Footwear-Based Body Presence Detector

Abstract

Active footwear can include a system for automatically detecting the presence or absence of a foot. In one example, the system can be configured to provide information about the liquid saturation level, which can affect the sensitivity or performance of the foot presence sensor. The system can use time-multiplexed signals to excite different electrodes within the foot presence sensor, which can generate respective electric fields within the footwear. Disruptions in the fields can be detected and used to determine the presence or absence of a foot and the liquid saturation level.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of and claims the benefit of priority to U.S. Provisional Application No. 63 / 388,900, filed July 13, 2022, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] A variety of shoe-based sensors have been proposed to monitor various conditions. For example, Brown provides several examples of shoe-based sensors in U.S. Patent No. 5,929,332, entitled "Sensor Shoe for Monitoring Foot Conditions." Brown states that a foot force sensor can include an insole made of a relatively thin, planar, flexible, and resilient layer of dielectric material. The foot force sensor can include a conductive interconnection means that can have an electrical resistance that changes based on the applied compressive force.

[0003] Brown further discusses a shoe worn by diabetics and those suffering from various types of foot ailments who are prone to ulcers when excessive pressure is applied to parts of the foot. The shoe body can include a force-sensing resistor (FSR), and a switching circuit coupled to the resistor can activate an alarm unit that alerts the wearer that a threshold pressure level has been reached or exceeded.

[0004] Devices for automatically tightening an article of footwear have been proposed previously. In U.S. Pat. No. 6,691,433, "Automatic Tightening Shoe," Liu provides a first fastener attached to the upper of the shoe and a second fastener connected to a closure member that can releasably engage the first fastener to hold the closure member in a tightened state. Liu teaches a drive unit attached to the heel portion of the sole of the shoe. The drive unit includes a housing, a spool rotatably mounted within the housing, a pair of drawstrings, and a motor unit. Each string has a first end connected to the spool and a second end corresponding to a string hole in the second fastener. The motor unit is coupled to the spool. Liu teaches that the motor unit is operable to drive the rotation of the spool within the housing to wind the drawstring around the spool and pull the second fastener toward the first fastener. Liu also teaches a guide tube unit through which the drawstrings can be threaded. [Brief explanation of the drawings]

[0005] To easily identify the description of a particular element or act, the most significant digit(s) of a reference number refers to the figure number in which that element is first introduced. [Figure 1] 1A-1C are schematic illustrations of examples of various components of an active article of footwear. [Figure 2A] 1 illustrates a schematic representation of a sensor system and an electric lacing engine for footwear. [Figure 2B] 1 illustrates a schematic representation of a sensor system and an electric lacing engine for footwear. [Figure 2C] 1 illustrates a schematic representation of a sensor system and an electric lacing engine for footwear. [Figure 3] 1 illustrates a schematic diagram of an example of components of a powered lacing system. [Figure 4A] 1 shows a schematic diagram of a body presence sensor in the midsole portion of an active article of footwear. [Figure 4B] 1 shows a schematic diagram of a body presence sensor in the midsole portion of an active article of footwear. [Figure 5A] 1 illustrates a schematic diagram of an example of a capacitive sensor system. [Figure 5B] 3A and 3B show schematic examples of electric fields generated by a first capacitive sensor system; [Figure 5C] 4A and 4B show schematic examples of electric fields generated by a second capacitive sensor system; [Figure 6] 1 shows a schematic diagram of an example of a first composite electrode assembly. [Figure 7] 10 shows a schematic diagram of an example of a second composite electrode assembly. [Figure 8] 10A and 10B are schematic diagrams illustrating an example of a chart showing capacitance indicative signals over time for different electrode combinations in a capacitive sensor system; [Figure 9] 1 illustrates generally an example method that includes determining a body proximity indication using a body presence sensor. [Figure 10] 1 illustrates generally one example of a method that includes providing near-body indication using a multiple electrode assembly. [Figure 11] 10 is a schematic illustration of an example chart showing a body position indication signal for various dynamically variable thresholds; [Figure 12] 1 illustrates a schematic diagram of an example method that includes determining footwear use characteristics based on sensor signals indicative of body position. [Figure 13] 1 illustrates generally one example of a method that includes modifying one or more thresholds for determining a footwear condition or footwear use characteristic. [Figure 14] FIG. 1 is a block diagram illustrating an example of a computing device capable of implementing aspects of the various techniques described herein. DETAILED DESCRIPTION OF THE INVENTION

[0006] The concept of self-tightening shoelaces was first popularized by the fictional powered Nike® sneakers worn by Marty McFly in the 1989 film Back to the Future II. Nike® has since released various versions of powered lace-up sneakers similar in appearance to the Back to the Future II film prop version, but the internal mechanical systems and surrounding footwear platforms employed are not necessarily suitable for mass production or everyday use. Furthermore, previous designs of powered shoelacing systems have relatively suffered from issues such as high manufacturing costs, complexity, assembly challenges, lack of maintainability, and weak or fragile mechanical mechanisms. The inventors have developed a modular footwear platform that accommodates powered and non-powered shoelacing engines, which, among other things, solves some or all of the problems discussed above. The components described below offer various advantages, including, but not limited to, maintainable components, replaceable automatic shoelacing engines, robust mechanical designs, robust control algorithms, reliable operation, streamlined assembly processes, and retail-level customization.

[0007] In one example, a modular automatic lacing footwear platform includes a midsole plate secured to the midsole of an article of footwear for receiving a lacing engine. The design of the midsole plate allows for the lacing engine to be added to the footwear platform at the point of purchase. Other aspects of the midsole plate and modular automatic footwear platform allow for different types of lacing engines to be interchangeable. For example, the electric lacing engine described below can be replaced with a human-powered lacing engine. Alternatively, a fully automatic electric lacing engine with foot presence sensing and other features can be incorporated into a standard midsole plate.

[0008] The automated footwear platforms discussed herein may include an outsole actuator interface to provide lacing control to the end user as well as visual feedback, for example, using LED lighting projected through a translucent protective outsole material. The actuator may provide tactile and visual feedback to the user to indicate the status of the lacing engine or other automated footwear platform components.

[0009] In one example, the footwear platform includes a foot presence sensor configured to detect the presence of a foot within the shoe and to detect the absolute or relative position of the foot, or a particular portion of the foot or ankle, within the shoe. Upon detection of the foot, one or more footwear functions or processes may be initiated, e.g., automatically, without further user input or command. For example, upon detecting that the foot is properly seated in the footwear relative to the insole, the control circuitry may automatically initiate lace tightening, data collection, footwear diagnostics, or other processes.

[0010] Premature activation or initiation of an automatic shoelacing mechanism or footwear tightening mechanism can inhibit or prevent a user from inserting their foot or donning the footwear. For example, if the shoelacing engine is activated before the foot is fully secured in the insole, the user may have difficulty inserting the rest of their foot into the footwear or may have to manually adjust the tension of the shoelaces. Accordingly, the inventors have recognized that the problem to be solved includes determining whether the foot is properly or completely seated within the article of footwear, such as whether the toe, midsole (i.e., arch), and heel portions are properly aligned with corresponding portions of the insole or footwear interior cavity. The inventors have further recognized that the problem includes accurately determining foot position or foot orientation using as few sensors as possible to reduce sensor and assembly costs and reduce device complexity.

[0011] Solutions to these problems include providing or using a foot presence sensor. In one example, the sensor is configured to generate one or more electric fields and sense changes or interruptions in the electric fields. The change in the electric field or change in capacitance is recognized when the foot moves in and out of the footwear, such as when a portion of the foot is farther from the sensor than another portion of the foot. In one example, the sensor is integrated with or incorporated within the lacing engine enclosure. In one example, at least a portion of the sensor is provided outside the lacing engine closure and includes one or more conductive interconnects to power storage or processing circuitry within the closure.

[0012] Sensors suitable for use in foot presence detection can have a variety of configurations. For example, a sensor can include a plate capacitor configured such that at least one plate moves relative to another plate in response to pressure or changes in pressure applied to one or more plates. In one example, a sensor can include multiple conductive traces arranged in a plane substantially parallel to or coincident with a foot-facing surface of the footwear, such as the upper surface of an insole, the lower surface of a tongue, or the inner surface of the upper part of the footwear. Such traces can be laterally separated by air gaps (or other insulating material, such as a circuit board) and can be selectively or cyclically driven by an electrical drive signal provided by an excitation circuit. In one example, the electrodes can include interleaved conductive traces, a comb-like configuration, a concentric ring or coaxial configuration, or other configuration. The sensor can provide a time-varying signal, for example, based on the relative movement of the electrodes themselves and / or based on interference of an electric field near the electrodes due to the presence, absence, or movement of a foot, footwear, or other object.

[0013] In one example, the foot presence sensor provides an analog electrical output signal indicative of the magnitude of capacitance or change in capacitance detected by the sensor. The output signal can have a first value (e.g., corresponding to a low capacitance) when a foot is present near the sensor and a different second value (e.g., corresponding to a high capacitance) when a foot is not present.

[0014] In one example, the foot presence sensor signal can provide information other than foot presence or foot position information. For example, there may be detectable fluctuations in the sensor signal that correlate to a user sit / stand event, or other user posture change event, step event, or other event. Additionally, there may be detectable long-term drift in the signal that indicates wear and / or remaining life of shoe components, such as insoles, orthotics, or other components.

[0015] In one example, the foot presence sensor includes or is coupled to an analog-to-digital (e.g., signal-to-digital indicative of the capacitance) converter circuit configured to provide a digital signal indicative of the magnitude of the capacitance sensed by the sensor. In one example, the sensor includes or is coupled to a local or remote processor circuit configured to provide an interrupt or logic signal indicative of whether the sensed value meets a specified threshold condition. In one example, the sensor measures the capacitance characteristics against a baseline or reference capacitance value, and the baseline or reference can be updated or adjusted to accommodate changes in the environment or other changes that may affect the sensed capacitance value.

