No Holds Barred for Industrial Sensing

Europe currently leads the Industrial Internet of Things (IIoT) market, but North America is not slacking when it comes to collecting and analyzing data for use in manufacturing, transportation, energy, and healthcare.

Europe has embraced the Industrial Internet of Things (IIoT) and currently accounts for 28 percent of the total market. The appeal is universal, though, as companies in North America are investing in IoT to the tune of $232 billion for hardware, software, services and connectivity, according to research by IDC. This investment is led by the manufacturing and transportation industries.

The IIoT is predicted to achieve a healthy CAGR between 2016 and 2021 and reach an estimated value of $123.89 billion by 2021. When factoring in so-called Big Data, the market could increase to $500 billion by 2020, says Accenture and GE in its Industrial Internet Insights Report.

Analyst firm Industry Arc reports that the healthcare and medical market will see nearly 60 percent (59.8 percent) year on year growth from 2016 to 2021. This will be followed by energy, both generation and distribution, which will realize a CAGR of 39.7 percent growth, in the same period. This is, in part, attributed to the increase in the implementation of smart grids around the world.

The IIoT reaches many, varied industrial sectors, including transportation, retail, and agriculture, in addition to manufacturing, energy and healthcare. The sector that generates the highest revenue is manufacturing.

Typically, the IIoT is made up of a wireless sensor network (Figure 1).

Figure 1: A typical wireless sensor network is made up of nodes. Image supplied by Linear Technology.

Figure 1: A typical wireless sensor network is made up of nodes. Image supplied by Linear Technology.

A wireless network is made up of individual nodes, usually arranged in a mesh configuration. “An individual node,” says Tony Armstrong, Director of Product Marketing for Power Products at Linear Technology, “is made up of a sensor, a microcontroller, a transceiver and a power source. This can be a battery, or an energy harvesting conversion circuit, or a combination of the two.”

A wireless sensor can fit anywhere a wired version can, and more. It is usually small, so can be fitted in space-constrained areas, but also in areas that were previously inaccessible. For example, a magnetic sensor can be clamped to a coupling on machinery or transportation stock.


This liberty from wires brings many, varied uses for sensors today. Armstrong cites exciting new areas, such as the fuel pipeline running from Canada to south Texas, which has a series of acoustic sensors to detect any leaks. There is also transport. He sets the scene of long trans-America railway tracks being bleak places for a train to break down, but if sensors are fitted to wheel bearings, and readings analyzed at each stopping stage, any preventative repair or maintenance can be done before the carriages are stranded in the middle of the Montana winter. Similarly with helicopters, vibration sensors can detect signs of wear before they pose a critical and imminent danger.

John Corbett, Sales Director, EnOcean, categorizes sensors into three groups— kinetic, light, and heat sensing—for switching, temperature, vibration, radiance, and biochemical monitoring.

While some are being installed into new environments, many, particularly in the industrial space, are retrofitted. Wireless sensors can limit downtime due to maintenance or breakdown, agrees Corbett. Transferring data to a central management hub can alert maintenance staff to changes in temperature, or vibration characteristics that may cause harm if not addressed. In industrial settings this ease of access and reduced maintenance time and costs are significant benefits.

Wireless sensors are particularly suited to industrial applications, he continues. Factories and warehouses can afford more open, uncluttered space for unfettered communications, than office or domestic buildings. He does sound one warning: to place sensors away from ducting, but otherwise the environment is conducive, he says. Another caveat is to avoid metal casings, as the sensor antenna cannot be used in a Faraday cage.

Range can be up to 300m, but is more likely to be 50 to 100m, he says, which means that a gateway is needed to extend the network.

Energy Harvesting
“Typically, industrial wireless system sensors are powered by batteries, as this sensor network communicates more than, say a smart building or water meter network,” says Corbett. Energy harvesting, however, results in even smaller sensors, as no battery is needed. This increases its attraction for maintenance savings, as replacing batteries can be time consuming and costly.

EnOcean patented energy harvesting wireless technology based on energy converters. Energy harvesting can be via kinetic, or inductive, i.e. movement, light or heat. Although energy harvesting has many benefits for a wireless sensor network, the energy savings, says Corbett, are in the end product.

“An energy harvesting temperature or humidity sensor can last three to seven days, depending on how often it is asked to ‘wake up’,” he explains. “If nothing is happening, the sensor will not transmit except to send out a ‘heartbeat,’ at pre-determined intervals, saving power.”

“Sensors can be grouped together, typically 20 to 30 in one group, although it can be as many as 200,” observes Corbett. “When a battery is exhausted, it is common to replace all batteries in the group at the same time, which can cause cost and stock issues.”

Figure 2: The Watchdog level switch generates an alarm signal when the liquid level rises and the probe is immersed in the liquid. (Picture credit: EnOcean)

Figure 2: The Watchdog level switch generates an alarm signal when the liquid level rises and the probe is immersed in the liquid. (Picture credit: EnOcean)

There are some limits to energy harvesting, says Armstrong, namely the reliability and variable magnitude of available power may be unknown. There are also limited transducer options, and many applications may still need a power source in case energy harvesting is inadequate or not available (for example, shade, even dust, can obscure a solar source). Despite all of these challenges, energy harvesting still adds value, he concludes.

The company offers a ‘one-stop shop’, he quips, with ICs that enable the conversion of an ambient energy source into that for a sensor node downstream and part of a network. One example of that is the LTC3330, which is a nano-power, buck-boost DC/DC converter that can extend the life of an energy harvesting battery. If it draws power from the ambient energy source, it draws zero current from the battery. A built-in Supercap charger and balancer can provide peak power if this is required by the downstream load.


hayes_caroline_115Caroline Hayes has been a journalist covering the electronics sector for over 20 years. She has worked on many titles, most recently the pan-European magazine, EPN.

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