THIS RESEARCH HAS BEEN SPONSORED BY SIEMENS PLM SOFTWARE

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You can learn more about MindSphere, the cloud-based, open IoT operating system from Siemens at http://siemens.com/mindsphere

WHY A DESIGN ENGINEER SHOULD READ THIS REPORT

The adoption of the Internet of Things is driven by the falling cost of smart sensors and the ease with which, as they become ever smaller, they can be deployed into new products.

In this report, engineering.com looks into the various types of sensors that designers are using to make their products smarter, from accelerometers, humidity sensors, LiDAR, temperature sensors, pressure sensors, and more.

Our goal with this report is to spark ideas and show design engineers how they might now employ sensors in their new products, which in turn will enable these products to connect to the Internet for reporting and analysis.

The report covers specifc sensors and discusses their prices and form factors. It also references relevant use cases (i.e., not just smartphones and Fitbits, but also industrial devices, machinery, etc.) which will help design engineers imagine how to make their products smarter by incorporating low cost sensors.

A CONFLUENCE OF TECHNOLOGY ADVANCES ENABLE THE IoT

Embedded controllers--small, single-chip computers--allow engineers to add “intelligence” to products at a relatively low cost. Features that are too expensive to implement in hardware become affordable with a low-end microcontroller and a few hundred lines of code.

Smart sensors evolved out of the embedded control movement. An inexpensive microcontroller monitors a sensor, reads its information, formats the data, and forwards it to a central computer for further processing, freeing the main computer from handling the minutiae. In the past, industrial machines were manually tested by technicians as part of a maintenance schedule; today, these machines are outftted with sensors that constantly monitor vibration, temperature, pressure, and other parameters, giving plant managers a constant picture of every machine’s health and status. Instead of waiting for equipment to fail or replacing a machine based on a statistical Mean Time Between Failures (MTBF), industrial engineers can see exactly when a fault is imminent and replace or repair the equipment just in time, reducing the costs associated with down time and premature equipment maintenance.

Wireless technology gives people the ability to communicate freely and untethered via cell phones, laptops, and tablets. The same concept now applies to machinery. Many sensors are located in places where it’s simply not feasible to run cables to them. Some are powered by batteries or energy-harvesting devices.

Biomedical sensors can be worn by patients throughout the day, with the vital signs constantly monitored as they go about their day-to-day business. The data can then be sent to a phone app via Bluetooth and transmitted to a physician’s database in the cloud.

The Internet of Things (IoT), often called the next industrial revolution, is the natural extension of the above technologies. IoT combines the “brains” of embedded control, the modularity of smart sensors, and the ubiquitous connectivity of wireless communication, allowing engineers to turn individual products into complete systems in a cost-effective way.

WHY INCORPORATE IoT INTO PRODUCTS?

The short answer is that IoT adds both function and value to a gadget.

IoT makes new product lines feasible, gives businesses an edge over their competition, responds to customer demands for new features, and reduces the cost of operating equipment.

The plummeting price and form factor of sensors, embedded controllers, and communication devices lets engineers add capabilities to a product without signifcantly affecting its cost, size, or weight. If you were designing a new line of sports equipment and a $5 (USD) impact sensor could detect and report a potential concussion in real time, you’d build the sensor into the product, right?

WHICH SENSORS ARE COMMONLY USED IN IoT

Engineering.com spoke with engineers from many industries in order to discover which sensors are most commonly utilized, and in what applications. We found that optical sensors are some of the most widely used, especially in the manufacturing, biomedical, and retail industries. Temperature, pressure, and humidity sensors are also quite popular and affordable, and motion sensors fnd their way into a multitude of applications.

OPTICAL SENSORS

Optical sensors are among the most popular devices on the market, probably because they’re so versatile. TT Electronics makes a refective optical sensor, the OPB 9000, a 3mm x 4mm surface-mount device that sells for less than $2 in production quantities. Does your machine need to know whether an object is present on an assembly line? Are you designing a safety system to ensure that an IV tube is in place? Check out some refective optical sensors--they might be just what the doctor ordered.

A refective sensor consists of a light source and a light detector. Many automatic garage door openers use a refective sensor as a safety feature--a beam of infrared light shoots from one side of the door to the other, where it gets refected back to the detector. If anything breaks the beam, the door stops closing. However, some optical sensors can be “overwhelmed” by direct sunlight. To combat this issue, some sensors such as the OPB 9000 feature ambient light fltering. The package includes the sensor, an application- specifc integrated circuit (ASIC), a digital interface that communicates with a microcontroller, and self-diagnostic capabilities. It can also be re-calibrated, via software, to respond to changing conditions such as the LED dimming with age.

