Abstract: Examples are disclosed that relate to generating expressive avatars using multi-modal three-dimensional face modeling and tracking. One example includes a computer system comprising a processor coupled to a storage system that stores instructions. Upon execution by the processor, the instructions cause the processor to receive initialization data describing an initial state of a facial model. The instructions further cause the processor to receive a plurality of multi-modal data signals. The instructions further cause the processor to perform a fitting process using the initialization data and the plurality of multi-modal data signals. The instructions further cause the processor to determine a set of parameters based on the fitting process, wherein the determined set of parameters describes an updated state of the facial model.

Abstract: An electronic device may utilize various methods or systems to determine whether the electronic device is indoors or outdoors. The electronic device transmits wireless signals (e.g., radio detection and ranging (RADAR) signals). The electronic device receives reflections of the wireless signals. Using these received reflections of the wireless signals, the electronic device determines whether a power amplitude of the reflections is greater than or equal to a threshold value. In response to a determination that the power amplitude is not greater than or equal to the threshold value, the electronic device operates in an outdoor mode or an indoor mode.

Abstract: A method for human movement classification includes a plurality of radio frequency (RF) antennas to expose a body surface of a human user to an E-field, at least a part of the human user positioned within a near-field region relative to the RF antennas. The plurality of RF antennas are scanned to determine ground-relative changes in electrical conditions. A differential-scanning subset of RF antennas are selected, including two or more RF antennas for which the changes in electrical conditions exceed a threshold. For each RF antenna in the differential-scanning subset, a set of antenna-relative changes in electrical conditions are determined by comparing the RF antenna to one or more other RF antennas in the differential-scanning subset as a plurality of pairs. Based at least in part on the ground-relative changes in electrical conditions and the antenna-relative changes in electrical conditions, a movement performed by the human user is classified.

Abstract: A method for training a neural network for facial expression recognition includes recognizing a plurality of digital human face models. For each of the plurality of digital human face models, a plurality of simulated facial expressions are simulated. Simulated capacitance measurements for an array of simulated radio frequency (RF) antennas are found for each of the plurality of simulated facial expressions. The simulated capacitance measurements for each simulated facial expression are provided as input training data to a neural network configured to output facial expression parameters based on input capacitance measurements.

Abstract: Examples are disclosed that relate to determining a capacitance based on a charge accumulated on a sense capacitor electrode. One example provides a head-mounted device comprising a facial-tracking sensor, a controller, and a charge sensing circuit connected to the facial-tracking sensor. The facial-tracking sensor comprises a sense capacitor electrode configured to be positioned proximate to a surface of a face and form a capacitance based upon a distance between the sense capacitor electrode and the surface of the face, and the controller configured to apply a reference voltage to the sense capacitor electrode. The charge sensing circuit is configured to determine the capacitance of the sense capacitor electrode by determining an amount of charge accumulated on the sense capacitor electrode resulting from the reference voltage.

Abstract: Techniques disclosed herein may be utilized to detect, measure, and/or track the location of objects via radar sensor devices that are affixed to a wearable device. Each of the radar sensors (e.g., MIMIC radar sensor) generates, captures, and evaluates radar signals associated with the wearable device (e.g., HMD) and the surrounding environment. Objects located within the field of view with sufficient reflectivity will result in radar return signals each with a characteristic time of arrival (TOA), angle of arrival (AOA), and frequency shift (Doppler shift). The sensed return signals can be processed to determine distance and direction, as well as identification of the objects based on radar characteristics of the object (e.g., radar back-scatter or cross-section pattern). Object information, including position and identification, may be further resolved based on correlation with measurements from one or more of the digital cameras or inertial measurement units.

Abstract: A head-mounted device (HMD) has a segmented metal chassis including a plurality of physically separate radio frequency (RF) antennas corresponding to different head regions. The HMD further includes a plurality of RF transceivers, each electrically connected to a corresponding RF antenna. Each RF transceiver is configured to drive the corresponding RF antenna with a drive signal at a frequency within a resonant frequency band of the corresponding RF antenna and sense a frequency response to the drive signal. The HMD further includes a plurality of notch filter circuits, each electrically connected in series with a corresponding RF antenna. Each notch filter is configured to attenuate signals at frequencies within the resonant frequency band of the corresponding RF antenna and pass signals at frequencies outside of the resonant frequency band, such that the segmented metal chassis functions as a common ground plane.

Abstract: Embodiments are disclosed for a low-frequency detection and ranging. In an embodiment, an apparatus comprises: an open electrode; an alternating current (AC) voltage source configured to supply an excitation voltage to the open electrode at an excitation frequency; a resonant circuit coupled to the open electrode, the resonant circuit configured to oscillate when an object is within a detection distance of the open electrode; one or more processors configured to: obtain time domain samples of an output voltage of the resonant circuit when the resonant circuit is oscillating; convert the time domain samples into frequency domain samples; for each frequency domain sample, determine an amplitude difference and a phase difference as compared to an amplitude and phase of the excitation voltage; and determine a material class of the object based on the amplitude difference and the phase difference.

Abstract: Examples are disclosed that relate to utilizing a facial tracking sensor for controlling computer-generated facial expressions. One example provides a method of controlling computer-generated facial expressions. The method comprises receiving a sensor value acquired via a facial tracking sensor and determining an interpolated value for the sensor value within a value range. The value range corresponding to a blendshape range for a facial expression. The method further comprises determining a blendshape mapping based at least upon the interpolated value, determining expression data based at least upon the blendshape mapping, and providing the expression data to a device.

