Monitoring wear of a wearable device

Abstract

To provide a method for evaluating the tightness of a wearable device through direct observation of how the device responds to physical stimuli.SOLUTION: By applying a changing vibration pattern, such as a chirp signal using a haptic output element or the like, to a device strapped to a wrist or other body part, the mechanical and / or optical response of the device can be measured to infer the amount of tension holding the device against the body, or more generally to assess whether the device is properly fitted to the user. The results may then be presented to the user either objectively using Newtons or some other metric, or by providing a qualitative assessment of fit subjectively. Also or alternatively, adjustment recommendations may be provided to the user regarding optimal performance of the wearable device.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 241438, filed September 7, 2021, the entire contents of which are incorporated herein by reference.

[0002] background Improper fit can be a major cause of discrepancies in data collection from wearable physiological monitors that use optical, capacitive, or other contact-based detection technologies. For example, if an optical monitoring system, such as a photoplethysmography monitor or blood oxygenation monitor, is too loose, the signal can deteriorate due to insufficient optical coupling between the sensor and the skin. Conversely, if the monitor is too tight, it can restrict blood circulation beneath the sensor, reducing the quality or strength of the optical signal. Fortunately, there may be an optimal normal force range for such sensors that can maintain the sensor firmly in contact with the skin without compromising signal collection or data accuracy, even during periods of intense activity and exercise. However, users typically adjust tightness based on a subjective sense of comfort or fashion rather than optimal device performance.

[0003] For example, there remains a need for technology to monitor the fit of wearable physiological monitors to provide objective user feedback with appropriate tension for good device performance.

[0004] overview The tightness of a wearable device can be assessed through direct observation of how the device responds to physical stimuli. For example, by using a tactile output element or the like to apply varying vibration patterns, such as CHIRP signals, to a device strapped to the wrist or other body part, the mechanical and / or optical response of the device can be measured to infer the amount of tension holding the device against the body, or more generally, to assess whether the device is properly fitted to the user. Results can then be presented to the user objectively using Newtons or some other metric, or by subjectively providing a qualitative assessment of fit. Additionally or alternatively, adjustment recommendations can be provided to the user for optimal performance of the wearable device.

[0005] In one aspect, a computer program product disclosed herein may include computer-executable code embodied in a non-transitory computer-readable medium that, when executed on one or more computing devices, performs the following steps: energizing a tactile output element of a wearable heart rate monitor coupled to a user's body with an elastic strap to cause vibration of the wearable heart rate monitor; measuring a response of the wearable heart rate monitor to the vibration; calculating a tension in the strap of the wearable heart rate monitor around the body by applying a physical model to the wearable heart rate monitor and the elastic strap in response to the vibration; and providing adjustment information to a user based on the tension indicating whether the tension is within an acceptable range. The physical model may be a resonance model.

[0006] In one aspect, the method disclosed herein may include generating vibrations in a wearable monitor coupled to a user's body; measuring a response of the wearable monitor to the vibrations; assessing the fit of the wearable monitor to the body based on the response; and providing adjustment information to the user to adjust the fit to a predetermined target.

[0007] Implementations may include one or more of the following features. The predetermined target may include tension of a band securing the wearable monitor to a user. The predetermined target may include a normal force of the wearable monitor against the user's skin. The response may include an optical response from one or more optical sensors and a mechanical response from one or more motion sensors, and the method may further include calculating a level of optical coupling of the wearable monitor to the user with a first signal from the one or more optical sensors; calculating a level of mechanical coupling of the wearable monitor to the user with a second signal from the one or more motion sensors; and assessing the fit based on a combination of the level of optical coupling and the level of mechanical coupling. The generating of vibrations may include energizing a tactile output element coupled to the wearable monitor. The assessing of fit may include calculating, with a processor on the wearable monitor, the level of mechanical coupling. Providing adjustment information to the user may include presenting the adjustment information on a user interface of a computing device associated with the user. The adjustment information may indicate a level of tightness of the wearable monitor. The adjustment information may include instructions for adjusting the wearable monitor around the body. Measuring the response may include receiving motion data during the vibration from one or more accelerometers. Measuring the response may include receiving motion data during the vibration from one or more gyroscopes. Measuring the response may include receiving optical data during the vibration from one or more photodetectors. Generating vibrations may include energizing linear tactile output elements. The wearable monitor may be coupled to a user's wrist with a wristband. The wearable monitor may be coupled to a body with elastic clothing.

[0008] In one aspect, the system disclosed herein includes a wearable monitor including a processor, at least one sensor, and a tactile output element; computer-executable code stored in a memory of the wearable monitor and configuring the processor to cause vibrations in the tactile output element and receive a response to the vibrations from the at least one sensor; and a remote processing resource communicatively coupled to the wearable monitor, the remote processing resource including a second memory storing a physical model of the wearable monitor and a second processor, the second processor receiving a response to the vibrations from the wearable monitor; calculating a level of mechanical coupling of the wearable monitor around a user's body based on the response; calculating a level of optical coupling of the wearable monitor around the body based on the response, independent of (regardless of) the level of mechanical coupling; assessing the fit of the wearable monitor to the user based on the level of optical coupling and the level of mechanical coupling; and communicating adjustment information to the user based on a difference between the fit and a predetermined target fit for the wearable monitor. The predetermined target fit may include at least one of a minimum tension, a maximum tension, and a range of tension. The predetermined target fit may include at least one of a minimum threshold, a maximum threshold, and a range.

[0009] These and other objects, features, and advantages of the devices, systems, and methods described herein will become apparent from the following description of specific embodiments thereof, as illustrated in the accompanying drawings. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the devices, systems, and methods described herein. In the drawings, like reference characters generally identify corresponding elements. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 illustrates a device for wearable physiological monitoring.

[0011] [Figure 2] FIG. 1 is a block diagram of a computing device that may be used herein.

[0012] [Figure 3] FIG. 1 illustrates a physiological monitoring system.

[0013] [Figure 4] 1 is a flow diagram illustrating a method for measuring the fit of a wearable monitor and providing actionable feedback to a user.

[0014] [Figure 5] 1 is a flow diagram illustrating a method for measuring the fit of a wearable monitor and providing actionable feedback to a user.

[0015] [Figure 6] FIG. 1 illustrates a coordinate system for measuring device movement.

[0016] [Figure 7] FIG. 1 illustrates a mapping of mechanical and optical coupling to device fit.

[0017] [Figure 8] FIG. 10 illustrates the user interface for user interaction with the device fit protocol.

[0018] [Figure 9] FIG. 10 shows motion data from a wearable monitor.

[0019] [Figure 10] FIG. 10 shows a confusion matrix for data-driven prediction of body parts for a wearable monitor.

[0020] [Figure 11]FIG. 10 illustrates the time to achieve a 95% confidence level in location prediction of a wearable monitor on multiple body sites.

[0021] Detailed Description The embodiments will now be described more fully below in connection with the accompanying drawings, in which preferred embodiments are shown. However, the embodiments may be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein. Rather, these illustrated embodiments are provided so that this disclosure will convey the scope to those skilled in the art.

[0022] All documents mentioned herein are incorporated herein by reference in their entirety. Reference to a singular element should be understood to include the plural element unless expressly stated otherwise or apparent from the context. Grammatical conjunctions are intended to represent any and all disjunctive and conjunctive combinations of coordinating clauses, coordinating sentences, coordinating conjunctions, and the like, unless stated otherwise or apparent from the context. Thus, the term "or" should generally be understood to mean "and / or," etc.

[0023] References herein to ranges of values ​​are not intended to be limiting unless otherwise indicated, but rather refer individually to any and all values ​​falling within that range, and each separate value within such a range is incorporated herein as if it were individually recited herein. The words "about," "approximately," or the like, when used in conjunction with numerical values, should be interpreted as indicating a deviation that one skilled in the art would recognize as operating satisfactorily for the intended purpose. Similarly, approximation words such as "approximately" or "substantially," when used in reference to physical properties, should be understood to contemplate a range of deviation that one skilled in the art would recognize as operating satisfactorily for the corresponding use, function, purpose, or the like. Value and / or numerical ranges are provided herein merely as examples and do not constitute limitations on the scope of the described embodiments. When ranges of values ​​are provided, they are also intended to include each value within the range as if it were individually set forth, unless explicitly stated otherwise. The use of any and all examples or exemplary language (such as, for example, or the like) provided herein is intended merely to better describe the embodiments and does not pose a limitation on the scope of the embodiments. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the embodiment.

[0024] In the following description, terms such as "first," "second," "top," "bottom," "up," "down," "above," "below," etc. are words of convenience and should not be construed as limiting terms unless specifically stated otherwise.

[0025] Exemplary embodiments provide physiological measurement systems, devices, and methods for continuous health and fitness monitoring, improving upon conventional heart rate monitors to overcome shortcomings. One aspect of the present disclosure is directed to providing a lightweight, wearable system with a strap that collects various physiological data or signals from a wearer. The strap can be used to position the system on a user's appendage or limb (e.g., wrist, ankle, etc.). The exemplary system is wearable and enables real-time, continuous monitoring of heart rate without the need for chest bands or other bulky equipment, which can be uncomfortable and inhibit continuous wear and use. The system may determine a user's heart rate without the use of electrocardiography and without the need for a chest band. The exemplary system can thereby be used for continuous monitoring of fitness as well as for assessing general health and well-being. In addition to heart rate, the exemplary system also enables monitoring of one or more physiological parameters, including, but not limited to, body temperature, heart rate variability, movement, sleep, stress, health level, recovery level, the effect of training habits on health and fitness, calorie expenditure, etc.

