Its all about fun with sensors!!

Amit Gaur

Outline

Description of Accelerometer based sensors

Bluetooth Technology and BlueSentry

Data Collection from BlueSentry Applications Research Challenges Further Work

Motivation for studying acceleration Accelerometers are used universally for the analysis of acceleration, velocity, and

displacement monitor the vibration level monitor and predict the health and condition of moving machinery Applications: Game Controllers Ultra-sensitive accelerometers : in personal computing devices

and handsets, eg accelerometer enable single-handed menu scrolling, map panning or web browsing without the use of a stylus or push buttons.

Designers of sports and health-related devices : pedometers and calorie counters for step counting, distance traveled and speed measurements.

Portable blood pressure monitoring devices to ensure proper arm positioning.

Used to measure the acceleration undergone by satellites

Accelerometers Sensor to measure

rate of change of velocity

Mass-spring system based on Newton’s 2nd Law & Hooke’s Law

Capacitor to measure displacement

http://ccrma-www.stanford.edu/CCRMA/Courses/252/sensors/node9.html

Crossbow Accelerometer Silicon

micromachined capicitive beam

General Purpose 3 Axis

Measures accelerations upto 4g

Other types of accelerometers piezoelectric accelerometer : based on

the property exhibited by certain crystals where a voltage is generated across the crystal when stressed.

Gyrometers: measure angular acceleration

Optical Accelerometers: use optical sensors

Heat Convection based

Bluetooth

Blue Teeth?? What are we talking about?

Harald Blåtand – 10th Century Viking King

Literal translated to “Bluetooth”

Bluetooth for the Real World short-range wireless communication technology Frequency hopping spread radio technology Wireless connection between devices changes frequency at

fixed intervals of time Master slave connection model Master determines timing of hopping, selection and sequence

of frequencies used.

BT Topology

Master

Slave

Piconet

ScatterNet

Bluetooth Piconet and Scatternet formation

Master / Slave

Scatternet Piconets

Ref:www.ccng.uwaterloo.ca/Seminars/Presentations/bilm.ppt

Advantages of using Bluetooth Allows tranmission range of upto 100

metres Not limited by line of sight Low power consumption Standardized protocol allowing for easy

interoperability Bidirectional mode Reduces the clutter of wires and

associated hazardous connections. Guarantee of data transmission by

acknowledgement system.

Bluetooth Profiles Wide variety of available services Generic Access Profile

Service Discovery Profile

Cordless Telephony Profile

Intercom Profile

Serial Port Profile

Headset Profile

Dial-up Networking Profile

For more on Profiles: http://www.swedetrack.com/usblue4.htm

Fax Profile

LAN Access Profile

Generic Object Exchange Profile

Object Push Profile

File Transfer Profile

Synchronization Profile

BlueSentry™: Bluetooth™ Sensor Adapter

Data Acquisition and Control Module 8 channel 16 bit AtoD converter Samples analog signals and converts to a

Bluetooth enabled digital data stream

Features and Specifications

Bluetooth: Serial Port Profile defines how to set-up virtual serial ports on

two devices and connecting these with Bluetooth.

forms the basis of a number of other profiles, such as dial-up networking, generic object exchange, and object push

Using this profile provides the Bluetooth units with an emulation of a serial cable using RS232 control signalling (RS232 is the standard protocol used in serial port communication)

This profile ensures that data rates up to 128 kbit/sec.

Programming Environment

Application developed on HP iPAQ with Microsoft Pocket PC 2003(OS)

Developer used: Microsoft Embedded Visual C++

Sensor Data collected from BlueSentry using Serial Port Programming

Data cleaning done using Perl and Python Scripts

Applications

1. Location Based Services2. Gesture Recognition3. Applications in Gaming

Overview of Localization Techniques Emerging mobile computing

applications often need to know where things are physically located.

mobile devices such as mobile robots, laptops and PDAs already use 802.11b protocol for wireless communication.

The IEEE 802.11b wireless Ethernet standard has been deployed in office buildings, museums, hospitals, shopping centers and other indoor environments

Ekahau Positioning System

802.11b Wireless Positioning Engine

Developed at the Univ of Helsinki

Tracking algorithm based on Received Signal Strength Intensity from Wireless Access Points

Improving Localization Performance All localization services have

shortcomings:1. Access point problems: rogue

access points, weak/absence of signal strength:signal strength available only in certain areas

2. Errors in accuracy due to signal fading, multipath

Navasync Experiment

Accel x

Accel yAccel z

Wireless xWireless y

Wireless Speed

Analysis of Accelerometer Data

Applications: BiometricsGesture Passwords

Gesture based Interaction Home appliance control with gestures

Simple Application to Gaming:Arkanoid

Aim: To control paddle via accelerometer

Game is played on the IPAQ

Accelerometer serves as a wireless joystick

Further Work Develop online streaming

application for data collection, cleaning, analysis and feedback for the following:

1. Improved localization (using data/sensor fusion techniques)

2. Online gesture recognition system3. Controlling paddle ball using

accelerometer

Work Ahead Sensor Fusion: Develop a model for

interpreting input from Localization Program as well accelerometer/sound sensor.

Eg. Which sensor stream is more reliable and when?

Gesture recognition: Training required for gesture, same applies for the game application

Key Takeaways so far….

Familiarity with devices: Accelerometer, BlueSentry , iPAQs

Working with sensor streams Sensor Fusion : Multi Sensor Data

Collection

And……I have miles to go before I sleep.

References http://www.palowireless.com/

infotooth/ Bluetooth.org http://www.vtt.fi/ict/publications/pl

omp_et_ailisto_030821.pdf Survey and Taxonomy of Location

Systems for Ubiquitous Computing: Hightower and Borrielo

Miscellaneous web references