Testing Mechanism Team

In order to monitor the Beta system’s water quality at all times, the team designed an automated testing mechanism in Fall 2017. The testing mechanism currently has a temperature sensor and a pH sensor with plans to add other water quality probes. The mechanism makes use of an Arduino microcontroller as well as a Raspberry Pi single board computer, and involved designing and building a circuit, machining various parts, 3D printing component housing, and coding for lever movement and data collection in Python. A motor powers a lever arm holding the test probes into the water for the duration of the test, and is raised following test completion. Limit switches and a potentiometer relate positional data to the Arduino and the Raspberry Pi, which make adjustments to the height of the lever arm accordingly. Tests can be run remotely from any device using Slack Messenger, and record data in a Google spreadsheet.

Finalizing circuit connections before adding to its housing.

Final Circuit Design

Circuit Design Basics:

The Raspberry Pi is essentially a miniature computer that allows us to read and write data from the connected sensors to Google Drive. It is connected to an Arduino microcontroller, which reads analog signals from a potentiometer, and converts them to digital signals. Limit switches are located on either side of the lever arm. When activated they send a signal to the Raspberry Pi, which then stops all motor movement, leaving the motor in the wait position. The potentiometer is additionally attached to the motor to relay positional data. The circuit also contains an H-Bridge to allow for back driving of the motor.

The motor in its housing as its function is being tested.

Motor, testing arm, and housing design.