Pedestrian direction of motion determination system and method

A mobile device, comprising:

• one or more processors;
• an accelerometer connected to the one or more processors;
• and
• a memory connected to the one or more processors, the memory storing computer program logic that is executable by the one or more processors to perform operations that include:
• obtaining a first series of accelerometer measurements from the accelerometer, the accelerometer measurements in the first series of accelerometer measurements being relative to a reference frame of the mobile device;
• converting the first series of accelerometer measurements into a second series of accelerometer measurements, the accelerator measurements in the second series of accelerator measurements being relative to a local level reference frame;
• filtering the second series of accelerometer measurements to obtain a first series of frequency components representing acceleration at an estimated stride frequency of a pedestrian in a first direction and a second series of frequency components representing acceleration at the estimated stride frequency of the pedestrian in a second direction that is orthogonal to the first direction;
• determining a heading angle of a major axis or a semi-major axis of an ellipse defined at least by one or more frequency components in the first series of frequency components and one or more frequency components in the second series of frequency components;
• and
• determining a direction of motion of the pedestrian based on the heading angle.

A computer program product comprising a computer-readable memory having computer program logic recorded thereon that when executed by at least one processor causes the at least one processor to perform a method comprising:

• obtaining a first series of accelerometer measurements from an accelerometer, the accelerometer measurements in the first series of accelerometer measurements being relative to a reference frame of a mobile device;
• converting the first series of accelerometer measurements into a second series of accelerometer measurements, the accelerator measurements in the second series of accelerator measurements being relative to a local level reference frame;
• filtering the second series of accelerometer measurements to obtain a first series of frequency components representing acceleration at an estimated stride frequency of a pedestrian in a first direction and a second series of frequency components representing acceleration at the estimated stride frequency of the pedestrian in a second direction that is orthogonal to the first direction;
• determining a heading angle of a major axis or a semi-major axis of an ellipse defined at least by one or more frequency components in the first series of frequency components and one or more frequency components in the second series of frequency components;
• and
• determining a direction of motion of the pedestrian based on the heading angle.