In industrial settings, refective sensors can detect the presence or absence of a product on an assembly line, whether there’s cash of a particular denomination in an ATM, or if there’s a paper jam in a desktop or mobile printer. Commercial self-serve soft drink machines use optical sensors to measure syrup levels; they can employ Zigbee,

Bluetooth, or cellular service to send a “low level” warning to the main offce of the facility.

Physiology collaborates with physics as the biomedical feld takes advantage of optical sensors’ adaptability. Hospitals employ optical fuid sensors to detect clear fuid fowing in a clear tube to look for bubbles and other IV tube issues. Some wearable products feature custom sensors that emit and detect many wavelengths of light to measure temperature, heart rate, oxygen levels, energy expenditure, and even blood pressure.

Maxim Integrated makes a photoplethysmography (PPG) device that uses optics to sense the changes in blood volume during different parts of the cardiac cycle and feeds the data into a digital signal processor

(DSP), which analyzes the waveform to diagnose possible medical conditions.

Instead of a stress test where a patient spends ffteen minutes on a treadmill in a clinically staged environment, a wearable sensor monitors the patient’s activities throughout the day in a natural setting. That data is sent to an app on the user’s phone, which can then transmit it to the cloud to be examined by a physician.

TEMPERATURE SENSORS

The world’s frst building automation system (BAS), patented by Warren Johnson in the late 1800s, was a thermostat that controlled a school’s furnace. Its temperature sensor--a simple bi-metallic strip--was crude by today’s standards, in that it provided a binary output: “too cold” or “not too cold.” Today’s temperature sensors deliver much more precise readings, often telling the temperature within a tenth of a degree. They can be resistive or semiconductor in both cases, the smart versions include on-board circuitry that performs calibration, signal conditioning, self-diagnostics, and communication.

Today’s building automation systems are a bit more sophisticated than Johnson’s thermostat, but temperature is still a fundamental quantity that’s measured and controlled. Between commercial and residential buildings, more than one-third of our energy bills pay for heating and cooling; intelligent controls can reduce that energy consumption by 29 percent. At the center of that control system: a $3 temperature sensor, like the Silicon Labs Si7013.

With a footprint of just 3mm x 3mm, this tiny piece of silicon includes a temperature sensor, humidity sensor, analog-to-digital converter, signal conditioning circuitry, and an I2C bus for interfacing with a microcontroller.

Building automation systems (BASs) do more than just control the HVAC and lighting; they also help facility managers deploy resources more wisely. When smart sensors are connected to the IoT, their readings are recorded and stored in a database. This enables data mining, which leads to machine learning algorithms that can predict energy needs and optimize power consumption. Even better, an IoT-connected BAS has access to weather forecasts, turning an ineffcient reactive control system into an intelligent predictive control system.

In addition to building thermostats, temperature sensors are frequently used to monitor the health of machines, control industrial processes, and detect changes in temperature that could lead to equipment failure. For

example, temperature fuctuations in industrial motors can lead to premature failures, so inexpensive thermal sensors are sometimes embedded into the motor windings. These devices will monitor and record the motor’s internal temperature throughout the day, wirelessly reporting the information to a dashboard that’s monitored by industrial engineers and technicians. This information is used to alter preventative maintenance schedules and predict impending motor failure.

The proliferation of rechargeable batteries has brought temperature-related failures to the forefront. In order to prevent thermal runaway, most battery chargers, especially those in high-power applications like electric vehicles, use temperature sensors to tell the charger to reduce or cut off the charging current when temperatures become excessively high.

HUMIDITY SENSORS

Most people think of humidity only in terms of how sweaty we’ll get in the summertime, but weather forecasters aren’t the only ones who measure humidity. Some industrial processes require a certain moisture content with tight tolerances; smart sensors with IoT help control and monitor those humidity levels. Medical devices such as CPAP machines, respirators, and incubators also employ humidity sensors with monitoring capabilities. In the agricultural feld, commercial hatcheries use incubators that monitor and regulate temperature and humidity levels for proper egg hatching. In fact, temperature and humidity are often correlated, so some sensors include both in one module, like the aforementioned Si7013.

PRESSURE SENSORS

Temperature, humidity, and barometric pressure make up the “big three” in weather forecasting. In fact, they’re so frequently used together that Bosch integrated all three into a single package: the BME 280.

The BME 280’s compact form factor (2.5 x 2.5 x 0.93mm) and low price (less than $4) allows this triple-duty sensor to ft into any portable weather station. The sensor includes I2C and SCI communication busses to send information to an embedded controller.

Pressure sensors are ubiquitous in manufacturing facilities, allowing industrial engineers to monitor the fuid pressure in pumps and compressors, as well as airfow in ducts. Pressure sensors also detect leaks in pneumatic systems and ensure suction levels in robotic pick-and-place applications. In the sustainable energy feld, wind turbines use hydraulic systems to control the blade pitch and yaw, allowing the turbine to balance energy production with turbine safety.

