Force Sensing Apparatus and Method to Determine the Radius of Rotation of a Moving Object

• US 20080255795A1
• Filed: 04/11/2008
• Published: 10/16/2008
• Est. Priority Date: 04/13/2007
• Status: Active Grant

• Current Assignee: KEYnetik, Inc.
• Original Assignee: KEYnetik, Inc.
• Inventors: Shkolnikov, Mark
• Granted Patent: US 7,966,146 B2
• Time in Patent Office: Days
• US Class Current: 702/141
• CPC Class Codes: G01P 15/00 Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G06F 1/1626 with a single-body enclosure integrating a flat display, e.g. Personal Digital Assistants [PDAs]
• CPC Class Codes: G06F 1/1684 Constructional details or arrangements related to integrated I/O peripherals not covered by groups G06F1/1635 - G06F1/1675
• CPC Class Codes: G06F 2200/1637 Sensing arrangement for detection of housing movement or orientation, e.g. for controlling scrolling or cursor movement on the display of an handheld computer

Abstract

An apparatus having an arrangement of two or more identical accelerometers with aligned sensitivity axes. Each of the accelerometers senses motion over at least one axis. The accelerometer readings include a component corresponding to gravitational force that is the same for each accelerometer in the arrangement. Logic circuitry in communication with the accelerometer arrangement couples accelerometer signals to a processor to compute motion variables.

Claims

1. An apparatus comprising:

a body having at least two accelerometers mounted in the body, the accelerometers are separated in space and sense movement on at least one sensitivity axis;

a processor in communication with the accelerometers to receive sensed motion data from said accelerometers and to compute motion of said body from said motion data; and

said processor to execute instructions to compute a radius of rotation and direction to an axis of rotation of the said body, said instructions to apply geometrical principals to real-time accelerometer readings and fixed orientation and position of the accelerometers in reference to the body.

2. The apparatus of claim 1, wherein said instructions is limited to incremental data in excess of a threshold.

3. The apparatus of claim 1, wherein angular acceleration and angular velocity are derived from the accelerometer readings and computed radii of rotations.

4. The apparatus of claim 1, wherein said accelerometers are substantially identical with aligned sensitivity axes.

5. The apparatus of claim 1, wherein each of said accelerometers are dual axis accelerometers that sense motion on two orthogonal axes.

6. The apparatus of claim 1, further comprising three accelerometers mounted in the body in a triangular arrangement.

7. The apparatus of claim 1, wherein each of said accelerometers are triple axis accelerometers and sense motion on three orthogonal axes.

8. The apparatus of claim 1, further comprising a substrate mounted within said body, and said accelerometers mounted on said substrate with aligned sensitivity axes.

9. The apparatus of claim 8, wherein said substrate is a microchip.

10. The apparatus of claim 1, wherein said body is a handheld device in communication with a visual display, wherein an image shown in the visual display is changed in response to said sensed motion in excess of a threshold.

11. The apparatus of claim 1, further comprising said processor to compute a radius of rotation of said body in real-time.

12. The apparatus of claim 11, further comprising a filter system in communication with said processor to parse signals based on the computed radius of rotation, including processing a signal with a radius of rotation less than a predetermined value as motion input, and to block a signal with a radius of rotation greater than a predetermined value.

13. The apparatus of claim 11, further comprising a filter system in communication with said processor to parse signals based on the direction to the axis of rotation, including to process a motion input signal associated with a certain direction to the axis of rotation and to block a signal associated with another direction to the axis of rotation.

14. The apparatus of claim 11, further comprising a filter system in communication with said processor to parse signals based on angular acceleration and angular velocity, including to process a signal with an angular acceleration and angular velocity of more than a predetermined value as motion input and to block a signal with an angular acceleration and angular velocity lesser than a predetermined value.

15. The apparatus of claim 1, further comprising a global positioning system receiver in communication with said processor.

16. The apparatus of claim 15, further comprising said global positioning system receiver to transmit location data in response to said sensed motion in excess of a threshold.

17. The apparatus of claim 1, further comprising the processor to compute a distance and a direction to an axis of rotation of said body using triangulation.

18. The apparatus of claim 1, further comprising the processor to reduce error induced by gravity through differential reading in near real-time.

19. The apparatus of claim 18, further comprising a correction of gravity induced error calculation based on a reading of said accelerometers before and after rotation of said body.

20. The apparatus of claim 18, further comprising a correction of gravity induced error by adding or subtracting a stored empirical gravity compensation value.

21. An article comprising:

a body having at least one mounted accelerometer, configured to sense movement on at least one sensitivity axis;

a computer readable carrier including a motion input algorithm configured to translate the sensed movement received from the at least one accelerometer into a command, and a step motion algorithm to process the command, the step motion algorithm including instructions comprising;

instructions to execute a command from the motion input algorithm,

instructions to send a sleep command to the motion input algorithm after the command is executed; and

instructions to re-activate the motion sensing algorithm from the sleep command after elapse of a defined period of time.

22. The article of claim 21, wherein the sleep communication instructions temporarily block execution of a new command from the motion sensing algorithm.

23. The article of claim 21, wherein the sleep command provides readjustment of the motion input algorithm between successive movements of the body.

24. The article of claim 21, wherein the re-activate instructions send an activate command to the motion input algorithm to resume sending motion input commands with a current placement of the body as a reference point of origin.

25. The article of claim 21, further comprising instructions to parse a signal with a radius of rotation less than a pre-determined minimum value as motion input, and to block a signal with a radius of rotation greater than a pre-determined value maximum value.

26. A method to sense movement of a body, comprising

mounting at least two accelerometers in a body, said accelerometers configured to sense movement on at least one sensitivity axis;

a processor in communication with the accelerometers for receiving sensed motion data from accelerometer data;

said processor computing motion of said body from said motion data; and

said processor executing instructions for computing a radius of rotation and direction to an axis of rotation of the body, and applying geometrical principals to real-time accelerometer readings and fixed orientation and position of the accelerometers.