NASA TETRIX Projects

Archive for July 7th, 2011

Day 3: Thursday, 7/7

by on Jul.07, 2011, under Week 1

Today we started the science intro and finished the holding bots.  Also, at 1pm, Jim Hoffman,
the Machine Shop Coordinator, took us on a tour of the Machine Shop in Bray.

For the science intros, I reviewed the Massachusetts engineering design process and it’s 8 steps.  Also, we researched possible NASA science ideas and came up with a list of possible ideas.  The list included physics project ideas and a PH analyzer, but mostly was different rover ideas.  We decided the final groups would be Dean and I, Lawrence and Jess, and Sarah and Briyana.  Lawrence and Jess decided on an Axel Rover, Sarah and Briyana decided on a crater detecting rover, and Dean and I decided on making a combined Space Elevator/Lunar Lander.  For that idea, the students would build a TETRIX robot that climbs a nylon cord, simulating climbing a space elevator.  A fan would simulate wind in the atmosphere and an ultrasonic sensor would slow the robot as it approaches the ceiling.  On the way down, it would have to slow down and land on an uneven surface.

We also finished the holding robots, focusing on the design process.

Lawrence/Briyana’s final robot worked well; previous version’s had a glitchy grabbing arm for holding onto other robots.  The only flaw was that the omni wheels provided by the TETRIX kits were so wobbly that no matter how they were attached, the cup of water would spill.  The CD was held in place by rubber bands forcing a pressure fit of two metal parts: strong enough to hold the CD but weak enough to allow a CD drive to pull the CD into itself.

Dean and Sarah’s final robot worked incredibly well: the wrench could spin 360 degrees, the Nintendo game was securely attached, and the change was held in a simple, modular compartment; it could be easily attached/detached and easy to build.

Jess and I’s final robot was unfinished since we hit the maximum build time.  The calculator was easy to mount as the edges of the TI-83 slid perfectly into the metal pieces; the width of the metal pieces is the same size as the gap on the edge of the calculator.  The screwdrivers were also easy to mount; their handles were larger than their shafts, so they could be slid into place and then suspended higher up with spacers.  The pencil/pen/sharpie however was a disaster as they were seemingly impossible to mount at first. When we finally came up with a solution (by rubberbanding them in place), we ran out of time. -Nicolas

Holding Project’s Design Process
Written Exercise:
The Steps:
1. Identify the problem
2. Research the problem
3. Develop possible solutions
4. Choose the best solutions
5. Construct a prototype
6. Test and evaluate prototype
7. Communicate the solution
8. Redesign

Jess:
1. Hold calculator, writing implements, screwdrivers
2. Trial and error with designs
3/4/5/6/8. Frames for calculator slots, tubes for screwdrivers, tube clamp for writing implements (the tube idea ended up being thrown away later in the design process (redesign).  A lot of trial and error went into the design phase.  Ideas were thought up and then mocked up sans screws, with some seeming better than others.  The best ideas were individually constructed based on function.  Putting them together is when problems arose. The tubes were shown to not work in this situation, as they didn’t attach well.  A lot of complex ideas were thrown away for simpler ones.  The wheels were really flimsy when we used LEGO axles, so we instead remade them with screws.  Finally, the individual writing holders were abandoned for a single, rubber-banded stick.  The only original idea to last was the calculator holder.
7. The only step we didn’t do is communicate, as we didn’t have time.

Briyana:
1. Finding a way to hold a CD without restricting the CD from being pulled out.
2. Rubber bands work to hold the CD in place.  Wheels could also work to move the CD through (small/big)
3.  Put two wheels together on each side of CD to guide through. Rubber bands hold in place.
4. Rubber bands and wheels to guide when pulled and hold in place.
5. Built around till we had a working prototype.
6. Holds everything; omni wheels however cause water to spill
7. Showed it off
8. Wrap rubber bands around prongs 3x for tight non-restraining hold. Don’t use omniwheels

Lawrence:
1. The problem was that  I had to make a robot that could hold a cup of water, a CD, and a crane to attach to other robots.
2. I didn’t do much research.  I just did trial and error, which in retrospect was bad.
3/4.  Our solutions were zipties and elastics because we needed the CD to be takeable, and they worked.
5. We made the CD holder tighter, we made the walls for the cup so it wouldn’t fall, and we made a long crane to attach to other robots.
6. The prototype holds CD steady and the cup is held securely, but when the robot moves the shaking caused by the omni wheels causes water to spill.
7. Handing in a written piece of paper containing this info (steps 1-8)
8.  Kept having to move crane up and down and added sides to keep from sliding off.

Dean:
Difficulties: Screws  are sometimes hard to reach, sometimes stuck, and the edges of the nut hurt to screw into place. Also, not many pieces.
Process: After starting out with a base, the attachments were redesigned to work and fit together. The game holder had to be redesigned to accommodate the wrench pivot device.  Upon realizing that the NXT brick had to be included, we had to find space on the base and we also tried out various brick support structures.  The omnidirectional wheels were originally to be on the outside but we decided to place them inside to give a sleeker look and coserve space

Conclusion: The majority of time was spent building, rather than thinking ahead.  This is both because people preferred to just build and use trial and error, but also because the unfamiliar TETRIX pieces take a long time to put together.

Daily Thoughts:

Dean: The machine shop tour was slightly boring and a little long, but the machines were cool.  Science ideas: I thought the space elevator idea was pretty cool.

Lawrence: This day was an interesting day because we got to visit the machine shops and I’ve always been interested in different types of machinery. One thing that was really amazing Jim showed us was this robot that was built and it could drive in another room an it had a camera on it so that when you put on the virtual reality goggles you could see everything. It really amazed me when I saw it. Also during day 3 we found the YouTube video of the NASA Axel Rover that was awesome. We decided to make a prototype of it because it was so cool.

Jess: I hadn’t previously known that Massachusetts has its own engineering design process. I also found it a bit difficult to brainstorm ideas for a robot and then isolate one good one. Despite this idea generation being the goal of this day, the idea for the Axel Rover technically did not come on this day. Seeing the machine shop was also pretty cool. Since my school is so small, I have never been inside an amateur machine shop, let alone a university one with advanced machines like the CNC. The CNC was pretty cool.

Sarah: I had the idea to mount the wrench on our robot using an axle in a vertical position. When the robot was completed Dean decided that he was going to turn it into a tank using the vertical axle to hold the turret.

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