Electrodes for gesture recognition
Electrodes that can be formed in a flexible band of a wrist-worn device to detect hand gestures are disclosed. Multiple rows of electrodes can be configured to detect electromyography (EMG) signals produced by activity of muscles and tendons. The band can include removable electrical connections (e.g., pogo pins) to enable the electrode signals to be routed to processing circuitry in the housing of the wrist-worn device. Measurements between signals from the active electrodes and one or more reference electrodes can be obtained to capture EMG signals at a number of locations on the band. The measurement method and mode of operation (lower power coarse detection or higher power fine detection) can determine the location and number of electrodes to be measured. These EMG signals can be processed to identify hand movements and recognize gestures associated with those hand movements.
1 . A device for gesture recognition, comprising:
a wearable band;
a housing including:
one or more multiplexers; and
one or more differential measurement circuits communicatively coupled to the one or more multiplexers and configured for making one or more referential measurements;
a plurality of electrodes located on one or both of the wearable band and the housing; and
one or more processors communicatively coupled to the one or more differential measurement circuits and the one or more multiplexers, the one or more processors programmed to:
determine a power state of the device;
in accordance with a determination that the device is in a first power state, configure the one or more multiplexers to electrically couple one or more first pairs of electrodes from a first set of the plurality of electrodes to one of the one or more differential measurement circuits to obtain a first referential measurement for recognizing a first gesture; and
in accordance with a determination that the device is in a second power state, configure the one or more multiplexers to electrically couple one or more second pairs of electrodes from a second set of the plurality of electrodes to one of the one or more differential measurement circuits to obtain a second referential measurement for recognizing a second gesture, wherein the second set of the plurality of electrodes is smaller than the first set of the plurality of electrodes.
2 . The device of claim 1 , the one or more processors further programmed to:
detect an activation event; and
in accordance with the detection of the activation event:
in accordance with the determination that the device is in the second power state, transition the power state of the device to the first power state, higher than the second power state; and
in accordance with a determination that the device is in the first power state, maintain the power state of the device.
3 . The device of claim 2 , wherein the activation event corresponds to a particular gesture.
4 . The device of claim 2 , the one or more processors further programmed to:
in accordance with the determination that the device is in the first power state, configure the one or more multiplexers to electrically couple one or more different pairs of electrodes from the first set of the plurality of electrodes to one of the one or more differential measurement circuits, to obtain a referential measurement for recognizing a subsequent gesture, wherein the subsequent gesture is recognized at a time after the activation event.
5 . The device of claim 1 , wherein:
in the first power state, the one or more processors and the one or more differential measurement circuits perform a first gesture recognition; and
in the second power state, the one or more processors and the one or more differential measurement circuits perform a second gesture recognition that has less granularity than the first gesture recognition.
6 . The device of claim 1 , wherein:
in accordance with the determination that the device is in the first power state, obtaining the one or more referential measurements at a first sampling rate; and
in accordance with the determination that the device is in the second power state, obtaining the one or more referential measurements at a second sampling rate lower than the first sampling rate.
7 . The device of claim 1 , the one or more processors further programmed to, in the first power state:
designate a first electrode of the first set of the plurality of electrodes as a reference electrode;
designate one or more second electrodes of the first set of the plurality of electrodes as active electrodes; and
configure the one or more multiplexers to electrically couple the reference electrode and one of the active electrodes to the one or more differential measurement circuits to obtain one or more unipolar measurements at one or more of the active electrodes relative to the reference electrode.
8 . The device of claim 7 , the one or more processors further programmed to dynamically configure the one or more multiplexers to electrically couple the one or more of the active electrodes to the one or more of the differential measurement circuits at different times to obtain unipolar measurements at the one or more of the active electrodes.
9 . The device of claim 1 , the one or more processors programmed to, in the first power state:
designate one or more first electrodes of the first set of the plurality of electrodes as reference electrodes;
designate one or more second electrodes of the first set of the plurality of electrodes as active electrodes; and
configure the one or more multiplexers to electrically couple the one or more first electrodes of the first set of electrodes designated as reference electrodes and the one or more second electrodes of the first set of electrodes in one or more different pairs of electrodes to the one or more differential measurement circuits to obtain one or more bipolar measurements of the active electrodes relative to the reference electrodes.
10 . The device of claim 1 , the one or more processors programmed to, in the second power state:
designate a first electrode and a second electrode of the first set of the plurality of electrodes as reference electrodes;
designate a third electrode and a fourth electrode of the first set of the plurality of electrodes as active electrodes; and
configure the one or more multiplexers to electrically couple the first electrode and third electrode as a first pair of electrodes to the one or more differential measurement circuits and couple the second electrode and fourth electrode in as a second pair of electrodes to the one or more differential measurement circuits to obtain first and second bipolar measurements.