[0026] Health or fitness monitors that include bulky components may hinder continuous wear. Existing fitness monitors often include wristwatch functionality, making the health or fitness monitor prohibitively bulky and inconvenient for continuous wear. Accordingly, one aspect is directed to providing a wearable health or fitness system that does not include bulky components, thereby making the bracelet thinner, less obtrusive, and more suitable for continuous wear. The ability to wear the bracelet continuously further enables continuous collection of physiological data and continuous, more reliable health or fitness monitoring. For example, embodiments of the bracelet disclosed herein allow users to monitor data at all times, not just during fitness sessions. In some embodiments, the wearable system may or may not include a display screen for displaying heart rate and other information. In other embodiments, the wearable system may include one or more light-emitting diodes (LEDs) for selectively providing feedback to the user and displaying the heart rate. In some embodiments, the wearable system may include a detachable or removable modular head that may provide additional functionality and display additional information. Such a modular head may be removably attached to the wearable system when additional information display is desired and may be removed to improve the comfort and appearance of the wearable system. In other embodiments, the head may be integrally formed with the wearable system.

[0027] Exemplary embodiments also include methods for measuring the tightness of a wearable monitor and providing actionable feedback to the user. The tightness of a wearable monitor may affect its performance. To ensure a good fit, a physical model, such as a spring model or a resonance model, may be created to characterize the behavior of the wearable monitor when elastically held in tension around a body part. The wearable monitor may then be vibrated, and the response to these vibrations may be applied to the model to estimate the tension. The estimated tension may be used to provide adjustment information to the user.

[0028] The term "continuous" as used herein in connection with heart rate data collection refers to collection of heart rate data at a frequency sufficient to allow detection of individual heartbeats, and also refers to collection of heart rate data continuously throughout the day and night. More generally, with respect to physiological signals that may be monitored by a wearable device, "continuous" or "continuously" will be understood to mean continuously at a rate appropriate for intended time-based processing and physically possible with the monitoring hardware, subject to normal data acquisition limitations such as sampling limits and sampling rates associated with converting physical signals to digital data, and physical disruptions during use (e.g., temporary displacement of the monitoring hardware due to sudden movement, changes in external lighting, loss of power, physical manipulation or adjustment by the wearer, physical displacement of the monitoring hardware due to external forces, etc.). It is also noted that heart rate data or monitored heart rate in this context may more generally refer to raw sensor data, heart rate data, signal peak data, heart rate variability data, or any other physiological or digital signal suitable for recovering heart rate data as contemplated herein, and that heart rate data may generally be captured (collected) over some historical period that may then be correlated to various metrics such as sleep state, activity recognition, resting heart rate, maximum heart rate, etc.

[0029] As used herein, the term "pointing device" refers to any suitable input interface, particularly a human interface device, that allows a user to input spatial data into a computing system or device. In exemplary embodiments, a pointing device may allow a user to provide input to a computer using physical gestures (e.g., pointing, clicking, dragging, and dropping). Exemplary pointing devices may include, but are not limited to, a mouse, a touchpad, a touchscreen, etc.

[0030] As used herein, the term "computer-readable medium" means persistent storage hardware, persistent storage device, or persistent computer system memory that can be accessed by a controller, microcontroller, computing system, or computing system module to encode computer-executable instructions or software programs thereon. A "computer-readable medium" can be accessed by a computing system or computing system module to search for, retrieve, and / or execute computer-executable instructions or software programs encoded thereon. A persistent computer-readable medium may include, but is not limited to, one or more types of hardware memory, persistent tangible media (e.g., one or more magnetic storage disks, one or more optical disks, one or more USB flash drives), computer system memory or random access memory (e.g., DRAM, SRAM, EDO-RAM), etc.

[0031] As used herein, the term "distal" means the part, end, or component of the physiological measurement system that is furthest from the user's body when worn by the user.

[0032] As used herein, the term "proximal" means the part, end, or component of the physiological measurement system that is closest to the user's body when worn by the user.

[0033] As used herein, the term "equal" is used in a broad and general sense to mean exactly equal or approximately equal within some tolerance.

[0034] Exemplary embodiments provide a wearable physiological measurement system configured to provide continuous measurements of physiological data such as heart rate, or other physiological data such as blood pressure, hydration status, blood oxygenation status, etc. The exemplary system is configured to be continuously wearable on an appendage (e.g., wrist or ankle) and does not rely on electrocardiography or a chest band to detect heart rate. The exemplary system includes one or more light emitters for emitting light at one or more desired frequencies toward a user's skin and one or more light detectors for receiving light reflected from the user's skin. The light detectors may include photoresistors, phototransistors, photodiodes, etc. When light (e.g., green light) from the light emitters penetrates the user's skin, the blood's natural absorbance or transmittance to the light imparts fluctuations to the photoresistor readings. These fluctuations have the same frequency as the user's pulse, since increased absorbance or transmittance occurs only when blood flow increases after a heartbeat. The system includes a processing module embodied in software, hardware, or a combination thereof for processing optical data received by the optical detector and continuously determining a heart rate based on the optical data, which may be combined with data from one or more motion sensors (e.g., an accelerometer and / or gyroscope) to minimize or remove noise in the heart rate signal caused by motion or other artifacts (or in other optical signals at different wavelengths).

[0035] FIG. 1 illustrates a physiological monitoring apparatus. The overall system 100 may generally include a device 104 (which may or may not include a display screen or other user interface) configured for physiological monitoring. The system 100 may further include a removable and replaceable battery 106 for recharging the device 104. A strap 102 may be provided and may include any configuration suitable for holding the device 104 in a predetermined position on a wearer's body for physiological data collection as described herein. For example, the strap 102 may include a thin elastic band formed from any suitable elastic material (e.g., rubber, woven polymer fibers such as woven polyester, polypropylene, nylon, spandex, etc.). The strap 102 may be adjustable to accommodate various wrist sizes and may include any latch, clasp, or the like for securing the device 104 in an intended position for monitoring physiological signals. While a wrist-worn device is shown, it will be understood that the device 104 may be configured for placement at any suitable location on a user's body based on the detection modality and characteristics of the signal to be collected. For example, device 104 may be configured for use on the wrist, ankle, bicep, rib cage, or any other suitable location(s), and strap 102 may be or include a waistband, other elastic band, or the like, within a garment or accessory. Additionally or alternatively, device 104 may be structurally configured for placement on or within a garment, e.g., permanently or detachably and replaceably. To that end, device 104 may be structurally configured for placement within a pocket, slot, and / or other insert that couples to or is embedded within the garment. In such a configuration, the garment may include a detection window or other pathway through which device 104 can detect physiological and / or biomechanical parameters from a user wearing a garment that includes device 104 therein or thereon.

[0036] System 100 may include any hardware components, subsystems, etc. for providing various functions such as data collection, processing, display, and communication with external resources. For example, system 100 may include a heart rate monitor using, for example, photoplethysmography, electrocardiography, or any other technology(ies). System 100 may be configured such that, when placed for use around the wrist, system 100 begins collecting physiological data from the wearer. In some embodiments, pulse or heart rate may be obtained using a light sensor coupled with one or more light-emitting diodes (LEDs), all in direct contact with the user's wrist. The LEDs may be positioned to direct illumination toward the user's skin and may be accompanied by one or more photodiodes or other photodetectors suitable for measuring illumination from the LEDs reflected and / or transmitted by the wearer's skin.

[0037] System 100 may be configured to record other physiological and / or biomechanical parameters, including, but not limited to, skin temperature (using a thermometer), galvanic skin response (using a galvanic skin response sensor), movement (using one or more multi-axis accelerometers and / or gyroscopes), blood pressure, etc., as well as environmental or situational parameters such as ambient light, air temperature, humidity, time of day, etc. System 100 may also include other sensors, such as accelerometers and / or gyroscopes for movement detection, and sensors for environmental temperature detection, electrodermal activity (EDA) detection, galvanic skin response (GSR) detection, etc.

[0038] System 100 may include one or more battery life sources, such as a first battery that is environmentally sealed within device 104 and a battery 106 that is removable and replaceable for recharging the battery within device 104. System 100 may perform many functions related to continuous monitoring, such as automatically detecting when a user is asleep, awake, exercising, etc., which may occur locally at device 104 or at a remote service coupled in communication with and receiving data from device 104. In general, system 100 may support continuous, independent monitoring of physiological signals, such as heart rate, and collected data may be stored at device 104 until it can be uploaded to a remote processing resource for more computationally expensive analysis.

