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![Page 1: Laboratory for Communications Engineering Engineering Department, University of Cambridge Location of Mobile Devices Using Networked Surfaces James Scott.](https://reader036.fdocuments.net/reader036/viewer/2022070307/551b0f57550346f70d8b5e1b/html5/thumbnails/1.jpg)
Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Location of Mobile Devices Using
Networked Surfaces
James Scott Frank Hoffmann [email protected] [email protected]
http://www-lce.eng.cam.ac.uk/
![Page 2: Laboratory for Communications Engineering Engineering Department, University of Cambridge Location of Mobile Devices Using Networked Surfaces James Scott.](https://reader036.fdocuments.net/reader036/viewer/2022070307/551b0f57550346f70d8b5e1b/html5/thumbnails/2.jpg)
Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Overview
• Quick intro to Networked Surfaces
• Location process
• Simulations, measurements and visualisations
• Improving accuracy
• Applications
![Page 3: Laboratory for Communications Engineering Engineering Department, University of Cambridge Location of Mobile Devices Using Networked Surfaces James Scott.](https://reader036.fdocuments.net/reader036/viewer/2022070307/551b0f57550346f70d8b5e1b/html5/thumbnails/3.jpg)
Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Networked Surfaces Concept• Provide network connectivity using physical surfaces
• Such as desks, floors, etc.• Make use of gravity
• No “plug”; no special position/alignment required• Provides mobility for devices• Offers transparency of connection for users
• Support a range of services• Ethernet-style inter-computer networks• Slower serial busses for peripherals• Power
![Page 4: Laboratory for Communications Engineering Engineering Department, University of Cambridge Location of Mobile Devices Using Networked Surfaces James Scott.](https://reader036.fdocuments.net/reader036/viewer/2022070307/551b0f57550346f70d8b5e1b/html5/thumbnails/4.jpg)
Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Networked Surfaces Implementation• Augment surface and objects with conductive pads
•Different object “footprints” guarantee different numbers of channels
• When connecting, “pad mappings” are discovered
• Prototype characteristics:– PCMCIA interface to notebooks – Connection in ~0.2s– Disconnection in ~0.1s– 5Mbit/s networking
![Page 5: Laboratory for Communications Engineering Engineering Department, University of Cambridge Location of Mobile Devices Using Networked Surfaces James Scott.](https://reader036.fdocuments.net/reader036/viewer/2022070307/551b0f57550346f70d8b5e1b/html5/thumbnails/5.jpg)
Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Object Pad Configurations
Links Required
Object Pads
Footprint Diameter
(mm)
2 5 26
3 9 46
4 12 68
5 16 88
6 19 110
![Page 6: Laboratory for Communications Engineering Engineering Department, University of Cambridge Location of Mobile Devices Using Networked Surfaces James Scott.](https://reader036.fdocuments.net/reader036/viewer/2022070307/551b0f57550346f70d8b5e1b/html5/thumbnails/6.jpg)
Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Location Process
Object Placement
Surface Strip Object Pad
3
16
5
10
7
4
Pad Mapping
LocationAlgorithm
Object Location
y
x
![Page 7: Laboratory for Communications Engineering Engineering Department, University of Cambridge Location of Mobile Devices Using Networked Surfaces James Scott.](https://reader036.fdocuments.net/reader036/viewer/2022070307/551b0f57550346f70d8b5e1b/html5/thumbnails/7.jpg)
Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Location Algorithm
![Page 8: Laboratory for Communications Engineering Engineering Department, University of Cambridge Location of Mobile Devices Using Networked Surfaces James Scott.](https://reader036.fdocuments.net/reader036/viewer/2022070307/551b0f57550346f70d8b5e1b/html5/thumbnails/8.jpg)
Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Location Characteristics
• Location available for 100% of connected objects
• Expect guarantee of bounded maximum error
• Algorithm is fast: ~1ms on modest hardware
• Tested using simulations, measurements and visualisation…
![Page 9: Laboratory for Communications Engineering Engineering Department, University of Cambridge Location of Mobile Devices Using Networked Surfaces James Scott.](https://reader036.fdocuments.net/reader036/viewer/2022070307/551b0f57550346f70d8b5e1b/html5/thumbnails/9.jpg)
Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Simulations• Simulation process:
– Simulate random placement
– Calculate pad mappings
– Execute location algorithm
– Compare result with original placement
• Allows fast testing of many placements– 1,000,000 locations tested for each data point
• Other advantages– Testing of various footprints
– Evaluation of possible improvements
![Page 10: Laboratory for Communications Engineering Engineering Department, University of Cambridge Location of Mobile Devices Using Networked Surfaces James Scott.](https://reader036.fdocuments.net/reader036/viewer/2022070307/551b0f57550346f70d8b5e1b/html5/thumbnails/10.jpg)
Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Simulation Results
17mm
61mm
10°
41°
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Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Comparison with Measurements
• 50 manual measurements
• 4 link object
• Est. 5mm accuracy
• Results very close to simulation
Variable Mean Simulated Error
Mean Measuremen
t Error
Difference
X 15mm 13mm 2mm
Y 3.6mm 3.0mm 0.6mm
(X,Y) vector
16mm 14mm 2mm
7.8° 6.3° 1.5°
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Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Visualisation Tool• Circle shows est. position,
rectangle shows bounds
• Lines show est. orientation and max orientation range
• Y accuracy >> X accuracy
• 2 column accuracy >> 1 column accuracy
![Page 13: Laboratory for Communications Engineering Engineering Department, University of Cambridge Location of Mobile Devices Using Networked Surfaces James Scott.](https://reader036.fdocuments.net/reader036/viewer/2022070307/551b0f57550346f70d8b5e1b/html5/thumbnails/13.jpg)
Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Improving Location Accuracy
• Current prototype does not provide full pad mapping info• Only as many links as necessary, and only one object pad per link
• Can augment with information on “Duplicate Pads”• For each surface pad used, list all object pads touching it (instead of just
one)
• Can also augment with information on “All Links”• Provide mappings for all surface pads sensed, not just those used for
connection
• Possible to implement in current prototype• Changes only required in FPGA programs, not in hardware• Use simulation to test improved performance
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Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Improved Simulations — (X,Y) vector
17mm
61mm
8mm
32mm
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Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Improved Simulations — Orientation
9°2°
10°
41°
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Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Integration and Applications
• Integration with context-aware middlewares– E.g. QoS DREAM Flame, SPIRIT (both at LCE)
• APP: Auto-configuration of devices– Automatically connect devices appropriately– e.g. keyboard connects to closest monitor
• APP: Interface mobility– Remote interfaces using devices with better I/O hardware– e.g. ad-hoc docking station for a notebook computer
![Page 17: Laboratory for Communications Engineering Engineering Department, University of Cambridge Location of Mobile Devices Using Networked Surfaces James Scott.](https://reader036.fdocuments.net/reader036/viewer/2022070307/551b0f57550346f70d8b5e1b/html5/thumbnails/17.jpg)
Laboratory for Communications EngineeringEngineering Department, University of Cambridge
Conclusions
• Networked Surface prototype is capable of locating devices with a mean error of 8mm and 2º
• Also guarantees maximum errors of 32mm and 9º
• Beats most “dedicated” location systems!
• Many useful applications, including surface-centric ones