MOTION SENSORS

Motion sensors encompass a wide variety of devices, including accelerometers, gyroscopes, and geomagnetic sensors. Accelerometers are used in automobile airbag systems to detect the rapid deceleration of a vehicle crash, gyroscopes measure the angular velocity of smartphones, and geomagnetic sensors provide directional information in navigation applications.

Motion sensors are also used in warehouses to detect the unintentional jarring of products. Forklift drivers sometimes bump into storage racks, which could render damage to the items on the shelves as well as impact the stability of the racks themselves. An inexpensive, battery-powered sensor with cloud connectivity can trigger a safety alert that identifes the fault and the location, thus avoiding a potential hazard. This requires a simple retroft--just slap a motion sensor onto each rack and it’s good to go.

Sometimes two or more of these sensors are incorporated into a single package. One such device, the Bosch BNO055, includes an accelerometer, a gyroscope, a geomagnetic sensor, and a 32-bit microcontroller, all in a package with a footprint that’s less than 20 mm2. It sells for about $7 in production quantities. The BNO055’s low profle and feather-light weight makes it perfect for unmanned aerial vehicle (UAV) applications, but it’s also fnding its way into other innovative products.

One Bosch engineer remembered his days growing up on a farm, spending countless hours monitoring cattle. He realized that an absolute orientation sensor could be embedded into a smart tag that’s worn by a cow--sort of a high-tech cowbell--allowing ranchers to know the exact location of every head of livestock. Also, by tracking motion, the software can record the cow’s eating habits, helping the farmer assess the animal’s Bosch overall health.

Another Bosch engineer invented a frefghter tracking device that uses the BNO055 to measure location and rotation, in order to record a frefghter’s path through a burning building during a search and rescue operation. This helps the frefghter fnd the best route out of the building as well as providing data to the rest of the team in case the frefghter becomes incapacitated.

VIBRATION SENSORS

Vibration analysis provides a good picture of a machine’s health, which is why technicians will run periodic vibration measurements as part of a machine’s routine maintenance. But why send a technician to test it once in a while when a sensor can monitor the machine continuously? Petasense produces a line of wireless vibration sensors that are a bit smaller than a D-Cell battery, allowing them to be mounted to a machine with minimal interference.

Using either Micro-Electro-Mechanical Systems (MEMS) or piezoelectric sensors, depending on the application, the vibration sensor continuously records the vibration waveform and sends it to the cloud through its built-in Petasense WiFi adapter. Waveform analysis algorithms determine whether the machine is operating within acceptable parameters, and send a warning signal if not.

The sensor runs on a small lithium battery that lasts for two years under normal operating conditions. These models are a little pricier--$399 to $599-- but it’s a small investment compared to the cost of the machine.

LIDAR SENSORS

Light Detection And Ranging (LiDAR) is an integral component of autonomous vehicle mapping and collision avoidance systems, allowing the computerized “driver” to fnd its way around and detect obstacles in its path. LiDAR sensors attached to UAVs create highly detailed topographical maps that help archaeologists fnd structures that would otherwise be hidden by foliage and show farmers where topsoil erosion is occurring. LiDAR is quickly becoming the preferred tool for solar array designers who conduct remote shading analyses.

LiDAR for autonomous vehicles is still quite pricey, but for modest applications like level sensing, distance, surveillance, and optical range fnding, a low-end LiDAR sensor like the LeddarOne gets the job done for less than $150.

HOW IS COMMUNICATION, STORAGE, AND SECURITY HANDLED ON THE IoT?

IoT sensors can connect to other devices through pretty much any communication protocol, depending on location and security needs. For short-range communication within a building, Zigbee, Bluetooth, and NFC are popular. Cloud-based storage requires WiFi or cellular technology.

Internet security is a specialty that many application-oriented engineers would prefer to leave to the experts. All wireless communication includes some form of data encryption. At the higher end, cloud-based apps need even more security, which is often purchased as a subscription service from security specialists.

Subscription security services allow engineers to get their designs on the cloud in less than a day, as opposed to several weeks or months. And since the security company handles all the updates, they’re applied immediately.

Electric Imp is one provider of security as a service that extends from the hardware all the way to the cloud.

Their platform supports a number of off-the-shelf microcontrollers that include a built-in real-time operating system (RTOS), allowing the engineer to focus on the application.

For engineers who want to experiment with the Imp platform, the company offers a variety of evaluation boards that feature a 32-bit processor, RTOS, general purpose I/O, sensors, and WiFi. Its service is free during the development stages; payment--a per device fee--begins once the product has been deployed.