[0039] FIG. 2 is a block diagram of an exemplary computing device 200 that can be used to perform any of the methods provided by the exemplary embodiments. The computing device may be, for example, a device used for continuous physiological monitoring. Alternatively or alternatively, the device may be any of the local computing devices described herein, such as a desktop computer, laptop computer, or smartphone. Alternatively or alternatively, the device may be any of the remote computing resources described herein, such as a web server, cloud database, file server, application server, or any other remote resource or the like. While described as a physical device, it should be understood that the exemplary computing device 200 may also or alternatively be implemented as a virtual computing device, such as a virtual computer running a web server or other remote resource in a cloud computing platform. In general, the device 200 may include one or more sensors 202, a battery 204, a storage device 206, a processor 208, a memory 210, a network interface 214, and a user interface 216, or one or more virtual instances of the above.

[0040] Sensors 202 may include any sensor or combination of sensors suitable for heart rate monitoring as contemplated herein, as well as sensors 202 for detecting calorie expenditure, location (e.g., via a global positioning system or the like), movement, activity, etc. In one aspect, this may include a light detection system including an LED or other light source along with a photodiode or other optical sensor that may be used in combination for photoplethysmographic measurement of heart rate, pulse oximetry measurement, and other physiological monitoring.

[0041] Additionally or alternatively, the sensors 202 may include one or more sensors for activity measurement. In some embodiments, the system may include one or more multi-axis accelerometers and / or gyroscopes for activity measurement. In some embodiments, the accelerometer may further be used to filter signals from an optical sensor for measuring heart rate to provide a more accurate measurement of heart rate. In some embodiments, the wearable system may include a multi-axis accelerometer for measuring movement and calculating distance. For example, a movement sensor may be used to classify or categorize activities such as walking, running, playing another sport, standing, sitting, or lying down. The sensors 202 may include, for example, a thermometer for monitoring the user's body or skin temperature. In one embodiment, the sensors 202 may be used to recognize sleep based on a drop in temperature, galvanic skin response data, a lack of movement or activity from data collected by an accelerometer, a decreased heart rate as measured by a heart rate monitor, etc. Body temperature, in conjunction with heart rate monitoring and movement, can be used to interpret, for example, whether a user is sleeping or just resting, and how well a person is sleeping. Also, as described in more detail below, body temperature, movement, and other sensed data can be used to determine whether a user is exercising, and to classify and / or analyze activity. In another aspect, sensor 202 may include one or more contact sensors, such as capacitive or resistive touch sensors, to detect the position of a physiological monitor for use on a user. More generally, sensor 202 may include any sensor or combination of sensors suitable for monitoring geographic location, physiological state, movement, motion, etc., in any manner useful for physiological monitoring as contemplated herein.

[0042] Battery 204 may include one or more batteries configured to allow for continuous wear and use of the wearable system. In one embodiment, the wearable system may include two or more batteries, such as an integral battery that maintains operation of device 200 while the main battery is charging, along with a removable battery that can be removed and recharged using a charger. In another aspect, battery 204 may include a wirelessly rechargeable battery that can be recharged using a short-range or long-range wireless recharging system.

[0043] Processor 208 may include any microprocessor, microcontroller, signal processor, or other processor or combination of processors and other processing circuitry suitable for performing the processing steps described herein. Generally, processor 208 may be configured with computer-executable code stored in memory 210 to perform the activity recognition and other physiological monitoring functions described herein.

[0044] Generally, memory 210 may include one or more non-transitory computer-readable media for storing one or more computer-executable instructions or software for implementing exemplary embodiments. Non-transitory computer-readable media may include, but are not limited to, one or more types of hardware memory, non-transitory tangible media (e.g., one or more magnetic storage disks, optical disks, one or more USB flash drives), etc. In one aspect, memory 210 may include computer system memory or random access memory, such as DRAM, SRAM, EDO-RAM, etc. Memory 210 may also include other types of memory, or combinations thereof, as well as virtual instances of memory, for example, if the device is a virtual device. Generally, memory 210 may store computer-readable and computer-executable instructions or software for implementing the methods and systems described herein. Additionally or alternatively, memory 210 may store physiological data, such as data collected by sensor 202 during operation of device 200, user data, or other data useful for the operation of a physiological monitor or other device described herein.

[0045] Network interface 214 may be configured to communicate data wirelessly to server 220 via an external network 218, such as any public network, private network, or other data network described herein, or any combination of the above, including, for example, a local area network, the Internet, a cellular data network, etc. If the device is a physiological monitoring device, network interface 214 may be used, for example, to communicate raw or processed sensor data stored in device 200 to server 220, as well as to receive updates, receive configuration information, and otherwise communicate with remote resources and users to support the operation of the device. More generally, network interface 214 may include any interface configured to connect to one or more networks (e.g., LAN, WAN, Internet, or cellular data network) via various connections, including, but not limited to, a standard telephone line, a local area network (LAN) or wide area network (WAN) link (e.g., 202.11, T1, T3, 56kb, X.25), a broadband connection (e.g., ISDN, Frame Relay, ATM), a wireless connection, or some combination of any or all of the above. Network interface 214 may include a built-in network adapter, a network interface card, a PCMCIA network card, a card bus network adapter, a wireless network adapter, a USB network adapter, a modem, or any other device suitable for connecting and operating computing device 200 with any type of network capable of communicating with and performing the operations described herein.

[0046] User interface 216 may include any components suitable for supporting interaction with a user, including, for example, a keypad, a display, a buzzer, a speaker, light-emitting diodes, and any other components for receiving input from or providing output to a user. In one aspect, device 200 may be configured to receive tactile input, for example, by responding to a series of taps on the surface of the device to change operating states, display information, etc. User interface 216 may also or alternatively include a graphical user interface rendered on a display for graphical user interaction with programs executing on processor 208 and other content rendered by a physical display of device 200.

[0047] FIG. 3 illustrates a physiological monitoring system. More specifically, FIG. 3 illustrates a system 300 for facilitating physiological monitoring that may be used with any of the methods or devices described herein. Generally, system 300 may include a physiological monitor 306, a user device 320, a remote server 330 having remote data processing resources (such as any of the processors or processing resources described herein), and one or more other resources 350, all of which may be interconnected via a data network 302.

[0048] The data network 302 may be any of the data networks described herein. For example, the data network 302 may be any network(s) or internetwork(s) suitable for conveying data and information between participating devices in the system 300. This may include public networks like the Internet, private networks, telecommunications networks such as public switched telephone networks or cellular networks using third-generation (e.g., 3G or IMT-2000), fourth-generation (e.g., LTE (E-UTRA) or WiMAX-Advanced (IEEE 802.16m)), fifth-generation (e.g., 5G), and / or other technologies, as well as any of various enterprise or local area networks and other switching devices (switches), routers, hubs, gateways, etc. that may be used to transmit data between participating devices in the system 300. It may also include local-range or short-range communication networks suitable, for example, for coupling the physiological monitor 306 to the user device 320 or for otherwise communicating with local resources.

[0049] Physiological monitor 306 may generally be any physiological monitoring device, such as any of the wearable monitors or other monitoring devices described herein, such as bracelet 100 of FIG. 1. Thus, physiological monitor 306 may generally be shaped and sized to be worn on a user's wrist or other appendage and held in a desired position relative to the appendage with a strap 310 or other attachment mechanism. Physiological monitor 306 may include a wearable housing 311, a network interface 312, one or more sensors 314, one or more light sources 315, a processor 316, a memory 318, and a wearable strap 310 for holding physiological monitor 306 in a desired location on the user.

[0050] Generally, physiological monitor 306 may include a wearable physiological monitor configured to collect heart rate data and / or other physiological data from a wearer. More specifically, wearable housing 311 of physiological monitor 306 may be configured to allow a user to wear wearable physiological monitor 306 to collect heart rate data and / or other physiological data from the user substantially continuously. Wearable housing 311 may be configured to cooperate with strap 310 or the like, for example, to engage an appendage of the user.

[0051] Network interface 312 may be configured to couple one or more participant devices of system 300 in communicative relationship with, for example, a remote server 330. Network interface 312 may be configured to couple one or more participant devices of system 300 in communicative relationship with, for example, a remote resource using technologies such as Bluetooth, Wi-Fi (Wireless Fidelity), mobile networks (3G, 4G, 5G, etc.), or near field communication (NFC).

[0052] The one or more sensors 314 may include any of the sensors described herein or any other sensor suitable for physiological monitoring. By way of example and not limitation, the one or more sensors 314 may include one or more light sources and light sensors, accelerometers, gyroscopes, temperature sensors, galvanic skin response sensors, environmental sensors (e.g., for measuring air temperature, humidity, lighting, etc.), geolocation sensors, time-related sensors, electrodermal activity sensors, etc. The one or more sensors 314 may be disposed in the wearable housing 311 or otherwise positioned and configured to capture data for physiological monitoring of the user. In one aspect, the one or more sensors 314 may include a photodetector configured to provide data to the processor 316 for calculating heart rate variability. Additionally or alternatively, the one or more sensors 314 may include an accelerometer configured to provide data to the processor 316, for example, to detect sleep states, walking events, movement, and / or other user activities. In one implementation, one or more sensors 314 may measure the user's galvanic skin response.

[0053] The processor 316 and memory 318 may be any of the processors and memories described herein and may be suitable for placement in a physiological monitoring device. In one aspect, the memory 318 may store physiological data obtained by monitoring the user with one or more sensors 314. The processor 316 may be configured to obtain heart rate data from the user based on the data from the sensors 314. The processor 316 may further be configured to assist in determining a health status of the user, such as whether the user has an infection or other illness of interest, as described herein.

