Low Cost Sensors and Greenhouse Control Systems: Raspberry Pi

While many automated agricultural control systems are expensive and geared towards commercial operations, a little Raspberry Pi is perfect for home growers. A single-board Raspberry Pi (originally developed to assist in computer technology needs in poor countries) works great as a controller for a bunch of single program operational micro-controllers like Arduino’s that can be looped indefinitely and will do simple and repetitive tasks.

The device is perfect for a hobby greenhouse.

“I call these folks micro-culture growers,” says Brian Little, agricultural and biosystems engineer and systems administrator at the University of Arizona. “Sophisticated environmental monitoring and control systems like those found in commercial controlled environment cultivation can often be cost-prohibitive, but a single board Raspberry Pi is inexpensive and works great as a controller that can be connected to a bread board and a ton of sensors. It’s a cheap way to monitor lighting, irrigation, water quality, humidity, temperature, wind speed, hydration rates — all kinds of applications to help the small grower. You don’t need scientific accuracy just to grow some tomatoes in your backyard, and slaving a bunch of Raspberry Pi’s together will do the job needed without any bells and whistles.”

Little explains further that a home grower can easily build a redundant system with more than one control in operation, should one happen to malfunction.

Read also: Artificial Intelligence and Controlled Environment Agriculture

“Build yourself something small to accomplish your needs. Don’t be afraid to try something new, because when your price point is less than $50, you’re less afraid of frying or bricking one of these devices and because of the limited dollars involved, it allows for a redundant system. The beauty of this is you can have several controls and if one goes down, it’s not going to take out your whole system.”

Billing himself as a pioneer in heuristic engineering, Little is a proponent of building an urban microculture entity that would target urbanites with a blockchain-based app to allow them to get started on growing their own food more efficiently. Based on local information, it would provide recommendations on what crops to grow, how and when — kind of a socially motivated data base of information that easily accessible for anyone.

Little recently returned from the Global Forum for Innovations in Agriculture in Abu Dhabi, where he presented his research on low-cost technology. His message was: “Recent advances in technology, like Raspberry Pi, Arduino, and other off-the-shelf products, have made a plethora of options available for low-cost sensors and controls to assemble do-it-yourself systems that will facilitate crop optimization.”

Little has built units that will sense low light and open a shade for more sun, or gas sensors that will monitor air quality, or note the presence of methane. He’s used the simple technology to rig a small container farm with integrated systems, everything from water quality monitoring to measuring pH, temperature, and dissolved oxygen, adjusting humidity, and even a fogger application to keep mushrooms moist. He’s rigged drones with a cheap camera system to automatically pollinates date palms.

Read also: Understanding the Microclimates in Your Summer Garden

In Glendale, AZ, he’s working on solving a bird problem at a dairy. “It’s biblical,” he says, “so many birds they blot out the sky. We created a bank of Raspberry Pi cameras and a control module that implements computer vision to detect the birds — and emit some sort of deterrent to send them on their way.”

Bottom line for Little is the DIY way for smaller-scale growers can be a viable alternative to commercial systems but, he adds, “By no means is a DIY system on par with a Hortimax controller.”

The old adage “size doesn’t matter” really does in this case with Little conveying the caveat he’s promoting the inexpensive, do-it-yourself approach “for small- and medium-scale food production.”

Bottom line? If you’re a small grower who likes to experiment, you belong to the group of backyard pioneers, the Carpe Diem group — seize the day. If your operation is larger, to the point where any sort of a process malfunction could damage crops beyond the required market quality condition, you probably belong to the Caveat Emptor sector — buyer beware.