Looking for more than communication, storage, and security? If your application would also beneft from data analytics, then Siemens MindSphere might be the platform for you. MindSphere, which works with any device that complies with the Open Platform Communications (OPC) standard, offers cloud-based storage, communication, and security as a service, while also providing “digital twins” that compare the actual product’s performance with that of a virtual model, helping engineers fnd ways in which to optimize their products and processes.

MindSphere comes with its own “app store” that includes code written by Siemens as well as third parties. App development tools are also included for those who need to write custom software.

Among the MindSphere applications, take note of the energy management and building technologies.

These work in conjunction with the temperature, humidity, and occupancy sensors mentioned earlier, giving facilities managers a holistic view of a building’s energy consumption and allowing them to run a variety of “what if” scenarios to help reduce energy consumption.

Along the same lines, Autodesk Fusion Connect is a cloud- based IoT platform that includes communication, storage, control, analysis, and data security.

Much like MindSphere, Fusion Connect has a drag-and-drop interface that allows engineers to incorporate pre-written or custom apps into their products.

One more IoT platform that engineers might consider is ThingWorx by PTC. Like the ones listed above, ThingWorx helps developers design, deploy, and monitor IoT devices in real time, in a secure, cloud-based environment. It also provides analysis tools, object-oriented apps, and an augmented reality (AR) creation module that lets engineers develop custom dashboards for their products without the need for coding skills.

HOW DOES AN ENGINEER DESIGN WITH IoT SENSORS?

You need tools? Luckily there’s no shortage of development products for engineers at every level, whether you’re new to IoT or you have several designs under your belt.

The Arduino line is very popular with hobbyists; engineers can also use it for rapid prototyping and proof of concept. Arduinos come with a real-time operating system that lets engineers focus on the application without worrying about the basic hardware functions. The Arduino platform also supports a plethora of low- cost interface boards, allowing you to experiment with a wide variety of devices.

NXP’s Rapid IoT Prototyping Kit includes an embedded microcontroller, a variety of sensors, and multiple communication interfaces. Intended for small to mid- sized companies, its integrated development environment features a graphical drag-and-drop programming interface that lets engineers create projects without programming in C or C++.

Electric Imp offers the low-cost impExplorer Developer Kit, which features temperature, humidity, pressure, and acceleration sensors, as well as a software development environment.

All of these kits are relatively inexpensive and easy to use. Explore them all, pick the one that suits your needs, and get your design from concept to implementation in a short timeframe.

WHAT NEXT?

So we’ve sparked your interest in exploring IoT--now what? If you like to roll up your sleeves, dive into a project, and learn as you go, then consider purchasing one of the development kits mentioned above. Then obtain a trial account with MindSphere, Thingworx, or Fusion Connect and see how your product’s data looks on the cloud.

If you prefer instructor-led learning, then you might want to check out a free online course in IoT. Engineering.com reported on a variety of free MOOCs related to IoT; they’re a great way to get an introduction to IoT concepts without leaving your desk.

https://www.engineering.com/Education/EducationArticles/ArticleID/13506/ Interested-in-IoT-These-MOOCs-Might-Be-for-You.aspx

Online courses and websites can give a decent overview, but if you’re ready to see the products and speak with company representatives, consider attending a conference like the Sensors Expo & Conference (https://www.sensorsexpo.com/).

Engineering.com conducted several enlightening interviews with engineers from companies that are exhibiting at this year’s Sensors Expo.

EXECUTIVE SUMMARY

The Internet of Things is a blend of embedded controllers, smart sensors, and wireless communication. IoT allows engineers to add function and value to a product without signifcantly affecting its cost, size, or weight.

Some of the most widely used IoT sensors include optical sensors, which fnd their way into medical, industrial, and personal products thanks to their versatility. Temperature, humidity, and pressure sensors are employed in meteorological as well as industrial applications. Motion and vibration sensors can give information about the health of a machine, preventing

costly downtime. And LiDAR isn’t just for unmanned vehicles--it’s also used in agriculture, sustainable energy, and factory automation systems.

IoT communication is supported by every wireless communication protocol, depending on the application. Security, especially in cloud-based applications, is often provided as a subscription service, letting the engineer focus on the product’s core purpose, while security experts keep the data protected with servers and software that’s constantly updated to protect against new and existing threats.

There’s no shortage of tools to help engineers design IoT products and applications. Most IoT development products feature a real-time operating system, hardware-based security, off-the-shelf apps, and the ability to create custom software without necessarily knowing C++ or another programming language.

Engineers who want to learn more about IoT without sitting in a classroom can take one of many free MOOCs related to IoT. Those who prefer to learn by doing can explore one of the development kits and IoT platforms, which allow designers to get a prototype online in a day or less.

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