[0054] One or more light sources 315 may be coupled to the wearable housing 311 and controlled by the processor 316. At least one of the light sources 315 may be directed toward the skin of the user's appendage. Light from the light sources 315 may be detected by one or more sensors 314.

[0055] System 300 may further include a remote data processing resource executing on remote server 330. The remote data processing resource may be any of the processors described herein and may be configured to receive data communicated from memory 318 of physiological monitor 306 and assess the health status of the user, such as whether the user has an infection or other condition of interest, as described herein.

[0056] The system 300 may also include one or more user devices 320, which may cooperate with the physiological monitor 306 to, for example, display user data and analysis results, and / or provide a communications bridge from the network interface 312 of the physiological monitor 306 to the data network 302 and the remote server 330. For example, the physiological monitor 306 may communicate locally with the user device 320, such as a user's smartphone, via short-range communications (e.g., Bluetooth or the like), for example, to exchange data between the physiological monitor 306 and the user device 320, and the user device 320 may communicate with the remote server 330 via the data network 302. Computationally intensive processing may be performed on the remote server 330, which may have greater memory and processing capabilities than the physiological monitor 306 that collects the data. However, as will be appreciated, processing may also or instead be performed on one or more of the physiological monitors 306, the user devices 320, etc. That is, it will be understood that one or more steps associated with the physiological monitoring techniques as described herein, or their associated sub-steps, calculations, functions, etc., may be performed locally, remotely, or some combination thereof. For example, the steps may be performed locally on a wearable device, remotely on a server or other remote resource, on an intermediate device such as a local computer used by a user to access a remote resource, or any combination thereof.

[0057] The user device 320 may include any computing device as described herein, including, without limitation, a smartphone, a desktop computer, a laptop computer, a network computer, a tablet, a mobile device, a personal digital assistant, a mobile phone, a portable media device, or a portable entertainment device. The user device 320 may provide a user interface 322 for a user to access data and analysis results and / or to control the operation of the physiological monitor 306. The user interface 322 may be maintained by an application running locally on the user device 320, or the user interface 322 may be served and presented remotely on the user device 320, for example, from a remote server 330 or one or more other resources 350.

[0058] In general, remote server 330 may include data storage, a network interface, and / or other processing circuitry. Remote server 330 may process data from physiological monitor 306, may perform any of the analyses described herein, and may provide a user interface for remotely accessing this data from, for example, user device 320. Remote server 330 may include a web server or other programmatic front end that facilitates web-based access by user device 320 and / or physiological monitor 306 to the capabilities of remote server 330 or other components of system 300.

[0059] Other resources 350 may include any resources that may be usefully employed in the devices, systems, and methods described herein. For example, these other resources 350 may include, without limitation, other data networks, human actors (e.g., programmers, researchers, annotators, editors, analysts, etc.), sensors (e.g., audio or visual sensors), data mining tools, computational tools, data monitoring tools, algorithms, etc. Additionally or alternatively, other resources 350 may include any other software or hardware resources that may be usefully employed in networked applications as contemplated herein. For example, other resources 350 may include a payment processing server or platform used to authenticate payments for access, content, or option / feature purchases, or otherwise. In another aspect, other resources 350 may include an authentication server or other security resource for third-party verification of identity, encryption or decryption of data, etc. In another aspect, other resources 350 may include a desktop computer or the like co-located with (e.g., on the same local area network or directly coupled via a serial or USB cable) user device 320, physiological monitor 306, and / or remote server 330. In this case, other resources 350 may provide additional functionality to other components of system 300.

[0060] Additionally or alternatively, other resources 350 may include one or more web servers that provide web-based access to / from any of the other participating devices (participants) in system 300. Although shown as a separate network entity, it will be readily appreciated that additional resources 350 (e.g., web servers) may also or alternatively be logically and / or physically associated with one of the other devices described herein and may include or provide user interfaces 322 for web access to remote servers 330 or databases to enable user interaction over data network 302, for example, from physiological monitors 306 and / or user devices 320.

[0061] FIG. 4 is a flow chart illustrating a method 400 for measuring the tightness of a wearable monitor and providing actionable feedback to a user based on a physical model. The tightness of a wearable monitor can affect performance. For example, if an optical monitor, such as a photoplethysmography monitor or a blood oxygenation monitor, is too wobbly, the resulting signal can be degraded due to insufficient optical coupling between the sensor and the skin. To achieve an optimal level of tightness, a physical model, such as a spring model or a resonance model, may be created to characterize the movement of the wearable monitor when elastically held in tension around a body part. The wearable monitor may then be vibrated, and the measured responses to these vibrations may be used with the physical model to estimate tension, for example, by calculating the tension in the physical model that produces a response to the vibration equal to the measured response. The estimated tension may then be used to provide adjustment information to the user, for example, to tighten, loosen, reposition, and / or otherwise adjust the monitor for improved or proper operation.

[0062] As shown in step 402, method 400 may include coupling a wearable monitor to the user's body. The monitor may include a physiological monitor, an optical monitor, a photoplethysmography system, a pulse oximetry monitor, or any other wearable physiological monitor described herein, or any other monitor that may be coupled to the user's body with an elastic strap, band, fabric, stretchable clothing, or the like. For example, the monitor may be coupled to the user's wrist with a wristband. Alternatively, the monitor may be coupled to the chest, biceps, ankles, calves, torso, waist, legs, arms, or some other body part with an elastic strap or elastic clothing formed from an elastic material such as athletic knit, spandex, elastane, one or more elastic straps, or some other fabric or polymer, urethane rubber, or the like. Such monitors may usefully include tactile output devices and motion sensors such as accelerometers, gyroscopes, and / or magnetometers to provide stimuli and responses for wear detection as described herein. Although the technology described herein is generally described in the context of wearable physiological monitors, the technology may be applied more generally to any system whose proper performance depends on tension (or corresponding normal force) to elastically hold a device in an intended position, all of which are intended to be within the scope of this disclosure unless expressly stated otherwise.

[0063] As indicated at step 404, method 400 may include storing a model of the wearable monitor's physical behavior with respect to movement. This may include, for example, a physical model, such as a resonance model, that characterizes how the wearable monitor and any elastic tension members move in response to applied forces, e.g., as a function of (or lumped characterization of) the tension in one or more elastic tension members. The model may be any empirical, analytical, or other model suitable for relating vibration response to tension in the elastic tension members. In one aspect, the resonance model provides a useful approximation that has been shown to yield accurate tension calculations suitable for the purposes contemplated herein. One such resonance model based on a spring system will now be described in more detail as an example. However, the physical model may more generally include any suitable type of system model based on mechanical input and resulting movement (or optical response, as described further below). Additionally or alternatively, the model of physical behavior may include an empirically based or data-driven model that is trained to identify tension based on a learning dataset of mechanical / optical responses classified by appropriate learning (training) metrics, such as physical strain, device fit, measurement accuracy, etc.

[0064] In general, the tightness of a wearable sensor can be characterized as the pressure that the sensor's optical interface applies to the skin to maintain contact. Given an overall normal force (F) pressing the strap against the skin and the contact area of ​​the sensor (A), and assuming that the pressure is uniformly distributed, the tightness of the strap can be calculated as F / A. Uniform distribution of pressure over the contact area is a very strong assumption, especially during movement. The force F between the sensor and the skin when the sensor is face up and secondarily face down can be adjusted according to gravity as follows: F=sin(α)2f+mg and F=cos(α)2f-mg where α is the angle between the strap and the garment, f is the tightness of the garment, m is the weight of the sensor, and g is the gravity coefficient (acceleration due to gravity). If the garment, strap, or other elastic tension member is elastic with a spring constant of k: f = k(dx).

[0065] where dx is the change in strap length and f is the tightness of the elastic tension member. In practice, k is a monotonic function of dx over the elastic range of interest. Given these equations, a direct relationship between the force between the strap and the skin and tightness in a stationary state can be derived. The force between the skin and the sensor during movement can be calculated given the acceleration vector and the weight of the sensor. This concept generally ensures that if the physical displacement of the device is a function of the strap tension and the applied force, and k is known or calculated, then the tightness (and therefore the force between the sensor and the skin) can also be calculated based on the acceleration vector and the mass of the device. However, direct calculation of tension on this basis requires at least calibration of the mechanical force applied by a stimulator (e.g., a haptic device) in response to a control signal. Thus, also or instead, a resonance model can be advantageously used to estimate the spring constant based on resonance in response to a frequency sweep or the like.

[0066] When a force is applied to a material, the material will stretch or contract in response to the force. The force per unit area is stress (σ). The degree to which the material stretches or compresses as it responds to the stress is the applied stress (ε). The applied stress is measured by the ratio of the difference in length L along the direction of the stress, ΔL, to the original length L0, i.e., ε = ΔL / L0.

[0067] Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied force is equal to or close to the natural frequency of the system on which it acts. When an oscillatory force is applied at the resonant frequency of a dynamic system, the system will vibrate at a higher amplitude than when the same force is applied at another non-resonant frequency. The Q factor relates the maximum or peak energy stored in a circuit (reactance) to the energy dissipated during each cycle of oscillation (resistance), and is the ratio of the resonant frequency to the bandwidth; the higher the circuit Q, the smaller the bandwidth: Q=f r This means that it is / BW.

