways to build and design on the fly. I have the skills to model up a design and fabricate it out of sheet metal, but this would cost much more time and money (mainly time as I work very slowly with metal). I would recommend this cardboard building process for a first time prototype of a robot you would like to turn out great. I learned a lot that would greatly improve my design if it is ever made out of more expensive materials. Had I started out with a prefabricated model, it would probably have to be scrapped once I figured out my battery pack would not work and my footprint was too big one the switch position was optimized.
BUILD YOUR OWN CARDBOARD ROBOT:
Philips screw driver (For work on servos)
Hot Glue Gun (High temp is better)
Box Cutter / Exacto Knife
Wire Crimper/Striper (optional)
Servo (find continuous rotation to skip extra steps)
Arduino Uno, Breadboard, Jumper Wires
Connector to attach wire to switch (any .187 QC female tab connector will work)