Among the challenges that remain before Wireless Sensor Network (WSN) technology becomes truly pervasive is that of positioning, both for the wireless devices that comprise the network and perhaps more importantly for the event that occurs within proximity of a device. This information can be used in a variety of ways ranging from simply locating the closest printer to positioning a rescue worker or injured party in a disaster scenario. Among the distinguishing features of WSNs is their interaction with the surrounding environment through actuation and sensing. It is for this very reason that WSNs are now envisaged as a viable tool in applications such as search and rescue and disaster relief where node location is an important aspect given human life may be at risk. Tyndall plays an active role in the development and systems integration of both indoor and outdoor localisation technologies. Focus is also placed on the design of novel positioning algorithms to improve the accuracy of the employed technologies.

Figure 1: Tyndall’s vision of the Position Aware Wireless Sensor Network

Localisation Technologies

There are a number of position aware technologies both emerging and pre-existing that are very useful in the WSN application space. Tyndall is presently developing, integration and employing a number of these technologies in a wide variety of deployments ranging from vehicle detection to wearable systems (link to wearable systems).

IEEE 802.15.4a Ultra Wide Band (UWB)

This standardized emerging transceiver technology can easily be placed in the next generation Wireless Sensor Network (WSN) category. The hardware boasts improved throughput, far superior energy efficiency, better resistance to interference and multi-path effects and a more secure channel when compared with existing WSN technologies such as IEEE802.15.4. Furthermore its precision ranging capabilities will inevitably result in the expansion of the WSN application space far beyond what was originally thought possible. The standardised technology is manufactured by the Irish company Decawave . Close collaborative contacts have been established between Decawave and Tyndall and the goal will be to integrate the technology into the Tyndall Wireless Sensor Platform.

Global Positioning System (GPS)

GPS location is available world wide courtesy of a constellation of 24 satellites orbiting the earth. To enable movement and tracking in an outdoor environment Tyndall have developed a 25mm GPS layer. The layer provides a serial interface to the positional information, satellite status, time/date information as well as speed, location information in terms of latitude, longitude and height and some information regarding the earth’s magnetic field.

Figure2: GPS Localisation Results (Left) using the Tyndall’s 25mm GPS Layer (Right)

Radio Frequency Identification (RFID)

Radio Frequency Identification (RFID) is a non contact method for information identification technology using radio waves. This well established mainstream technology has been incorporated into the Tyndall 25mm wireless sensor platform and can be employed in a wide variety of applications including remote environmental monitoring, inventory tracking, transport payments, security and in passport control.  

Figure 5: Radio Frequency Identification (Left), Tyndall’s 25mm RFID Layer (Right)

Assisting Localisation with Sensor Fusion

The environments in which the localisation technologies mentioned above are deployed introduce stochastic exogenous disturbances into the system which can in turn affect localization accuracy. One means of overcoming this often unavoidable occurrence is the use of additional sensors to correct or fine tune the precision of the positioning system. In this regard Tyndall have developed a number of sensor layers including the Inertial Measurement Unit (IMU). The IMU has 3 axis accelerometer, gyroscope and magnetometer capabilities and measurements taken using the IMU can be fused with real-time localization information to improve and enhance the accuracy of the system.  

Figure 5: The Tyndall 25mm Wireless Inertial Measurement Unit

Publications

Conferences

• Giuseppe Torre, Javier Torres, Mikael Fernstrom, Brendan O’Flynn, “Algorithm for Tracking Orientation Development of POINTINGAT”, Proc.NIME2008, 8th International Conference on New Interfaces for Musical Expression, 5 - 7 June 2008, Genova, Italy

• Javier Torres, Brendan O'Flynn, Philip Angove, Frank Murphy and Cian O'Mathuna “Motion Tracking Algorithms for Inertial Measurement”, Proc. BodyNets 2007, 2nd International Conference on Body Area Networks, 11-13 June, 2007, Florence, Italy

Posters

Philip Angove, Javier Torres, Brendan O’Flynn and Frank Murphy, “Development & characterization of a low cost miniaturised inertial tracking wireless module”, Information Technology & Telecommunications Conference 2006, Institute of Technology, Carlow, October 25-26, 2006. Proc pp 191-192