Capstone Project

Senior Capstone Design Project at the University of Colorado Boulder

August 2015 - May 2016

design team
My senior design team right after winning the People's Choice Award at the Spring 2016 Senior Design Expo. Back row, from left to right: Systems Engineer Andriy Wybaczynsky, Test Engineer Alex Enright, Financial Manager Sawyer Bluhm, Advisor/Director Stefan Berkower, CAD Engineer Zachary Ott. Front row, from left to right: Communications Director Victoria Danner, Project Manager Catherine Villa, Test Engineer Hannah Hall, Manufacturing Engineer Ashley Zimmerer, Systems Engineer Alex Karpilow.



Program Background

All undergraduate Mechanical Engineering students complete a Senior Design Project prior to graduating. Teams of five or more ME students work for two semesters on an industry sponsored project for the sponsoring client.


Interactive Model Greenhouse Senior Design Project

My team of eight other ME students and I worked on a project for Surna, a local Boulder start-up that makes agricultural technology. Surna needed a model of their 'hybrid' greenhouse, a large-scale smart greenhouse that combined the best aspects of indoor and outdoor agriculture. They wanted to take a interactive model of the product to tradeshows around the country to demonstrate its functionality to potential customers. My team worked closely with Surna to determine which aspects of their greenhouse to model.


My Role

As the Manufacturing Engineer for my team, I was responsible for reviewing our designs for manufacturability, scheduling shop time, and ensuring that our manufacturing schedule stayed on track. I also took responsibility for the complete design of the model's electro-mechanical blackout curtain system.



Design

model prototype
We designed the model in two halves so it could be opened for people to get a closer look at the different systems. My team and I built a cardboard model of our initial design so we could visualize where all the systems would go. We presented this model to Surna to get their thoughts.
curtain prototype
I built a simple prototype of the curtain system as a proof-of-concept. I thought that the curtain could be held up by a series of 'curtain rods' to prevent it from sagging in the middle. These rods would slide along a closed track as the curtain opened and closed.
curtain diagram
My blackout curtain system was composed of two identical curtains each opened and closed by its own stepper motor. This diagram shows my concept of the different parts making up the electro-mechanical curtain. Each motor would rotate a shaft fitted with drive pulleys. A loop of cable would wrap around the drive pulleys and corresponding free-spinning pulleys on the opposite side of the model. The loop would be fixed to the leading 'curtain rod', pulling the curtain open or closed depending on the direction of the motor.
curtain render
In my final design for the blackout curtain, I used a ball chain and chain sprockets like those used on a roller curtain to pull the curtain. Rather than a closed track, the 'curtain rods' hang from rails by small metal loops, to eliminate the risk of binding if the curtain slid at an angle.
iso cross section
The curtain was mounted in the hallways adjacent to the floor of the greenhouse, to minimize shadows cast by the hardware.

sprocket render
I designed a customized ball chain sprocket for the curtain system. A set screw secured each sprocket to the rotating shafts. The ball shaped depressions fit the ball chain perfectly, so the risk of the chain slipping or getting stuck is minimal. The final parts were 3D printed and are easy to replace, should the metal chain wear down the plastic over time.
motor render
I designed special plates to secure the stepper motors to the floors of the hallway. The motor bolts to the plate, and the plate bolts to the floor.

Manufacturing

motor mount draw
This is part of the drawing I used to manufacture the motor mounting plates.

machining
I made one plate for each motor. I manufactured them at the same time, stacking the aluminum plate and using a CNC mill to cut them out.

Testing

motor driver
I used a motor driver board with each of the stepper motors. I tested each motor on a breadboard with simple code.
arduino
I uploaded the test code to control the motors to an Arduino-like board. Once the motors behaved as intended, I hooked them up to the custom board we used in the model.

assembly
I integrated the curtain system with the rest of the greenhouse to test the functionality of the code. This also allowed me to determine how many steps each motor should take so they would stop when the leading edges of curtains contacted the walls.

Result

greenhouse expo
The model worked beautifully. When the 'sun' reaches a certain position, representing how many hours of light the greenhouse receives, the control system closes the curtain. Users can also operate all systems independently, including the curtain. The model greenhouse won the People's Choice award for excellence in design at our Senior Design Expo. Surna was impressed with the quality and interactivity of the model, and planned to begin showing it at tradeshows soon after.

The model curtain works exactly as designed.


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