Tuesday, August 27, 2013

Start of 1st Project

Hello my name is Jordan Yamada and this will be my engineer's journal and documentation for the class intro to engineering design. Today we were assigned group and I was teamed up with Alison Lanzi another student in the class.
So far I've looked at the challenge which is to design and build a car using a mouse trap spring as a mechanical source of energy. The way I see it, since I'm on the RPI Formula Hybrid Racing team and have worked a bit with race car dynamic, getting the energy from the spring to the wheels of the car is the most important thing. Doing some research I've found that to do this most simple designs use line of some sort to wind around an axle. Then as the trap is released and the string is tensioned the line unwraps and transfers the energy to the axle and thus the wheels. To extend the amount of travel of the spring they suggest adding a longer lever arm which pulls out more line.
One idea that I had was to make the actual axle that was connected the spring, directly, or through a gear ratio, to drive the back wheels. This would emulate pull back windup toy cars. I don't have much experience with the springs or the mouse trap itself so I’m not certain the ability of me to implement that design. Also seeing as though I might not have enough time to really get my head around it, it might be more trouble than it’s worth. Another thing that this system has either going for or against it is since the spring is always directly connected to the axle, when the spring runs out the travel the spring will stop the car. This is will either make it have a braking system which is great when we need to stop at a certain mark, or the travel will be so short that the car can make many revolutions without a huge gear.
Another idea I had was adjustability. The Idea isn't flushed out yet but maybe trying to make certain components out of threaded rod would be great for fine tuning, such as attaching the wheels (e.g. 2 nuts on a bolt) for a wheel alignment.

Lastly I was also thinking about the wheels themselves. I really don't like the cds and hobby type wheels seen in some designs. One because of the low co-efficient of friction means that energy isn't getting the wheels, and because they seem flimsy. I was envisioning something more like Lego wheels with rubber tires for grip. I made a mock up to see how they interacted with the ground and it seem to fit my needs. Also another thing might be wheel  tow in, which would make the car self-correct straighter but might also make it more prone to friction.
Random Frame with Wheels to Better Understand Dynamics

In any case I think this little brainstorming session was good and that I can maybe start mocking up a table of some sort to see what are the pros and cons of each idea. Also getting the material would be a big advantage because then I can actually experiment and measure some of the materials so I can start doing CADing of my ideas to show to my partner and the teachers.
Sketches in Notebook