Incuvers Mechanical Stage

Project Description:

To develop a solution for automating the focusing process of a microscope camera in an incubator. This process is required to keep material in an observable state during remote observation when manual adjustment is not possible, or would be inconvenient. The specifications of the proposed solution are a 10cm square platform that is translated vertically via stepper motor to a resolution of 2 microns. The software responsible for controlling the stage is written in python (version 3.7) and executed on a raspberry pi 4 running a Raspbian or Ubuntu operating system.

The incubator designed and manufactured by IncuversTM is designed to provide scientists and biologists with an observation platform as convenient as possible, including remote monitoring and recording of specimen. Currently, the model includes a separate stage that is placed inside the main box and manually adjusted to bring the observed materials into focus.

Our solution is as follows: Considering the stage resolution IncuversTM requested, it was determined that the versatility of a stepper motor would provide the most precise position control, and finest adjustment. The stepper motor utilizes a 2mm pitch threaded rod and a micro-stepping driver to meet the 2 micron resolution. The driver design is based on an A4988 micro-step stepper motor driver, which allows up to 1/16th of a step, which would provide a step as small as 0.1125°. When considering the 2mm pitch of the threaded rod, could provide a vertical resolution of 0.625 micron, well exceeding the requirements defined by the client. Since the signals controlling step and direction require 5V inputs, a level shifter was implemented to the circuit to shift the 3.3V logic form the raspberry pi to 5V. The Raspberry Pi 4 is running a python based computer vision program utilizing the Open CV libraries to evaluate for an image capture’s grayscale brightness. By analyzing captures taken throughout the range of the platform’s span, the best point of focus can be determined by the brightest image. Optimizations to the system were included, such as a modification to the image area under analysis, and the number of reading averages taken were included to provide finer control to the speed and accuracy of the system.

As a team, we primarily learned about project management. We were able to stay on track and managed the project by having weekly meetings to discuss progress to date and what was left to do. We divided up the work into 3 main parts and assigned each group member a specific task. This allowed us to be more focused on the task we were assigned. We also created a project plan/Gantt chat to help the whole group with time management and to ensure members took responsibility for their work.

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