[0016] In one example, the foot presence sensor is provided under the foot near the arch or heel region of the shoe insole. The sensor can be provided elsewhere, such as in the ankle region, the tongue region of the footwear, or other regions of the shoe. The sensor can be substantially planar or flat. In one example, the sensor can be rigid or flexible and configured to conform to the contours of the foot or footbed. In some cases, an air gap having a relatively low dielectric constant or low relative permittivity can be provided between a portion of the sensor and the foot when the shoe is worn. A gap filler having a relatively high dielectric constant or a relative permittivity greater than that of air can be provided on the capacitive sensor to fill the air gap between the sensor and the surface of the foot. The gap filler can be compressible or non-compressible. In one example, the gap filler is selected to provide a suitable compromise between dielectric value and suitability for use in footwear to provide the sensor with suitable sensitivity and underfoot comfort.

[0017] The following describes various components of the automated footwear platform, including the powered lacing engine, foot presence sensor, midsole plate, and various other components of the platform. While much of this disclosure focuses on foot presence sensing as a trigger for the powered lacing engine, many aspects of the discussed design are also applicable to other circuits and features that can interface with the foot presence sensor, such as to automate the human-powered lacing engine or other footwear functions, such as data collection, physiological monitoring, or as input or output to a virtual environment or metaverse. The term "automatic," as used in "automated footwear platform," is not intended to cover only systems that operate without specific user input. Rather, the term "automated footwear platform" includes various mechanisms, both powered and human-powered, self-activated and human-activated, for tightening footwear laces or retention systems or controlling other aspects of the active footwear and its functionally coupled components. In one example, the automated footwear platform is configured to interface with one or more digital worlds, for example, by providing a tangible interface to a user's digital avatar.

[0018] FIG. 1 schematically illustrates an exploded view of components of an active footwear article according to one embodiment. The example of FIG. 1 includes a powered lacing system 100 with a lacing engine 110, a lid 120, an actuator 130, a midsole plate 140, a footwear midsole 155, and an outsole 165. The lacing engine 110 may include a user-replaceable component within the system 100 and may include or be coupled to one or more foot presence sensors. In one example, the lacing engine 110 includes or is coupled to a capacitive foot presence sensor. The capacitive foot presence sensor may include multiple electrodes, although not shown in the example of FIG. 1 . The electrodes may be provided on or around the footwear article in various configurations. In one example, one or more electrodes may be provided on a foot-facing side of the lacing engine 110. In one example, the electrodes of the capacitive foot presence sensor may be contained within the lacing engine 110, may be integrated into the housing of the lacing engine 110, or may be located elsewhere near the lacing engine 110 and coupled to a power source or processing circuitry within the lacing engine 110 using one or more electrical conductors.

[0019] In one example, powered lacing system 100 can be assembled by fastening midsole plate 140 to midsole 155. Actuator 130 can then be inserted into an opening in a side of midsole plate 140, such as opposite an interface button that can be embedded in outsole 165. Lacing engine 110 can then be inserted into midsole plate 140. In one example, lacing engine 110 can be coupled to one or more sensors located elsewhere on the footwear. Other assembly methods can similarly be performed to construct powered lacing system 100. The assembly methods described are provided by way of example and not limitation, as alternative methods are contemplated.

[0020] In one example, lacing system 100 is inserted with a continuous loop of lacing cable, and the lacing cable is aligned with a spool in lacing engine 110. To complete assembly, lid 120 can be inserted into a receiving means in midsole plate 140, secured in a closed position, and latched into a recess in midsole plate 140. Lid 120 can capture lacing engine 110 and, in one example, can help maintain alignment of the lacing cable during operation.

[0021] Midsole plate 140 includes lacing engine cavity 141, medial and lateral lace guides 142, a front flange 143, a rear flange 144, an upper (top) surface and a lower (bottom) surface, and an actuator notch 145. Lacing engine cavity 141 is configured to receive lacing engine 110. In this example, lacing engine cavity 141 retains lacing engine 110 laterally and fore-aft, but does not include features for locking lacing engine 110 within cavity 141. Optionally, lacing engine cavity 141 includes detents, tabs, or other mechanical features along one or more side walls to securely retain lacing engine 110 within lacing engine cavity 141.

[0022] The lace guide 142 can help guide the lacing cable into position with the lacing engine 110. The lace guide 142 can include chamfered edges and downwardly sloped surfaces to help guide the lace or lacing cable into a desired position relative to the lacing engine 110. In this example, the lace guide 142 includes an opening in the side of the midsole plate 140 that is many times wider than the diameter of a typical lacing cable, although other dimensions can be used.

[0023] In the example of FIG. 1 , the midsole plate 140 includes a sculpted or contoured forward flange 143 that extends further medially of the midsole plate 140. The illustrative forward flange 143 is designed to provide additional support under the arch of the footwear platform. However, in other examples, the forward flange 143 may be less pronounced on the medial side. In this example, the rear flange 144 includes a contour with extensions on both the medial and lateral sides. The illustrated rear flange 144 can improve the lateral stability of the lacing engine 110.

[0024] In one example, one or more electrodes may be embedded in or disposed on the midsole plate 140 and may form part of a foot presence sensor, such as part of a capacitive foot presence sensor. In one example, the lacing engine 110 includes a sensor circuit electrically coupled to one or more electrodes on the midsole plate 140. The sensor circuit may be configured to use electric field or capacitance information sensed from the electrodes to determine whether a foot is present in an area adjacent to the midsole plate 140. That is, the sensor may be configured to sense information regarding the presence or absence of a foot in a foot-receiving cavity or space within the article of footwear. In one example, the electrodes extend from the forward-most end of the front flange 143 to the rearward-most end of the rear flange 144, while in other examples, the electrodes extend over a portion of one or both of the flanges.

[0025] In one example, footwear or powered lacing system 100 includes or interfaces with one or more sensors capable of monitoring or determining the presence of a foot within the footwear, the absence of a foot from the footwear, or positional characteristics of a foot within the footwear. Based on information from one or more such foot presence sensors, footwear including powered lacing system 100 can be configured to perform various functions. For example, the foot presence sensor can be configured to provide binary information regarding the presence or absence of a foot within the footwear. In one example, a processor circuit coupled to the foot presence sensor receives and interprets digital or analog signal information to provide binary information regarding the presence or absence of a foot within the footwear. If the binary signal from the foot presence sensor indicates the presence of a foot, lacing engine 110 of powered lacing system 100 can be activated to automatically increase or decrease tension in lacing cables or other footwear tightening means to tighten or loosen the footwear around the foot. In one example, lacing engine 110, or other portions of the footwear article, includes a processor circuit capable of receiving or interpreting signals from the foot presence sensor and initiating various responsive actions.

[0026] In one example, the foot presence sensor can be configured to provide information regarding the position of the foot entering the footwear. The powered lacing system 100 can generally be activated, such as to tighten the lacing cables, only when the foot is properly positioned or planted within the footwear against all or a portion of the insole. A foot presence sensor that senses information regarding the movement or position of the foot can provide information regarding whether the foot is fully or partially seated against the insole or other feature of the article of footwear. The automatic lacing procedure can be paused or delayed until information from the sensor indicates the foot is properly positioned.

[0027] In one example, a foot presence sensor can be configured to provide information regarding the absolute or relative position of a foot within footwear. For example, the foot presence sensor can be configured to sense whether the footwear properly "fits" a particular foot, such as by determining the relative position of one or more of the foot's arch, heel, toe, or other components relative to a corresponding portion of the footwear configured to receive such foot components. In one example, the foot presence sensor can be configured to sense whether the position of the foot or foot components changes over time relative to a specified or previously recorded reference position, such as due to slackening of lacing cables over time or the natural expansion and contraction of the foot itself.

[0028] In one example, the foot presence sensor may include an electrical, magnetic, thermal, capacitance, pressure, optical, or other sensor device configured to sense or receive information about the presence or proximity of a body. For example, the electrical sensor may include an impedance sensor configured to measure impedance characteristics between at least two electrodes. When a body, such as a foot, is located near or adjacent to the electrodes, the electrical sensor may provide a sensor signal having a first value, and when the body is located away from the electrodes, the electrical sensor may provide a sensor signal having a different second value. For example, the first impedance value may be associated with an empty footwear state, and a second, smaller, impedance value may be associated with a worn footwear state.

[0029] In one example, the foot presence sensor may include an AC signal generator circuit and an antenna configured to emit or receive radio frequency signal information, including wireless frequency information. Based on the proximity of an object to the antenna, one or more electrical signal characteristics, such as impedance, wireless frequency, or signal amplitude, may be received and analyzed to determine whether an object is present. In one example, a received signal strength indicator (RSSI) provides information regarding the power level of the received wireless signal. A change in RSSI compared to some baseline or reference value may be used to identify the presence or absence of an object. In one example, WiFi frequencies may be used in one or more of the 2.4 GHz, 3.6 GHz, 4.9 GHz, 5 GHz, and 5.9 GHz bands, for example. In one example, frequencies in the kilohertz range, for example, approximately 400 kHz, may be used. In one example, changes in the power signal may be detected in the milliwatt or microwatt range.

[0030] Any of multiple different types of foot presence sensors (e.g., sensors configured to measure capacitance, impedance, magnetic field, temperature, light, pressure, etc.) can be used independently, or information from two or more different sensors or sensor types can be used together to provide detailed information regarding the presence, absence, orientation, compatibility with footwear, or other information regarding the foot and / or its relationship to the footwear.

[0031] 2A-2C schematically illustrate a sensor system and a powered lacing engine according to some illustrative embodiments. FIG. 2A illustrates various features of an example lacing engine 110, including a housing structure 150, a case screw 108, a lace channel 112 (also referred to as a lace guide relief 112), a lace channel transition 114, a spool recess 115, a button opening 122, a button 121, a button membrane seal 124, a programming header 128, a spool 131, and a lacing groove 132 in the spool 131. Other designs may be used as well. For example, other switch types, such as a sealed dome switch, may be used, or the membrane seal 124 may be omitted. In one example, the lacing engine 110 may include one or more interconnects or electrical contacts for connecting the lacing engine's internal circuitry with circuitry external to the lacing engine 110 (e.g., an external foot presence sensor or component thereof, an external actuator such as a switch or button, or other device or component).

