Processing signals to determine spatial positions
View Patent ↗An apparatus is disclosed for supplying input signals to a computer. A sensor having the form of a sphere has a touch sensitive surface for generating position data for touch events. The sensor includes orientation sensors that determine rotation with respect to the earth's magnetic and gravitational fields. Orientation data may be combined with position data to interpret the orientation of touch events on the surface with respect to the computer's display. Cursor movement or text may be generated from touch events. Preferably the sphere has a roughened surface that generates sound when touched. Position data is generated by processing signals from microphones under the sphere's surface.
1. A method of determining the location of contact between a moving fingertip and a surface across which it is moving, comprising the steps of:
generating random sound at the location of said contact by a process of substantially continuous frictional interaction between said surface and said moving fingertip,
conducting sound waves from the location of said interaction to at least one microphone via sound-conducting material,
analyzing signals from said at least one microphone, and
processing results of said analysis to identify said location of contact.
2. The method of claim 1 , wherein said surface is optimized for a combination of smoothness to the sense of touch and generating random sound by friction.
3. The method of claim 1 , wherein said step of conducting sound waves includes conducting said sound waves to a plurality of microphones at a plurality of respective microphone locations.
4. The method of claim 1 , wherein said step of analyzing signals includes frequency domain analysis.
5. The method of claim 4 , wherein said step of analyzing signals includes frequency domain analysis for a plurality of respective microphone signals.
6. The method of claim 1 , wherein said step of processing results includes combining results of frequency domain analysis for a plurality of respective microphone signals.
7. The method of claim 1 , wherein said step of processing results includes comparing a result of said analysis with templates representing known locations on said surface.
8. The method of claim 7 , wherein a location is identified by interpolating between selected location templates.
9. The method of claim 1 , wherein a sequence of touch locations determined over time is used to select a text character or characters for text input to a computer system.
10. A touch-operable input device comprising:
a surface for generating random sound by a process of substantially continuous frictional interaction with a moving fingertip,
at least one microphone arranged to receive sound waves from the location of said frictional interaction via sound-conducting material, and
means for supplying signals to processing means configured to identify a fingertip location by processing signals from said at least one microphone.
11. The touch-operable input device of claim 10 , wherein said surface is a solid surface.
12. The touch-operable input device of claim 10 , wherein said surface is optimized for a combination of smoothness to the sense of touch and generating random sound by friction.
13. The touch-operable input device of claim 10 , further including said processing means.
14. The touch-operable input device of claim 13 , wherein said processing means is configured to perform the steps of:
performing a frequency domain analysis of signals from said at least one microphone, and
processing results of said frequency domain analysis to identify said location of contact.
15. The touch-operable input device of claim 14 , further including a template memory storing templates of known touch locations.
16. The touch-operable input device of claim 15 , including the additional step of comparing a result of said analysis with templates representing known locations on said surface.
17. The touch-operable input device of claim 16 , including the further additional step of identifying a location by interpolating between selected location templates.
18. The touch-operable input device of claim 10 , including a plurality of microphone means.
19. The touch-operable input device of claim 10 , wherein said surface is curved.