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Published byBelinda Payne Modified over 9 years ago
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1 Clever Pointer Device Samer Aamar Post PC Course – 2002
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2 It would be great to be able to… move next/previous without the need to be near your PC/Laptop mark important words / draw basic shapes (circles, arrows, etc.) with his pointer device press on buttons on the screen, activate shortcuts, surf in WEB…
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3 Well, sounds like a Mouse!
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4 How does it work? The pointing device will plot a virtual ray! The intersection with the projection screen will be calculated (3D space) The computer will translate the intersection 3D point into a 2D point on the screen. Mouse Move events will be fired to the system
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5 xx y/yy = h/hh x/xx=w/ww w h x y ww hh yy
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6 Some mathematics The points p1, p2 are in 3D space The ray vector p2-p1 It would be easy to calculate the intersection point with the screen BUT, before all the coordinates of the projection screen should be defined p1 p2
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7 Components Basic components: 2 Tri-Axis Accelerometers Three buttons Transmitter/Receiver (wireless) 3D Accelerometers button s Transmitter
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8 Buttons The device has three buttons: ‘Activate’ button: When down the MOUSE_MOVE event is fired ‘LButton’ / ‘RButton’ button: samples the Left/Right Button on the regular mouse
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9 Press On Activate
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10 Press On Activate
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11 Hold Activate and Move Pointer!
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12 Release Activate button!
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13 Release Activate button! Press on LButton/RButton
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14 Accelerometers We need: 3-Axis Accelerometer MEMS ( Micro Electro Mechanical Systems ) Acc. : Small Light Ability to measure hand motion (next slide)
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15 Measuring Hand Motion Target ValueParameter 0.1 to 25 HzFrequency Range +/- 5 gAcceleration Amplitude 1 mgAcceleration Resolution g ~ 9.8 m/sec2
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16 Accelerometers (II) Good enough (according to the sheets) Analog Device iMEMS accelerometers ADXL105 ADXL150 Microsystems Technology Laboratory (MTL) 3-Axis accelerometers: TG Series Accelerometers: CXL10TG3 (crossbow tech.) ACCELEROMETERS by Vernier
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17 Analog Devices Performance Resolution of ADI accelerometer sensors over time Cost of performance in ADI accelerometer sensors over time
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18 Relevant Thesis Graham B.; Using an Accelerometer Sensor to Measure Human Hand Motion; Massachusetts Institute of Technology; 2000. He achieved the following: Frequency:0.1 – 25 Hz Amplitude:±10g Mass:4.88 grams Size:(17mm)^3
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19 Transmitter/Receiver Frequency: 25 Hz Data (bits): 2 x 3 x 32 (X, Y, Z) 3 (buttons) Total (per second) 25 x 194 = 4850 = 4.8 Kb per sec Possibilities Bluetooth – too much! Radio transmitter/receiver – simple: 10 Kb per sec is OK!
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20 Summary ExistingRequired Three single-axis accelerometers (Analog Devices) 3-Axis Accelerometers RadioReceiver/Transmitter
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21 Open Issues! CPU Consuming? Sudden movements – like sharply putting the device on the table (20g) What happens if the connection between transmitter and receiver was interrupted temporarily for some reason (example by moving to another room)
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22 Related Sites http://www.analog.com http://www.analog.com http://shop.store.yahoo.com/crossbow/index.html http://shop.store.yahoo.com/crossbow/index.html http://www-mtl.mit.edu/MEngTP/Graham_Thesis.pdf http://www-mtl.mit.edu/MEngTP/Graham_Thesis.pdf
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23 END
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