Burst-based non-gesture rejection in a micro-gesture recognition system
An electronic device includes a transceiver configured to transmit and receive radar signals and a processor operatively coupled to the transceiver. The processor is configured to identify, based on the received radar signals, a plurality of radar frames related to an activity of a target. The processor is further configured to extract a plurality of features from the plurality of radar frames, compute burst attributes for the extracted features, predict a gesture based on the burst attributes, determine whether the predicted gesture is a valid gesture, and if the predicted gesture is a valid gesture, perform an action corresponding to the predicted gesture.
1 . An electronic device comprising:
a transceiver configured to transmit and receive radar signals; and
a processor operatively coupled to the transceiver, the processor configured to:
identify, based on the received radar signals, a plurality of radar frames related to an activity of a target;
extract a plurality of features from the plurality of radar frames;
compute burst attributes for the extracted features;
predict a gesture based on the burst attributes;
determine whether the predicted gesture is a valid gesture; and
if the predicted gesture is a valid gesture, perform an action corresponding to the predicted gesture.
2 . The electronic device of claim 1 , wherein to extract the plurality of features from the plurality of radar frames, the processor is further configured to, for each radar frame:
obtain a Range-Doppler map;
select a column corresponding to a peak of the target in a range profile;
calculate an average radial velocity of the target;
obtain an azimuth and elevation angle spectrum corresponding to a target peak;
calculate an average angle of the target; and
obtain average azimuth/elevation tangential velocities based on a target angle variation over two frames.
3 . The electronic device of claim 1 , wherein the processor is further configured to:
determine, based on the burst attributes, whether the activity of the target is a valid activity,
wherein the gesture is predicted based on the activity of the target being the valid activity.
4 . The electronic device of claim 1 , wherein to predict the gesture, the processor is further configured to:
determine whether symmetry and pattern criteria for the burst attributes are met;
based on whether the symmetry and pattern criteria for the burst attributes are met, determine whether the activity is a valid activity;
perform a gesture classification on the activity if the activity is a valid activity, wherein the gesture classification is based on a previously obtained gesture set; and
predict the gesture based on the gesture classification.
5 . The electronic device of claim 4 , wherein the previously obtained gesture set comprises:
a swipe center-left-center (CLC) gesture;
a swipe center-right-center (CRC) gesture;
a swipe center-down-center (CDC) gesture; and
a swipe center-up-center (CUC) gesture.
6 . The electronic device of claim 4 , wherein to obtain the previously obtained gesture set, the processor is further configured to:
define a set of gestures with common burst attributes;
collect a plurality of samples for each gesture;
compute burst attributes for each sample;
derive statistical summaries for each burst attribute; and
obtain a set of thresholds to separate gestures from non-gestures.
7 . The electronic device of claim 6 , wherein the processor is further configured to:
collect a plurality of samples for non-gestures;
determine whether a probability of false positive and false negative gesture classifications is below an acceptable threshold; and
if the probability of false positive and false negative gesture classifications is below the acceptable threshold, accept the set of thresholds to separate gestures from non-gestures.
8 . The electronic device of claim 6 , wherein each gesture from the gesture set is defined in relation to a number of major bursts, minor bursts, and a pattern of bursts in a sequence.
9 . The electronic device of claim 1 , wherein to determine whether the predicted gesture is a valid gesture, the processor is further configured to:
determine a correlation between the extracted features; and
determine whether the predicted gesture is a valid gesture based on the correlation between the extracted features.
10 . The electronic device of claim 1 , wherein the plurality of features comprises:
radial velocity;
azimuth velocity; and
elevation velocity.
11 . The electronic device of claim 1 , wherein the burst attributes comprise at least one of:
burst length;
burst height;
burst area;
burst sign; and
whether a burst is part of a burst chain.
12 . A method of operating an electronic device, the method comprising:
identifying, based on received radar signals, a plurality of radar frames related to an activity of a target;
extracting a plurality of features from the plurality of radar frames;
computing burst attributes for the extracted features;
predicting a gesture based on the burst attributes;
determining whether the predicted gesture is a valid gesture; and
if the predicted gesture is a valid gesture, performing an action corresponding to the predicted gesture.
13 . The method of claim 12 , wherein extracting the plurality of features from the plurality of radar frames comprises, for each radar frame:
obtaining a Range-Doppler map;
selecting a column corresponding to a peak of the target in a range profile;
calculating an average radial velocity of the target;
obtaining an azimuth and elevation angle spectrum corresponding to a target peak;
calculating an average angle of the target; and
obtaining average azimuth/elevation tangential velocities based on a target angle variation over two frames.
14 . The method of claim 12 , further comprising:
determining, based on the burst attributes, whether the activity of the target is a valid activity,
wherein the gesture is predicted based on the activity of the target being the valid activity.
15 . The method of claim 12 , wherein to predicting the gesture comprises:
determining whether symmetry and pattern criteria for the burst attributes are met;
based on whether the symmetry and pattern criteria for the burst attributes are met, determining whether the activity is a valid activity;
performing a gesture classification on the activity if the activity is a valid activity, wherein the gesture classification is based on a previously obtained gesture set; and
predicting the gesture based on the gesture classification.
16 . The electronic device of claim 15 , wherein obtaining the previously obtained gesture set comprises:
defining a set of gestures with common burst attributes;
collecting a plurality of samples for each gesture;
computing burst attributes for each sample;
deriving statistical summaries for each burst attribute;
obtaining a set of thresholds to separate gestures from non-gestures;
collecting a plurality of samples for non-gestures;
determining whether a probability of false positive and false negative gesture classifications is below an acceptable threshold; and
if the probability of false positive and false negative gesture classifications is below the acceptable threshold, accepting the set of thresholds to separate gestures from non-gestures.
17 . The method of claim 15 , wherein each gesture from the gesture set is defined in relation to a number of major bursts, minor bursts, and a pattern of bursts in a sequence.
18 . The method of claim 12 , wherein determining whether the predicted gesture is a valid gesture comprises:
determining a correlation between the extracted features; and
determining whether the predicted gesture is a valid gesture based on the correlation between the extracted features.
19 . The method of claim 12 , wherein the plurality of features comprises:
radial velocity;
azimuth velocity; and
elevation velocity.
20 . The method of claim 12 , wherein the burst attributes comprise at least one of:
burst length;
burst height;
burst area;
burst sign; and
whether a burst is part of a burst chain.