Movement-triggered action for mobile device

1. A method comprising:

by a computing device, receiving sensor data from a sensor on the computing device indicating physical movement of the computing device over a period of time;

by the computing device, determining, based on the sensor data, two contemporaneous signals comprising:

a motion-trigger signal corresponding to a first characteristic of the physical movement of the computing device; and

a motion-confirm signal corresponding to a second characteristic of the physical movement of the computing device;

by the computing device, determining whether:

the motion-trigger signal comprises a transition from within a pre-defined threshold band to outside of the pre-defined threshold band, wherein the pre-defined threshold band comprises a range of physical movement along the first characteristic and the second characteristic; and

the motion-confirm signal is within the pre-defined threshold band;

by the computing device, when the motion-trigger signal comprises the transition from within the pre-defined threshold band to outside of the pre-defined threshold band and the motion-confirm signal is within the pre-defined threshold band, initiating a pre-defined action of the computing device, wherein the pre-defined action is associated with the first characteristic and not associated with the second characteristic; and

by the computing device, when the motion-trigger signal comprises the transition from within the pre-defined threshold band to outside of the pre-defined threshold band and the motion-confirm signal is outside the pre-defined threshold band, preventing initiation of the pre-defined action.

2. The method of claim 1 , wherein the sensor comprises one or more accelerometer, gyroscope, or magnetometer.

3. The method of claim 1 , wherein:

the first characteristic of the physical movement comprises an acceleration of the computing device along an axis perpendicular to a front surface of the computing device; and

the second characteristic of the physical movement comprises a rolling or yawing rotational motion of the computing device.

4. The method of claim 1 , wherein:

the physical movement of the computing device comprises a sudden acceleration followed by a sudden deceleration along an axis perpendicular to a front surface of the computing device; and

the pre-defined action comprises zooming into or out of an image displayed by the computing device.

5. The method of claim 1 , wherein:

the motion-trigger signal comprises data from an accelerometer; and

the motion-confirm signal comprises data from a gyroscope.

6. The method of claim 1 , further comprising processing the sensor data by one or more low-pass filters to reduce noise.

7. The method of claim 1 , wherein preventing initiation of the pre-defined action comprises performing a peak-hold that persists for a predetermined period of time on the motion-confirm signal so that an action lock-out condition persists for at least the predetermined period of time when the motion-confirm signal is outside of the pre-defined threshold band.

8. The method of claim 1 , wherein the method further comprises:

computing a probability that the motion-trigger signal will comprise a transition from within the pre-defined threshold to outside of the pre-defined threshold band; and

initiating the pre-defined action of the computing device comprises only partially initiating the pre-defined action if the probability exceeds a pre-determined value.

9. The method of claim 8 , wherein:

the pre-defined action comprises zooming into an image displayed by the computing device; and

the partially initiating the pre-defined action comprises partially zooming into the image.

10. The method of claim 1 , wherein the speed with which the pre-defined action is performed is proportional to the amplitude of the motion-trigger signal.

11. The method of claim 1 , wherein the computing device is a smartphone.

12. One or more computer-readable non-transitory storage media embodying software that is operable when executed to:

receive sensor data from a sensor on a computing device indicating physical movement of the computing device over a period of time;

determine, based on the sensor data, two contemporaneous signals comprising:

a motion-trigger signal corresponding to a first characteristic of the physical movement of the computing device; and

a motion-confirm signal corresponding to a second characteristic of the physical movement of the computing device;

determine whether:

the motion-trigger signal comprises a transition from within a pre-defined threshold band to outside of the pre-defined threshold band, wherein the pre-defined threshold band comprises a range of physical movement along the first characteristic and the second characteristic; and

the motion-confirm signal is within the pre-defined threshold band;

when the motion-trigger signal comprises the transition from within the pre-defined threshold band to outside of the pre-defined threshold band and the motion-confirm signal is within the pre-defined threshold band, initiate a pre-defined action of the computing device, wherein the pre-defined action is associated with the first characteristic and not associated with the second characteristic; and

when the motion-trigger signal comprises the transition from within the pre-defined threshold band to outside of the pre-defined threshold band and the motion-confirm signal is outside the pre-defined threshold band, prevent initiation of the pre-defined action.

13. The media of claim 12 , wherein the sensor comprises one or more accelerometer, gyroscope, or magnetometer.

14. The media of claim 12 , wherein:

the first characteristic of the physical movement comprises an acceleration of the computing device along an axis perpendicular to a front surface of the computing device; and

the second characteristic of the physical movement comprises a rolling or yawing rotational motion of the computing device.

15. The media of claim 12 , wherein:

the physical movement of the computing device comprises a sudden acceleration followed by a sudden deceleration along an axis perpendicular to a front surface of the computing device; and

the pre-defined action comprises zooming into or out of an image displayed by the computing device.

16. The media of claim 12 , wherein:

the motion-trigger signal comprises data from an accelerometer; and

the motion-confirm signal comprises data from a gyroscope.

17. The media of claim 12 , wherein the software is further operable when executed to process the sensor data by one or more low-pass filters to reduce noise.

18. The media of claim 12 , wherein preventing initiation of the pre-defined action comprises performing a peak-hold that persists for a predetermined period of time on the motion-confirm signal so that an action lock-out condition persists for at least the predetermined period of time when the motion-confirm signal is outside of the pre-defined threshold band.

19. The media of claim 12 , wherein the software is further operable when executed to:

compute a probability that the motion-trigger signal will comprise a transition from within the pre-defined threshold to outside of the pre-defined threshold band; and

initiate the pre-defined action of the computing device comprises only partially initiating the pre-defined action if the probability exceeds a pre-determined value.

20. A system comprising:

one or more processors; and

a memory coupled to the processors comprising instructions executable by the processors, the processors being operable when executing the instructions to:

receive sensor data from a sensor on a computing device indicating physical movement of the computing device over a period of time;

determine, based on the sensor data, two contemporaneous signals comprising:

a motion-trigger signal corresponding to a first characteristic of the physical movement of the computing device; and

a motion-confirm signal corresponding to a second characteristic of the physical movement of the computing device;

determine whether:

the motion-trigger signal comprises a transition from within a pre-defined threshold band to outside of the pre-defined threshold band, wherein the pre-defined threshold band comprises a range of physical movement along the first characteristic and the second characteristic; and

the motion-confirm signal is within the pre-defined threshold band;

when the motion-trigger signal comprises the transition from within the pre-defined threshold band to outside of the pre-defined threshold band and the motion-confirm signal is within the pre-defined threshold band, initiate a pre-defined action of the computing device, wherein the pre-defined action is associated with the first characteristic and not associated with the second characteristic; and

when the motion-trigger signal comprises the transition from within the pre-defined threshold band to outside of the pre-defined threshold band and the motion-confirm signal is outside the pre-defined threshold band, prevent initiation of the pre-defined action.