Motion direction determination and application

A mobile device comprising:

• one or more sensors configured to measure acceleration data for the mobile device in each of one or more directions;
• one or more processors;
• and
• a memory storing instructions that, when executed by the one or more processors, implement a plurality of modules including:
• a motion direction estimation module configured to estimate a motion direction of the mobile device relative to a coordinate system based at least in part on the acceleration data;
• and
• a reliability metric computation module configured to:
• estimate two or more of:
• a first reliability metric based on a process used to estimate the motion direction;
• a second reliability metric based on a measure of stability of the mobile device;
• and
• a third reliability metric based on a measure of consistency in the estimated motion direction over a period of time;
• and
• calculate a composite reliability metric for the estimated motion direction that indicates a measure of certainty in the estimated motion direction based on the estimated two or more reliability metrics.

Tangible computer-readable storage media including non-transitory instructions that, when executed by one or more processors, are configured to:

• receive acceleration data for a mobile device in each of one or more directions;
• estimate a motion direction of the mobile device relative to a coordinate system based at least in part on the acceleration data;
• estimate two or more of:
• a first reliability metric based on a process used to estimate the motion direction;
• a second reliability metric based on a measure of stability of the mobile device;
• and
• a third reliability metric based on a measure of consistency in the estimated motion direction over a period of time;
• and
• calculate a composite reliability metric for the estimated motion direction that indicates a measure of certainty in the estimated motion direction based on the estimated two or more reliability metrics.

An apparatus comprising:

• means for obtaining acceleration data for the apparatus in each of one or more directions;
• means for estimating a motion direction of the apparatus relative to a coordinate system based at least in part on the acceleration data;
• means for estimating two or more of:
• a first reliability metric based on a process used to estimate the motion direction;
• a second reliability metric based on a measure of stability of the apparatus;
• and
• a third reliability metric based on a measure of consistency in the estimated motion direction over a period of time;
• and
• means for calculating a composite reliability metric for the estimated motion direction that indicates a measure of certainty in the estimated motion direction based on the estimated two or more reliability metrics.