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1 Clever Pointer Device Samer Aamar Post PC Course – 2002.

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1 1 Clever Pointer Device Samer Aamar Post PC Course – 2002

2 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…

3 3 Well, sounds like a Mouse!

4 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

5 5 xx y/yy = h/hh x/xx=w/ww w h x y ww hh yy

6 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

7 7 Components Basic components:  2 Tri-Axis Accelerometers  Three buttons  Transmitter/Receiver (wireless) 3D Accelerometers button s Transmitter

8 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

9 9 Press On Activate

10 10 Press On Activate

11 11 Hold Activate and Move Pointer!

12 12 Release Activate button!

13 13 Release Activate button! Press on LButton/RButton

14 14 Accelerometers We need: 3-Axis Accelerometer MEMS ( Micro Electro Mechanical Systems ) Acc. : Small Light Ability to measure hand motion (next slide)

15 15 Measuring Hand Motion Target ValueParameter 0.1 to 25 HzFrequency Range +/- 5 gAcceleration Amplitude 1 mgAcceleration Resolution g ~ 9.8 m/sec2

16 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

17 17 Analog Devices Performance Resolution of ADI accelerometer sensors over time Cost of performance in ADI accelerometer sensors over time

18 18 Relevant Thesis  Graham B.; Using an Accelerometer Sensor to Measure Human Hand Motion; Massachusetts Institute of Technology;  He achieved the following: Frequency:0.1 – 25 Hz Amplitude:±10g Mass:4.88 grams Size:(17mm)^3

19 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!

20 20 Summary ExistingRequired Three single-axis accelerometers (Analog Devices) 3-Axis Accelerometers RadioReceiver/Transmitter

21 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)

22 22 Related Sites   

23 23 END


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