[0032] The lacing engine 110 may be held together by one or more screws, such as case screws 108. The case screws 108 may be located near the main drive mechanism to increase the structural integrity of the lacing engine 110. The case screws 108 also function to hold the housing structure 150 together and aid in the assembly process, such as ultrasonically welding external seams.

[0033] In the example of FIG. 2A , the lacing engine 110 includes a lace channel 112 for receiving a shoelace or lacing cable when the engine is assembled to an automated footwear platform. The lace channel 112 may include channel walls with chamfered edges to provide a smooth guide surface through which the lacing cable can travel during operation. A portion of the smooth guide surface of the lace channel 112 may include a channel transition 114, which is a widened portion of the lace channel 112 that leads to a spool recess 115. The spool recess 115 transitions from the channel transition 114 to a generally circular section that closely matches the contours of the spool 131. The spool recess 115 not only holds the spool 131 in place, but can also serve to retain the spooled lace cable. Other aspects of the design may provide other means for retaining the spool 131. In the example of FIG. 2A, spool 131 is shaped similarly to half of a yo-yo, with raceways 132 running through a flat top surface and a spool shaft (not shown in FIG. 2A) extending downward from the opposite side.

[0034] The side of lacing engine 110 includes a button opening 122 that accommodates a button 121, which may be configured to activate or adjust one or more features of the automated footwear platform. Button 121 may provide an external interface for activating various switches included in lacing engine 110. In some examples, housing structure 150 includes a button membrane seal 124 that provides protection from dirt and water. In this example, button membrane seal 124 is a clear plastic (or similar material) up to a few mils (thousandths of an inch) thick and may be glued from the top surface of housing structure 150, for example, over the corners and along the sides. In another example, button membrane seal 124 is an approximately 2-mil thick vinyl adhesive-backed membrane that covers button 121 and button opening 122. Other types of buttons and sealants may be used as well.

[0035] 2B is a diagram of a housing structure 150 including an upper section 102 and a lower section 104. In this example, the upper section 102 includes features such as a recess for receiving the case screw 108, a lace channel 112, a lace channel transition 114, a spool recess 115, a button opening 122, and a button seal recess 126. In one example, the button seal recess 126 is a portion of the upper section 102 that is opened up to provide an inset for the button membrane seal 124.

[0036] 2B, bottom section 104 includes features such as wireless charger access 105, joint 106, and grease isolation wall 109. Also shown, although not specifically shown, are case screw bases for receiving case screws 108 and various features within grease isolation wall 109 for retaining portions of the drive mechanism. Grease isolation wall 109 is designed to keep grease or similar compounds surrounding the drive mechanism away from various electrical components of lacing engine 110.

[0037] The housing structure 150 can include one or more electrodes 170 in one or both of the top section 102 and the bottom section 104, embedded in or applied to the structure surface. In the example of FIG. 2B , the electrode 170 is shown coupled to the bottom section 104. In one example, the electrode 170 forms part of a capacitance-based foot presence sensor circuit (see, for example, the body presence sensor 302 described herein). Although shown as complementary and alternating conductors, the electrodes 170 can have various shapes, sizes, or orientations, as described in further detail herein. Additionally or alternatively, one or more of the electrodes 170 can be coupled to the top section and the bottom section 102. Electrodes 170 coupled to the top and / or bottom sections 102 or 104 can be used for wireless power transfer and / or as part of a capacitance-based foot presence sensor circuit. In one example, the electrode 170 includes one or more portions disposed on an outer surface of the housing structure 150, and in another example, the electrode 170 includes one or more portions disposed on an inner surface of the housing structure 150.

[0038] FIG. 2C illustrates various internal components of a racing engine 110 according to one embodiment. In this example, the lacing engine 110 includes a spool magnet 136, an O-ring seal 138, a worm drive 140, a bushing 141, a worm drive key, a gearbox 148, a gear motor 145, a motor encoder 146, a motor circuit board 147, a worm gear 151, a circuit board 160, a motor header 161, a battery connection 162, and a wired charging header 163. The spool magnet 136 serves to track the movement of the spool 131, for example, through detection by a magnetometer (not shown in FIG. 2C). The O-ring seal 138 blocks dirt and moisture that may enter the lacing engine 110 around the spool shaft. The circuit board 160 may include one or more interfaces or interconnects for a foot presence sensor or one or more other sensors. In one example, the circuit board 160 includes one or more traces or conductive planes that provide part of the foot presence sensor.

[0039] In the illustrated example, the primary drive components of the racing engine 110 include the worm drive 140, worm gear 151, gear motor 145, and gearbox 148. The worm gear 151 is designed to prevent reverse driving of the worm drive 140 and gear motor 145, meaning that the primary input force from the lacing cable via the spool 131 can be resolved over the relatively large worm gear and worm drive teeth. This arrangement eliminates the need for the gearbox 148 to incorporate gears strong enough to withstand both the dynamic loads from active use of the footwear platform and the clamping loads from tightening the lacing system. The worm drive 140 includes additional features to help protect various sensitive parts of the drive system, such as a worm drive key. In this example, the worm drive key is a radial slot on the motor end of the worm drive 140 that interfaces with a pin that runs through the drive shaft exiting the gearbox 148. This arrangement allows the worm drive 140 to move freely axially (away from the gearbox 148) and transfers those axial loads to the bushing 141 and housing structure 150, thereby preventing the worm drive 140 from applying excessive axial forces to the gearbox 148 or gear motor 145.

[0040] 3 shows a schematic block diagram of components of a powered lacing system 300 according to one embodiment. System 300 includes some (but not necessarily all) components of a powered lacing system, such as a housing structure 150 enclosing a printed circuit board assembly (PCBA) with an interface button 301, a body presence sensor 302, a processor circuit 320, a battery 321, a charging coil 322, an encoder 325, a motion sensor 324, and a drive mechanism 340. Drive mechanism 340 may include a motor 341, a transmission 342, and a lace spool 343. Motion sensor 324 may include, among other things, a single-axis or multi-axis accelerometer, magnetometer, gyrometer, or other sensor or device configured to sense movement of housing structure 150 or one or more components within or coupled to housing structure 150.

[0041] 3, processor circuitry 320 (sometimes referred to herein as control circuitry or controller) is in data or power signal communication with one or more of interface button 301, body presence sensor 302, battery 321, charger coil 322, and drive mechanism 340. Transmission 342 couples motor 341 to spool 343 to form drive mechanism 340. As shown in the example of FIG. 3, button 301, body presence sensor 302, and environmental sensor 350 may be located outside or partially outside housing structure 150.

[0042] In alternative embodiments, one or more of button 301, body presence sensor 302, and environmental sensor 350 may be housed within housing structure 150. In one example, body presence sensor 302 is located inside housing structure 150 to protect the sensor from sweat, dirt, and debris. Minimizing or eliminating connections through the walls of housing structure 150 can help increase the durability and reliability of the assembly.

[0043] In this example, processor circuit 320 controls one or more aspects of drive mechanism 340. For example, processor circuit 320 can be configured to receive information from button 301, and / or from body presence sensor 302, and / or from motion sensor 324, and in response control drive mechanism 340 to tighten or loosen the footwear around the foot. In one example, processor circuit 320 is additionally or alternatively configured to issue commands to acquire or record sensor information from body presence sensor 302 or other sensors, among other functions. In one example, processor circuit 320 conditions the operation of drive mechanism 340 based on one or more of detecting the presence of a foot using body presence sensor 302, detecting the orientation or position of the foot using body presence sensor 302, or detecting a specified gesture using motion sensor 324.

[0044] In one example, system 300 includes an environmental sensor 350. Information from environmental sensor 350 can be used to update or adjust the baseline or reference value of body presence sensor 302. For example, body presence sensor 302 can include a capacitance sensor, and the capacitance values ​​measured by the capacitive foot presence sensor can change over time, such as in response to ambient conditions near the sensor. Thus, using information from environmental sensor 350, processor circuit 320 and / or body presence sensor 302 can be configured to update or adjust the measured or sensed capacitance values.

[0045] In one example, the body presence sensor 302 can be disabled by the processor circuit 320 under various conditions, or the signal from the body presence sensor 302 can be ignored. For example, if the drive mechanism 340 is activated and actively winding or unwinding, the processor circuit 320 can be configured to ignore an interrupt or other signal from the body presence sensor 302. In one example, if the footwear is being charged, such as using the charging coil 322 or wired charging header 163, the processor circuit 320 can be configured to ignore an interrupt or other signal from the body presence sensor 302.

[0046] 4A and 4B show schematic diagrams of a body presence sensor, such as a capacitance-based foot presence sensor, used in the midsole of an article of footwear, according to an exemplary embodiment. The body presence sensor can be located below the surface of an object, such as a foot, or body 402 when an article incorporating the sensor is being worn.

[0047] 4A , the body presence sensor can include a first electrode assembly 406 coupled to a control circuit 404. In one example, the control circuit 404 includes the processor circuit 320. In the example of FIG. 4A , the first electrode assembly 406 and / or the control circuit 404 can be included within, mounted within, or coupled to a PCBA within a housing 410, which can comprise the housing structure 150. In one example, the first electrode assembly 406 can be disposed on or adjacent to a foot-facing surface of the housing 410. In one example, the first electrode assembly 406 includes a plurality of conductors or traces distributed across an interior top surface area of ​​the housing 410.

