Final Project: Week 1

This past week and a half, we began to work on our final project. Before break, we visited the place we would implement our projects and brainstormed ideas that addressed some problems we saw/heard about.

Xixi and I came up with two ideas – one that would monitor water levels in the water play area and one that would make sure hands were washed properly.

We were assigned the topic of using feedback and control to ensure proper hand washing.

Now that we knew what topic we would pursue, we began to brainstorm different ways of presenting the process visually, as our targeted users interpret information better when it is visual. This made us prioritize the visual aspect, as we knew that we would be able to figure out the programming and mechanisms behind it after selecting the best prompt geared toward our audience.

We came up with a few ideas, with variations.

In each, we needed to have 8 sections on the visual to prompt the 8 successive steps of washing one’s hands.

The first idea we had was a rotating wheel with an arrow that indicated what the current step in the process was.

The first design had the indicating arrow pointing down and the second had the arrow pointing up with a light directly above it. The idea was to have the servo rotate the wheel showing the steps of washing while the light drew attention to where the audience is supposed to look to see the picture of the step.

 

The second idea was to have a system of arrows and lights that lit up in order. We realized that this was a little too abstract; an arrow pointing to the faucet that means turning the water off may not be clear to our audience.

The next idea we had showed a more linear approach to depicting the steps.

A strip with all the steps would run through a box, into which was cut a window so that the current step was framed inside the box.

The final few ideas we had were generated on this design:

The basic idea was to have a linear strip that moved laterally, with an arrow that indicated the current step.

We thought of having lights to further draw attention to the step: Either lights on top of each step lighting up in succession, or backlights that did the same thing.

We also thought briefly about how we might get the arrow to move across the strip. We immediately thought of gears, but were unsure of how to realize this idea.

Before we could go further, we needed to make an appointment to get feed back about our project. We met with the head of the program to ask questions.

Our first and most important question was to ask for input about which design would be best for our audience.

A: Our specific audience interprets visuals much better when they are linear, rather than rotating. (That narrowed it down to 2 ideas.) It is also important that they can see what will follow the current step.

Based on this answer, we went with our last idea.

Q: Would an arrow suffice to indicate the step? Or would lights help? We noticed that the bathroom is well lit so backlights will not be that helpful.

A: Too much visual stimulus would detract attention from the picture. The arrow will be more than enough.

Q: Is there any specific color that draws attention, but not too much?

A: Stay away from pink/purple, stick with primary colors if necessary. A bold black arrow would probably be the best.

Q: Can we clarify what the 8 steps of washing your hands are?

A: Roll up sleeves, wet hands, turn off water, get soap, rub hands, rinse hands, turn off water, dry hands.

We asked to see the bathroom. We began to formulate ideas about where to place sensors.

Q: If we placed a sensor beneath the edge of the counter, a little behind flush with the plane, would they notice?

A: Not very likely.

Q: Do they lean up against the counter while they wash their hands?

A: Yes.

We then took pictures of us completing the 8 steps and went back to the lab to compile our information.

We had our design and valuable information that would help our design process. We then began to think about the mechanics of our idea.

We brainstormed about what we would need for this project.

In order to incorporate feedback and control, we thought of two ways that would use input from the audience to run our idea.

1    1)Ultrasonic sensors recognize when somebody is “ready” to wash their hands. We would have the ultrasonic sensor take a reading, and if the reading is below a certain value (indicating proximity), the program would start.

      2)   Another sensor that would determine if the audience had turned off the water. It would prevent the program to run further without this step being completed. This is to conserve any water that may otherwise be wasted.

Looking at the other mechanics:

Our first challenge was to recognize the limitations of servo. We originally overlooked that servo can only turn 180 degrees. This created a problem with our idea of using gears to move the indicator. This limitation made us change the length of our picture strip while also creating the need for a gear train so that the indicator could move across the strip of pictures in 180 degrees of turn in the servo or less.

Each step of the process became 1.75” wide (8 steps, = 14” total).

Our gear train had a 1:5 ratio: Each turn of the 40 tooth input gear would result in 5 turns of the next 8 tooth gear. This gear was directly attached to another 40 tooth gear, so that gear would also turn 5 times every time the input gear turned once. However, Servo is only capable of turning a gear 180 degrees. This leads to the second 40 tooth gear turning only 2.5 times. But this correlates to the 14” visual strip.

After initially exploring gears and pinions, we had decided to advance with gears and treads to keep the design compact. We played around with the number of individual links in the chain. With exactly the number of links to complete the gear-pulley system, the system would work. However, if we added a single link to the chain, it became much easier (torque required decreased) to move the gear train.

Here, there is the extra link in the chain.

We created the indicator in white for now. We will use delrin and press fitting to create the two parts.

We decided to place the indicator on top so that it would make the design more compact. The chain, having that extra link wouldn’t sag below the picture strip because of the weight of the indicator. This allows us to place the strip in front of the gear train/pulley system to decrease the amount of mechanisms that show. This minimizes the distraction to the audience.

Our final adjustment of the day was to connect the input gear to the servo motor. We used piano wire to attach the gear to the rotating face of servo. We have yet to test this modification.

We will need to construct a shelf and/or support system for this, because it will be mounted on the wall for easier access.

Next, we want to address where we would put our sensors. We have an idea for a system of ultrasonic sensors, but we may only need just one.