Robust step detection using low cost MEMS accelerometer in mobile applications, and processing methods, apparatus and systems

An electronic circuit for use with an accelerometer, the electronic circuit comprising:

• a nonvolatile memory having stored representations of instructions to generate a signal stream representing magnitude of acceleration, to electronically correlate a sliding window of the signal stream with itself to produce peaks at least some of which represent walking steps, and to electronically execute a periodicity check to compare different step periods, and to update a walking-step count;
• a sensor input port;
• a display port;
• and
• a processor circuit programmably operable in response to the instructions in said nonvolatile memory for at least addition and multiplication and conditional operations responsive to said sensor input port, thereby to effectuate the instructions and drive said display port;
• wherein the periodicity check includes such instructions to electronically record relative times of successive peaks, and execute a search of pairs of the times over those peaks to find a succession of peaks that are at an equal interval from each other based on the relative times, and to generate an estimate of walking-step length as a function of that interval;
• and
• wherein the processor circuit includes a clock circuit and the memory includes a step frequency module for execution by the processor with the periodicity check and with the clock circuit.

A process implemented using an electronic circuit responsive to an accelerometer, the process comprising:

• generating a signal stream representing magnitude of acceleration;
• electronically correlating a sliding window of the signal stream with itself to produce peaks at least some of which represent walking steps;
• electronically executing a periodicity check comparing different step periods updating a walking-step count;
• generating display information at least in part based on the step count;
• wherein the periodicity check includes electronically recording relative times of successive peaks, and searching pairs of the times over those peaks to find a succession of peaks that are at an equal interval from each other based on the relative times, and generating an estimate of walking-step length as a function of that interval;
• and
• monitoring step frequency with the periodicity check and a clock circuit.