[0048] 4B , the body presence sensor can include a second electrical assembly 414 coupled to the control circuitry 404. The second electrode assembly 414 can be mounted on or near an exterior portion of the housing 410 and can be electrically coupled to a PCBA on the interior of the housing 410, such as using a flexible connector 416. In this example, the second electrical assembly 414 can be positioned on or adjacent to a foot-facing surface of the housing 410. In one example, the second electrode assembly 414 includes a flexible circuit that is affixed to an interior or exterior surface of the housing 410 and coupled to the control circuitry 404 using one or more conductors.

[0049] In this example, the control circuitry 404 includes a general-purpose or special-purpose processor. The control circuitry 404 can be configured to, among other things, provide alternating current drive signals to selected pairs of the plurality of electrodes, including the first electrode assembly 406 or the second electrode assembly 414. In response to the alternating current drive signals, the control circuitry 404 can sense information regarding changes in the electric field at or near the electrode assemblies based on corresponding changes in the proximity of the object or body 402 to the electrodes, as described below.

[0050] Various materials can be provided between the body 402 and an electrode assembly, such as the first electrode assembly 406 or the second electrode assembly 414. For example, electrode insulators, housing 410 material, insole material, dielectric insert 412, socks or other foot coverings, body tape, kinesiology tape, or other materials can be interposed between the body 402 and one or more electrodes to change the dielectric properties of the footwear and thereby affect the detection sensitivity of the body sensor. The control circuitry 404 can be configured to update or adjust the excitation signal or sensing parameters based on the number or type of intervening materials to increase the sensitivity or signal-to-noise ratio of the sensor.

[0051] In the example of FIG. 4A or 4B , the first electrode assembly 406 or the second electrode assembly 414 can be excited by a signal generator in the control circuit 404, resulting in an electric field that at least partially projects from the foot side of the electrode assembly. In one example, the electric field beneath the electrode assembly can be at least partially blocked using a drive shield disposed beneath the sense electrode. The drive shield and the electrode assembly can be electrically isolated from each other. For example, if the first electrode assembly 406 is on one surface of the PCBA, the drive shield can be disposed on the bottom layer of the PCBA or on one of multiple inner layers on a multi-layer PCBA. In one example, the drive shield can be equal to or larger than the surface area of ​​the electrodes that make up the first electrode assembly 406 or the second electrode assembly 414, and in some examples, can be centered directly beneath the electrode assembly.

[0052] In one example, the drive shield can receive a drive signal (e.g., from the control circuit 404) and generate an electric field in response thereto. The field generated by the drive shield can have substantially the same polarity, phase, and / or amplitude as the field generated by the first electrode assembly 406 or the second electrode assembly 414. The electric field from the drive shield can repel the electric fields of the other electrode assemblies, thereby isolating the sensor field from various parasitic effects, such as undesired coupling to the PCBA's ground plane. The field generated by the drive shield can help focus detection toward a specific area, reduce environmental effects, and reduce the effects of parasitic capacitance. In one example, including a drive shield can help mitigate the effects of temperature changes on the sensor assembly. Temperature can affect parasitic offset characteristics; for example, temperature changes can change parasitic ground plane capacitance. Using a shield, such as inserting a shield between the sensor electrode and ground, can help mitigate the effects of parasitic ground plane capacitance on sensor measurements.

[0053] In one example, a preferred location for placing the housing 410 is within the arch region of the footwear because it is an area less likely to cause discomfort or discomfort to the wearer. One advantage of using capacitive sensing to detect the presence of a foot in footwear is that the sensor is placed in the arch region and can perform well even if the user's foot has a relatively or abnormally high arch. For example, the amplitude or morphology characteristics of the sensor drive signal can be modified or selected based on the desired signal-to-noise ratio of the signal received from the capacitive sensor. In one example, the sensor drive signal can be updated or adjusted each time the footwear is used, thereby responding to, for example, changes in one or more materials (e.g., socks, insoles, etc.) positioned between the body 402 and the body sensor electrode assembly.

[0054] In one example, an electrode assembly of a capacitive sensor, such as first electrode assembly 406 or second electrode assembly 414, can include multiple different electrodes that can be selectively coupled or separated to form various electrode pairs that can be separately driven or used as sensors. For example, different pairs can be configured to sense respective signals, and differences between the signals can be used to determine various characteristics of the foot or footwear. In one example, the electrodes that make up different electrode pairs can be oriented along different axes or can be generally concentric or adjacent electrodes.

[0055] 5A schematically illustrates a capacitive sensor system 500 for detecting the presence of a body or foot, according to one embodiment. The example capacitive sensor system 500 includes a body 402 (e.g., representing a foot in or near an active footwear item) and a first electrode 514 and a second electrode 516. In one example, the first electrode 514 and / or the second electrode 516 may include the first electrode assembly 406 or the second electrode assembly 414, or another assembly of the body presence sensor 302. Each electrode may include a plate, trace, or other conductor including a conductive material such as copper, carbon, silver, or a conductive foil. In one example, any conductive material may be used for the electrodes, including a conductive film, ink, deposited metal, or other material.

[0056] While the first electrode 514 and the second electrode 516 are shown as being vertically spaced apart from one another (and relative to the body 402) in the example of FIG. 5A , the electrodes can similarly be horizontally spaced apart or offset or spaced apart. In one example, the electrodes can be positioned in a plane generally parallel to the underside of the body 402 to be sensed. That is, at least a portion of the electrodes can include a surface that is parallel to a corresponding underside or surface of the body 402. In some examples, the electrodes can be contoured or shaped to correspond to, for example, a curved or arched region of the foot. In the example of FIG. 5A , the first electrode 514 is configured as a drive or transmit electrode and is coupled to a signal generator that provides an excitation signal 518. In one example, the signal generator forms part of the control circuitry 404.

[0057] As a result of exciting the electrodes using excitation signal 518, an electric field 526 may be generated primarily between first electrode 514 and second electrode 516. That is, various components of the generated electric field 526 may extend between the electrodes, and other fringe components of the generated electric field 526 may extend in other directions. For example, fringe components may extend from the transmitting or first electrode 514 away from the housing 410 (not shown in the example of FIG. 5A ) and terminate at the receiving or second electrode 516 or elsewhere.

[0058] Information regarding the electric field 526, including information regarding changes or interruptions in the field due to the proximity of the body 402, can be sensed or received, for example, using the second electrode 516. The signal sensed from the second electrode 516 can be processed using various circuitry (e.g., using the control circuit 404) and used to provide an analog or digital signal indicative of the presence or absence of the body 402.

[0059] For example, the field strength of the electric field 526 detected by the second electrode 516 can be measured using a sigma-delta analog-to-digital converter circuit 520 (ADC). The ADC can be configured to convert the analog capacitance representative signal to a digital signal. In one example, when an object, such as the body 402, enters the electric field 526 and its fringe components, the electrical environment near the electrodes changes. When the body 402 enters the field, a portion of the electric field 526 is diverted (e.g., grounded or absorbed) instead of being received and terminated at the second electrode 516, or passes through the body 402 before being received by the second electrode 516 (e.g., instead of passing through the air). This interruption of the electric field causes a change in capacitance that is detected by a sensor using the first electrode 514 and the second electrode 516.

[0060] In one example, the second electrode 516 can receive the electric field information substantially continuously, which can be sampled continuously or periodically by an analog-to-digital converter circuit 520. The information from the analog-to-digital converter circuit 520 can be processed using a filter circuit 522, such as by introducing an offset or calibration factor. The system can then provide a digital output signal 524. In one example, the filter circuit 522 can introduce a specified or programmable (e.g., internal to the control circuit 404) capacitance offset or can be based on a separate capacitor used to track changes in the environment over time, temperature, and other variable characteristics of the environment.

[0061] In one example, the digital output signal 524 may include binary information that determines the presence, absence, or location of the body 402, such as by comparing the measurements to specified thresholds. In one example, the digital output signal 524 may include qualitative information regarding the measured capacitance, which may be used (e.g., by the control circuitry 404) to indicate the likely presence or absence of the body 402.

[0062] Periodically, or when the body presence sensor 302 is inactive (e.g., as determined using information from the motion sensor 324), a value indicative of capacitance may be measured and stored as a reference, baseline, or ambient value. As a foot or body (e.g., body 402) approaches the body presence sensor 302 and its electrodes, the measured capacitance may decrease or increase, for example, relative to the stored reference value. In one example, one or more threshold capacitance levels may be stored, for example, in an on-chip register of the control circuit 404. When the measured capacitance value exceeds a specified threshold, it may be determined that the body 402 is present (or not) in the footwear including the body presence sensor 302.

[0063] The body presence sensor 302 and the various electrodes comprising the body presence sensor 302 can take a variety of different forms, as illustrated by the following non-limiting examples. In one example, the electrodes of the body presence sensor 302 can be arranged in a grid pattern. In an example where the body presence sensor 302 is a capacitance sensor, the sensor electrode grid can include a variable capacitor at each intersection of each row and each column of the grid. Optionally, the electrode grid includes electrodes arranged in one or more rows or columns. A voltage signal can be applied to the rows or columns, and an object or foot near the surface of the sensor can affect the local electric field and reduce mutual capacitance effects. In one example, changes in capacitance at multiple points on the grid can be measured to determine the position of the body relative to the grid or the position of the body relative to the footwear item, such as by measuring the voltage on each axis. As one example, mutual capacitance measurement techniques can provide information from multiple locations around the grid simultaneously.

[0064] As an example, mutual capacitance measurements use an orthogonal grid of transmitting and receiving electrodes. A sensor system based on such a grid can detect measurements for multiple distinct X-Y coordinate pairs. In one example, capacitance information from multiple capacitors can be used to determine the presence or orientation of a foot in footwear. In another example, capacitance information from one or more capacitors can be acquired over time and analyzed to determine the presence or orientation of a foot. In one example, rate-of-change information for the X and / or Y detection coordinates can be used to determine whether a foot is properly or fully seated or seated in a footwear insole.

