Motion plane correction for MEMs-based input devices

• US 8,050,886 B2
• Filed: 08/15/2008
• Issued: 11/01/2011
• Est. Priority Date: 08/15/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Moussavi, Farshid
• Primary Examiner(s): KHUU, HIEN DIEU THI
• Application Number:
  US12/192,909
• Publication Number:
  US 20100042358A1
• Time in Patent Office: 1,173 Days
• Field of Search: 702/141
• US Class Current: 702/141
• CPC Class Codes: G06F 3/0346 with detection of the device orientation or free movement in a 3D space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors
• CPC Class Codes: G06F 3/03543 Mice or pucks G06F3/03541 takes precedence
• CPC Class Codes: G06F 3/0383 Signal control means within the pointing device

Abstract

An electronic motion-based input device and method for correcting errors in acceleration due to a deviation from a horizontal plane of motion by correcting for gravitational acceleration components due to the deviation in the plane of motion.

Claims

1. An electronic input device, comprising:

one or more motion sensors operable to generate one or more signals indicative of a measured acceleration of the input device moving in a plane of motion that is tilted relative to a horizontal plane;

a processing element coupled to the one or more motion sensors and operable to;

receive the one or more signals;

based at least in part on the one or more signals, calculate one or more corrected motion values that are indicative of an actual motion of the input device and that compensate for one or more effects of movement in the plane of motion that is tilted relative to the horizontal plane; and

determine if an angle of tilt of the plane of motion with respect to the horizontal plane is not outside of a range; and

an external interface operable to send one or more signals indicative of the corrected motion values to a receiving device if the angle of tilt of the plane of motion with respect to the horizontal plane is not outside of a range.

2. The device of claim 1, wherein at least one motion sensor comprises a MEMS-based accelerometer.

3. The device of claim 1, wherein the processing element is further operable to calculate one or more error values corresponding to an effect of gravity on the input device, wherein the processor additionally bases the calculation of the one or more corrected motion values on the one or more error values.

4. The device of claim 1, wherein the processing element is further operable to calculate the angle of tilt of the plane of motion with respect to a horizontal plane.

5. The device of claim 1, wherein the processing element is further operable to calculate an x′

gravity error component and y′

gravity error component and wherein the one or more corrected motion values are additionally based on the x′

gravity error component and the y′

gravity error component.

6. The device of claim 1, wherein the device comprises a plurality of motion sensors, and wherein each motion sensor comprises an accelerometer.

7. An electronic input device, comprising:

a plurality of accelerometers configured to each generate a respective signal of acceleration along a respective axis of a plane of motion of the input device;

a sensor configured to generate a sensor signal of acceleration along an axis at an angle to the plane of motion of the input device; and

a processor configured to;

receive the accelerometer signals and the sensor signal;

determine a corrected motion value indicative of an actual motion of the device;

determine if an angle of tilt of the plane of motion with respect to the horizontal plane is not outside of a range; and

determine if the corrected motion value is to be used, the corrected motion value reflecting whether the plane of motion is tilted relative to a horizontal plane,

wherein the processor determines that the corrected motion value is to be used if the angle of tilt of the plane of motion with respect to the horizontal plane is not outside of a range.

8. The device of claim 7, wherein the processor is configured to determine a corrected motion value by executing a plurality of instructions stored in a machine readable storage medium, to perform operations comprising,

determining a gravitational force value, and

determining the corrected motion value in reference to the gravitational force value.

9. The device of claim 7, wherein the processor is configured to determine a corrected motion value by executing a plurality of instructions stored in a machine readable storage medium, to perform operations comprising,

identifying an initial set of motion values based on the received accelerometer signals;

determining a gravitational force value,

using the determined gravitational force value to determine the presence of an error amount in at least one initial motion value, and

determining a position value through use of the determined error amount.

10. The device of claim 7, wherein the processor is further configured to determine a position value through use of the corrected motion value.

11. The device of claim 7, wherein the sensor comprises an accelerometer sensitive to an axis that is perpendicular to the axis of sensitivity of at least two other accelerometers.

12. An electronic input device, comprising:

one or more motion sensors operable to generate one or more signals indicative of a measured acceleration of the input device in a three dimensional space, wherein two dimensions of said three dimensional space form a plane of motion of the input device, the plane of motion being tilted relative to a plane that is normal to the effect of gravity;

a processing element coupled to the one or more motion sensors and operable to;

receive the one or more signals;

based at least in part on the one or more signals, calculate one or more corrected motion values that are indicative of an actual motion of the input device and that compensate for one or more effects of movement in the plane of motion that is tilted relative to the plane that is normal to the effect of gravity; and

determine if an angle of tilt of the plane of motion with respect to the plane that is normal to the effect of gravity is not outside of a range; and

an external interface operable to send one or more signals indicative of the corrected motion values to a receiving device if the angle of tilt of the plane of motion with respect to the plane that is normal to the effect of gravity is not outside of a range.