Title: Design of a Wearable Sensor Badge for Smart Kindergarten
1Design of a Wearable Sensor Badge for Smart
Kindergarten
- Sung Park, Ivo Locher, Andreas Savvides, Mani B.
Srivastava, Alvin Chen, Richard Muntz, Spencer
Yuen - University of California, Los Angeles
- ISWC, October 10, 2002
2Wireless Networking and Computing Technology
- So far focus on richer person - person and
person - computer interaction - Cellular telephony
- Personal communications
- Wireless internet access to web services
- Future communication between people and their
physical environment - Mark Weisers vision
- Allow users to query, sense, and manipulate the
state of the physical world - Add a sense of real world to user interaction
with computer systems - Context-aware applications that exploit computing
and networking infrastructure melded into the
environment
3Smart Kindergarten (SmartKG)
- Wireless networked sensors densely embedded in a
kindergarten room - create a problem solving environment that can is
continually sensed in detail - kids, toys, blocks, playthings, classroom
woodwork - Background computing data management
infrastructure for on-line and off-line sensor
data processing and mining - Sensor information used for
- assessment of student learning
- problem solving tasks that are adaptive and
reactive - services beneficial to teacher and students
4Smart Kindergarten (SmartKG) System Architecture
and iBadge
iBadge Speech Processing Wireless
Communication Localization Orientation
Sensing Environment Sensing
Networked Toys
5Smart Kindergarten (SmartKG) System Architecture
- Sensing Infrastructure-
- A Suite of sensors that collects the context
information in SmartKG - video camera, microphone, motion detectors, and
iBadge - Middleware Infrastructure Sylph
- provides various services that process, store,
fuse, manage, and present the data collected from
Sensing Infrastructure - manages the interaction between applications and
other higher-level services such as speech
recognition, sensor data storage and sensor data
browsing
6iBadge Wearable Sensor Badge System
- Wearable Design worn by kindergarten children
to monitor the context information of the student - Sensors - Ultrasound Transceiver, Accelerometer,
Magnetometer, Temperature, Humidity, Light,
Atmospheric Pressure
7iBadge Architecture
- ATMega128L, Wireless Communication Unit, Speech
Processing Unit, Power Management and Tracking
Unit, Localization Unit, Orientation and Tilt
Sensing Unit, Environment Sensing Unit
8iBadge Functional Units
- Main Processing Unit
- ATMega128L Microcontroller from Atmel
- Responsible for power management, localization,
and interfaces different functional units - Localization Unit
- Relative and absolute positioning
- responsible for obtaining precise 3D location of
iBadge in the classroom - estimates its 3D location using an ad-hoc
localization process - Speech Processing Unit
- Consists of TI DSP and CODEC
- Performs speech codec and front end processing of
the real time speech of the children - Two modes (Simple Coding or Front End Processing)
of operation based on power requirements and user
request.
9iBadge Functional Units (Continued)
- Power Management/Tracking Unit
- Battery Monitors (DS2438) keep track of energy
usage of various functional units - CMOS switches provides control to turn on/off
different part of the circuits - Orientation/Tilt Sensing Unit
- Accelerometer combined with magnetometer provides
the orientation of the children with earths
magnetic field - Environment Sensing Unit
- Temperature, Humidity, Atmospheric Pressure, and
Light Intensity
10The Sylph Middleware
11The Sylph Middleware
- Modular, Layered Design
- Sensor module
- Service discovery module
- Proxy core
- Query Language
- READ temperature EVERY 30 seconds FOR 1 hour
- Sensor Stream Processing
12Sylph Components
- Sensor Module
- Strong Abstraction Barrier
- Derived from IEEE 1451 Transducer Electronic Data
Sheet (TEDS) - Metadata - name, manufacturer, etc.
- Attributes - device status, sampling interval,
etc. - Data available data, return types
- Service Discovery Module
- Device Proxy
- Common Service Discovery Mechanisms (e.g., Jini)
13Sylph Components (Continued)
- Proxy Core
- Device Manager
- Sensor Proxy
- Service discovery
- Layered functionality (e.g., buffering)
- Query Processor
- Query parsing
- Directed graph of stream operators
- Query optimization
- Query Distribution - Gateways
14Localization Subsystem
- iBadges equipped with a 40KHz ultrasonic receiver
circuit - Allows high precision distance measurements to
other devices in its immediate environment - Ad-Hoc Flavor
- Many devices can collaborate
- together to solve a problem
- that none of the devices can
- solve individually
- When distance measurements
- are available, track the iBadge
- using dead-reckoning
15Localization Process
- Atomic Multilateration
- Collaborative Multilateration
- iBadges and other nodes collaborate with each
other to form a non-linear optimization problem
and solve it efficiently in a fully distributed
manner
Known Location
Unknown Location
16Distributed Computation
- Use a distributed approximation to estimate node
locations - Nodes organize themselves in to groups that
provide well-constrained configurations
collaborative subtrees - Use known beacon information to obtain an initial
estimate of location - Refine initial estimates using iterative least
squares - Each node performs a multilateration using only
next-hop neighbor information in the context of a
collaborative subtree - Much less computation, similar result, fully
distributed operation
17Distributed Computation
1. Obtain initial estimates 2. for each
unknown 2.1 Perform Atomic Multilateration
if the neighbor is beacon use
beacon location else use current
position estimate 2.2 Broadcast new
location estimate 3. Repeat step 2 every time a
new position estimate is received until
the convergence criteria are met
The unknown nodes need to perform their atomic
multilateration in the same order, driven by a
Distributed Depth First Search algorithm gt
local computations, follow a global gradient
18Convergence Process
- From SensorSim
- simulation
- 40 nodes, 4 beacons
- IEEE 802.11 MAC
- 10Kbps radio
- Average 6 neighbors
- per node
19Gains in Computation Overhead
- Computation cost based on MATLAB FLOPS outputs
- Result difference between centralized and
distributed is very small - Mean 0.015 mm, Standard Deviation 0.0054mm
- A group of nodes can collectively solve a
non-linear optimization problem than none of the
nodes can solve individually.
20Summary
- SmartKG constructs the context information of the
classroom based on information from sensing
infrastructure (iBadge) and middleware
infrastructure (Sylph) - iBadges wearable platform provides detailed
information about the wearer - Precise localization is one key research challenge
21Conclusions
- Node development completed, finishing firmware
integration - Still a lot of things to be learned from
programming and using the system - Success defined by proving the usefulness of such
a system to educators - Lots of privacy issues are still pending
- For more information visit
- http//nesl.ee.ucla.edu/projects/smartkg
- Thank you!