Date of Graduation

5-2021

Document Type

Thesis

Degree Name

Bachelor of Science in Biological Engineering

Degree Level

Undergraduate

Department

Biological and Agricultural Engineering

Advisor/Mentor

Costello, Thomas

Committee Member/Reader

Li, Yanbin

Committee Member/Second Reader

Saunders, Robert

Abstract

This honors thesis covers the planning, development, and implementation of system controls and human-machine interface (HMI) for a demonstration plant growth chamber. The work is a continuation of an ongoing project to be used as an educational and recruiting tool manifesting the skills acquired from the Biological and Agricultural Engineering Department at the University of Arkansas’ College of Engineering. This work includes emergency controls, overall design interface, and controls for both the aeration and lighting subsystems of the growth chamber. Overall design interface controls established included development of two user modes, Administrator and Visitor. The Administrator user will have full access to system controls, while Visitor users have limited access intended for more educational and exploratory use. Each of the subsystems include differing controls for administrators and visitors. Aeration system controls were designed with three modes: automatic, manual, and visitor. Automatic controls allow an administrator to determine the conditions under which the system will ventilate or recirculate air. Manual controls allow an administrator to switch aeration mode on command. Visitor controls were developed to overlap with manual controls, with the intention that subsequent work on the growth chamber project will expand upon these controls as the system is transitioned from a prototype to the final demonstration unit. Lighting system controls were broken into three segments: Calibration, Movement, and Power. Each of the segments has an automatic and manual mode, and both movement and power controls have extended Visitor control regulations. Light Calibration controls ensure proper functioning of Light Movement controls, which involve raising and lowering the light fixture. Lighting power controls tell the lamps when to turn on or off. Automatic modes maintain system 4 functions based on user-defined setpoints without requiring additional input; for example, the user can set lamps to turn on at 6 AM and off at 6 PM if they want to simulate a diurnal cycle. Manual modes allow users to directly make changes to the system functions. Visitor controls are limited to only manual commands, so they cannot make changes to system setpoints.

Keywords

Plant growth; growth chamber; logic controller; emergency controls

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