Integrating the Internet of Awareness into our smart SSL systems (MAGAZINE)

Feb. 23, 2015
Tom Griffiths projects the role that interconnected LED-based lighting systems will play in hosting sensors and adding awareness as the Internet of Things comes to our buildings.

TOM GRIFFITHS projects the role that interconnected LED-based lighting systems will play in hosting sensors and adding awareness as the Internet of Things comes to our buildings.

The phrase "Internet of Things" (IoT) is being used so often that it would be easy to write it off as simply the latest buzzword for objects with Internet Protocol (IP) addresses. While the age of ubiquitous Internet-connected toasters is not quite upon us, the next era of device interconnectivity certainly is here now, and the coming growth of "connectedness" is undeniable. In buildings, we are moving rapidly toward a future where all physical systems including lighting, HVAC, security, and others will rely on Internet-enabled components, sensors, and subsystems. Such a reality, however, will require that we first resolve the need to create awareness in the subsystems - an "Internet of Awareness," if you will. LED-based lighting is an ideal place to integrate such awareness combined with the functionality required for smart lighting systems.

To see the potential of connectedness, all we have to do is look into our pockets and see our smartphones. Such devices, combined with apps and the cloud, are already cognizant of where we are and already predicting what we might be doing - or more to the commercial point, what might be interesting to us.

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The point of this connectedness is to create more interaction with the space around us. As we drive by the local shopping center, apps such as RetailMeNot will push offers and coupons at us. While initially somewhat random, it doesn't take long for the cloud-based servers to begin to correlate what e-coupons we actually use and where we use them, with details that include the time of day, the day of the week, our location, and what other coupons we've used in the proximity. This successful data-mining might initially seem intrusive, but as the app adapts to the individual user's patterns, more and more of the offers begin to actually fit our lifestyles, predicting when we're in the shopping mode, and what we might actually be shopping for. At that point, the connectedness moves from simple advertising into becoming a value service.

FIG. 1. The Internet of Things in a commercial building will include connectivity of diverse systems including lighting, security, HVAC, and more, ultimately with cloud-connected building management systems in control.

In the same way, the spaces we occupy, the so-called "microspaces" in our daily lives - most often our offices or homes - are poised to become the primary value delivery point for IoT value services. And while all those "things" in the IoT will be ready and willing to respond to our preferences and needs, they'll need more than just our ID and location for the IoT to be of value to us. The things will need to know about the space and what is going inside it. An Internet of Awareness will need to be created to complement the Internet of Things. Those microspaces will need sensors.

Age of awareness

Our built environments have some very common ingredients, including walls, windows, furnishings, HVAC systems, and lighting. Due to the combination of its hardwired electrical nature and its ubiquity across our microspaces, lighting is the natural system to host many of the sensor systems that create the Internet of Awareness that will enable the IoT (Fig. 1).

While the concept of connected lighting doesn't sound particularly earthshaking, the reality is that very few of today's lighting installations can really be called connected. A modern building management system may be able to command banks of light on or off in a prescribed schedule, tally the overall trend of occupancy sensor triggers in a series of spaces, or may even be able to infer the amount of energy usage/savings that those events trigger. But in regard to the benefits of connectivity, things pretty much stop there.

In reality, prior to the start of the LED-based solid-state lighting (SSL) revolution, there really wasn't much to control beyond on and off. Today, SSL systems enable precise dimming based on light and occupancy sensing and even color tuning for productivity or preference, and a place to layer other sensors.

Indeed, recent component advances are enhancing both the capabilities and connectedness of our lighting (Fig. 2). The lighting-centric sensing provides a preview of the coming tsunami of sensor-driven awareness that will include not only information on lighting levels and energy usage, but data that will encompass everything from air quality and space utilization to the wearable-transmitted vital signs of the users of those spaces.

Step 1: Sense it

Now let's discuss the hierarchy of embedding awareness. The whole point of the Internet of Awareness is sensing, so the critical determiner of any architecture will be what we intend to sense. The architecture in Fig. 3 begins from integrated occupancy and ambient light sensing as part of a smart lighting manager IC, on top of which the system integrator can add such things as temperature, humidity, CO/CO2, motion, and presence sensing. Some of these sensor additions, such as direction of travel motion/presence, are useful information for the lighting system, while others are pass-through information that will be provided in response to building management system (BMS) queries for the data.

FIG. 2. Sensors integrated into luminaires enable optimal tuning of task lighting, daylight harvesting, occupancy detection, and even color tuning in smart lighting systems.

To facilitate sensor extensibility, industry-standard platforms should be considered. In the previous example, the microprocessor industry I2C serial interface has been chosen for core expansion. Simple UART-based connectivity, such as RS-485, can also be employed, with or without distributed intelligence, the need for which would be driven by the frequency and volume of the sensor data being captured. Whether you look at it as "sensors, with intelligence at no extra charge," or vice versa, the simplest approach for widely distributed sensing will be a single dedicated controller that includes one or more integrated sensors.