Abstract: Examples are disclosed that relate to displaying computer-generated facial expressions. One example provides a method for displaying computer-generated facial expressions. The method comprises receiving expression data, and generating one or more facial expressions for an eye region of a user based at least on the expression data. The method further comprises displaying the one or more facial expressions for the eye region on an outward-facing display of a head-mounted device.

Abstract: A shield for redirecting magnetic field generated from a plurality of transmitter coils includes a ferromagnetic structure divided into segments by a plurality of boundary regions, each segment comprises a first material having a first magnetic permeability and each boundary region comprises a second material having a second magnetic permeability lower than the first magnetic permeability, where the plurality of boundary regions are configured to resist a propagation of magnetic field from a first area of the ferromagnetic structure to a second area of the ferromagnetic structure, where the first area intercepts the magnetic field generated from at least one active transmitter coil of the plurality of transmitter coils.

Abstract: Examples are disclosed that relate to a battery and a functional module on a detachable module. One example provides a wearable device comprising a frame configured to support the wearable device on a user, internal charge storage located within the frame, a module interface located on the frame, and an electrical connector located within the module interface to electrically connect to a detachable module positioned in the module interface such that that detachable module is replaceable while being worn without powering down the wearable device by operating the wearable device using the internal charge storage.

Abstract: A method for operating a head-mounted display device is presented. An RF face tracking system is operated at a first, lower power level. Based at least on an output of the RF face tracking system while operating at the first, lower power level, a first likelihood is determined that the head-mounted display device is positioned on a head of a user. If the first likelihood is greater than a first confidence threshold, the RF face tracking system is operated at a second, higher power level. A second likelihood that the head-mounted display device is positioned on the head of the user is determined based at least on an output of the RF face tracking system while operating at the second, higher power level. If the second likelihood is greater than a second confidence threshold, an eye-tracking system of the head-mounted display device is activated.

Abstract: An electronic device may utilize various methods or systems to determine whether the electronic device is indoors or outdoors. The electronic device transmits wireless signals (e.g., radio detection and ranging (RADAR) signals). The electronic device receives reflections of the wireless signals. Using these received reflections of the wireless signals, the electronic device determines whether a power amplitude of the reflections is greater than or equal to a threshold value. In response to a determination that the power amplitude is not greater than or equal to the threshold value, the electronic device operates in an outdoor mode or an indoor mode.

Abstract: A method for a wearable computing device is presented. The wearable computing device includes one or more radio frequency (RF) antennas that are driven to expose a first body part of a user to an E-field. The first body part of the user located within a threshold distance of the RF antennas when the wearable computing device is worn by the user. Movement of the first body part of the user is determined based on changes in electrical conditions at the RF antennas over time. Movement of a second body part of the user is inferred based on the determined movement of the first body part, the second body part being located outside of the threshold distance of the RF antenna. The first and second body parts are coupled via interconnective tissues. An indication of the inferred movement of the second body part is output.

Abstract: Examples are disclosed that relate to sensing a position of a surface proximate to a resonant LC sensor. One example provides a method on a sensing device comprising one or more resonant LC sensors each configured to output a signal responsive to a position of a surface proximate to the resonant LC sensor. The method comprises, for each LC sensor, generating an oscillating signal on an antenna of the resonant LC sensor and detecting a near-field response of the resonant LC sensor at a selected frequency.

Abstract: A system for facilitating secure communications accesses a secure element in response to determining that an authorized user operates the system. The system causes a light emitter to emit an output light signal for detection by a second system. The output light signal is emitted according to a predefined field of view, which operates as a constraint to prevent devices outside of the field of view from detecting the output light signal. The system also configures the light detector to detect a second output light signal emitted by a second light emitter of the second system. In response to (i) detection of the output light signal by a second light detector of the second system and (ii) detection of the second output light signal by the light detector, the system enables secure communication between the system and the second system.

Abstract: To track an object with radar, and achieve greater than range resolution precision, the phase of a difference signal can be utilized and adjusted as the tracked object crosses between resolution ranges. Changes in the object's distance can be detected with greater than range resolution precision by utilizing the phase. Such changes can iteratively inform the determined distance across multiple phase cycles within a single distance range. As the movement of the object approaches, and then crosses, between resolution ranges, the phase as determined within an origin resolution range can be compared with a coincident phase within the destination resolution range and the difference can then be utilized to adjust the phase as the object then remains within the destination resolution range. Such phase adjustments can be applied across multiple resolution ranges, allowing for the tracking of an object, utilizing radar, while achieving greater than range resolution precision.

Abstract: A method for human movement classification includes a plurality of radio frequency (RF) antennas to expose a body surface of a human user to an E-field, at least a part of the human user positioned within a near-field region relative to the RF antennas. The plurality of RF antennas are scanned to determine ground-relative changes in electrical conditions. A differential-scanning subset of RF antennas are selected, including two or more RF antennas for which the changes in electrical conditions exceed a threshold. For each RF antenna in the differential-scanning subset, a set of antenna-relative changes in electrical conditions are determined by comparing the RF antenna to one or more other RF antennas in the differential-scanning subset as a plurality of pairs. Based at least in part on the ground-relative changes in electrical conditions and the antenna-relative changes in electrical conditions, a movement performed by the human user is classified.

Abstract: An extended reality headset has light-based communication transceivers coupled to the extended reality headset. The relative position of a remote transceiver with respect to the current position and orientation of the extended reality headset is determined. A line-of-sight is calculated from the light-based communication transceivers to the remote transceiver. The light-based communication transceivers emit a light-based communications beam in accordance with the calculated line-of-sight. The light-based communications beam is adjusted in response to changes to the relative position of the remote transceiver with respect to the current position and orientation of the extended reality headset.