Fotolia
单点是否传感下一代IoT传感器网络？
Single-point sensing systems help developers use advanced algorithms to replace the number of sensors in a network. But it's not a fail-proof method -- yet.
许多硅供应商，设备制造商和企业一直在采取一项策略，假设企业和消费者希望将设备放置在各地进行监视。尽管此策略具有一定的优点，但随着监视设备的成本降低，它仍然伴随着安装的每个设备的关联管理，功率和安全开销。
An alternative single-point sensing approach around the concept of infrastructure-mediated sensing lies in deploying an IoT sensor network of relatively fewer sensors with highertelemetryresolution, coupled with back-end cloud analytics. This approach promises to reduce cost, management and user challenges, and it's already seeing some traction for replacing a network ofpower monitoring devices单个设备位于主电源盒中。
Another example of an IoT sensor network that uses single-point sensing is microphones that detect windows breaking. A single microphone, for example, would reduce the need to rely on dedicated sensors on each window in terms of security.
Early work on infrastructure-mediated sensing
In the early 2000s, led by Washington Research Foundation Entrepreneurship Endowed Professor Shwetak Patel, researchers at the University of Washington began experimenting with strategically placed sensors to monitor the electricity usage of each appliance in a house based on their electrical signal. Not only could they see if a light went on, but they found a lightbulb in the living room had a slightly different signal than one in the kitchen due to the topology of the wiring. Patel envisioned this new type of ubiquitous compute-sensing infrastructure could improve elder care, electrical consumption monitoring, home automation and entertainment.
Researchers coined the terminfrastructure-mediated sensingbecause it uses a single sensor on a type of system to monitor events throughout the house. Similar approaches were used to monitor用水量和气体用具的使用。研究人员甚至发现，气管中的单个气压传感器可以追踪整个房屋的人类运动。
Through single-point sensing, a single sensor in a strategic location can measure pressure signals in air vents and waterlines, as well as electrical signals on power lines.机器学习technologies are used to correlate physical events, such as turning on a light, flushing a toilet or opening a door, with different signals. One of the primary goals of single-point sensing systems is to reduce the economic, aesthetic, installation and maintenance barriers by reducing the cost and complexity of deploying and maintaining an activity-sensing infrastructure, Patel said.
进行这项工作的一个关键在于从基础设施中获取高分辨率录音。虽然功率计以15分钟的增量量化使用情况，但这些传感器将以1,000 Hz的间隔记录微小变化，以测量每个设备独特的信号。研究人员还花了很大的努力来创造新的机器学习算法to convert these signals into events corresponding to power usage of each appliance.
False start to commercialization
单点传感在为研究设计的测试房屋中效果很好，但是最初的研究并没有立即导致任何商业产品。核心技术被烘烤成一个名为Zensi的新创业公司，该公司于2010年作为其家庭门户部门的一部分出售给Belkin。Belkin改善了核心算法，甚至赞助了Data Science Community网站Kaggle的竞争，以为开发人员提供激励措施来制作更准确的算法。但是，贝尔金并未基于基础设施介导的传感推出任何商业产品。
The Energy Detective, a competitor that makes a power monitoring device, pursued a similar single-point sensing approach before declaring individual appliance monitoring from a centralized point is a myth. According to acompany FAQ, "While it worked well for large appliances like an HVAC/water heater, it was extremely inconsistent and frustrating for smaller appliances." The company ultimately pursued an alternative approach to measuring each outlet from the utility box.
New entrants move single-point sensing forward
More recently, interest in infrastructure-mediated sensing began making a comeback, in part, due to better algorithms, improved machine learning infrastructure in the cloud and simplicity. The initial infrastructure-mediated sensing algorithms were optimized usingneural networksor machine learning algorithms running individual PCs. But the development ofAIGoogle的工具链以及后来的工具链使在云中实现大量神经网络变得更加容易。此外，增长IoT devicesand better communications protocols make it much easier to gather more data from consumer and business users to further improve these algorithms.