[0068] These properties can be used to characterize the frequency response of the sensor / elastic combination to a mechanical stimulus, such as vibration of a tactile output element, as described herein. A model based on these properties can be stored in any suitable memory location, such as in the memory of the wearable monitor, in the memory of a personal computing device or the like used to perform the tension calculations, or on a remote server that performs the tension calculations and provides actionable feedback to the user via the personal computing device (or any combination thereof). In one aspect, the resonance model may include an analytical model that characterizes, for example, the strap tension of a wrist-worn device as a function of the resonant frequency of the spring system. Depending on the desired range and accuracy of the calculations, this may be a linear model, an exponential model, a quadratic model, or any other model that physically represents the spring system and can fit experimental data for the spring system. In another aspect, the resonance model may be an empirical or experimental model that correlates, for example, measured resonant frequency to measured strap tension. In another aspect, especially if the observed response does not follow a simple computational model, the experimental data may be modeled as a lookup table or the like, in which case the tension may be looked up (or interpolated) based on the measured resonant frequency. The actual resonance may be estimated, for example, based on the wavelength that maximizes the measured accelerometer response to the tactile input (e.g., the ratio of the accelerometer signal to the tactile input signal, each of which may be measured in the frequency domain, for example, to reduce the effects of phase changes or other artifacts).

[0069] As shown in step 406, method 400 may include vibrating the wearable monitor. The vibration may occur upon user request or automatically during a specific event or time. For example, the device may include a button, such as a physical button on the device or a button on the user interface of another device, that the wearer can press to check the proper fit of the device. In another example, the device may automatically test for fit in response to a detected event, such as detecting that the user has put on the device or detecting a drop in data quality below a predetermined threshold while the device is being worn. Vibrating the wearable monitor may include, for example, causing vibration of the wearable monitor by energizing a tactile output element, a piezoelectric element, a buzzer, an eccentric motor, a linear vibration motor, or other linear tactile actuator, or other vibrator or the like associated with the wearable monitor (mechanically coupled to and / or within the housing of the wearable monitor). This may include a rotary tactile element, a linear tactile element, or any other tactile element. Although the rotating vector of the vibration may complicate individual spring measurements, locating the resonant response may advantageously be performed without resolving the linear components of the haptic output and without calibrating the haptic amplitude. For example, the control signal for the vibration may include a chirp signal that increases or decreases in frequency over time to sweep a range of frequencies to locate the resonant frequency (or range of resonant frequencies) of the wearable monitor and elastic tension member(s). However, as will be appreciated, other signals are possible for use herein, such as any signal that covers a sufficiently large frequency range for locating the resonance. In one aspect, signals such as a swept sine or swept cosine may be utilized. For example, y=sin[2π(at+f)t] More generally, any linear frequency chirp, exponential chirp, hyperbolic chirp, or other function that increases or decreases the signal frequency over time may be used. The frequency sweep may continue until either (1) a predetermined confidence level in resonance detection (or corresponding tension calculation) is achieved, or (2) the test times out, whichever occurs first. Thus, for example, if a reliable tension measurement cannot be obtained in 180 seconds (or some other time window appropriate for one or more complete sweeps of the target frequency range), the test may be terminated and an error message may be provided.

[0070] As indicated at step 408, method 400 may include measuring the response of the wearable monitor to the vibrations, such as by measuring the response with one or more gyroscopes, accelerometers, optical sensors (e.g., by measuring movement relative to the user's skin), or any combination of the above or the like. This data may be processed by the wearable monitor or transmitted to a remote resource, such as the user's personal computing device or a remote server for analysis to determine the elastic tension or circumferential force holding the wearable monitor in place.

[0071] As indicated at step 410, method 400 may include calculating tension in an elastic tension member (e.g., garment, strap, band, or the like) holding the wearable monitor to the body. Typically, this may involve locating the resonant frequency of the strap / monitor system in response to a chirp or other stimulus and using this resonant frequency to calculate the system's spring constant and infer radial tension. Typically, the resonant frequency is identified at the frequency corresponding to the maximum amplitude in the associated mechanical response. If an analytical model is derived and utilized, tension (or other appropriate metric) may be calculated by inputting the measured resonant frequency into an analytically derived equation for calculating tension. As noted above, and / or alternatively, the model may be an empirical or empirical model that correlates resonance to tension based on experimental observations. The empirical model may be embodied, for example, in a lookup table, a linear regression model, or some other model that fits the measured resonance data to the measured strap tension data in a statistically significant manner. If a lookup table is used, interpolation (e.g., linear interpolation) may also be used, where appropriate / necessary, to calculate tension for gap frequencies between values ​​stored in the lookup table. In the latter case, measuring tightness may be performed by simply stimulating the device with a frequency sweep, locating the peak of the resonant response, and then, given this resonant frequency, looking up the tension in a lookup table or calculating the tension using a regression model or the like.

[0072] As indicated at step 412, method 400 may include providing adjustment information to the user, e.g., using any of the techniques described herein. This may include, for example, a quantitative description of the tension, e.g., a calculated circumferential or normal force expressed in Newtons or some other physical unit. Also or alternatively, this may include, for example, a score of -10 to 10, where zero is the optimal tension, a score of -5 to 5 that is acceptable for accurate data collection, and anything outside the -10 to 10 range that is unlikely to yield accurate or meaningful data. In another aspect, the adjustment information may include a qualitative assessment of whether the current tension is within an acceptable range, such as "too tight" (corresponding to a score as described above greater than 5), "too loose" (e.g., corresponding to a score less than -5), "OK" (e.g., corresponding to a score of -5 to 5), or "optimal" (corresponding to a score of -1 to 1), or using a natural language description of any similar range boundary. If information is available regarding the circumference and / or material of the elastic tension member(s), or if the model otherwise provides appropriate output or analysis, this may include actionable instructions such as "tighten the strap at least 1 mm." In one embodiment, the actionable instructions may include a visual element illustrating the instruction. Also, or alternatively, if the strap has a built-in controllable tensioning system that provides specific feedback (e.g., audio feedback, visual feedback, or tactile feedback), the actionable instructions may include a specific command such as "tighten the strap 3 clicks" or the like. In another embodiment, if the strap has a built-in automatic tension controller, method 400 may include generating a control signal to automatically adjust the tension of the strap toward a predetermined tension target.

[0073] The adjustment information may be displayed on the wearable monitor or on a local computing device. In one aspect, the adjustment information may be displayed simultaneously with one or more other quantitative or qualitative pieces of information, such as the user's current physiological measurements. If the wearable monitor detects a user adjustment to strap tension, the monitor may automatically retest the strap tension and / or update the tension scale (metric) or recommendation.

[0074] As will be appreciated, tension measurements may be usefully repeated under a variety of conditions. For example, tension measurements may be performed initially when the wearable monitor is placed on the body. Tension measurements may be repeated on a regular schedule, for example, as a maintenance function or under conditions indicating changes in tension, such as a deterioration in signal strength or a decrease in quality / reliability with respect to physiological metrics such as heart rate. In one aspect, tension measurements may be repeated continuously over a period of time, for example, at regular short intervals while the device is being worn and available information indicates that tension is outside of an acceptable range. In this case, tension measurements may be repeated until tension is determined to be within an acceptable range or until a timeout limit is reached. In the latter case, an error notification may be reported to the user, warning that accurate data is not currently being collected. Alternatively, or additionally, tension measurements or other fit assessments may be performed on demand based on a predetermined user command, such as touching a button on a user interface, double-tapping the device, or the like.

[0075] In accordance with the above, the systems described herein include a wearable monitor and a remote processing resource (which may be a remote server or a personal computing device such as a laptop or smartphone of a user of the wearable monitor). The wearable monitor may include a processor, a sensor, and a tactile output element. Computer-executable instructions stored in a memory of the wearable monitor may configure the processor to cause vibrations of the tactile output element and receive a response to the vibrations from the sensor. The remote processing resource may be communicatively coupled to the wearable monitor and may include a second memory storing a physical model of the wearable monitor and a second processor configured to receive the response to the vibrations from the wearable monitor, apply the physical model to calculate tension in the wearable monitor around a portion of the user's body, and communicate tension information to the user based on the tension. As described herein, tension may be reported as a physical measurement, an objective fit score, a human-readable assessment, instructions for adjustment, or some combination thereof.

[0076] 5 is a flow chart illustrating a method 500 for measuring the fit of a wearable monitor. Generally, the mechanical and optical coupling of a wearable monitor can be measured based on low-resolution tactile stimuli and used to assess fit and provide actionable feedback. As a significant advantage, this approach alleviates the need to calibrate the tactile output or generate time-varying control signals such as frequency sweeps. Instead, method 500 can be implemented using, for example, a binary tactile device operable only in "on" and "off" modes and / or with an unknown and / or changing mechanical positional relationship to the device being tested.

