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

## Presentation on theme: "1 Clever Pointer Device Samer Aamar Post PC Course – 2002."— Presentation transcript:

1 Clever Pointer Device Samer Aamar Post PC Course – 2002

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 Well, sounds like a Mouse!

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

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

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 Press On Activate

10 Press On Activate

11 Hold Activate and Move Pointer!

12 Release Activate button!

13 Release Activate button! Press on LButton/RButton

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

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

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

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

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

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 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

23 END

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