11 . A method comprising:
at a device comprising a wearable band, a housing, one or more multiplexers, one or more differential measurement circuits, a plurality of electrodes located on one or both of the wearable band and the housing, and one or more processors:
determining a power state of the device;
in accordance with a determination that the device is in a first power state, configuring the one or more multiplexers to electrically couple one or more first pairs of electrodes from a first set of the plurality of electrodes to one of the one or more differential measurement circuits to obtain a first referential measurement for recognizing a first gesture; and
in accordance with a determination that the device is in a second power state, configuring the one or more multiplexers to electrically couple one or more second pairs of electrodes from a second set of the plurality of electrodes to one of the one or more differential measurement circuits to obtain a second referential measurement for recognizing a second gesture, wherein the second set of the plurality of electrodes is smaller than the first set of the plurality of electrodes.
12 . The method of claim 11 , further comprising:
detecting an activation event; and
in accordance with the detection of the activation event:
in accordance with the determination that the device is in the second power state, transitioning the power state of the device to the first power state, higher than the second power state; and
in accordance with a determination that the device is in the first power state, maintaining the power state of the device.
13 . The method of claim 12 , further comprising:
in accordance with the determination that the device is in the first power state, configuring the one or more multiplexers to electrically couple one or more different pairs of electrodes from the first set of the plurality of electrodes to one of the one or more differential measurement circuits, to obtain a referential measurement for recognizing a subsequent gesture, wherein the subsequent gesture is recognized at a time after the activation event.
14 . The method of claim 11 , further comprising:
in the first power state, performing a first gesture recognition; and
in the second power state, performing a second gesture recognition that has less granularity than the first gesture recognition.
15 . The method of claim 11 , further comprising:
in the first power state, obtaining a plurality of unipolar measurements at one or more active electrodes relative to a reference electrode; and
in the second power state, obtaining one or more bipolar measurements at a first of the one or more active electrodes relative to a first reference electrode and at a second of the one or more active electrodes relative to a second reference electrode.
16 . A non-transitory computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by one or more processors of a device comprising a wearable band, a housing, one or more multiplexers, one or more differential measurement circuits, and a plurality of electrodes located on one or both of the wearable band and the housing, cause the device to:
determine a power state of the device;
in accordance with a determination that the device is in a first power state, configure the one or more multiplexers to electrically couple one or more first pairs of electrodes from a first set of the plurality of electrodes to one of the one or more differential measurement circuits to obtain a first referential measurement for recognizing a first gesture; and
in accordance with a determination that the device is in a second power state, configure the one or more multiplexers to electrically couple one or more second pairs of electrodes from a second set of the plurality of electrodes to one of the one or more differential measurement circuits to obtain a second referential measurement for recognizing a second gesture, wherein the second set of the plurality of electrodes is smaller than the first set of the plurality of electrodes.
17 . The non-transitory computer readable storage medium of claim 16 , the instructions, when executed by the one or more processors, further cause the device to:
detect an activation event; and
in accordance with the detection of the activation event:
in accordance with the determination that the device is in the second power state, transition the power state of the device to the first power state, higher than the second power state; and
in accordance with a determination that the device is in the first power state, maintain the power state of the device.
18 . The non-transitory computer readable storage medium of claim 17 , the instructions, when executed by the one or more processors, further cause the device to:
in accordance with the determination that the device is in the first power state, configure the one or more multiplexers to electrically couple one or more different pairs of electrodes from the first set of the plurality of electrodes to one of the one or more differential measurement circuits, to obtain a referential measurement for recognizing a subsequent gesture, wherein the subsequent gesture is recognized at a time after the activation event.
19 . The non-transitory computer readable storage medium of claim 16 , the instructions, when executed by the one or more processors, further cause the device to:
in the first power state, perform a first gesture recognition; and
in the second power state, perform a second gesture recognition that has less granularity than the first gesture recognition.
20 . The non-transitory computer readable storage medium of claim 16 , the instructions, when executed by the one or more processors, further cause the device to:
in the first power state, obtain a plurality of unipolar measurements at one or more active electrodes relative to a reference electrode; and
in the second power state, obtain one or more bipolar measurements at a first of the one or more active electrodes relative to a first reference electrode and at a second of the one or more active electrodes relative to a second reference electrode.