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The COSI project has begun its development after the team meeting on February 26th. The highlights of the meeting were the modifications from the Design Review, project timeline, and task/group assignments.

It was noted from the Design Review on February 20th that the design should include an aspect of fun, as to inspire interest in potential viewers. Because of this, the team decided to structure the exhibit as a competition, having users try different levers and compete against friends/family to get the highest score. There is also potential for a “high score of the day”, letting users see how others have measured up.

Another topic discussed was the actuation point. Little thought had been given to it until the meeting on the 26th. A few ideas were suggested for users to input force. One idea had a rope hung from the actuation point and letting users pull down, allowing for easy actuation of body weight. Yet another idea had a handle at the end with users pushing downward at waist-height to input force. In the end, it was decided that the latter idea would work best, since it would make it easiest to control the input force from users.

An example of a handle that could be used

After deciding on the method of force actuation, the team needed to discuss initial specifications for input force range. Two main quantities will be analyzed: absolute maximum input force and typical input force. Various numbers were thrown around, including 75% of user body weight as a typical input. However, if a user jumps before pushing on the handle, it could be possible of up to 150% of user body weight. In the end, no decision was made and further investigation was deemed necessary.

The final, and primary part of the meeting was to discuss tasks and timelines. While the complete timeline from the meeting can be found from the meeting notes, the highlights were a total time of 120 hours of work (about 17 hours per person for a group of 7), with SolidWorks drawings estimated to take the most time.

As stated before, the main areas of interest will be

1. Spring Fixtures
2. Tension Spring
3. Lever Beam
4. Fulcrum Bearing
5. Bearing Pin
6. Bearing Fixture
7. User / Setup

The team decided that having multiple members in each team would be best, since workload could be divided up. The meeting notes depict the full setup, but I was tasked with the Lever Beam, Bearing Fixture, and Tension Spring teams.

As a whole, the meeting on the 26th gave a rough idea of the workload required for the project. Although we estimated the time for each item, it is expected to run into countless issues. Because of this, the team will get started as soon as possible.

With the in-class design review today, it seemed like a good time to begin documenting the process. It started with 7 potential designs and one was chosen to move on in the process.

The design, titled “The Siegel Seesaw” after team member Jordan Siegel, clearly displays the factors that affect torque and spring forces. The design is simple yet interactive, allowing users to try pushing on various levers to investigate the resistance of the spring.

Since the mechanical advantage of a lever depends on its lengths, they will be varied to demonstrate torque. In addition, different sizes of springs will show how a spring resists changes in length. Users will clearly be able to compare displacements using a set of lights that illuminate with increasing displacement.

The basic setup of the Siegel Seesaw

Now that the design has been selected, team members must be assigned to each component of the project. After a quick brainstorming session, the team decided that the following elements must be analyzed:

1. Spring Fixtures
2. Tension Spring
3. Lever Beam
4. Fulcrum Bearing
5. Bearing Fixture
6. Bearing Pin
7. User & Setup

With these initial areas, the team set out to investigate reasonable parameters for the design to create the best exhibit possible.