[0065] In one example, a body presence sensor 302 including a foot presence sensor based on self-capacitance can have the same XY grid as a body presence sensor 302 including a mutual capacitance sensor, but the columns and rows can operate independently. The self-capacitance sensors can detect the capacitive loading of an object in each column or row individually.

[0066] 5B and 5C schematically illustrate examples of different electrode configurations that can comprise the body presence sensor 302. The figures show depictions of the electrostatic or electric fields generated from various electrode configurations. For each electrode pair or capacitor plate, the effective dielectric between the electrodes includes any air gap (or other material) disposed between the electrodes. For each electrode pair, any portion of the body or foot near it can be part of or affect the effective dielectric of that particular pair. That is, a variable dielectric can be provided between each electrode pair depending on the proximity of the object between each electrode pair and each electrode. For example, the closer the body or foot is to a particular electrode pair, the greater the effective dielectric value. As the value of the permittivity increases, the value of the capacitance also increases. This change in capacitance value can be received by the processor circuit 320 and used to indicate whether a body is present at or near the body presence sensor 302.

[0067] FIG. 5B illustrates a vertically stacked electrode configuration similar to that shown in the example of FIG. 5A. The example of FIG. 5B includes an upper electrode 502 and a lower electrode 504. When the upper electrode 502 and the lower electrode 504 are coupled to receive respective portions of an AC drive signal (e.g., including excitation signal 518), a first projected electric field 506 is provided. The first projected electric field 506 can include electric field lines or components that extend in three dimensions, including components that extend linearly or laterally between the upper electrode 502 and the lower electrode 504 as shown. Some electric field components can extend away from or around the edges of the electrodes, as illustrated by the lines extending to the left or right of the upper electrode 502 and the lower electrode 504. It is understood that some components extend into or out of the page to provide a three-dimensional field. The shape of first projected electric field 506 may be generally spherical or non-spherical, and may be contoured depending on, for example, the dimensions, positions, or orientations of various electrodes configured (e.g., passively or actively) to contribute to or selectively impede the electric field.

[0068] FIG. 5C illustrates a horizontally spaced electrode configuration. The example in FIG. 5C includes a left electrode 508 and a right electrode 510. When the left electrode 508 and the right electrode 510 are coupled to receive respective portions of an AC drive signal (e.g., including excitation signal 518), a second projected electric field 512 can be provided. The second projected electric field 512 can include field lines or components that extend in three dimensions, including components that extend linearly or laterally between the left electrode 508 and the right electrode 510 as shown. As discussed above, it is understood that some components extend into or off the page to provide a three-dimensional field.

[0069] In one example, a dielectric member, such as a dielectric insert 412, can be provided between the body 402 and one or more electrodes of the body presence sensor 302. The dielectric member can have a dielectric constant that is the same as or greater than that of air (e.g., k=1.0). The dielectric member can increase the sensitivity of the body presence sensor 302 to changes in the position or location of the body 402 by providing a conduit that helps selectively direct the generated electric field to specific regions. For example, the dielectric member can help focus the generated electric field in a central, foot-receiving portion of the footwear article.

[0070] In one example, the dielectric member can increase the sensitivity of the body presence sensor 302 by extending or pushing the electric field outward or laterally from the electrodes of the body presence sensor 302. While this change in sensitivity may be desirable in some circumstances, it may be undesirable if it increases the sensitivity of the body presence sensor 302 or other adjacent materials, such as conductive surfaces or liquids, on which the footwear item may be used. In other words, the increased sensitivity may be undesirable if it results in a false detection of body presence due to changes in the environment or factors other than, for example, the presence of a foot in the footwear item.

[0071] The inventors have recognized that a solution to the sensitivity or field location problem can include or use a body presence sensor 302 that includes three or more electrodes. The electrodes can be paired in various combinations and driven together, such as in a time-multiplexed manner, to more accurately detect body presence. The inventors have further recognized that this solution can help improve the sensor's resistance to drift due to sweating and other environmental influences. For example, using information about multiple fields together can help reduce the body presence sensor's 302 sensitivity to objects to the sides of the sensor and also help reduce its sensitivity to objects on the opposite side of the sensor's focal area (e.g., the interior of the footwear item).

[0072] The inventors have recognized that additional problems to be solved include, for example, obtaining adequate sensitivity or response of a capacitive foot presence sensor when all or part of the foot presence sensor is separated from the foot or body being sensed, for example, by an air gap or other intervening object. The inventors have recognized that a solution may involve using multiple electrodes of specific shapes, sizes, and orientations to enhance the direction and relative strength of the electric fields generated when the electrodes are energized. That is, the inventors have identified an optimal electrode configuration for use in capacitive foot presence sensing. The inventors have further recognized that the solution may involve using information from multiple electrode sensing pairs together.

[0073] 6 schematically illustrates an example of a first composite electrode assembly 602 that can include multiple conductors. In one example, the first composite electrode assembly 602 constitutes part of the body presence sensor 302. The example first composite electrode assembly 602 includes a main or central electrode 604 and a ring electrode 606. The ring electrode 606 and the central electrode 604 can be separated by an insulator 612 or a non-conductive region. In one example, the ring electrode 606 completely surrounds or encircles the central electrode 604, and in another example, the ring electrode 606 extends partially, but not completely, around the central electrode 604.

[0074] In one example, the center electrode 604 and the ring electrode 606 are coplanar and may be conductive plates or traces disposed on a common or shared substrate, such as FR4, polyimide, PET, or other material. Each of the center electrode 604 and the ring electrode 606 may be coupled to a drive circuit to receive an excitation signal, such as excitation signal 518, from the control circuit 404. Either the center electrode 604 or the ring electrode 606 may be configured by the control circuit 404 for use as an anode or a cathode. For example, the center electrode 604 may be coupled to the control circuit 404 using a first lead 608, and the ring electrode 606 may be coupled to the control circuit 404 using a different second lead 610, with each lead receiving a different drive signal or a different portion of a drive signal from the control circuit 404.

[0075] In one example, the ring electrode 606 and the center electrode 604 can be driven using respective portions of an AC excitation signal. That is, one of the ring electrode 606 and the center electrode 604 can function as a drive electrode, and the other of the ring electrode 606 and the center electrode 604 can function as a reference or ground electrode. In response to the AC excitation signal, the resulting electric field generally corresponds in part to the electric field extending between the left electrode 508 and the adjacent right electrode 510 shown in the example of FIG. 5C.

[0076] In one example, the insulator 612 can provide a generally uniform or non-uniform spacing between the outer edge of the center electrode 604 and the inner edge of the ring electrode 606. In some examples, the insulator 612 can provide a gap of approximately 1-2 mm between the electrodes. Increasing the gap distance increases power consumption but helps generate a larger electric field. In general, the spacing can be selected as a compromise between power consumption limitations and the desired characteristics of the generated electric field.

[0077] The inventors have further recognized that noise immunity, ground fault avoidance, and resistance to external influences on the generated electric field may be other variables to consider in the design of the body presence sensor 302 and the electrodes used therein. For example, using the ring electrode 606 as the sensing electrode and the center electrode 604 as the reference electrode may minimize the sensor's sensitivity to noise and external influences compared to other configurations using the center electrode 604 as the sensing electrode and the ring electrode 606 as the reference electrode.

[0078] Furthermore, when the generated electric field is concentrated in a limited interior space and lateral electric fields are minimized, the system can be more tolerant to ground faults. Ground faults can include false readings due to the body presence sensor 302 being placed on or near a physical ground (i.e., Earth) with different dielectric or conductivity properties (e.g., asphalt, concrete, soil, metal, etc.). Such ground substrates can, in some circumstances, change the sensitivity of the body presence sensor 302 to objects within the focal detection zone or cause the body presence sensor 302 to falsely indicate the presence of a body.

[0079] 7 schematically illustrates an example of a second composite electrode assembly 702. The second composite electrode assembly 702 may include the first composite electrode assembly 602 of the example of FIG. 6 and at least one other electrode. For example, the second composite electrode assembly 702 may include a planar electrode 704 that may be positioned near, but spaced apart from, the first composite electrode assembly 602. The planar electrode 704 may be coupled to an excitation circuit, such as the control circuit 404, using a third lead 710.

[0080] In the example of FIG. 7 , the second composite electrode assembly 702 includes the first composite electrode assembly 602 separated from a planar electrode 704 by an electrode spacing 708. The electrode spacing 708 may be an air gap, or one or more intermediate components may be provided between the electrodes. For example, a circuit housing 706 (e.g., including the housing 410) may be provided between the first composite electrode assembly 602 and the planar electrode 704. In one example, the circuit housing 706 provides a fixed spacing between at least a portion of the planar electrode 704 and at least a portion of the first composite electrode assembly 602. In the example of FIG. 7 , the circumference of the circuit housing 706 is generally smaller than each of the adjacent electrode assemblies, although other configurations or sizes of housings may be used as well. In other examples, the circuit housing 706 may be located elsewhere, with different insulating dielectric materials interposed between the electrode assemblies.

[0081] In one example, the control circuitry 404 can be configured to provide respective components of an AC drive signal to any pair of electrodes in the second composite electrode assembly 702. Each pair of drive electrodes can include a different sensor (sometimes referred to herein as a capacitance sensor or a body presence sensor). For example, the control circuitry 404 can provide respective components of a first AC drive signal to the ring electrode 606 and the central electrode 604, provide respective components of a second AC drive signal to the ring electrode 606 and the planar electrode 704, and provide respective components of a third AC drive signal to the central electrode 604 and the planar electrode 704. The various AC signals can have different amplitude, frequency, duty cycle, or waveform morphology (shape) characteristics that can be selected depending on the intended or desired characteristics of the electric field to be generated.