Startup Neurio developed the Neurio Home Energy Monitor and associated software tomonitor energy usagein the home from the breaker panel. The company took a much less aggressive approach in only characterizing energy usage patterns of more power-hungry appliances, like air conditioning, heaters and dryers. The electrical signals of large appliances tend to be much easier to decipher, and there are fewer of them. These represent the low-hanging fruit in terms of measurement, but they also have a more significant impact on energy consumption than individual appliances or light.
Another startup, home-monitoring company Sense, has taken a much more aggressive approach in creating an app to quantify energy usage at the appliance level in the home. The Sense module plugs clip onto the circuit breaker box in a user's home. The device sits in the background, learning the behavior of someone's appliances. When it sees an electrical signature for a device it doesn't recognize, it simply records it. Users can then name it after the fact, and it will continue to track the usage of this device over time.
Sense also developed Network Device Identification, a new data collection tool that listens for communication of devices in the home via Bluetooth and Wi-Fi networks sent via Simple Service Discovery Protocol and Universal Plug and Play, Zeroconf and ARP protocols used for IoT communications. These messages are used by devices to broadcast their knowledge about their state. The Sense device also periodically sends out apingto prompt devices that might not be actively broadcasting their status. This allows Sense to better correlate changes in a device's state with changes in the electrical signals it receives to improve its algorithms.
The pings allow Sense to accurately register that asmart speaker例如，待命或积极播放音乐。然后，了解数据科学家可以更轻松地阐明由设备在背景上默默产生的电信号。该公司计划使用这些数据来改善感官用户社区的设备检测。
为了处理可变性，Sense设备需要收集一些目标对象的示例，例如车库门开启器，以及它不想将目标混淆的竞争对象。这些过程使用算法，例如深度学习或隐藏的马尔可夫建模来可靠地识别感兴趣的对象。识别取决于代表目标类别的对象和其他潜在混淆对象的样本。
例如，车库门具有签名，具有相似的瓦痕和持续时间，代表门开口的不同阶段，滑动障碍物和轨道，然后停下来。相比之下，由于线圈的电阻负载，加热器之类的签名大为不同。大型电动机的另一个负载将具有由电动机负载的特征节奏引起的不同电特征。该应用程序可能会识别信号是来自热为导向的设备或面向电机的设备。然后，人类可以描述这些神秘信号。然后将数据馈回Sense的云应用程序，以帮助提高其他家庭或办公室中类似设备的识别。
More recently, companies are beginning to use the principles of infrastructure-mediated sensing in other areas, as well. For example, the SwannOne home security system uses single-point sensing via a microphone on each floor to listen for the sound of breaking glass. This provides one more level of security when homeowners have not installed detectors on each window.
展望未来，可以想到类似的功能，可以烘烤到现代家庭助理，例如Google Home或Amazon Echo。开发人员可以制作在这些设备上运行的应用程序以监视安全事件。可以使用在云中运行的机器学习算法来改进用于检测这些事件的算法。
基础架构介导的感应的未来
基础架构介导的感应的另一个有希望的方面是扩展了使用更多主动传感器的基础设施介导的传感系统用于工业应用的能力。这将在传统的测试方法中使用与正在监视的基础架构类型相关的雷达。电话和网络安装程序长期以来一直依赖于时间域反射仪，该反射仪会向下发送信号或local area networkwire, and water pipes use high-frequency ultrasonic sounds to find leaks and broken faucets in water systems.
Infrastructure-mediated sensing is not a perfect system. While better algorithms can greatly improve the accuracy of single-point sensing, this approach tends to be limited in relying on a single signal of measurement. Going forward, researchers and businesses are going to have to look at how to use information from different types of sensors to significantly increase the accuracy and precision of event measurements from the single sensors used in traditional infrastructure-mediated sensing architectures.