[0077] As shown in step 502, method 500 may include causing a vibration in a wearable monitor coupled to a user's body. The monitor may include a physiological monitor, an optical monitor, a photoplethysmography system, a pulse oximetry monitor, or any of the other wearable physiological monitors described herein that may be coupled to the user's body with an elastic strap, band, fabric, or the like. For example, the monitor may be coupled to the user's wrist with a wristband. Alternatively, the monitor may be coupled to the chest, biceps, ankles, calves, torso, waist, legs, arms, or some other body part with an elastic strap or some other fabric made from athletic knit such as Lycra®, spandex, elastane, polymers, urethane rubber, or the like, or any of the other elastic straps or the like described herein. Although the technology described herein is generally described in the context of wearable physiological monitors, the technology may be applied more generally to any system in which proper performance depends on tension holding a monitor or sensor elastically in an intended position, and all such uses are intended to fall within the scope of this disclosure unless expressly stated otherwise.

[0078] Vibration of the wearable monitor may occur when a user is wearing the wearable monitor, or more generally, at any time and / or automatically at the user's request, such as with any user command described herein, or during a specific event or time. Vibrating the wearable monitor may include, for example, causing vibration of the wearable monitor by energizing a tactile output element, such as a piezoelectric element, buzzer, eccentric motor, or other vibrator or the like associated with the wearable monitor (e.g., mechanically coupled to and / or within the housing of the wearable monitor). In some embodiments, the tactile output element may be a linear tactile output element configured to deliver tactile output along a particular axis. In some embodiments, the vibration may continue for one minute or more.

[0079] As indicated at step 504, method 500 may include measuring a response of the wearable monitor to the vibration. For example, measuring the response may include receiving motion data during the vibration, such as data from one or more gyroscopes, accelerometers, or the like, or a combination of the above. Also, or alternatively, measuring the response may include receiving optical data from one or more photodetectors during the vibration. The response may be processed by the wearable monitor or transmitted to a remote resource, such as a user's personal computing device or a remote server, for analysis of the elastic tension or circumferential force holding the wearable monitor in place.

[0080] As shown in step 506, method 500 may include calculating a level of mechanical coupling of the wearable monitor around the body based on the response. Generally, this includes coupling between motion along two or more axes. For example, the level of mechanical coupling between a first axis and a second axis may be measured as the phase relationship between the force along the first axis and the force along the second axis. Generally, the tighter the wearable monitor is around the body, the smaller the phase relationship (e.g., the closer the response), and thus the greater the mechanical coupling. For multiple axis sensors, the coupling between force and motion in each axis pair can be inferred from the cross-correlation between the measured motion about each axis of the axis pair over time, which in this context is measuring the correlation between motion in each axis over time. Thus, for example, a three-axis accelerometer system will yield three cross-correlations in XY, XZ, and YZ. Similarly, gyroscope data may yield three cross-correlations in rotation about three similar axis pairs. In this context, instantaneous measurements may not provide meaningful results, but the average for each axis pair over many samples will tend to converge to the true cross-correlation for that axis pair where actual mechanical coupling exists between the axes. Therefore, data may be obtained over a wide interval, such as 30 seconds, 60 seconds, 90 seconds, or 180 seconds, and / or up to a confidence level that the calculated value(s) meet a predetermined threshold. In this context, the predetermined threshold may be a statistical measure of confidence, for example, based on the variability of the calculated results or the mean squared error against a measurement benchmark.

[0081] Any of the above cross-correlations may be used to measure mechanical coupling as contemplated herein, and while each generally correlates with tightness, a monotonic relationship between ZY mechanical coupling and strap tightness has been observed, where the Z axis is perpendicular to the skin and the Y axis is parallel to the skin and parallel to the strap (as shown in FIG. 6 below). This mechanical coupling can be used to estimate strap tension based exclusively on ZY mechanical coupling. Additionally or alternatively, other couplings between the accelerometer and / or gyroscope axes can be used, for example, by themselves in combination with ZY coupling, or as a supplemental or quality control check on inferences based on ZY coupling.

[0082] As shown in step 508, method 500 may include calculating a level of optical coupling of the wearable monitor around the body based on the response. The level of optical coupling may be calculated separately from the level of mechanical coupling based on the motion data and the optical data. However, in this case, a similar cross-correlation may be used with the acceleration-correlated optical data to characterize the ratio between two components of the optical signal: the heart rate signal (expected to be independent of instantaneous motion) and the motion artifact (expected to be dependent on the measured instantaneous motion). In some embodiments, the motion data may have at least three axes (i.e., from a three-axis IMU, gyroscope, accelerometer, or the like), where the X-axis data in particular has been demonstrated to be highly correlated to strap tension. As shown in FIG. 6 below, in this context, the X-axis of the device is parallel to the skin and perpendicular to the strap.

[0083] As indicated at step 510, method 500 may include evaluating the fit, which may include scaling, transforming, or otherwise processing the mechanical and optical coupling to arrive at a conclusion regarding quantitative tension (e.g., a specific physical measure of tension) or qualitative tension (e.g., a category or human-readable rating of tension).

[0084] In one aspect, a proper fit may be determined by applying ranges and / or thresholds to the calculated mechanical and / or optical coupling. In some embodiments, a wearable monitor may be determined to be too tight if the level of mechanical coupling exceeds the threshold and the level of optical coupling is not within the range. In some embodiments, a wearable monitor may be determined to be too loose if the level of mechanical coupling does not exceed the threshold and the level of optical coupling is not within the range. In some embodiments, a wearable monitor may be determined to have an acceptable level of tightness and be coupled to a body appendage if the level of mechanical coupling exceeds the threshold and the level of optical coupling is within the range. As will be recognized, in this context, the numerical values ​​are relatively arbitrary and depend on how the mechanical and optical coupling values ​​are calculated and reported. However, empirical ranges and thresholds may be readily established to distinguish between properly and improperly worn devices. It will also be understood that the conditions for proper fit of a strap, such as a wrist strap or biceps strap, may differ from the conditions for proper fit of a monitor in clothing. Thus, for example, in some embodiments, a wearable monitor may be determined to have an acceptable level of tightness and be coupled to a user's garment if the level of mechanical coupling does not exceed a threshold and the level of optical coupling is within a range, The threshold and range may be predetermined values ​​based on the physical characteristics of the wearable monitor, the location of the device, the physical characteristics of the wearable monitor's tensile members, data quality goals, etc.

[0085] In one embodiment, fit may be reported as a quantitative description of tension, such as a calculated circumferential force or normal force. In another embodiment, fit may be reported using a quantitative score, such as a score ranging from -10 to 10, with zero being optimal tension, a score of -5 to 5 being acceptable for accurate data collection, and anything outside the -10 to 10 range being unlikely to produce accurate or meaningful data. In another embodiment, fit information may include a qualitative assessment of whether the current tension is within an acceptable range (e.g., "too tight" (corresponding to a score greater than 5 as described above), "too loose" (corresponding to a score less than -5), "OK" (e.g., corresponding to a score of -5 to 5), or "optimal" (e.g., corresponding to a score of -1 to 1)), or using a natural language description of any similar range boundaries. Additionally or alternatively, the adjustment information may include actionable instructions such as "tighten the strap at least 1 mm," where an estimate of physical adjustment is calculated based on the position of the monitor and corresponding estimates of body circumference and / or material of the elastic tension member(s).

[0086] It should also be recognized that while various specific techniques for measuring fit based on response to tactile vibration or other mechanical stimuli (particularly measuring resonant frequency location or mechanical / optical coupling) are disclosed herein, other techniques for measuring fit based on response to tactile vibration may also or instead be used. In one embodiment, two or more techniques (such as mathematical modeling using optical-mechanical coupling and resonant frequency) may be used simultaneously or sequentially, for example, as a quality control measure or as a fallback if one technique does not produce useful results.

[0087] As shown in step 512, method 500 may include providing adjustment information by, for example, displaying adjustment information to the user based on the level of mechanical coupling and the level of optical coupling. This may include communicating or displaying any of the fit information described herein to the user. In one embodiment, this may include actionable instructions, including, for example, verbal or visual instructions regarding adjustment. Also or alternatively, if the strap has a built-in controllable tensioning system that provides specific feedback (e.g., audio feedback, visual feedback, or haptic feedback), the actionable instructions may include specific instructions such as "tighten strap three clicks" or the like. In another embodiment, if the strap has a built-in automatic tension controller, providing adjustment information may include generating a control signal to automatically adjust the tension of the strap toward a predetermined tension target.

[0088] The adjustment information may be displayed on the wearable monitor, on a local computing device, or on any other suitable display device. In one aspect, the adjustment information may be simultaneously displayed with one or more quantitative or qualitative pieces of information, such as current physiological data about the user. If the wearable monitor detects a user adjustment to strap tension, the monitor may automatically retest the strap tension and / or update the tension measure (metric) or recommendation.

[0089] The adjustment information may be provided conditionally. For example, providing the adjustment information may be based on a threshold for a level of mechanical coupling and a range for a level of optical coupling. The adjustment information may include a determination of the location of the wearable monitor based on the threshold and range, which may be reported to the user and / or applied to select an appropriate model for assessing fit as generally described herein.