[0082] In one example, the control circuitry 404 can be configured to electrically couple any two or more electrodes together and use the combined electrodes as a composite electrode. As used herein, a “composite electrode” refers to two or more individual conductors or electrode features that are electrically coupled and driven together. For example, the ring electrode 606 and the central electrode 604 can be electrically coupled as a first composite electrode. The first composite electrode can receive a first portion of an AC signal from the control circuitry 404, and the planar electrode 704 can receive a complementary second portion of the AC signal from the control circuitry 404. Similarly, either the ring electrode 606 or the central electrode 604 can be electrically coupled to the planar electrode 704 and driven together, while the other of the ring electrode 606 and the central electrode 604 can be driven separately. Thus, depending on the particular electrode configuration used, multiple different electric fields can be generated within and around the second composite electrode assembly 702.

[0083] 7, the control circuitry 404 may be configured to provide a first electric field 712 by driving the center electrode 604 and the ring electrode 606 of the first composite electrode assembly 602 with respective components of the first alternating current signal. The first field 712 and various characteristics of the first field 712, such as its direction and range, may be affected by whether the ring electrode 606 or the center electrode 604 is selected as the anode and which is selected as the cathode.

[0084] The control circuitry 404 can be further configured to provide the second field 714 by providing respective components of the second alternating current signal to the planar electrode 704 and the electrically coupled combination of the ring electrode 606 and the center electrode 604. In one example, the first alternating current signal and the second alternating current signal can be provided at different times or in a time multiplexed manner, with or without a blanking period between excitation intervals.

[0085] The inventors have recognized that different combinations of electrodes used for excitation may have or exhibit different sensitivities to noise, the effects of moisture or liquids, and the presence or proximity of a body 402. For example, if the ring electrode 606 and the center electrode 604 are driven separately relative to the planar electrode 704, they will exhibit different sensitivities to the proximity of a body 402 and different resistances or susceptibilities to noise and liquids.

[0086] In some instances, capacitance-based foot sensing technologies may be relatively invariant to sweating or moisture in insoles or socks around the foot. Because the presence of moisture can increase the measured capacitance, the effect of such moisture can reduce the dynamic range of detection. However, in some instances, the dynamic range is sufficient to accommodate this effect within expected moisture levels within the footwear.

[0087] The inventors have recognized that a body presence sensor 302 that includes or uses multiple different electrode combinations to generate different electric fields can be used to detect the presence of liquid or sweat, including, but not limited to, footwear. For example, using any two of at least three different electrode combinations, signal drift due to liquid saturation (e.g., drift relative to a baseline or reference value) can be represented by the difference between the two signals, which is proportional to the amount of liquid present. In other words, information about the difference between multiple electric field indicative signals can be used to isolate and remove the effects of liquid saturation from, for example, body presence detection. Therefore, noise or signal corruption due to the presence of liquid can be identified and removed, improving the accuracy of foot presence determination.

[0088] 7, the ring electrode 606 and the center electrode 604 can have different sensitivities, or different responses, to the presence and amount of liquid in the sensor when driven separately relative to the planar electrode 704. Similarly, when the planar electrode 704 is driven relative to the combination of the ring electrode 606 and the center electrode 604, the sensor can have another different sensitivity to the presence and amount of liquid.

[0089] 8 schematically illustrates a first chart 800 showing signals indicative of capacitance over time (expressed in units of "counts" as a proxy for capacitance) for different electrode combinations in a body presence sensor that includes or uses second composite electrode assembly 702. First chart 800 depicts a period during which liquid is gradually introduced into an article of footwear (e.g., saline solution introduced at a rate of approximately 10 mL per minute), the footwear including second composite electrode assembly 702. The responses of the various electrode combinations were measured at various time-multiplexed intervals to monitor the effect of the liquid.

[0090] In the first example chart 800, a first trace 802 represents the drift in the response of the capacitance indicating signal from the center electrode 604 when driven relative to the planar electrode 704. A second trace 804 represents the drift in the response of the capacitance indicating signal from the ring electrode 606 when driven relative to the planar electrode 704. A combined trace 806 represents the drift in the response of the capacitance indicating signal from the electrically coupled ring electrode 606 and center electrode 604 when the pair is driven relative to the planar electrode 704. A difference signal 808 represents the difference between the second trace 804 and the combined trace 806.

[0091] 8, as fluid is added and saturation increases, the magnitude of the difference signal 808 increases and is proportional to the amount of fluid present. In other words, the measured magnitude information from multiple different electrode pairs can be used to determine information about the fluid saturation level in or around the body presence sensor 302. The fluid saturation level information can be used to modify or calibrate the response information from one or more of the electrode pairs, for example, by indicating the need to introduce an offset or correction factor to mitigate the effect of the fluid present.

[0092] 9 illustrates a schematic example of a first method 900 that may include determining a body proximity indication using information from a body presence sensor 302, where the body presence sensor 302 may include or use at least three different electrodes. For example, the body presence sensor 302 may include or use a second composite electrode assembly 702.

[0093] At block 902, the first method 900 may include providing time-multiplexed first and second excitation signals to respective first and second electrode pairs, thereby generating respective first and second electric fields. For example, block 902 may include generating a first alternating current signal using an excitation circuit, where components of the first alternating current signal may be provided to respective electrodes in the body presence sensor 302. In one example, at least one of the electrodes of the body presence sensor 302 is or includes a combination of two or more electrodes, such as the ring electrode 606 and the center electrode 604 of the first composite electrode assembly 602. Block 902 may further include generating a second alternating current signal using an excitation circuit, where components of the second alternating current signal may be provided to respective other electrodes in the body presence sensor 302. In response to the first and second alternating current signals, corresponding first and second electric fields may be generated, for example, within or near a foot-receiving cavity in the article of footwear.

[0094] In one example, block 902 can include providing the first and second excitation signals to different electrode pairs at different times. The different times can include non-overlapping excitation intervals. In one example, blanking periods or intervals without excitation signals can be inserted between the excitation signals. The first and second excitation signals can be transmitted in a repeating sequence, for example, over a longer period of time. That is, the first and second excitation signals can be provided intermittently at different times. Each excitation interval can be, for example, several milliseconds or longer in duration.

[0095] At block 904, the first method 900 may include receiving first and second response signals from a first electrode pair and a second electrode pair of the body presence sensor 302. For example, the control circuitry 404 may be configured to receive information from each electrode pair regarding a detected interruption in the electric field. The interruption may indicate, for example, the presence, absence, or change in position of a body at or near the body presence sensor 302. In one example, block 904 may include receiving a capacitance indication signal representative of a change in capacitance measured by the electrode pairs.

[0096] At block 906, the first method 900 may include determining a liquid saturation level within the item including the body presence sensor 302. Block 906 may include determining the liquid saturation level using the response signal received in block 904. For example, block 906 may include or use the control circuitry 404 to measure the first response signal and the second response signal and determine a difference between the two response signals. The magnitude of the difference may be proportional to the liquid saturation level within the item.

[0097] In block 908, the first method 900 may include determining a body proximity indication for the body presence sensor 302. For example, block 908 may include using the response signal received in block 904, and optionally using information about the liquid saturation level from block 906, to determine whether an object is near or may be near the body presence sensor 302.

[0098] In one example, block 908 may include determining a body proximity indication by comparing one or more of the response signals (e.g., from block 904) or a portion thereof to a specified threshold. In one example, block 908 may include or use information regarding a morphological characteristic of one of the response signals to determine a body proximity indication. In one example, the body proximity indication may include binary information regarding the presence or absence of a body (e.g., whether a foot is present in the footwear) and may also include relative information regarding whether a body is fully present or partially present. For example, the body proximity indication may include information regarding whether a footwear putting on or taking off event is occurring (i.e., whether a foot is present but not within or adjacent to the footbed of the footwear item). In one example, block 908 may include or use information regarding the fluid saturation level from block 906 to adjust a value or characteristic, such as a threshold or morphological characteristic, used to determine a body proximity indication.

[0099] Figure 10 schematically illustrates an example of a second method 1000 that includes providing a body proximity indication using the second composite electrode assembly 702 of Figure 7. In the example of Figure 10, the second composite electrode assembly 702 may form part of a body presence sensor 302 within an article of footwear and may be used to determine the presence or absence of a foot within the footwear.

[0100] At block 1002, the second method 1000 may include electrically coupling a first conductor and a second conductor or electrode to form a first composite electrode. For example, block 1002 may include electrically coupling the ring electrode 606 and the center electrode 604 of the first composite electrode assembly 602 such that the ring electrode and the center electrode are electrically driven together. At block 1004, the second method 1000 may include providing a first AC signal to the first composite electrode. For example, block 1004 may include providing respective components of the first AC signal to the planar electrode 704 and the first composite electrode.

[0101] At block 1006, the second method 1000 can include receiving a first response signal in response to the first alternating current signal. The first response signal can include information about the first electric field or information about a change in the first electric field. The first electric field can be an electric field generated using a first composite electrode when excited by the first alternating current signal.

[0102] In block 1008, the second method 1000 may include electrically isolating the first conductor and the second conductor of the composite electrode. For example, block 1008 may include electrically isolating the ring electrode 606 from the center electrode 604. When the electrodes are isolated, they can be driven separately and independently.

[0103] In block 1010, the second method 1000 can include electrically coupling the first conductor and the reference electrode to form a second composite electrode. In one example, block 1010 can include electrically coupling the center electrode 604 to the planar electrode 704 such that the center electrode and the planar electrode can be electrically driven together. In block 1012, the second method 1000 can include providing a second AC signal to the second composite electrode. For example, block 1012 can include providing respective components of the second AC signal to the ring electrode 606 and the second composite electrode. In one example, the first AC signal and the second AC signal are the same, while in other examples, the first AC signal and the second AC signal can have different signal characteristics.

[0104] At block 1014, the second method 1000 can include receiving a second response signal in response to the second alternating current signal. The second response signal can include information about the second electric field or information about a change in the second electric field. The second electric field can be an electric field generated using a second composite electrode when excited by the second alternating current signal.

