Detection of incorrect arrangement of inertial measurements units of a motion tracking system

A motion tracking system comprising:

• a computing device comprising at least one processor and at least one memory;
• and
• a plurality of units adapted to be arranged on body members of a person, each unit at least comprising an accelerometer and a gyroscope;
• wherein the at least one processor is configured, together with the at least one memory, to perform operations comprising:
• processing first sets of measurements of the person comprising at least a first set of measurements provided by each unit of the plurality of units, the first sets of measurements provided while the person is performing a first predetermined movement with the plurality of units arranged on the person, the first predetermined movement involving movement of at least one or more body members having a unit of the plurality of units arranged thereon, and the processing being so as to determine at least one of:
• that a respective unit of the plurality of units is arranged on a body member of the person with an orientation outside of a predetermined orientation range for a unit on that body member, according to both a predetermined unit arrangement and at least one of predetermined acceleration or orientation constraints to be met by the respective unit when the person performs the first predetermined movement, at least based on one or more of accelerations or orientations measured by the respective unit;
• or
• that two or more units of the plurality of units are arranged on interchanged body members of the person, according to both the predetermined unit arrangement and at least one of predetermined acceleration or orientation constraints to be met by the two or more units when the person performs the first predetermined movement, at least based on one or more of the accelerations or the orientations measured by the two or more units;
• in response to determining, based on at least the first sets of measurements that are provided while the person performs the first predetermined movement, at least one of that the respective unit of the plurality of units is arranged on the body member of the person with the orientation outside of the predetermined orientation range or that the two or more units are arranged on interchanged body members, adjusting operation of the motion tracking system, the operation being adjusted in such a way that at least one of:
• the at least one processor digitally modifies, according to the determination made at least based on one or more of the accelerations or the orientations measured by one or more of the plurality of units, at least one of:
• the predetermined unit arrangement or measurements provided by at least one of the plurality of units, the measurements digitally modified at least comprising measurements subsequent to the first sets of measurements;
• or
• the at least one processor causes to provide at least one user perceptible signal indicating that at least one of the plurality of units is or are arranged on interchanged body members of the person or indicating how to rearrange the at least one of the plurality of units on the body members of the person to fulfill the predetermined unit arrangement according to the determination made at least based on one or more of the accelerations or the orientations measured by one or more of the plurality of units;
• and
• processing at least second sets of measurements after the adjustment of the operation of the motion tracking system, each second set of measurements in the second sets of measurements being provided by a unit of the plurality of units while the person is performing a second predetermined movement with the plurality of units arranged on the person, the second predetermined movement involving movement of at least one or more body members having a unit of the plurality of units arranged thereon, a physical exercise performed by the person comprising the second predetermined movement, and the processing being so as to determine whether the person has performed the second predetermined movement according to a set of predetermined movement constraints, the set of predetermined movement constraints comprising, at least for each of one or more body members that are to move in the second predetermined movement and to have a unit of the plurality of units arranged thereon according to the predetermined unit arrangement, one or more of:
• a predetermined movement orientation threshold or range, a predetermined movement motion threshold or range, or a predetermined movement acceleration threshold or range.

A non-transitory computer-readable storage medium comprising instructions which, when executed by a device, cause the device to perform operations comprising:

• processing first sets of measurements of a person comprising at least a first set of measurements provided by each unit of a plurality of units of a motion tracking system with each unit at least comprising an accelerometer and a gyroscope, the first sets of measurements being provided while the person is performing a first predetermined movement with the plurality of units arranged on body members of the person, the first predetermined movement involving movement of at least one or more body members having a unit of the plurality of units arranged thereon, and the processing being so as to determine at least one of:
• that a respective unit of the plurality of units is arranged on a body member of the person with an orientation outside of a predetermined orientation range for a unit on that body member, according to both a predetermined unit arrangement and at least one of predetermined acceleration or orientation constraints to be met by the respective unit when the person performs the first predetermined movement, at least based on one or more of accelerations or orientations measured by the respective unit;
• or
• that two or more units of the plurality of units are arranged on interchanged body members of the person, according to both the predetermined unit arrangement and at least one of predetermined acceleration or orientation constraints to be met by the two or more units when the person performs the first predetermined movement, at least based on one or more of the accelerations or the orientations measured by the two or more units;
• in response to determining, based on at least the first sets of measurements, at least one of that the respective unit of the plurality of units is arranged on the body member of the person with the orientation outside of the predetermined orientation range or that the two or more units are arranged on interchanged body members, adjusting operation of the motion tracking system upon determining, the operation being adjusted by at least one of:
• digitally modifying, according to the determination made at least based on one or more of the accelerations or the orientations measured by one or more of the plurality of units, at least one of:
• the predetermined unit arrangement or measurements provided by at least one of the plurality of units, the measurements digitally modified at least comprising measurements subsequent to the first sets of measurements;
• and
• causing to provide at least one user perceptible signal indicating that at least one of the plurality of units is or are arranged on the interchanged body members of the person or indicating how to rearrange the at least one of the plurality of units on the body members of the person to fulfill the predetermined unit arrangement according to a determination made by the device at least based on one or more of the accelerations or the orientations measured by one or more of the plurality of units;
• and
• processing at least second sets of measurements after the adjustment of the operation of the motion tracking system, each second set of measurements in the second sets of measurements being provided by a unit of the plurality of units while the person is performing a second predetermined movement with the plurality of units arranged on the person, the second predetermined movement involving movement of at least one or more body members having a unit of the plurality of units arranged thereon, a physical exercise performed by the person comprising the second predetermined movement, and the processing being to determine whether the person has performed the second predetermined movement according to a set of predetermined movement constraints, the set of predetermined movement constraints comprising, at least for each of one or more body members that are to move in the second predetermined movement and to have a unit of the plurality of units arranged thereon according to the predetermined unit arrangement, one or more of:
• a predetermined movement orientation threshold or range, a predetermined movement motion threshold or range, or a predetermined movement acceleration threshold or range.