[0090] As will be appreciated, tightness measurements may be usefully repeated under a variety of conditions. For example, tightness measurements may be performed initially when the wearable monitor is placed on the body. Tightness measurements may be repeated periodically, for example, as a maintenance function, or under conditions indicating a change in tightness, such as a deterioration in signal strength or a decrease in the quality / confidence of a physiological metric such as heart rate. In one aspect, tightness measurements may be repeated continuously when calibration information indicates that tightness is outside of an acceptable range. Tightness measurements may be repeated until tightness is determined to be within an acceptable range or until a timeout limit is reached.

[0091] In accordance with the above, the system described herein includes a wearable monitor and a remote processing resource (which may be a remote server or a personal computing device such as a laptop or smartphone of a user of the wearable monitor). The wearable monitor may include a processor, a sensor, and a tactile output element. Computer-executable code stored in a memory of the wearable monitor may configure the processor to cause vibrations of the tactile output element and receive a response to the vibrations from the sensor. The remote processing resource may be communicatively coupled to the wearable monitor and may include a second memory storing a physical model of the wearable monitor, and a second processor configured to receive a response to the vibrations from the wearable monitor, calculate a level of mechanical coupling of the wearable monitor around the user's body based on the response, calculate a level of optical coupling of the wearable monitor around the body based on the response independently of the level of mechanical coupling, and communicate adjustment information to the user based on the level of mechanical coupling and the level of optical coupling.

[0092] FIG. 6 illustrates a coordinate system for measuring device movement. In general, device 600 may be a wrist-worn device or any of the other devices described herein. The coordinate system of device 600 may include an X-axis 602 in a plane that is substantially parallel to the user's skin, which contacts device 600 when positioned for use, but substantially perpendicular to the strap 604 that holds the device in place. As will be appreciated, the strap is a complex contoured surface, but in this context, as illustrated, perpendicular to the strap should be understood to mean substantially perpendicular to a plane that intersects a path that follows the circumferential tension band around the strap, or in other words, substantially perpendicular to the device's major axis (e.g., Y-axis 606 in FIG. 6 ) and substantially parallel to the device's minor axis (e.g., X-axis 602 in FIG. 6 ). The coordinate system may also include a Y-axis 606 in a plane that is parallel to the user's skin and parallel to strap 604, e.g., substantially parallel to the plane through the strap described above. The coordinate system may include a Z-axis 608 that is substantially perpendicular to a plane that is substantially parallel to a user's skin that contacts the device 600 when positioned for use. An accelerometer, such as any of the accelerometers described herein, may be positioned to measure movement in each of the X-axis 602, Y-axis 606, and Z-axis 608, e.g., for mechanical or optical coupling measurements as described herein. Additionally or alternatively, a gyroscope, such as any of the gyroscopes described herein, may be positioned to measure rotation about each of the X-axis 602, Y-axis 606, and Z-axis 608, e.g., for mechanical or optical coupling measurements as described herein.

[0093] FIG. 7 illustrates a mapping of mechanical and optical coupling to device fit. Generally, mechanical and optical coupling ranges, as described herein, may be mapped to fit categories. As will be appreciated, the categories and locations are conceptual only, and the contours of any particular category and / or corresponding measured mechanical or optical coupling ranges will depend on the particular type of device, the device's location, and the particular type of restraint system. Thus, for example, the mechanical and / or optical coupling characteristics for a properly tensioned device within a pocket of a wearable garment may differ significantly from the mechanical and / or optical coupling characteristics for a properly tensioned device strapped to a wearer's wrist. However, in general, optical and mechanical coupling ranges may be identified that reliably correlate to proper or improper tension and used to generate user recommendations regarding adjustments as contemplated herein.

[0094] FIG. 8 illustrates a user interface 800 for user interaction with a device fit protocol, such as any of the user operations described herein. Generally, the user interface 800 may be rendered in a smartphone application, a web page, or other environment using any of the computing devices described herein. Generally, the user interface 800 may be launched, for example, in response to a user request for a test, in response to an event such as detecting that the user has started wearing the device, in response to a drop in data quality below a threshold, and / or on some predetermined schedule (e.g., once a day or once a week, upon waking, etc.). The user interface 800 may present the user with options such as using the current tightness or running the test again, for example, after the user has made adjustments based on device feedback. The user interface 800 may display, for example, a quantitative and / or qualitative assessment of the current fit and / or a fit assessment history for the user and device.

[0095] In another aspect, the selection of a model or parameters for analyzing fit may depend on where the device is located and / or the type of device (e.g., a device strapped to the body, a device in a garment pocket, an optical sensor, an electrical sensor, etc.). Thus, a location detection algorithm can be used to determine the location of the wearable monitor on the body, based on data from, for example, an accelerometer, gyroscope, optical sensor, and other sensors integrated into the wearable monitor, to facilitate the selection of an appropriate model for assessing fit. This may be particularly useful, for example, when the monitor may be placed on a wristband or elsewhere on the body, such as on an athletic apparel garment such as a sock, underwear, pants, or the like, or held by some other elastic strap or combination of straps. The location of the monitor, such as a photoplethysmography-based heart rate monitor, may imply different tension requirements, for example, where different locations require tension / location combinations as a significant influence on the selection of an algorithm or model for processing the data (e.g., to account for different motion cancellations) to support the identification of an appropriate heart rate calculation algorithm. Location may also more specifically influence the selection and use of different physical models for assessing fit as described herein.

[0096] In one aspect, a data-driven algorithm can be used to locate a wearable monitor without user input by using sensors such as motion and touch sensors within the wearable monitor. Generally, the physical relationship and movement of the accelerometer and gyroscope depend on the location of the monitor on the body. For example, as a user moves forward, a torso-mounted monitor maintains this relationship while the relationship between the two sets of sensors continuously changes when the monitor is on the wrist. FIG. 9 shows accelerometer data patterns for different regions of the body. These empirical patterns of accelerometer data can be used to estimate the location of the sensor, for example, by mapping motion data from the sensor to one or more regions of these patterns. Similar patterns can be used, for example, based on magnitude, cross-correlation, rotation (e.g., gyroscope measurements), etc., to identify the location of the sensor, which can then be used to select an appropriate data model for evaluating the fit as described herein.

[0097] With respect to the user's range and the monitor's location range, the data-driven model can be used to detect location during reset, during activities with harmonic motion, and during activities with inharmonic motion. FIG. 10 shows a confusion matrix comparing actual results with predicted results using the data-driven model. FIG. 11 shows the amount of time (in seconds of activity) required to achieve 95% confidence in location for each of the test locations using the techniques described above. In general, these figures show that a data-driven model can be derived to usefully detect object location based on sensor data from a wearable monitor across a range of body parts, including at least the wrist, biceps, underarm, buttocks, calf, and ankle. This data can be used to select a resonance model corresponding to the object's location for use in estimating strap tension (e.g., method 400 of FIG. 4 ), and more generally, to select processing models, filters, parameters, etc. for processing data from the wearable monitor, especially in situations where the wearable monitor is specifically adapted for use with various body parts. For example, it may be determined that the wearable monitor is located on the user's wrist, and then a wrist-based model may be selected to estimate strap tension or otherwise assess the fit of the sensor.

[0098] More generally, various models are known in the art for determining the location of a device on a user's body, and any such technique may be used, alone or in combination with the techniques described above, to select an appropriate model for assessing the fit of the device and / or to estimate the location of the device to provide feedback for user adjustments to the device.

[0099] The above-described systems, devices, methods, processes, etc. may be implemented in hardware, software, or a combination thereof suitable for the control, data collection, and data processing described herein. This includes realizations in one or more microprocessors, microcontrollers, embedded microcontrollers, programmable digital signal processors, or other programmable devices or processing circuits, along with internal and / or external memory. Additionally, or alternatively, this may include one or more application-specific integrated circuits, programmable gate arrays, programmable array logic components, or any other device(s) that can be configured to process electronic signals. It will be further recognized that realizations of the above-described processes or devices may include computer-executable code created using a structured programming language such as C, an object-oriented programming language such as C++, or any other high-level or low-level programming language (including assembly language, hardware description languages, and database programming languages ​​and techniques), that can be stored, compiled, or interpreted for execution by one of the above-described devices, as well as heterogeneous combinations of processors, processor architectures, or combinations of different hardware and software.

[0100] Thus, in one aspect, each of the methods described above, and combinations thereof, may be embodied in computer-executable code that performs the steps when executed on one or more computing devices. In another aspect, the methods may be embodied in a system that performs the steps, may be distributed across devices in numerous ways, or all of the functionality may be integrated into a dedicated standalone machine or other hardware. The code may be stored in a persistent manner in computer memory, which may be program execution memory (such as random access memory associated with a processor) or storage such as a disk drive, flash memory, or any other optical, electromagnetic, magnetic, infrared, or other device or combination of devices. In another aspect, any of the systems and methods described above may be embodied in any suitable transmission or propagation medium that carries computer-executable code and / or any input or output therefrom. In another aspect, means for performing the steps associated with the processes described above may include any of the hardware and / or software described above. All such permutations and combinations are intended to be within the scope of this disclosure.