[0105] At block 1016, the second method 1000 may include determining a body proximity indication using the first response signal received at block 1006 and the second response signal received at block 1014. In one example, block 1016 may include combining the first response signal and the second response signal (e.g., by summing or differencing) to determine a signal of interest, which may be used to determine a body proximity indication, for example, by comparing the signal of interest to a specified reference threshold or condition.

[0106] The inventors further recognized that the problem to be solved includes determining when or whether to update threshold conditions that can be used to detect the presence or absence of a body at or near the body presence sensor 302. The inventors recognized that the solution can include or use algorithms that dynamically or continuously update the threshold conditions to track changing real-world conditions in which the body presence sensor 302 is used. As an example, the solution can include or use a recursive filter, such as a Kalman filter, to ensure smooth and predictable operation and to resist noisy input signals.

[0107] For example, events such as "put on" and "take off" events, or state information such as "put on shoes" and "take off shoes" classifications, can be identified using algorithms that estimate, filter, and track body position-indicating signals that can be received from the body presence sensor 302. The algorithms can compare the filtered estimates to various thresholds to determine whether an event has occurred and whether a particular state or state change is indicated. In one example, the body position-indicating signals represent relative changes, and the sensors themselves may be susceptible to external influences and noise. Therefore, thresholds can be dynamically updated to ensure proper operation as use conditions change.

[0108] In one example, the algorithm includes sampling a body position-indicating signal from the body presence sensor 302. After each sample is taken, a future sample value can be estimated using a recursive estimation filter, such as a Kalman filter. Subsequent actual samples can then be measured and the difference between the estimated future sample value and the actual sample value can be determined. This difference can be considered an error signal. The error signal can be used, for example, to update future predictions.

[0109] Because noise is inherent in sensor systems, measurements of body position indication signals are typically not assumed to be precise or absolutely correct. Instead, updated predictions, i.e., future predictions, can be weighted combinations of previous predictions and measurements, reducing error over time and providing a good approximation of the body presence information sensed by the sensors.

[0110] FIG. 11 schematically illustrates an example of a second chart 1100 containing information regarding dynamic threshold updates, a body position-indicating signal, and a predicted signal. For example, the second chart 1100 includes a raw signal 1102 corresponding to an output from the body presence sensor 302 and indicating the position or proximity of a body (e.g., a foot) relative to the sensor. The second chart 1100 includes a predicted signal 1104 corresponding to the output of a recursive filter that receives the raw signal 1102 as input. In one example, the predicted signal 1104 represents an output or calculated signal based on a low-pass filtered version of the raw signal 1102. The predicted signal 1104 may represent an estimate of a joint probability distribution over a particular time frame for values ​​measured by the body presence sensor 302. In other words, the predicted signal 1104 may represent the result of processing multiple measurements (e.g., a continuous time series of measurements) from the noisy body presence sensor 302 to generate an estimated or predicted output.

[0111] In one example, the predicted signal 1104 may include the output of a Kalman filter or the output of a function that includes or uses a Kalman filter or similar recursive filter or algorithm. The filter may receive the raw signal 1102 and provide an estimated future value. Once the actual future value is measured, the variables that provide the estimated future value may be updated based on the error between the original estimated future value and the actual future value. As an example, the estimated future value may be calculated using a weighted average that favors more accurate results. In one example, the filter may operate in real time using information about current sensor output values ​​and previously calculated estimates. Various techniques may be used to optimize or enhance the accuracy of the filter or to tune the filter to work best in a particular environment, such as a body sensor in footwear.

[0112] The second chart 1100 further includes various thresholds that can be used to determine, along with the predicted signal 1104, various state information about the body or the body associated with the body presence sensor 302 or the body associated with the items comprising the body presence sensor 302. The second chart 1100 further includes various thresholds that can be used to determine, along with the predicted signal 1104, various state information about the body or the body associated with the body presence sensor 302 or the body associated with the items comprising the body presence sensor 302. One or more thresholds can be updated or changed dynamically or on the fly to accommodate different users who may have different anatomies, different gaits, or be in different environments.

[0113] The example second chart 1100 includes a take-off threshold 1112 and a put-on threshold 1114. Comparing the value of the predicted signal 1104 to the take-off threshold 1112 can determine whether a foot is or may be in the footwear. Comparing the value of the predicted signal 1104 to the put-on threshold 1114 can determine whether a foot has been or is about to be taken off the footwear. For example, if the value of the predicted signal 1104 exceeds the take-off threshold 1112, the foot can be considered to be in the footwear (i.e., state 1110 = put-on). After the footwear is determined to be occupied, if the value of the predicted signal 1104 falls below the put-on threshold 1114, the footwear can be considered not to be occupied by a foot (i.e., state 1110 = off). In one example, information from one or more other sensors (e.g., a motion sensor 324, such as an accelerometer) can be used in combination with the threshold comparison of the predicted signal 1104 to verify or improve the reliability of the state determination. For example, if the predicted signal 1104 exceeds the take-off threshold 1112 and the accelerometer indicates footwear movement, the footwear may be considered to be on.

[0114] An example of the second chart 1100 includes a load threshold 1106 and a no load threshold 1108. Comparing the value of the predicted signal 1104 to the load threshold 1106 can determine whether the user is standing or "loading" the sensor. Comparing the value of the predicted signal 1104 to the no load threshold 1108 can determine whether the user is sitting or the sensor has been "no load" by the user.

[0115] 12 generally illustrates an example of a third method 1200 that may include or use information regarding a body position-indicating sensor signal from a body presence sensor 302 to determine footwear use characteristics of an active article of footwear. At block 1202, the third method 1200 may include measuring a foot presence-indicating sensor signal value. For example, block 1202 may include measuring a signal value from the body presence sensor 302, where the measurement may indicate an interruption or change in the electric field generated by the body presence sensor 302.

[0116] At block 1204, the third method 1200 may include identifying a gait state of the footwear. For example, block 1204 may include receiving information regarding footwear movement from a motion sensor 324, such as an accelerometer, or receiving information from the body presence sensor 302. In one example, block 1204 may include receiving the motion information and processing the information to identify whether the signal includes or indicates a periodic signal corresponding to walking or running. In one example, block 1204 may include processing the motion information to identify footwear movement signals that indicate the footwear is undergoing or may be undergoing a put-on or take-off event. That is, the processing may compare the measured motion information to a motion profile or template to determine whether the footwear movement is consistent with the user's movement when putting on or taking off footwear. For example, a portion of the spectral content (e.g., frequency and energy information) from the sensor signal may be compared to, for example, a template or other spectral content from the same signal to determine the gait state. In one example, a machine learning algorithm may be applied to analyze motion information (e.g., from one or more of the motion sensors 324 or body presence sensors 302, or other sensors capable of communicating with the active footwear) to provide gait state information, such as distinguishing between walking, running, other rhythms or patterns of use, or non-use. In one example, if footwear movement or walking is not identified in block 1204, the third method 1200 may indicate a stationary state of the footwear, and the method may return to block 1202 without proceeding to block 1206.

[0117] At block 1206, the third method 1200 may include determining a predicted subsequent value of the foot presence indicating sensor signal value. Block 1206 includes using a processor (e.g., processor circuit 320) to receive the sensor signal from the body presence sensor 302 and, based on the current value of the sensor signal, predicting the next or subsequent value of the sensor signal using an algorithm. In one example, block 1206 may include or use an estimation filter, such as a recursive estimation filter or other filter, that can be used to find coefficients to minimize a cost function associated with the input signal and provide an output representing a prediction of the subsequent value of the input signal.

[0118] At block 1208, the third method 1200 may include updating a threshold for the sensor signal based on a predicted subsequent value of the sensor signal. For example, block 1208 may include updating one or more of the doffing threshold 1112, the donning threshold 1114, the loading threshold 1106, or the no-load threshold 1108, which may be used to determine state information about the footwear or a user of the footwear.

[0119] In one example, the third method 1200 may proceed from block 1208 to block 1210 and / or block 1212. At block 1210, the third method 1200 may include determining an entry of the foot into the footwear (i.e., an on event) or an exit of the foot from the footwear (i.e., an off event) based on a comparison of the current value of the sensor signal to the updated off-dock or on-dock threshold from block 1208. At block 1212, the third method 1200 may include determining a load characteristic of the footwear based on a comparison of the current value of the sensor signal to the load threshold uploaded from block 1208. For example, block 1212 may include determining whether the user is or may be standing or sitting while wearing the footwear.

[0120] 13 schematically illustrates an example of a fourth method 1300 that may include or use information about the body position-indicating sensor signal from the body presence sensor 302 to modify thresholds or determine footwear conditions or footwear use characteristics. Initial thresholds may be set or determined, for example, based on historical data or based on data from a population of users of the body presence sensor 302. During use, sensor signal delta information from the body presence sensor 302 may be received and processed using a recursive filter to predict future values ​​of the sensor signal. One or more thresholds that may be used to indicate a condition or change in condition may be updated or modified for each user or user environment.

[0121] The fourth method 1300 may begin with block 1302, which initializes variables. For example, block 1302 may include initializing predicted values ​​of sensor signals from the body presence sensor 302 to initial values ​​(e.g., zero). Block 1302 may include initializing thresholds, such as the doffing threshold 1112, the donning threshold 1114, the loading threshold 1106, or the no-loading threshold 1108, to respective baseline values, which may be based on previous data from the same user or the same footwear, or based on demographic or other historical data. In one example, block 1302 may include initializing one or more scaling factors that may be used throughout the fourth method 1300, as described further below. In one example, the predicted sensor signal initial values ​​and threshold conditions may be optimized to minimize false triggers and false indications of the presence or absence of a foot in the footwear.

[0122] At block 1304, the fourth method 1300 includes measuring a signal value from the body presence sensor 302. For example, block 1304 includes measuring a raw or unfiltered value from the body presence sensor 302. The measurement may indicate a change in capacitance or electric field generated by the body presence sensor 302 inside the footwear in an area that may be affected by the presence or absence of a body or foot.

