Method and system for determining a direction of movement of an object

A system for determining a direction of movement of an object, the system comprising:

• a receiver for receiving signals from an external positioning system,
• at least one of an accelerometer or an inertial sensor,
• a magnetometer,
• at least one memory unit, and
• a processing unit comprising at least one processing core, at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processing core, cause the system at least to:
• determine a cyclical motion of a cyclically moving part of the object by recording acceleration data of said cyclically moving part over a plurality of cycles using an accelerometer or inertial sensor attached to said cyclically moving part,
• integrate said acceleration data over at least one cycle of movement to determine a tilting of said cyclically moving part of the object relative to a horizontal plane,
• measure an external magnetic field of said cyclically moving part of the object using a magnetometer to determine an orientation of said cyclically moving part of the object relative to the external magnetic field, and
• determine the direction of movement of the object based on the tilting and the orientation of said cyclically moving part of the object,
• wherein the system is configured to determine the tilting of the accelerometer or inertial sensor using the formula
• ∫C{tilde over ({right arrow over (a)})}=∫C{right arrow over (a)}+∫Cf({right arrow over (g)})≈{right arrow over (0)}+{right arrow over (O)}·Δt, and
• wherein {right arrow over (a)} is the acceleration of the second part, {right arrow over (g)} is the gravity in global coordinates, {right arrow over (O)} is the tilt, C is a cycle denoting the integral is calculated over a cycle and t is the time.

A non-transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least to:

• determine a cyclical motion of a cyclically moving part of the object by recording acceleration data of said cyclically moving part over a plurality of cycles using an accelerometer or inertial sensor attached to said cyclically moving part,
• integrate said acceleration data over at least one cycle of movement to determine a tilting of said cyclically moving part of the object relative to the horizontal plane,
• measure an external magnetic field of said cyclically moving part of the object using a magnetometer to determine an orientation of said cyclically moving part of the object relative to the external magnetic field, and
• determine the direction of movement of the object based on the tilting and the orientation of the cyclically moving part of the object,
• wherein the system is configured to determine the tilting of the accelerometer or inertial sensor using the formula
• ∫C{tilde over ({right arrow over (a)})}=∫C{right arrow over (a)}+∫Cf({right arrow over (g)})≈{right arrow over (0)}+{right arrow over (O)}·Δt, and
• wherein {right arrow over (a)} is the acceleration of the second part, {right arrow over (g)} is the gravity in global coordinates, {right arrow over (O)} is the tilt, C is a cycle denoting the integral is calculated over a cycle and t is the time.