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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
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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.
Scatternet Piconets Master BT Topology Master / Slave Slave Piconet ScatterNet Bluetooth Piconet and Scatternet formation 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.
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 Bluetooth Profiles Wide variety of available services
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
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 • Location Based Services • Gesture Recognition • 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: • Access point problems: rogue access points, weak/absence of signal strength:signal strength available only in certain areas • Errors in accuracy due to signal fading, multipath
Accel x Accel y Accel z Wireless x Wireless y Wireless Speed Navasync Experiment
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: • Improved localization (using data/sensor fusion techniques) • Online gesture recognition system • 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/plomp_et_ailisto_030821.pdf • Survey and Taxonomy of Location Systems for Ubiquitous Computing: Hightower and Borrielo • Miscellaneous web references