System and method for determining engagement level of a human being using a millimeter-wave radar sensor

A system, comprising:

• a processing system configured to be coupled to a millimeter-wave radar sensor, wherein the processing system is configured to:
• instruct the millimeter-wave radar sensor to transmit a series of chirps within a field of view of the millimeter-wave radar sensor;
• identify a set of targets within the field of view based on radar data received by the millimeter-wave radar sensor and in response to transmission of the series of chirps;
• extract a filtered vital-Doppler signal from the radar data, wherein extracting the filtered vital-Doppler signal from the radar data comprises:
• capturing the radar data corresponding to the set of targets across a vital-Doppler frame;
• performing a first filtering on the vital-Doppler frame to produce a first-filtered vital-Doppler frame;
• and
• performing a second filtering on the vital-Doppler frame to produce a second-filtered vital-Doppler frame;
• designating at least one of the first-filtered vital-Doppler frame or the second-filtered vital-Doppler frame as a time-domain vital-Doppler signal;
• filtering the time-domain vital-Doppler signal with a window function that is localized in time and frequency to generate a windowed time-frequency signal, the filtering the time-domain vital-Doppler signal comprising convolving the time-domain vital-Doppler signal with the window function;
• determining initial filter coefficients of a frequency filter;
• performing a Gabor time-frequency transform on the windowed time-frequency signal;
• filtering a result of the Gabor time-frequency transform step using the frequency filter having the initial filter coefficients;
• performing an inverse Gabor time-frequency transform on an output of the frequency filter to generate an interim filtered vital-Doppler signal;
• determining a ratio of an out-of-band energy of the interim filtered vital-Doppler signal to a total energy of the interim filtered vital-Doppler signal;
• and
• in response to the ratio being greater than a threshold, iteratively performing the following steps:
• selecting new filter coefficients of the frequency filter based on a predetermined sequence of filter coefficients;
• performing the Gabor time-frequency transform;
• filtering the result of the Gabor time-frequency transform step using the frequency filter having the new filter coefficient;
• and
• performing the inverse Gabor time-frequency transform;
• determine an emotion of the set of targets based on the filtered vital-Doppler signal;
• and
• generate a user-engagement rating indicative of a level of engagement of the set of targets in an activity performed in the field of view based on the emotion.

A non-transitory computer readable storage medium with an executable program stored thereon, the executable program including instructions to:

• instruct a millimeter-wave radar sensor to transmit a series of chirps within a field of view of the millimeter-wave radar sensor;
• identify a biological target within the field of view based on radar data received by the millimeter-wave radar sensor and in response to transmission of the series of chirps;
• extract a filtered vital-Doppler signal from the radar data, wherein extracting the filtered vital-Doppler signal from the radar data comprises:
• capturing the radar data corresponding to the biological target across a vital-Doppler frame;
• performing a first filtering on the vital-Doppler frame to produce a first-filtered vital-Doppler frame;
• and
• performing a second filtering on the vital-Doppler frame to produce a second-filtered vital-Doppler frame;
• designating at least one of the first-filtered vital-Doppler frame or the second-filtered vital-Doppler frame as a time-domain vital-Doppler signal;
• filtering the time-domain vital-Doppler signal with a window function that is localized in time and frequency to generate a windowed time-frequency signal, the filtering the time-domain vital-Doppler signal comprising convolving the time-domain vital-Doppler signal with the window function;
• determining initial filter coefficients of a frequency filter;
• performing a Gabor time-frequency transform on the windowed time-frequency signal;
• filtering a result of the Gabor time-frequency transform step using the frequency filter having the initial filter coefficients;
• performing an inverse Gabor time-frequency transform on an output of the frequency filter to generate an interim filtered vital-Doppler signal;
• determining a ratio of an out-of-band energy of the interim filtered vital-Doppler signal to a total energy of the interim filtered vital-Doppler signal;
• and
• in response to the ratio being greater than a threshold, iteratively performing the following steps:
• selecting new filter coefficients of the frequency filter based on a predetermined sequence of filter coefficients;
• performing the Gabor time-frequency transform;
• filtering the result of the Gabor time-frequency transform step using the frequency filter having the new filter coefficient;
• and
• performing the inverse Gabor time-frequency transform;
• determine an emotion of the biological target based on the filtered vital-Doppler signal;
• and
• generate a user-engagement rating indicative of a level of engagement of the biological target in an activity performed in the field of view based on the emotion.