New Project (finished too) - "Anti-Gravity" Robot

We have a fun little competition at school called the Awesome Things Competition. There aren't really any rules, you just have to make something cool and it gets arbitrarily judged by a few professors who volunteer to see all of the cool projects. If you enter you get $100 to make your project. You can spend more if you want, but most people try to keep it within that budget in the spirit of competition. The winner collects another $100.

My roommate and I were brainstorming ideas for another project we are working on, and we had a funny idea. Could a fan be used to let a robot drive up walls and on ceilings?

We started our design by doing some simple math: addition and subtraction! We added up the weights of the components we wanted on the robot (motors, fan, batteries, chassis, wheels, etc..) and subtracted the thrust from the fan. If our number was negative we were good! We figured the thrust from the fan had to provide the normal force for the robot to drive. We figured any suction effects from the fan would add to a factor of safety to ensure the robot wouldn't drop.

We wanted the project to be super fast to make, so we laser cut all the custom parts from acrylic and used glue to hold them together. We reused transmissions, motors, wheels, and electronics from a robot used in a freshman engineering elective we both took. We only purchased the acrylic sheet, radio, batteries, and fan. Lots of blue tape was used to hold the thing together.

Here's what the robot looked like without all of its hardware. It's kind of cute!

The robot easily held onto the ceiling as 20% throttle when we added some cardboard skirts to create essentially a fancy suction cup. Our dorm room had some silly Christmas decorations because we like to stick things to our ceiling.

We also made a pretty sweet dorm Christmas photo without the need for Photoshop!

The robot ended up "blowing away" the competition. One thing that came up during the project descriptions was how many amps the project drew. It started with one project drawing 2 amps. The next project drew 6 amps and had to have a very interesting power supply to use the small voltage regulators. Then ours came up which could draw 60 amps! This little robot was fun to drive around and led us to victory!

PROS
-Fun to play with
-Loud (it sounds menacing)
-Cheap
-Quick to make
-Won the Awesome Things Competition

CONS
-Loud (We got noise complaints when testing it at 3am)
-Under-powered drivetrain (it's neither fast nor able to push stuff)
-Cludgey electronics (we had to be careful not to short wires or have it fall apart)

Overall this robot was awesome... you might even say the most awesome. At some point if I have free time I'll rebuild it with proper electronics and a nice drivetrain so it moves better.

Long Board Actually Complete!

I finally beasted out the under glow modules for the board.

 I decided to make two separate modules because I didn't have a way to run wires across the board in a clean way. Since the deck is clear everything is visible. KLUDGES ARE UNACCEPTABLE! (unless you can hide them =D)

 The parts were all machined from acrylic because it was the cheapest thing in the scraps bin at the local plastic store. I hadn't CNC'd any acrylic before. Its harder to cut, but it looked a lot better after machining.

There are four blue LEDs per module. I tried to keep everything as waterproof as possible, but it's more water "resistant" than water proof. The LEDs are all run in parallel from the two AAA batteries. I looked at the data sheets for the LEDs and found I didn't need a special LED driving circuit because the maximum voltage from the two AAA batteries was less than the maximum voltage the LEDs could handle without burning up. I attempted to seal the LEDs with hot glue into the modules. The machined paths for the wires look amazing especially when lit in the dark.

It's nice to complete a project for once. I always seem to get a project mostly finished but then move onto something new. The under glow was really fast to machine. I guess I was just a little lazy and put it off because it wasn't necessary to use the board for transportation.

Here's a list of PROS and CONS for the board:

PROS
-Looks hella beast (that means it looks great in Northern California)
-Extremely smooth ride. The incredible mass of the board keeps it from getting stuck on the usual pebbles and other junk on the ground that can stop a normal board.
-INDESTRUCTIBLE! The 1/2" polycarbonate combined with the two 1/2" x 1" solid aluminum rails give this board 0 flex. Some FEA simulations in SolidWorks suggest it may be able to handle up to around 800 pounds. That's plenty strong enough to stop me from breaking it while jumping. (I have tested by stomping on it... It's not going to break)
-It's reliable. The components were all made from high quality non-corrosive materials (aluminum, plastic, stainless steel). Water and other things in a normal environment won't cause this board any problems.
-It has headlights for night riding. The under glow's position and brightness lights up the road ahead for a good 20 feet.
-It's safe(er). The under glow makes it visible at night so your'e less likely to get run over.

CONS
-It's HEAVY. By the end of spring semester I'm going to look like the hulk after carrying this board where I'm not allowed to ride. Pushing off is also going to bulk up my legs. You can SERIOUSLY feel its mass.
-The wheels suck in wet conditions. I found this out with the wooden board. If its even slightly damp you will   beef it on a corner. The wheels hydroplane really easily.
-It has terrible ground clearance. Some of the bolts in the trucks hang down too low. They catch on minor cracks in the ground. I've already chipped some concrete while riding. Thankfully the mass of the board kept me going without falling.

Overall I really like it. Even the weight of the board has become somewhat of a feature to me. When this board gets moving it doesn't want to stop, so I don't have to bail as often. I guess I'll see how it survived during the coming semester.