Multi-Sensor Modules Ease Indoor Agriculture Design Challenges



 

Controlled-environment agriculture employs technology so that it is not dependent on expensive arable land, embracing the Industrial Internet of Things.

Controlled-environment agriculture (CEA, also called vertical farming due to multistoried facilities that house the crops and infrastructure) is a promising niche. By embracing the Industrial Internet of Things (IIoT) and employing fully enclosed, climate-controlled environments to eliminate external factors such as disease, pests, or seasonal weather variations, yields of plants such as leafy greens, herbs, and tomatoes can multiply dramatically. The technology is not dependent on expensive arable land and is therefore suitable to establish anywhere—including the center of urban communities.

Behind the high yields that vertical farming generates are some leading-edge electronic engineering developments that include wireless sensors, mesh networking, and cloud connectivity. The infrastructure is vital for the success of a CEA enterprise, but it adds costs due to the complex and time-consuming design, commission, and configuration. The engineering expertise required to build and the costs to purchase today’s CEA limits its adoption to large, rich organizations and discourages the spread of the technology to places where it could have the highest impact, such as in the developing world. However, electronics manufacturers are working hard to change this trend by introducing products that combine multiple sensors, which are essential for successful vertical farming, into a single module, making it much easier to implement and shave down costs.

A Tricky Enterprise

While vertical farming is gaining momentum, as this global CEA market hit about $1.5 billion in value in 2016 and projects growth of about $6.4 billion by 2023, its adoption is currently limited to rich countries, analytics company Statista reports. Research analyst MarketsandMarkets notes that China, Japan, Singapore, the United States (US), and the Netherlands are by far the biggest players. Likewise, though the LEDs, wireless sensors, Internet connectivity, and online software and hardware resources required for vertical farming are proven and accessible, large commercial implementations are rare. A major reason for the relative scarcity is that CEA systems are challenging to design and implement.

Vertical farming success depends on the precise management and maintenance of a farm’s environment. By controlling factors such as light intensity and wavelengths, temperature, humidity, airflow and CO2 and volatile organic compound (VOC) concentrations, supervisors can ensure plants grow as fast as possible while retaining their aesthetic, taste, and nutritional value for consumers. For example, research has shown that constant air movement (at a constant vapor pressure) in the range of 0.3 to 0.5mps provides an optimum diffusion of CO2 and water vapor into leaves to aid photosynthesis and maximize the growth of tasty leafy greens.

Such delicate management of growth conditions demands the supervision of computer-based, closed-loop process-control systems that employ sensors that wirelessly forward data to a supervisory computer that is in the facility or in a remote location. If a sensor reading detects a drift from an optimum diffusion rate, the supervisory computer can make appropriate adjustments to reset conditions back to the desirable level. Connectivity ensures that the system retains all the data and can use it to calculate which conditions prove to be the best for a particular plant’s growth.

For example, CEA scientists from the Newark, New Jersey-based AeroFarms monitor more than 130,000 data points every harvest. The technicians then use the information together with predictive analytics to review, test, and enhance the growth systems for the next harvest.

CEA Electronic Engineering Made Simple

A closed-loop, networked, wireless sensor system for a single variable is a challenge to implement, but the difficulty significantly multiplies when control extends to multiple variables that determine the success of CEA. These challenges include:

  • Financing the installation and maintenance of large sensor populations,
  • Building and verifying sensor-based systems and the associated mesh networks,
  • Commissioning and configuring multiple sensor types,
  • Ensuring conflict-free communications across large networks, and
  • Managing power to widespread sensor populations.

One solution for these CEA engineering challenges is arriving in the form of a commercial introduction of modules that integrate multiple sensors onto a single module. Products such as TE Connectivity’s AmbiMate sensor module provide multiple sensors on a ready-to-attach printed circuit board (PCB) assembly for easy integration into a host product. Each of the modules combines four core sensors (i.e., motion, light, temperature, and humidity) while variants can add CO2, VOC, and sound (microphone) capabilities.

The sensors are linked to a single onboard microprocessor and leverage a single power supply. The embedded microprocessor is equipped with an I2C interface that makes linking to a wireless transceiver for data transfers relatively straightforward. Each module variant is manufactured on the same footprint, making it simple for designers to swap to a different sensor mix when it is necessary. Finally, the onboard sensors are capable of measuring parameters with the precision required for CEA. For example, the temperature and humidity sensors offer ±0.3°C and ±2 percent relative humidity (RH) measurement accuracy, respectively, and a one-second acquisition rate (Figure 1).

Figure 1: TE Connectivity’s AmbiMate sensor module MS4 series is based on a common footprint, making it easier for designers to customize end products for a specific application. (Source: TE Connectivity)

By integrating multiple sensors into a single module, products such as AmbiMate’s MS4 series can reduce the number of nodes in a CEA process-control system and ease many of the key engineering challenges. Fewer nodes lead to simpler networks and lower complexity and cost levels as well as accelerates tests, configurations, and commissions.

Encouraging Vertical Farming

Traditional farming already consumes 40 percent of the planet’s land and finding more space to grow crops requires cutting down valuable rainforests. Yet, according to US newspaper Newsweek, food production will need to expand by 70 percent by 2050 to feed a predicted global population of nearly 10 billion.

According to the CEA Global Association, vertical farming is the answer because it combines the sciences of agriculture, engineering, and technology to grow fresh food in scaled and sustained environments 365 days a year and in locations where weather and outdoor environments would otherwise limit or preclude fresh food production. Furthermore, localizing fresh food production near urban populations is smart and efficient. By integrating agriculture and engineering, conservation of finite resources such as water, arable land, and energy becomes feasible.

Conclusion

There is no doubt CEA is a promising technology, considering the best-run installations produce annual yields approaching 400 times greater than the equivalent area of traditional farmland. Still, it is a fledgling enterprise, and the barriers to entry are currently so high that anything other than very rich nations are excluded from adopting the technology. The barriers are high because CEA’s success relies heavily on technology that is currently complex and expensive. The introduction of multi-sensor modules, such as TE Connectivity’s AmbiMate, is a significant step on a path to simplifying CEA-based engineering and releasing the technology to further help and feed the world.


Steven Keeping gained a BEng (Hons.) degree at Brighton University, U.K., before working in the electronics divisions of Eurotherm and BOC for seven years. He then joined Electronic Production magazine and subsequently spent 13 years in senior editorial and publishing roles on electronics manufacturing, test, and design titles including What’s New in Electronics and Australian Electronics Engineering for Trinity Mirror, CMP and RBI in the U.K. and Australia. In 2006, Steven became a freelance journalist specializing in electronics. He is based in Sydney.

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