Abstract: A device for determining a heart rate of a user has a PPG sensor and an accelerometer to compensate for acceleration artifacts within the PPG signal. The device transforms time domain PPG and accelerometer signals into the frequency domain using a Fourier transformation and utilizes the Fourier coefficient magnitudes as indicative of the probability of candidate heart rate values. Candidate heart rate values are determined at sampling times over a time interval and a most probable heart rate path during the time interval is determined using a reward/penalty algorithm.

Abstract: A device for determining a heart rate of a user has a PPG sensor and an accelerometer to compensate for acceleration artifacts within the PPG signal. The device transforms time domain PPG and accelerometer signals into the frequency domain using a Fourier transformation and utilizes the Fourier coefficient magnitudes as indicative of the probability of candidate heart rate values. Candidate heart rate values are determined at sampling times over a time interval and a most probable heart rate path during the time interval is determined using a reward/penalty algorithm.

Abstract: A wearable device that attaches to a body part of a user via an attachment member operates in at least a connected and a disconnected state. One or more sensors located in the wearable device and/or the attachment member detect the user's body part when present. Such detection may only be performed when the attachment member is in a connected configuration and may be used to switch the wearable device between the connected and disconnected states. In this way, the wearable device operates in the connected state when worn by a user and in the disconnected state when not worn by the user.

Abstract: A wearable device that attaches to a body part of a user via an attachment member operates in at least a connected and a disconnected state. One or more sensors located in the wearable device and/or the attachment member detect the user's body part when present. Such detection may only be performed when the attachment member is in a connected configuration and may be used to switch the wearable device between the connected and disconnected states. In this way, the wearable device operates in the connected state when worn by a user and in the disconnected state when not worn by the user.

Abstract: A wearable device that attaches to a body part of a user via an attachment member operates in at least a connected and a disconnected state. One or more sensors located in the wearable device and/or the attachment member detect the user's body part when present. Such detection may only be performed when the attachment member is in a connected configuration and may be used to switch the wearable device between the connected and disconnected states. In this way, the wearable device operates in the connected state when worn by a user and in the disconnected state when not worn by the user.

Abstract: Algorithms for detecting whether a device is properly secured to a user's skin are described. The operation of a device, such as a wearable device, can be adjusted based on whether the device is properly secured to a user's skin (e.g., on-wrist) or not properly secured to the user's skin (e.g., off-wrist). For example, certain functions can be disabled for power-saving, security or other purposes if the device is off-wrist. In order to avoid falsely identifying the device as off-wrist or on-wrist, algorithms for detecting whether the device is on-wrist or off-wrist can calculate one or more variances based on signals measured by a light sensor and compare the one or more variances with one or more thresholds. Comparing the one or more variances to the one or more threshold can improve the accuracy of wrist-detection algorithms.

Abstract: A device for determining a heart rate of a user has a PPG sensor and an accelerometer to compensate for acceleration artifacts within the PPG signal. The device transforms time domain PPG and accelerometer signals into the frequency domain using a Fourier transformation and utilizes the Fourier coefficient magnitudes as indicative of the probability of candidate heart rate values. Candidate heart rate values are determined at sampling times over a time interval and a most probable heart rate path during the time interval is determined using a reward/penalty algorithm.

Abstract: A device for determining a heart rate of a user has a PPG sensor and an accelerometer to compensate for acceleration artifacts within the PPG signal. The device transforms time domain PPG and accelerometer signals into the frequency domain using a Fourier transformation and utilizes the Fourier coefficient magnitudes as indicative of the probability of candidate heart rate values. Candidate heart rate values are determined at sampling times over a time interval and a most probable heart rate path during the time interval is determined using a reward/penalty algorithm.

Abstract: Algorithms for detecting whether a device is properly secured to a user's skin are described. The operation of a device, such as a wearable device, can be adjusted based on whether the device is properly secured to a user's skin (e.g., on-wrist) or not properly secured to the user's skin (e.g., off-wrist). For example, certain functions can be disabled for power-saving, security or other purposes if the device is off-wrist. In order to avoid falsely identifying the device as off-wrist or on-wrist, algorithms for detecting whether the device is on-wrist or off-wrist can calculate one or more variances based on signals measured by a light sensor and compare the one or more variances with one or more thresholds. Comparing the one or more variances to the one or more threshold can improve the accuracy of wrist-detection algorithms.

Abstract: Algorithms for detecting whether a device is properly secured to a user's skin are described. The operation of a device, such as a wearable device, can be adjusted based on whether the device is properly secured to a user's skin (e.g., on-wrist) or not properly secured to the user's skin (e.g., off-wrist). For example, certain functions can be disabled for power-saving, security or other purposes if the device is off-wrist. In order to avoid falsely identifying the device as off-wrist or on-wrist, algorithms for detecting whether the device is on-wrist or off-wrist can calculate one or more variances based on signals measured by a light sensor and compare the one or more variances with one or more thresholds. Comparing the one or more variances to the one or more threshold can improve the accuracy of wrist-detection algorithms.

Abstract: A photoplethysmogram (PPG) signal may be obtained from a pulse oximeter, which employs a light emitter and a light sensor to measure the perfusion of blood to the skin of a user, and multiple wavelengths of light may be employed. For various wavelengths, relatively long wavelengths may interrogate relatively deep blood vessels in comparison to relatively short wavelengths, which may interrogate relatively shallow blood vessels. Accordingly, for co-located emitters of different wavelengths, there may be a time delay in the pulse signal measured by each wavelength. The time delay as a function of time may vary according to the constriction and dilation of the blood vessels, which itself may vary according to the respiratory rate of a user.

