Ubiquitous User Localization for Pervasive Context-Aware Construction Applications - Mobile and Pervasive Computing in Construction - page 99

• Connect to Positioning Engine on port 8548 using connect()
• Create a TrackedDevice instance using a Device Object
1. Create a Device Instance
2. Retrieve a Device Object using FindDevice method of the Positioning EngineClass

3. Create a TrackedDevice Object
• Add a LocationEstimateListener for a TrackedDevice object
1. LocationEstimateListener receives LocationEstimate objects
2. LocationEstimate contains location : getLatestLocation()
3. Use addLocationEstimateListener method and receive automatic location updates
• Add a Status Listener for a TrackedDevice object
1. Use addStatus Listener method to get the Tracked Device's State
• Start tracking by calling the setTracking(true) method
• Get all location values
• Stop Tracking by calling the setTracking(false) method
• Disconnect from Positioning Engine using disconnect()

Figure 6.8 Pseudo code of the client application SimpleTrack.java using JAVA SDK

The TrackedDevice class is the key class for Ekahau Java SDK's functionality. The
Positioning Engine's TrackedDevice objects represent wireless devices, so one
object needs to be created for each physical device to be tracked. After recording
a Positioning Model and saving it in the Positioning Engine with Ekahau Manager,
TrackedDevice objects are used to return the coordinates, timestamp, status, speed,
map, and any “logical area” information. The client receives the information via
two main kinds of Listener classes. The Listener interfaces are LocationEstimate-
Listener used to obtain automatic location updates, and StatusListener used to get
information about the device's state, whether it has been detected or not. Figure 6.8
presents pseudo code reflecting one of the Ekahau ready examples or client
applications ( SimpleTrackExample.java) using the JAVA SDK to obtain the 2D
coordinates of a device/user(x, y coordinates).
Knowing that positioning information (x, y, floor level) is directly accessible
using JAVA SDK (Ekahau, 2007), the next step is to combine it with the orientation
information (roll, yaw, and pitch) in a single application as reflected in the pseudo
code shown in Figures 6.9 and 6.10. This was achieved by creating a “pipe” between
the JAVA application communicating with Ekahau and the C

þþ application

communicating with the magnetic orientation tracker.

6.3.2 UWB-based user position tracking

The second tracking system studied in this research is the Sapphire DART Ultra-
Wide Band (UWB) Digital Active Real Time Tracking system (Multispectral
Solutions, 2007). It is designed for tracking personnel and/or equipment. A system