Fire Fighting Robot- Part 1

For our final project in this class, the challenge is to make a fire fighting robot. We can use and build upon our existing MotorCar and use a mechanism primarily built from laser cut parts. The goal is to extinguish a candle that will be placed 10 feet away from the MotorCar. The car will not be necessarily placed directly facing the candle. We are also limited to one motor to power our mechanism.

Esther and I first started brainstorming about different ways to put out a fire. We needed to think of a clever, yet simple, idea that would get the job done because we knew that we did not have a lot of time to complete this project. So we had a few ideas:

1. snuffing the candle
2. using vinegar and baking soda
3. "pinching" the flame
4. throwing a heavy fabric on top of the flame
5. using a spritzer

In the end, we decided to go with the spritzer idea because it put out the flame effectively and also because no previous groups, that we know of, had used a spritzer. For example, we really liked the snuffing idea, but a previous group created a really cool robot with a snuffer and we really wanted to be original.

So we looked at the spritzers that were located in the room. We decided to use the green and white spritzer because it had the most powerful spray and because it had a longer handle which would help us get a good grip on it. We knew that the size of the bottle were too big and would probably make the MotorCar topple over, so we had to find a replacement.

Now that we knew with what we were going to extinguish the fire with, we had to figure out a mechanism to actually do it. We decided that it would be best to pull the handle in repeatedly until the candle was out. We thought that we could attach a string to the bottle, which would lie on the handle and be pulled on the other end. The question now was, how to pull the string back a forth?

We looked at previous motion modules. For example, like the one below. We could tie the string to the end and have a motor rotating the circle piece, which would pull the string and in the end pull the handle in. The good thing about this mechanism is that we could just continuously rotate it would just move the string back and forth.
So using that motion module, would be relatively simple but the problem is that we didn't know how strong it could be. It takes a certain amount of power to pull the handle in and we didn't think that this motion module was powerful enough for that. So looked at a different mechanism. This time we looked at a project from last year and we were intrigued with their idea. Below is a picture of it. As you rotate the gear, the Lego blocks contract and extend. This is the kind of motion that we were interested in and it looked a lot sturdier than the other motion module. It is a bit more complex than the other, but we thought that it would be more effective.
Now we had to think of various ways to place all these elements on the MotorCar. This was a bit tricky because had to make sure that the MotorCar and our bottle wouldn't topple over and that our mechanism wouldn't get in the way of the photo transistors and breadboard.

Here are some our sketches describing the motion that we wanted and how we wanted to design our robot.


I went to a convenience store and bought a small bottle to which I attached the spritzer. Here is a picture of it:
We tested it out just to see if it would still work and it did! So now that we reduced the size of the bottle, we were able to start modifying our MotorCar. We decided to place the spritzer in the front of the MotorCar above the breadboard. We attached the photo transistors to the side in the front, so that nothing could interfere with them. Because the spritzer is placed so high, we knew that would have to use a tall candle.
Then, we wanted to incorporate the mechanism into our design. Instead of directly creating the pieces on SolidWorks, we wanted to see how it would fit on the MotorCar so we could make precise measurements. Below is a sketch of our motion module:

Instead of having a gear to make the motion module move, we wanted to directly attach the pieces to the rotating motor. Professor Turbak said that it was possible to press fit a wire on the delrin with the motor, so we would definitely use that technique to attach the two pieces. We made a model in Legos and made a foundations on the MotorCar to support it. We would use the exact same dimensions as the Lego pieces when creating our pieces on SolidWorks. We also have to imagine that a string would be attached to the end of the mechanism and to the bottle. Here is a picture of what our basic design looks like.