I’d like to introduce you to Scruffy the robot. I should start by saying that he doesn’t have any superpowers, he can’t fly or swim, he’s very vulnerable to radiation, and he can’t save people. Nevertheless, he has one very important duty in life. Cleaning whiteboards!
Not like any other competition that I’ve participated in before, this challenge didn’t have a clear goal or constraints. Our only goal was to mimic something from the nature, and we were constrained only by time and our own imagination.
My uncle suggested that we should either design a robot that would be superior to others and would definitely win the challenge, or just make something really silly and make everyone laugh. We followed my uncle’s advice and decided to go with the latter. Scruffy had to mimic the guy who is cleaning whiteboards in lecture theaters after lectures. And to make it more hilarious we gave our robot a grumpy attitude, so that he could keep moaning and complaining about life and his job.
Because we only had five days to design and build the robot, we decided to keep the design simple. We used the “stock” chassis and modified the wheel design to meet our needs. We also used two Tamiya gearboxes set to maximum torque, and an Arduino with Sparkfun’s motor shield.
Now to enable Scruffy to do his job, we had to somehow make him stick to the whiteboard. And one thing that sticks well on all whiteboards is a magnet. So we came up with a wheel design that could hold 50 neodymium magnets in each wheel. Each magnet was a 3mm x 3mm x 3mm cube and had a horizontal pull force of 250g, which – according to our calculations – had to be just enough to hold our almost 1kg robot on the whiteboard. The problem was, that the vertical pull force was only ~150g, which wasn’t sufficient for us, so our wheel design featured slots for rubber bands to increase traction.
All custom parts were 3D printed in the university’s workshops. But because one of the printers broke down in the middle of the week, we only had two wheels for testing. But even with only two magnetized wheels, our robot passed the vertical inclination test!
Although this is not a perfectly vertical whiteboard, but it showed promising results. To make Scruffy aware of unclean parts of the board, we decided to stick an IR sensor in front. And in no time Scruffy was following lines. We actually used two sets of sensors to detect the left and the right edges of the line.
Line following was cool, but we also wanted to be able to control Scruffy manually. So we used an IR transmitter and a receiver. Unfortunately, the transmitter didn’t come with a set of codewords, so we had to decode them ourselves. And it turned out to be easier than it sounds. All we had to do is hook up the IR receiver to the Arduino running an example sketch from the IRremote library by Ken Shirriff and write down the codewords for each transmitter button.
And finally, Scruffy’s most important feature that gave him that grumpy attitude towards life. Because we didn’t have an MP3 shield on our hands, we decided to disassemble an old MP3 player and soldered transistors to buttons. This allowed us to control the MP3 player with an Arduino. We recorded about 15 different phrases and played them using small portable speakers.
On friday all teams presented their robots to the audience. There were 7 teams in total and every robot was different. Some robots were really simple and could move on a pre-programmed path, others were controlled with an Xbox controller, some had legs, others had wheels, and there even was a snake robot!
After the presentations, teams were invited to demonstrate and present their robots at the TEDx Edinburgh. Eventually we got bored just talking about our robots and started robot wars to entertain TEDx participants
More photos of how Scruffy was made and amazing robots made by other teams:
Photos taken by Dave Laurenson:
Big thanks to Adam Stokes, Dave Laurenson, Les Haworth and the university staff for organizing this challenge as well as helping us out. And of course, big thanks to my great team-mates Paulius, Marius and Kestas. Great effort guys!
Scruffy was designed and built in five days for the Biobot Challenge in Edinburgh University during the Innovative Learning Week 2014. The only moaning and complaining robot that I know of