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Bench Talk for Design Engineers

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Bench Talk for Design Engineers | The Official Blog of Mouser Electronics

Make Ceilings Smarter with Sensors, Actuators Charles Byers

Smart Ceiling Image

(Source: APChanel/Shutterstock.com)

Have you ever looked up and noticed all the interconnected devices hanging from the ceiling of a modern building? Today’s smart buildings often have dozens of sensor and actuator types interconnected by many parallel networks. Common examples include:

  • Security cameras (on analog or digital coaxial cable networks)
  • Environmental sensors and fire/smoke/heat alarms (supported on distinct networks, often twisted pair)
  • Lighting devices (often supported by standard breaker panel circuits for the main lighting and separate uninterruptible power supply [UPS] circuits for the few emergency fixtures)
  • Wi-Fi access points (supported by CAT5/7 Ethernet or Power over Ethernet [PoE] wiring to internet routers)
  • Public address speakers (with analog audio wiring)
  • Actuators associated with managing heating, ventilation, and air conditioning airflow
  • Controlling emergency devices such as exit signs, sprinkler heads, and alarm/strobe boxes

More sophisticated buildings add many more types of ceiling-mounted sensors and actuators that all need to interconnect with computer networks, including occupancy sensors, digital sign boards, air-quality monitors, tightly zoned air-mixing boxes, individually controlled light fixtures, and evacuation-assist devices.

The big problem with the traditional approach to wiring a ceiling that contains the devices mentioned above is the complexity, time, and expense associated with installing all those distinct networks and then interconnecting them with the large number of sensors and actuators. This problem leads indirectly to the trend of cubical farms or open office plans where many of us work. If office walls go all the way to the ceiling, safety codes require that each enclosed space has its own set of ceiling safety and lighting devices, with connections to a half dozen or more networks. It’s far cheaper to build one homogenous ceiling over a bunch of tables or low cubicles and never change it than to install and manage the frequent changes to all these networks that tall walls would necessitate. What’s needed is a way to merge all the functions of all these sensors and actuators into a single common network that is easy to install and modify (Figure 1).

Overhead projector image

Figure 1: Adding devices, such as an overhead projector, to a smart ceiling can typically be accomplished with standard building maintenance staff. (Source: Eakrin Rasadonyindee/Shutterstock.com)

Smart Ceilings to the Rescue

This is where the smart ceiling comes in. In a common implementation, PoE is used to both power and communicate with all ceiling-mounted devices over a common twisted-pair network. A central PoE switch is typically installed in a wiring closet adjacent to the space being served, and CAT7 wiring is pulled to the location of each ceiling device. Because these wires are cheap, a few extra connections can be run and left coiled up above the ceiling to serve future devices. The central switch is connected to the building’s internet service to provide enough bandwidth to manage the expected traffic and connect the sensors and actuators to the internet. The switch is connected to the building’s electrical distribution system to provide enough energy to run all the ceiling-mounted devices. A UPS can be sized to power the subset of devices that are critical to a building’s safety or mission from batteries or generators. The central switch can also include local edge computing processors, capable of providing local analysis and control of a smart ceiling’s systems without needing to send lots of data back and forth to the cloud.

Adding or reconfiguring a smart ceiling device is simple in the above scenario. Just pop a ceiling tile, find an Ethernet cable, mount the device, and plug it in. Union electricians are typically not needed to work on low-voltage Internet of Things (IoT) devices on PoE networks, so standard building maintenance staff can do it. Devices range from a simple temperature sensor to an LED-based smart lighting fixture (which can be as bright as a ~400-watt incandescent fixture on the energy available on a 60W PoE) to digital signs. The PoE switch can auto-discover the new device, configure its data and power feeds, and load the applications into the local edge processor needed to take full advantage of its functionality.

We can go even further in improving the versatility, efficiency, and convenience of smart ceilings. A device similar to a track light track can accept the PoE devices anywhere along its length. If a number of these tracks are integrated into the suspended ceiling support rails and include the required network wiring, IoT devices can literally be hung anywhere on a 2’ x 2’ grid. Need more light, a fan, better Wi-Fi coverage, or a digital sign above your work location? Just get your ladder and snap the required device onto the track using a locking fastener similar to those found on a track light. In less than a second, the network discovers, configures, and enables the new device. My US Patent 10,030,398 discusses this sort of system.

Going further still, the actual placement and movement of ceiling-mounted devices can be automated using robotic techniques. Instead of a track light type of interconnect, the tracks can support a fleet of small, motorized shuttle vehicles that move about the ceiling to position the IoT devices wherever the building occupants or building automation software commands them to go. Switches between the many parallel tracks spanning the ceiling allow the shuttles to get to new places or bypass each other. A storage closet maintains an inventory of assorted spare devices ready to move out onto the ceiling as requested. This system would use sliding contacts and busbars integrated into the track to provide power to each IoT device (and the robotic shuttle that hosts it). Data connections to the devices and shuttle vehicles would be through optical beams within the tracks, or they could be on radio networks. My US Patent 10,148,355 has details on this system.


Smart buildings require smart ceilings. Configuring and reconfiguring ceiling-mounted devices can be expensive and inefficient, but moving to smart ceiling techniques with integrated IoT networks and local edge computing can really improve the situation. The most advanced smart ceilings will use reconfigurable tracks and robotic techniques to provide highly dynamic and customized environments.

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CHARLES C. BYERS is Associate Chief Technology Officer of the Industrial Internet Consortium, now incorporating OpenFog. He works on the architecture and implementation of edge-fog computing systems, common platforms, media processing systems, and the Internet of Things. Previously, he was a Principal Engineer and Platform Architect with Cisco, and a Bell Labs Fellow at Alcatel-Lucent. During his three decades in the telecommunications networking industry, he has made significant contributions in areas including voice switching, broadband access, converged networks, VoIP, multimedia, video, modular platforms, edge-fog computing and IoT. He has also been a leader in several standards bodies, including serving as CTO for the Industrial Internet Consortium and OpenFog Consortium, and was a founding member of PICMG's AdvancedTCA, AdvancedMC, and MicroTCA subcommittees.

Mr. Byers received his B.S. in Electrical and Computer Engineering and an M.S. in Electrical Engineering from the University of Wisconsin, Madison. In his spare time, he likes travel, cooking, bicycling, and tinkering in his workshop. He holds over 80 US patents.

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