Lego Mindstorms MOCs: October 2013

This one's probably going to need a bit more explanation that usual.

So, my engineering course at university began with a Lego Mindstorms activity. In groups of three, our task was to create something that demonstrated an engineering principle: typical projects included pendulum clocks, balances and steam engine simulators.
We decided to measure the coefficient of restitution (a.k.a. bounciness) between a ball and a plank of wood, resulting in the contraption you see on the left. The way it works is that the claw drops the ball, which passes a light sensor (on the pulley) first on its way down and then for a second time on its way back up. Using the time taken for these two events we can calculate the coefficient of restitution and, from that, the height of the peak of the first bounce. To demonstrate this, the pulley then shifts upwards to the newly calculated height while we reload the ball; all being well, the peak of the first bounce should be at the height of the orange Bohrok eye pointer. Calculating the heights of subsequent bounces would be a fairly simple process, but by then the bounce would be too low to indicate.

But of course, the staff at the Engineering Department couldn't place two large boxes of Lego pieces on my desk without expecting me to tinker with it! On the right are the five miniMOCs I made. They are as follows:
- Wall. Originally this was the platform off of which the ball would bounce, but it was far too small and fragile for this purpose. The plate is actually the unused battery cover for the NXT brick!
- Tyreman revisited.
- Bopper. Our initial plans for the project was to catch the ball at a particular height, using a mechanism consisting of two tyres pressing together, but this proved to be too ambitious. I kept one half of this capturing mechanism and adapted it into a handheld device, where the tyre pushes forwards as you spin the cog with your thumb. I used it to bop people's noses.
- Cart. Something to hold the ball while we weren't using it, to put it simply. When you pull the cart in one direction, the ball appears to roll in the opposite direction, which is fun.
- Pistol. By far my favourite of the bunch, unsurprisingly. As you pull the trigger, the technic beam pushes down on the ammunition, letting it fire! There is also a safety catch you can activate to prevent the pistol from firing, since it is pretty sensitive.

_{Lego Mindstorms (c) Lego
Designing, building and photography (c) Me and my two comrades}