IoT analog and wireless manufacturers seek to add value with integration of sensor fusion devices.
By Sally Ward-Foxton, European Correspondent
The Internet of Things was certainly a buzzword at Electronica 2014 in Munich, Germany. Alongside many developments in communications solutions intended for the smart home, smart factory or smart transportation, sensor manufacturers showed off their innovations for gathering information about the real world at the front end of the IoT. A major theme was sensor fusion: combining signals from multiple sensors to improve the usefulness of the data. Many sensor companies also added intelligence to their sensor products in order to differentiate them. Here are some of the sensor highlights from the show.
Fairchild showed a great example of sensor fusion at work in the form of this motion capture suit that is used by professional animators, demonstrated on their Electronica booth by break dancers (figure 1). Developed by Dutch company Xsens (which was acquired by Fairchild earlier this year), the suit incorporates 17 sensors and a dedicated DSP which pre-processes the data ready for analysis.
Joseph Notaro, VP motion tracking, explains, “The key IP is in extracting the signal from the noise and compensating for sensor characteristics and drift to give real drift-free sensor fusion.”
Notaro added that aside from the relatively small professional animation market, the same technology could be used for medical applications like physical therapy and sports analysis, and high end camera stabilisation in things like drones.
Belgium-based Melexis, well known for its automotive sensing products, launched a magnetometer at the show that is targeting more IoT-like applications such as water flow metering, position sensing in robotics and industrial automation, as well as human-machine interfaces like buttons and joysticks. The MLX90393 (figure 2) is a 3D magnetometer based on the company’s Triaxis technology.
Melexis added some new built-in smart features, including a wake-up on magnetic field change function with programmable threshold.
“You could have the sensor go to sleep, only consuming micro-amps of current, but when it sees the magnet move, or the magnetic field change, it wakes itself up, goes to full function mode, wakes up the MCU with an interrupt and the whole system is alive and making decisions,” explains Peter Riendeau, the company’s Marketing Communications Manager.
In fact, the sensor draws just 2.5µA when idle. The duty cycle of the sensor is programmable, to allow the response time to be balanced against power consumption. The sensor can also be tuned for applications that require low noise sensing (sensing the Earth’s magnetic field, for example), but at the expense of power consumption and speed.
Bosch Sensortec introduced the world’s first single-package pressure, humidity and temperature sensor, the BME280 (figure 3). This sensor can be used to gather data on the weather or indoor environment for HVAC systems, or to determine altitude via barometric pressure for indoor navigation.
CEO of Bosch Sensortec, Dr. Stefan Finkbeiner, explained that software sensor fusion can be used to verify signals. He gave the example of walking through a building and passing an escalator. This large metal object would disturb the smartphone’s compass sensor, but could be compared with accelerometer data to tell whether the person actually changed direction.
“Software is getting more and more important, even for a sensor supplier, because it adds value for customers,” he says. “Sensor hub solutions which add more and more intelligence can now be inside the sensor itself to optimise the signal, or you could send signals to the system processor. This has led to sensors becoming a lot more powerful – you now get a whole sensor system inside the sensor package.”
Several companies demonstrated a desire to add value to sensor systems by offering a larger part of the system for development purposes. Analog Devices launched a wireless sensor node development kit at the show (figure 4) that combines a base station board with two end nodes and an emulator platform to program them. Each end node board features five sensors: a low power accelerometer (the ADXL362 with active current of 2µA which can be used as a standby switch), a temperature sensor, a combined temperature and humidity sensor, a PIR sensor and an ambient light sensor.
The kit uses ADI’s proprietary sub-GHz wireless protocol called AD Radio Net, which was internally developed with a focus on making it easy to use, small footprint and very low power. However, a 6LoWPAN version of the kit is coming soon.
Taking integrated offerings for the IoT even further was Murata, who in a deviation from previous strategy showed a complete sensor node system with wireless gateway ready for re-badging and resale. The sensor component and module manufacturer has developed end nodes based on its sensor technology, alongside a gateway (figure 5). The mini gateway (SHGC200) is essentially a web server running embedded Linux with WLAN, Ethernet and ZigBee capability, which is the apparently the smallest of its type in the world.
The Murata system includes middleware plus an android app to control the system (iOS app coming soon). Demo-ing on the Murata booth was the gateway communicating with a remote control and smart plug, plus PIR, magnetic and humidity sensors to switch lights on and off.