Abstract: A system to combine inertial-based measurements and optical-based measurements via a Kalman-type filter. For example, a sensor module uses an inertial measurement unit to generate first positions and first orientations of the sensor module at a first time interval during a first period of time containing multiple of the first time interval. At least one camera is used to capture images of the sensor module at a second time interval, larger than the first time interval, during the first period of time containing multiple of the second interval. Second positions and second orientations of the sensor module during the first period of time are computed from the images. The filter receives the first positions, the first orientations, the second positions, and the second orientations to generate estimates of position and orientation of the sensor module at a time interval no smaller than the first time interval.

Abstract: A system to track orientations of parts of a user based on both images and inertial measurement units (IMUs). For example, the system receives images showing a portion of the user wearing sensor modules. The system receives a first set of orientation measurements generated by the sensor modules attached to some parts of the user. The system determines the second set of orientation measurements of one or more features of the portion of the user from the images. The system provides the first set of orientation measurements and the second set of orientation measurements as input to an artificial neural network that is configured to predict orientation measurements of the one or more other parts of the user that would be measured by additional sensor modules if the additional sensor modules were to be attached to the other parts of the user.

Abstract: A system having a plurality of sensor modules and a stereo camera and a computing device. Each sensor module has an inertial measurement unit (IMU) measuring its orientation relative to a reference orientation. Different IMUs may have different reference orientations. To calibrate the IMUs with respect to a common reference (e.g., defined based on a standardized pose of a user), the stereo camera captures a stereo image of a respective sensor module attached to a respective portion of the user; the inertial measurement unit of the respective sensor module generates an orientation measurement at a time of capturing the stereo image; and the computing device calculates, based on the stereo image, at least one orientation and uses the orientation and the orientation measurement in determining a rotation that calibrates measurements of the inertial measurement unit relative to the common reference.

Abstract: A system including a plurality of sensor modules, each module having an inertial measurement unit (IMU) and being attached to a respective body portion of a user (e.g., upper arm, hand, and/or head) to measure the current orientation of the corresponding portion of the user. A computing device coupled to the sensor modules is configured to identify that a user is at a predefined pose, which the predefined pose of the user is representative of the forearms and the upper arms of the user lying in a horizontal plane. A head mount display (HMD) attached to a head of the user using a camera to generate camera data, the HMD calculating the first length using the camera data, and the first length is calculated as corresponds to a distance between hands of the user and shoulders of the user; the computing device determining one or more lengths of one or more bones of the user based on the first length and the plurality of orientations of arm bones of the user at the predefined pose.

Abstract: A method to calibrate orientation measurements of an inertial measurement unit of a sensor device based on an image of a portion of a user to which the sensor device is attached. For example, the sensor device can be configured to be attached to the middle phalange of the index finger and configured with a touch pad. In response to the determination that the thumb of the user is placed on the touch pad of the sensor device, the camera of the system can capture the image showing that the hand of the user. A convolutional neural network is configured to determine, from the image, orientations of predefined features of the hand of the user. A further artificial neural network is configured to determine the orientation of the sensor device based on the orientations of the predefined features to calibrate the orientation measurements of the inertial measurement unit.

Abstract: A method to calibrate orientation measurements of an inertial measurement unit of a sensor device based on an image of a portion of a user to which the sensor device is attached. For example, the sensor device can be configured to be attached to the middle phalange of the index finger and configured with a touch pad. In response to the determination that the thumb of the user is placed on the touch pad of the sensor device, the camera of the system can capture the image showing that the hand of the user. A convolutional neural network is configured to determine, from the image, orientations of predefined features of the hand of the user. A further artificial neural network is configured to determine the orientation of the sensor device based on the orientations of the predefined features to calibrate the orientation measurements of the inertial measurement unit.

Abstract: A system to track orientations of parts of a user based on both images and inertial measurement units (IMUs). For example, the system receives images showing a portion of the user wearing sensor modules. The system receives a first set of orientation measurements generated by the sensor modules attached to some parts of the user. The system determines the second set of orientation measurements of one or more features of the portion of the user from the images. The system provides the first set of orientation measurements and the second set of orientation measurements as input to an artificial neural network that is configured to predict orientation measurements of the one or more other parts of the user that would be measured by additional sensor modules if the additional sensor modules were to be attached to the other parts of the user.

Abstract: A system including a plurality of sensor modules, each module having an inertial measurement unit (IMU) and being attached to a respective body portion of a user (e.g., upper arm, hand, and/or head) to measure the current orientation of the corresponding portion of the user. A computing device coupled to the sensor modules is configured to identify that a user is at a predefined pose, which the predefined pose of the user is representative of the forearms and the upper arms of the user lying in a horizontal plane. A head mount display (HMD) attached to a head of the user using a camera to generate camera data, the HMD calculating the first length using the camera data, and the first length is calculated as corresponds to a distance between hands of the user and shoulders of the user; the computing device determining one or more lengths of one or more bones of the user based on the first length and the plurality of orientations of arm bones of the user at the predefined pose.

Abstract: A system having a plurality of sensor modules and a stereo camera and a computing device. Each sensor module has an inertial measurement unit (IMU) measuring its orientation relative to a reference orientation. Different IMUs may have different reference orientations. To calibrate the IMUs with respect to a common reference (e.g., defined based on a standardized pose of a user), the stereo camera captures a stereo image of a respective sensor module attached to a respective portion of the user; the inertial measurement unit of the respective sensor module generates an orientation measurement at a time of capturing the stereo image; and the computing device calculates, based on the stereo image, at least one orientation and uses the orientation and the orientation measurement in determining a rotation that calibrates measurements of the inertial measurement unit relative to the common reference.