Post on 28-Nov-2014
description
Are indoor positioning systems mature for cartographic tasks? Evaluating the performance of a commercial indoor positioning system
Terje Midtbø Norwegian University of Science and Technology
View of the world?
When we move indoor....
Overview
• Indoor maps • Indoor navigation • Testing the WiFi positioning system at NTNU
• Measurements • Results
• Discussions and conclusions
Do we need indoor navigation? • Localization of persons and equipment at
for example hospitals • Find your way in large complex and
unknown buildings • Find products in large shopping areas • Most efficient shopping based on shopping
list • Tourists at a museum • Alternative emergency exits • Localization of firefighter • …….
Indoor maps
Indoor visualization
Indoor maps
Floor plans
Map made by Jaan Tarmak
Floor plans
Indoor tube
Indoor navigation
GPS-”repeaters”
RFID-system
- Present?
Systems based on ultrasound
- Need free line of sight
Infrared signals
- Present?
Bluetooth
Location by phone signals
WiFi positioning systems
WiFi positioning systems • Time for signal one way • Time for signal both ways • Time for signal in combination with angle
to the access points • Phase measurements • Signal strength
Indoor navigation
Cisco positioning system at Norwegian University of Science and Technology (NTNU)
Investigation of the Cisco-system at NTNU
Network of control points
Measurements • Accurate measurement of control points by
surveying equipment and methods • New measured coordinates for the access
points • Coordinates measured in UTM, Zone 32N • Transformed into local system used by the
Cisco system. Units in feet.
New coordinates for the access points
• Average 2D differences: 11.7 feet • Min: 3.7 feet • Max: 19.2 feet
Measurement of positions by using WiFi
Measurement application
• Web-based interface • Measured data stored in SQLite database • Both UTM and local coordinate systems
Equipment for the measurement
• Laptop with external antenna • Fixed height over the floor • Easy to move to next position
Measurements based on 4 configurations • Old coordinates for access points – no
fingerprinting • Old coordinates for access points with
fingerprinting • New coordinates for access points – no
fingerprinting • New coordinates for access points with
fingerprinting
Measurements based on 4 configurations • 10 points were measured in the 1st floor of
Lerkendalsbygget • 5 measurements for each point in each
configuration
Results
Differences from true values
Measured point and access points
Correlation coefficients
X-components, 1- 4 Y-components, 1- 4
Variances
Differences from true values
Discussion and conclusions
• More accurate coordinates for access points gave no significant improvement for measured position
• Fingerprinting as it is used today shows no significant improvement in the measured position. Lower variance is still observed.
• Correlation between different types of measurements in the same control points indicate that geometry and obstacles are the dominating sources of error
• Further research: include obstacles in the model
• More accurate coordinates for access points gave no significant improvement for measured position
• Fingerprinting as it is used today shows no significant improvement in the measured position. Lower variance is still observed.
• Correlation between different types of measurements in the same control points indicate that geometry and obstacles are the dominating sources of error
• Further research: include obstacles in the model • Still too poor precision and accuracy for turn-by-turn
navigation • Acceptable for localize equipment • Acceptable for overview of peoples position in social
applications