Friday, July 23, 2010

Day 14- Let's get gardening!

I'm back, and diving right into the final project. My partner and I are designing a robot that can measure the water levels in soil, and water the soil accordingly. It uses the new Vernier water level sensors.

The front of the robot has a mechanism that moves up and down to poke a 3 inch hole in the soil, and place the sensor in the hole to read the water values. Then, according to our program, if the water levels are below a certain value (yet to be determined), a servo controller will rotate a certain number of degrees (also yet to be determined) to raise a pipe. The pipe covers a hole in the bottom of a plastic bin filled with water; when the pipe is raised, the water pours in a small stream out the bottom of the bin.

Note: This description is the result of continuous trial and error, as our initial design used a water bottle and sliding plate to release the water. The bin, found conveniently in the storage closet (old junk can be so useful sometimes!), was more sturdy and could hold more water than the bottle.

We chose to divide up this ominous task into two parts:
1) The front of the bot that digs the hole and places the sensor.
2) The back of the bot that releases the water.

I chose to work out the watering mechanism, and began by rummaging in the storage closet to find a plastic bin (again, useful junk!). I then designed a platform to hold the bin in place, and, to my general excitement, it fit perfectly! It used four corner pieces attached to the flat base to form a "cradle" of sorts.

When constructing the original plate that was supposed to slide out from under the plastic bin, I realized that it wouldn't stay tightly enough to the bottom of the bin to hold the water in, and there was no Tetrix piece that would function as a movable cover. All the plat pieces had holes in them for attaching other pieces. The holes do serve a useful purpose, but in this case, they were a nuisance! Eventually, I concluded that I would need to cover the hole from the inside of the plastic bin, and the pipes seemed to be the best piece for this purpose. So, I built a stand for the Servo motor and connected it to a pipe so that the pipe was directly covering the hole in the plastic bin. By the end of the day, I was in the process of attaching the pipe to the Servo motor, so I have yet to test the effectiveness of this method.

It's good to be back~ ^_^

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