[0101] The steps of the methods of the embodiments described herein, unless a different meaning is expressly provided or otherwise apparent from the context, are intended to include any suitable manner in which such method steps are performed, consistent with the patentability of the following claims. Thus, for example, performing step X includes any suitable manner in which another party, such as a remote user, a remote processing resource (e.g., a server or cloud computer), or a machine, performs step X. Similarly, performing steps X, Y, and Z may include any manner in which one or more other parties or entities manage or control any combination of such other individuals or resources to perform steps X, Y, and Z to benefit from such steps. Thus, the steps of the methods of the embodiments described herein, unless a different meaning is expressly provided or otherwise apparent from the context, are intended to include any suitable manner in which one or more other parties or entities manage or control such steps, consistent with the patentability of the following claims. Such parties or entities need not be under the management or control of any other party or entity, and need not be located within any particular jurisdiction.

[0102] It should be recognized that the methods and systems described above have been described by way of example, and not by way of limitation. Numerous variations, additions, omissions, and other modifications will be apparent to those skilled in the art. Furthermore, the order or presentation of method steps in the above description and drawings is not intended to require this order of performing the recited steps, unless a particular order is explicitly required or otherwise apparent from the context. Thus, while particular embodiments have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications in form and detail may be made therein without departing from the spirit and scope of the present disclosure, which are intended to form a part of the present invention as defined by the following claims.

[0103] In the following, exemplary embodiments of the present invention are presented, each of which is made up of a combination of various elements. 1. A computer program product comprising computer executable code embodied in a non-transitory computer readable medium that, when executed on one or more computing devices, performs the following steps: sending a control signal to a wearable heart rate monitor coupled to the user's body by an elastic strap to activate a tactile output element of the wearable heart rate monitor, thereby causing the wearable heart rate monitor to vibrate; measuring a response of the wearable heart rate monitor to the vibrations by processing data received from the wearable heart rate monitor; calculating a level of mechanical coupling of the wearable heart rate monitor around the user's body based on the response; calculating a level of optical coupling of the wearable heart rate monitor around the user's body based on the response; calculating tension in the strap of the wearable heart rate monitor around the body by applying a physical model to the wearable heart rate monitor and the elastic strap for the level of optical coupling and the level of mechanical coupling; providing adjustment information to a user based on the tension indicating whether the tension is within an acceptable range. 2. The computer program product of claim 1, wherein the physical model is a resonance model. 3. A method comprising: causing a vibration of a wearable monitor coupled to the user's body; measuring an optical response of the wearable monitor to the vibrations from one or more optical sensors; measuring a mechanical response to the vibration from one or more motion sensors; calculating a level of optical coupling of the wearable monitor to the user with a first signal from the one or more optical sensors; calculating a level of mechanical coupling of the wearable monitor to the user with a second signal from the one or more motion sensors; assessing the fit of the wearable monitor to the body based on a combination of the level of optical coupling and the level of mechanical coupling; providing adjustment information to a user to adjust the fit to a predetermined goal. 4. The method described in claim 3, wherein the predetermined target includes tension in a band that secures the wearable monitor to the user. 5. The method described in claim 3, wherein the predetermined target includes a normal force of the wearable monitor against the user's skin. 6. The method of claim 3, wherein generating the vibration includes energizing a tactile output element coupled to the wearable monitor. 7. The method of claim 3, wherein assessing the fit includes calculating, with a processor on the wearable monitor, a level of mechanical coupling. 8. The method of claim 3, wherein providing the user with adjustment information includes presenting the adjustment information on a user interface of a computing device associated with the user. 9. The method according to claim 3, wherein the adjustment information indicates a level of tightness of the wearable monitor. 10. The method of claim 3, wherein the adjustment information includes instructions for adjusting the wearable monitor around the body. 11. The method of claim 3, wherein measuring the mechanical response includes receiving motion data during the vibration from one or more accelerometers. 12. The method of claim 3, wherein measuring the mechanical response includes receiving motion data during the vibration from one or more gyroscopes. 13. The method of claim 3, wherein measuring the optical response includes receiving optical data during the vibration from one or more optical detectors. 14. The method of claim 3, wherein generating the vibration includes energizing a linear tactile output element. 15. The method according to claim 3, wherein the wearable monitor is coupled to the user's wrist with a wristband. 16. The method of claim 3, wherein the wearable monitor is coupled to the body with elastic clothing. 17. A system comprising: a wearable monitor including a processor, at least one sensor, and a tactile output element; computer-executable code stored in a memory of the wearable monitor and configuring the processor to cause vibrations of the tactile output element and receive a response to the vibrations from the at least one sensor; a remote processing resource communicatively coupled to the wearable monitor; The remote processing resource includes a second memory that stores a physical model of the wearable monitor, and a second processor, the second processor being configured to receive a response to the vibration from the wearable monitor, calculate a level of mechanical coupling of the wearable monitor around the user's body based on the response, calculate a level of optical coupling of the wearable monitor around the body based on the response independent of the level of mechanical coupling, evaluate the fit of the wearable monitor to the user based on the level of optical coupling and the level of mechanical coupling, and communicate adjustment information to the user based on a difference between the fit and a predetermined target fit for the wearable monitor. 18. The system described in claim 17, wherein the predetermined target fit includes at least one of a minimum tension, a maximum tension, and a range of tension. 19. The system of claim 17, wherein the predetermined target fit includes at least one of a minimum threshold, a maximum threshold, and a range. 20. The computer program product of claim 1, wherein the level of optical coupling is calculated separately from the level of mechanical coupling.

Claims

1. 1. A computer program product comprising computer executable code embodied in a non-transitory computer readable medium that, when executed on one or more computing devices, performs the following steps: energizing a tactile output element of a wearable heart rate monitor coupled to a user's body by an elastic strap with a frequency sweep to cause vibration of the wearable heart rate monitor; determining a resonant frequency of the wearable heart rate monitor based on the response of the wearable heart rate monitor to the frequency sweep vibration; calculating tension in the strap of the wearable heart rate monitor around the body by applying a physical model to the wearable heart rate monitor and the elastic strap for the resonant frequency measured in response to the vibration; providing adjustment information to a user based on the tension indicating whether the tension is within an acceptable range.

2. The computer program product of claim 1 , wherein the physical model is a resonance model.

3. The computer program product of claim 2 , wherein the resonance model is utilized to estimate a spring constant based on resonance in response to the frequency sweep.

4. 1. A method comprising: generating vibrations including a frequency sweep in a wearable monitor coupled to a user's body; measuring a resonant frequency of the wearable monitor based on a response of the wearable monitor to the frequency sweep vibration; assessing the fit of the wearable monitor to the body based on a resonant frequency of the wearable monitor in response to the frequency sweep; providing adjustment information to a user to adjust the fit to a predetermined goal.

5. The method of claim 4 , wherein the predetermined goal comprises tension in a band that secures the wearable monitor to a user.

6. The method of claim 4 , wherein the predetermined target comprises a normal force of the wearable monitor against the user's skin.

7. The method of claim 4 , wherein causing the vibration includes energizing a tactile output element coupled to the wearable monitor.

8. The method of claim 4 , wherein assessing the fit includes calculating, with a processor on the wearable monitor, a level of mechanical coupling.

9. The method of claim 4 , wherein providing the user with adjustment information comprises presenting the adjustment information on a user interface of a computing device associated with the user.

10. The method of claim 4 , wherein the adjustment information indicates a level of tightness of the wearable monitor.

11. The method of claim 4 , wherein the adjustment information includes instructions for adjusting the wearable monitor around the body.

12. The method of claim 4 , wherein the response of the wearable monitor is a mechanical response.

13. The method of claim 12 , wherein the mechanical response is based at least in part on motion data received from one or more of an accelerometer and a gyroscope.

14. The method of claim 4 , wherein the response of the wearable monitor is an optical response.

15. The method of claim 14 , wherein the optical response is based at least in part on optical data received from one or more photodetectors.

16. The method of claim 4 , wherein the causing vibrations comprises energizing a linear tactile output element.

17. The method of claim 4 , wherein the wearable monitor is coupled to a user's wrist.

18. The method of claim 4 , wherein the wearable monitor is coupled to the body with clothing.

19. 1. A system comprising: a wearable monitor including a processor, at least one sensor, and a tactile output element; computer-executable code stored in a memory of the wearable monitor and configuring the processor to cause vibrations of the tactile output element, the vibrations comprising a frequency sweep, and to receive a response to the frequency sweep from the at least one sensor; a remote processing resource communicatively coupled to the wearable monitor; The remote processing resource includes a second memory that stores a physical model of the wearable monitor, and a second processor, the second processor being configured to receive a response to the vibration from the wearable monitor, calculate a level of mechanical coupling of the wearable monitor around the user's body based on the response, calculate a level of optical coupling of the wearable monitor around the body based on the response independent of the level of mechanical coupling, evaluate the fit of the wearable monitor to the user based on the level of optical coupling and the level of mechanical coupling, and communicate adjustment information to the user based on a difference between the fit and a predetermined target fit for the wearable monitor.

20. 20. The system of claim 19, wherein the predetermined target fit comprises at least one of a minimum tension, a maximum tension, and a range of tension.

21. 20. The system of claim 19, wherein the predetermined target fit comprises at least one of a minimum threshold, a maximum threshold, and a range.

22. 20. The system of claim 19, wherein the level of optical coupling is calculated separately from the level of mechanical coupling.

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