| CPC A63B 24/0006 (2013.01) [A63B 2024/0012 (2013.01); A63B 2220/12 (2013.01); A63B 2220/18 (2013.01); A63B 2220/44 (2013.01); A63B 2220/76 (2013.01); A63B 2220/836 (2013.01)] | 21 Claims |
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1. An apparatus comprising:
a portable personal electronic device that wirelessly receives acceleration data and rotational data from a foot-mounted sensor module that includes at least two accelerometer sensors to provide the acceleration data representing acceleration measurements in at least two orthogonal directions and at least one gyroscope sensor to provide the rotational data representing rotational or gyroscopic measurements around at least one axial directions;
a processor that calculates foot angles at a plurality of successive positions within each of a plurality of strides of a human user during an athletic activity based on the received acceleration data and rotational data, wherein the processor includes:
digital-filter algorithms that are applied to the acceleration data to obtain top-dead-center (TDC), right-hand (RH), bottom-dead-center (BDC) and left-hand (LH) time values, and
a low-pass filter that is applied to the rotational data to obtain low-pass-filtered rotational data that includes gyro-drift data,
wherein the processor calculates drift-filtered gyro data from differences between the rotational data and the low-pass-filtered rotational data in order to remove gyro drift, and wherein the processor uses the TDC, RH, BDC and LF time values to calculate foot angle data from the drift-filtered gyro data; and
an output device in the personal electronic device that presents human-perceptible indications based on the calculated foot-angle data.
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