Electric Chair

Attributes linked to this design project (CEAB's Graduate Attributes):

> Knowledge base for engineering

> Problem analysis

> Investigation

> Design

> Use of engineering tools

> (Individual and) Teamwork

> Communication skills

> Professionalism

> Impact of engineering on society and the environment

> Life-long learning

INTRODUCTION

Putting both my engineering and design skills, close to the end of the first semester of Engineering Science, while working with my Praxis I team on solutions to the problem students at UofT face while locating vacant study spots, I came up with the idea of making a chair that indicates someone sitting on it. I searched the web but could not find anything like what I had in mind, so I was unsure if it was feasible. I discussed my idea with my team, and they loved it and asked me to work on it.

DRAFTING

I initially made a quick draft plan in 5 minutes with different possible ways I could approach the task with different mechanisms and the materials I would require putting it all in one piece and making it operational.

CAD MODELING

I used Autodesk Fusion 360 to create a to-scale 3D model of the chair’s in and out, and the display used to indicate the seat's vacancy. 

PROTOTYPING

I finally got the materials and used power tools to accurately cut the outer body of the chair, display, and box to be inserted in the chair to act as a switch. After many hours of working on it, I finally completed my initial prototype. I assembled all the pieces. Now was the time for the wiring, so I initially connected everything in series. My initial design turned on the light on the display when someone sat on it. I then tested it 100 times by sitting on it and getting up 100 times. It turned out to have a 94 percent accuracy. 

DESIGN IMPROVEMENTS

After getting input from my team members and colleagues, I realized that it would be easier for people if the light turned on the seat was vacant, so I modified my design accordingly. I also replanned my circuit layout and connected everything in parallel, allowing multiple seats to be connected to a single display. I looked further into my design and worked out ways to increase efficiency by modifying the internal mechanism of the switch. In my new design, the circuit always remains closed when power is being supplied to the display and chair and breaks when someone sits on it. From the start, I made a loop inside the chair using bolts, but this time I also bridged the circuit inside the chair so that if one of the bolts failed to work as desired, the chair would still do its function. This time, after testing it 100 times myself and letting others test it for another 100 times, the accuracy turned out to be 100 percent. 

EXPERIENCE

Through all this experience, I was able to apply my engineering knowledge to engineering design and learned how to assess and improve an existing design. It has also polished my communication skills, and I have learned how to appreciate others’ opinions and improve my work accordingly.