Step 2: Control it

In terms of both performance and cost, there are many different aspects of a next-generation luminaire that benefit from sensors and local control. Once we know what we're going to sense, step 2 in the development of the Internet of Awareness becomes control of our lighting system. Welcome to smart lighting.

Given the lighting industry's century-long track record of simply needing to bring the specified voltage (directly or through a ballast) to a socket into which a bulb was installed, the move to engineering, rather than just mechanically integrating light sources, is proving to be painful to many of the lighting-industry players. A standard approach is often to delegate the LED light engine and power system designs to knowledgeable suppliers who can deliver an off-the-shelf or semi-custom plug-and-play solution.

As market requirements move forward, however, more than a few of the thousands of lighting manufacturers have been left wondering how they add California Title 24-compliant daylight responsiveness into a subsystem they didn't really engineer in the first place. With the coming need to engineer our lighting into the IoT, implementing a truly extensible sensing and IoT-capable lighting system can add an order of magnitude to the challenge. Fortunately, challenge equates to opportunity, and the semiconductor industry is poised to ride in to the rescue.

New sensor-fused intelligent component solutions that can simply be inserted between the luminaires and their existing control points, such as dimmers and occupancy sensors, are arriving now. The example in Fig. 4 illustrates one example of a sensor-driven smart lighting manager that illustrates basic control within the luminaire. In this architecture, the smart lighting manager is placed between the 0-10V dimmer control and the LED or fluorescent luminaire's 0-10V dimming input to the ballast. In this most basic intelligence-enabled luminaire, sliding the dimmer opens the control loop, directly varying the fixture's lumen output, which changes the illumination level of the space. Once adjustment is completed, the built-in daylighting sensor reads the resulting lux (lumens per square meter) of the target space, and enters a closed-loop control mode that will maintain that new target lux.

FIG. 3. The wired lighting system makes the luminaire the ideal place to integrate sensors, and lighting-management functionality can be used to enable support for other automated building systems via temperature, safety, location, and other sensors.

As daylight enters the space, the luminaire's output is seamlessly adjusted to keep that constant lux on the target. Over the long term, as the fluorescent lamps or LED emitters experience their normal lumen depreciation, or even as the fixture gets dusty, the closed-loop nature of the system will also adjust the luminaire output to simply maintain the lux in the target space regardless of the changing nature of the emission source.

Step 3: Connect it

An extensible lighting manager added to the system will also provide a connection point to off-the-shelf networking options, making the otherwise daunting task of connecting the individual luminaires to the IoT a manageable challenge. Adding on to the example from before, the smart lighting manager in Fig. 5 illustrates a serial UART connection that provides a straightforward connection to standard networking platforms.

Borrowing some ideas from the old dial-up Hayes modem days, the manager responds through the UART to simple AT-type (modem) text commands, creating a driverless command interface. The network component provider will have done the heavy lifting that implements the stacks and protocols for such popular wireless connectivity approaches as Bluetooth (BLE/Smart), Wi-Fi, and ZigBee, as well as wired versions including Ethernet.

Application-level embedded or reference code from the lighting manager supplier then bridges the gap between the network controller and the lighting manager, as well providing any needed hooks to a core set of additional controls or protocols that can be expected to make use of the UART connection, including DALI (digital addressable lighting interface) or even good old RS-485. With reference design approaches, a delivered integration kit will include Bluetooth connectivity to an Android or iPhone or wired connectivity that implements text-based commands such as Set_Lux_Target, Read_Lux_Level, or Set_Luminaire_Output_Level (with GUI-based scrolls, selectors, or sliders, of course).

FIG. 4. Once sensor support is integrated in lighting, a building management system can control both the lighting and other building systems.
FIG. 5. Standard wired and wireless networks will carry the relatively simple commands and data passed between physical building systems and the building management devices.

And then... Evolve it

With such baseline architecture to work from, the lighting manufacturer can evolve the functionality. The basic definition of smart lighting implies, at a minimum, luminaire-centric sensing and control. As we have seen in example after example, from our entertainment devices to our automobiles, once intelligence is introduced and semiconductor technologies can be turned loose on high-volume systems, the costs scale down while the value-added features and capabilities scale up with only minor increments in cost. As the basic smart lighting architecture is put in place in most luminaires and in every space, the evolution of the smart lighting sensor hub will move at a rapid pace. As cost-effective processing power increases, items such as arrayed presence detection will be enhanced to include detailed people counting and direction of travel and dwell time information, all compiled and summarized for the BMS to use in broader space planning.

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Individualized data will also be incorporated into self-learning approaches, which will then optimize the space around us in a variety of ways. Our personal wearable technologies, whether the simple RFID in our employee badges or more complex data communication from our bio-monitoring smart watches, will be used to correlate our presence and status with our learned preferences to deliver everything from customized lighting scenes to optimized temperature and humidity levels. All of these capabilities will come without a significant added cost, courtesy of the cognition available from our intelligent sensor-integrated smart lighting systems serving as sensor hubs for the coming Internet of Awareness.

TOM GRIFFITHS is marketing manager for sensor driven lighting at ams (