Abstract: A light emitter and light sensor pair can be used to determine one or more characteristics of a user's vasculature. For example, a pulse oximeter employs a light emitter and a light sensor to measure the percentage of oxygenated blood in a subject. In examples of the present disclosure, light emitters and light sensors can be used to perform biometric identification of a user based on identifying characteristics of the user's vasculature. For example, light information can be obtained at one or more light sensors, and the information can be compared to stored information associated with a user identity. Based on the comparison, the user of the device can be identified as having the user identity.

Abstract: The present embodiments provide a system that dynamically controls power consumption in a computing device. During operation, the system measures the performance of the computing device while executing a work-loop. Next, the system determines a derived completion time for the work-loop based on the measured performance. (For example, the derived completion time can be an expected completion time, a maximum completion time, or more generally a completion time distribution.) The system then determines a deadline-proximity for the work-loop based on a comparison between the derived completion time and a deadline for the work-loop. (For example, the deadline-proximity can be an expected deadline-proximity, a minimum deadline-proximity, or more generally a deadline-proximity distribution.) Finally, the system controls the power consumption of the computing device based on the determined deadline-proximity for the work-loop.

Abstract: A wearable device that attaches to a body part of a user via an attachment member operates in at least a connected and a disconnected state. One or more sensors located in the wearable device and/or the attachment member detect the user's body part when present. Such detection may only be performed when the attachment member is in a connected configuration and may be used to switch the wearable device between the connected and disconnected states. In this way, the wearable device operates in the connected state when worn by a user and in the disconnected state when not worn by the user.

Abstract: Algorithms for detecting whether a device is properly secured to a user's skin are described. The operation of a device, such as a wearable device, can be adjusted based on whether the device is properly secured to a user's skin (e.g., on-wrist) or not properly secured to the user's skin (e.g., off-wrist). For example, certain functions can be disabled for power-saving, security or other purposes if the device is off-wrist. In order to avoid falsely identifying the device as off-wrist or on-wrist, algorithms for detecting whether the device is on-wrist or off-wrist can calculate one or more variances based on signals measured by a light sensor and compare the one or more variances with one or more thresholds. Comparing the one or more variances to the one or more threshold can improve the accuracy of wrist-detection algorithms.

Abstract: A light emitter and light sensor pair can be used to determine one or more characteristics of a user's vasculature. For example, a pulse oximeter employs a light emitter and a light sensor to measure the percentage of oxygenated blood in a subject. In examples of the present disclosure, light emitters and light Receive motion sensors can be used to perform biometric identification information of a user based on identifying characteristics of the user's vasculature. For example, light information can be obtained at one or more light sensors, and the information information can be compared to stored information associated with a user identity. Based on the comparison, the user of the device can be identified as having the user identity.

Abstract: A photoplethysmogram (PPG) signal may be obtained from a pulse oximeter, which employs a light emitter and a light sensor to measure the perfusion of blood to the skin of a user. However, the signal may be compromised by noise due to motion artifacts. That is, movement of the body of a user may cause the skin and vasculature to expand and contract, introducing noise to the signal. To address the presence of motion artifacts, examples of the present disclosure can receive light information from two light sensors situated in a line parallel to the direction of the blood pulse wave. The light information from each sensor may include the same noise signal, and thus subtracting one from the other can result in a heart rate signal where the noise has been canceled out. In some examples, a signal from one of the light sensors may be multiplied by a scaling factor before cancellation to account for response differences in each light sensor.

Abstract: A device for determining a heart rate of a user has a PPG sensor and an accelerometer to compensate for acceleration artifacts within the PPG signal. The device transforms time domain PPG and accelerometer signals into the frequency domain using a Fourier transformation and utilizes the Fourier coefficient magnitudes as indicative of the probability of candidate heart rate values. Candidate heart rate values are determined at sampling times over a time interval and a most probable heart rate path during the time interval is determined using a reward/penalty algorithm.

Abstract: The present embodiments provide a system that dynamically controls power consumption in a computing device. During operation, the system measures the performance of the computing device while executing a work-loop. Next, the system determines a derived completion time for the work-loop based on the measured performance. (For example, the derived completion time can be an expected completion time, a maximum completion time, or more generally a completion time distribution.) The system then determines a deadline-proximity for the work-loop based on a comparison between the derived completion time and a deadline for the work-loop. (For example, the deadline-proximity can be an expected deadline-proximity, a minimum deadline-proximity, or more generally a deadline-proximity distribution.) Finally, the system controls the power consumption of the computing device based on the determined deadline-proximity for the work-loop.

Abstract: A structure and method for routing information desired by a particular entity within a pen-based computer system to that entity are provided. The desired information is contained in “packages” containing the desired information in one or more “parts” and also containing a package directory (located in front of the parts) that identifies the package and provides selected information about the package and its parts. The packages are received and processed by a package manager that maintains a registry of entities that desire specified types of information (parts) that might be found in an incoming package. When the package manager receives a package containing such information, it routes the part containing that information to a “part handler” associated with the entity requesting the information. The package manager then updates a package registry to reflect that the package has been successfully delivered.