Duke Gardens Cold Frames Project
Our project focuses on the problem of the cumbersome and unreliable operation of two cold frames located in the Discovery Garden of the Duke Gardens. A cold frame is a type of greenhouse that acclimates plants that have been in greenhouses to the climate of a specific region. In order to do this, the frames need to open when it is warm outside and close when it is cold. The initial problem was proposed to our team by Jason Holmes, the curator of the Doris Duke Center Gardens. He explained that the staff at the Duke Gardens have to raise and lower the lids manually based on the outside temperature. He related that this process was time-consuming and unreliable because the staff could not monitor the frames all day and night. Therefore, he proposed the idea of creating an automated, temperature-dependent system to open and close the cold frames. This solution would minimize staff maintenance of the cold frames and guarantee safe growing conditions for the plants inside of the cold frames.
The original team began this project as part of last year’s pilot of the new freshman design class, EGR 101. The team began last fall by completely and exhaustively analyzing the problem through research, meetings with the client, and meetings with technical mentors. We then developed and ranked design criteria and constraints, making the goals for the project clear and setting up a basis from which to evaluate potential solutions. From here, the team transitioned to the solution phase. The team brainstormed different solutions and then began to evaluate and combine them. The team completed a morph chart and Pugh scoring matrix in order to select their final solution. The final solution was an Arduino-controlled winch system with lid props to hold the frame up when operated by hand. Next, the team began the prototyping phase. The team began with low-fidelity models, and then constructed a medium fidelity prototype. At the end of the semester, the team had created a medium-fidelity prototype with two winches, a hand-soldered PCB, and temperature sensing capabilities.
Determined to finish, three of the five team members committed to another semester’s worth of work in the half credit course, Design to Deliver. One member was added, Trevor Fowler, who joined from another team once he had successfully completed his project. In this course, the students work to prototype their project until completion. The team worked to improve their system by adding hall sensors to create a closed-loop system, printing PCB boards with Christopher Bingham, and building a high fidelity prototype to serve as a testing rig. However, the team was unable to finish the high fidelity prototype by the end of the semester due to the poor connections between circuit boards. With no high fidelity prototype at the end of the semester, we failed to progress as far as we had intended. Nonetheless, we held a technical review meeting, at which a board of professors assembled to evaluate the project and provide new perspectives on what progress still needed to be made.
Unsatisfied, Connor decided to stay for summer term one in order to finish the high fidelity prototype and reorganize the milestones, timeline, Gantt chart, and organizational structures of the project. He was successful in his endeavors and has set a baseline for efficient prototyping for the project.
This semester, only Connor and Trevor returned to continue work on the project. They are working in the Foundry under the name of “Gardens Project.” Their recent work is focused on finishing the milestone of updating the code and circuitry of the project to meet all required functions of the system and to account for any errors that may appear.
Connor Johnston, Electrical/Code Lead, Pratt, 2021
Trevor Fowler, Mechanical Lead, Pratt, 2021