[0123] At block 1306, a residual value may be calculated based on the measured signal values ​​and the predicted values ​​of the sensor signals from block 1304. In one example, the residual value may be based on the difference between the predicted value and the measured actual value of the sensor signal from the body presence sensor 302. The predicted value may initially be an initial value (e.g., zero) but may be updated or changed using an estimation filter as described elsewhere herein.

[0124] In block 1308, the residual value from block 1306 may be scaled according to a scaling factor. The scaling factor may be a specified scalar value selected, for example, based on historical data, demographic data, or other data, to optimize the fourth method 1300 and increase the accuracy of the algorithm. In one example, the scaling factor may be initialized in block 1302 and updated periodically or may be a static value.

[0125] At block 1310, the fourth method 1300 may include updating the predicted value of the sensor signal to provide an updated predicted value. In one example, the updated predicted value may be a function of the residual value or the scaled residual value and the previous predicted value. For example, the updated predicted value may be the sum of the previous predicted value and the scaled residual from block 1308.

[0126] At block 1312, the fourth method 1300 further processes the sensor signal using the updated prediction to provide a condition signal. For example, the value of the condition signal may correspond to the difference between a current measurement of the sensor signal (e.g., from block 1304) and the updated prediction from block 1310. At block 1314, the fourth method 1300 may include determining a variance of the condition signal. That is, block 1314 may include quantifying the deviation of the condition signal from its average or other expected value.

[0127] At decision block 1316, the fourth method 1300 may include comparing the determined variability from block 1314 to a variability threshold. The variability threshold may optionally be one of the variables initialized at block 1302 and may be a static or dynamic threshold. At decision block 1316, if the determined variability is relatively low or less than the variability threshold, the fourth method 1300 may proceed to decision block 1326. If the determined variability is relatively high or greater than the variability threshold, the fourth method 1300 may proceed to block 1318.

[0128] At block 1318, the fourth method 1300 may include updating various thresholds according to the previous thresholds and the magnitude of the variation determined from block 1314. For example, at block 1318, the shoe-off threshold 1112 or the shoe-on threshold 1114 may be updated according to the sum of the previous corresponding threshold and the scaled residual from block 1308 (e.g., the updated shoe-off threshold 1112 is the sum of the previous take-off threshold 1112 and the scaled residual, and the updated put-on threshold 1114 is the sum of the previous put-on threshold 1114 and the scaled residual). Similarly, the shoe-load threshold 1106 or the shoe-off threshold 1108 may be updated according to the sum of the previous corresponding threshold and the scaled residual from block 1308 (e.g., the updated load threshold 1106 is the sum of the previous load threshold 1106 and the scaled residual, or the updated no-load threshold 1108 is the sum of the previous no-load threshold 1108 and the scaled residual).

[0129] Following updating the thresholds at block 1318, the fourth method 1300 may include a decision block 1320 for determining a state of the footwear including the body presence sensor 302. For example, at decision block 1320, if the updated predicted value of the sensor signal (e.g., the value determined at block 1310) is greater than the updated removal threshold 1112, the footwear may be considered to be on or on the foot. Conversely, if the updated predicted value of the sensor signal (e.g., the value determined at block 1310) is less than the updated removal threshold 1112, the footwear may be considered to be unworn or removed from the foot. After determining the state, the fourth method 1300 may proceed to decision block 1326.

[0130] At decision block 1326, the fourth method 1300 may include determining whether a walk or step event is detected. The step event may be detected in a variety of ways, such as using information from the motion sensor 324 or using information regarding the periodicity or other characteristics of the sensor signal from the body presence sensor 302 or another sensor. In one example, the periodicity may generally correspond to a foot drop or foot lift (or footwear drop or footwear lift) event evident in a change in the magnitude or frequency of the sensor signal. If a walk or step event is not detected at decision block 1326, the fourth method 1300 may return to block 1304 without performing any further updates to the thresholds or scaling factors. If a walk or step event is detected at decision block 1326, the fourth method 1300 may proceed to block 1328.

[0131] In block 1328, one or more thresholds or scaling factors can be updated for use in further analyzing the footwear condition. For example, in block 1328, the take-off threshold 1112 or the put-on threshold 1114 can be updated according to the previous value of the corresponding threshold and a specified scaling factor. For example, the take-off threshold 1112 can be updated according to a minimum value (e.g., a local minimum) of the sensor signal (or predicted signal) scaled according to a first scaling factor. The put-on threshold 1114 can be updated according to the same minimum value of the sensor signal scaled according to the same first scaling factor or a different scaling factor. In one example, the no-load threshold 1108 can similarly be updated according to a maximum value (e.g., a local maximum) of the sensor signal (or predicted signal) scaled according to a second scaling factor. The load threshold 1106 can similarly be updated according to the same maximum value of the sensor signal (or predicted signal) scaled according to a third scaling factor. In one example, the value of the second scaling factor may be smaller than the value of the third scaling factor. One or more of the scaling factors may be specific to a user, a particular item of footwear, a particular condition or environment of use, or may be global scaling factors. Following block 1328, the fourth method 1300 proceeds to block 1304, where the updated thresholds may be used in subsequent determinations of the footwear state. The fourth method 1300 operates as a loop, continuously and dynamically updating the thresholds used to determine the footwear state or status.

[0132] FIG. 14 is a diagrammatic representation of a machine 1400 upon which instructions 1408 (e.g., software, programs, applications, applets, apps, or other executable code) are executed to cause the machine 1400 to perform one or more of the methodologies described herein. For example, the instructions 1408 may cause the machine 1400 to perform one or more of the methods described herein, such as controlling a footwear system using or in response to information from a body presence indicating sensor. The instructions 1408 transform a generic, unprogrammed machine 1400 into a specific machine 1400 that is programmed to perform the functions described and illustrated in the manner described. The machine 1400 can operate as a standalone device or can be coupled (e.g., networked) to other machines, such as to coordinate the actions or operation of multiple different shoes or footwear systems. In a networked deployment, the machine 1400 may operate as a server machine or a client machine in a server-client network environment, or as a peer machine in a peer-to-peer (or dynamic) network environment. Machine 1400 includes, but is not limited to, a server computer, a client computer, a personal computer (PC), a tablet computer, a laptop computer, a netbook, a set-top box (STB), a PDA, an entertainment media system, a mobile phone, a smartphone, a mobile device, a wearable device (e.g., a smart watch), a smart home device (e.g., a smart appliance), other smart devices, a web appliance, a network router, a network switch, a network bridge, or any machine capable of executing, sequentially or otherwise, instructions 1408 that specify actions to be performed by machine 1400. Additionally, while only a single machine 1400 is illustrated, the term "machine" is intended to include a collection of machines that individually or jointly execute instructions 1408 to perform one or more of the methodologies described herein.

[0133] Machine 1400 may include processor 1402, memory 1404, and I / O components 1442, which may be configured to communicate with each other via bus 1444. In one embodiment, processor 1402 (e.g., a central processing unit (CPU), a reduced instruction set computing (RISC) processor, a complex instruction set computing (CISC) processor, a graphics processing unit (GPU), a digital signal processor (DSP), an ASIC, a radio frequency integrated circuit (RFIC), another processor, or any suitable combination thereof) may include, for example, processor 1406 and processor 1410 that execute instructions 1408. The term "processor" includes multi-core processors that may include two or more independent processors (sometimes referred to as "cores") that may execute instructions simultaneously. While multiple processors 1402 are shown in FIG. 14, machine 1400 may include a single processor with a single core, a single processor with multiple cores (e.g., a multi-core processor), multiple processors with a single core, multiple processors with multiple cores, or any combination thereof.

[0134] The memory 1404 includes a main memory 1412, a static memory 1414, and a storage unit 1416, all of which are accessible to the processor 1402 via a bus 1444. The main memory 1404, the static memory 1414, and the storage unit 1416 store instructions 1408 that embody any one or more of the methodologies or functions described herein. The instructions 1408 may also reside, completely or partially, within the main memory 1412, within the static memory 1414, within a machine-readable medium 1418 in the storage unit 1416, within at least one of the processors 1402 (e.g., within a processor's cache memory), or any suitable combination thereof during execution by the machine 1400.

[0135] I / O components 1442 may include various components that receive input, provide output, generate output, transmit information, exchange information, take measurements, etc. The specific I / O components 1442 included in a particular machine will vary depending on the type of machine. For example, a portable machine such as a mobile phone may include a touch input device or other input mechanism, while a headless server machine may not include such a touch input device. It is understood that I / O components 1442 may include many other components not shown in FIG. 14 . In various exemplary embodiments, I / O components 1442 may include output components 1428 and input components 1430. Output components 1428 may include visual components (e.g., a display such as a plasma display panel (PDP), a light-emitting diode (LED) display, a liquid crystal display (LCD), a projector, or a cathode ray tube (CRT)), acoustic components (e.g., speakers), haptic components (e.g., vibration motors, resistance mechanisms), other signal generators such as control circuitry 404 and processor circuitry 320, etc. The input components 1430 may include an alphanumeric input component (e.g., a keyboard, a touchscreen configured to receive alphanumeric input, an optical keyboard, or other alphanumeric input component), a point-based input component (e.g., a mouse, touchpad, trackball, joystick, motion sensor, or other pointing instrument), a tactile input component (e.g., a physical button, a touchscreen that provides the position and / or force of a touch or touch gesture, or other tactile input component), an audio input component (e.g., a microphone), etc.

[0136] In a further exemplary embodiment, the I / O component 1442 may include various sensors, which may include one or more of various components, such as a biometrics component 1432, a motion component 1434, an environmental component 1436, or a position component 1438. For example, the biometrics component 1432 may include a component that detects facial expressions (e.g., hand expressions, facial expressions, vocal expressions, body gestures, or eye tracking), a component that measures biosignals (e.g., blood pressure, heart rate, body temperature, sweating, muscle oxygenation, or brain waves), a component that identifies a person (e.g., voice identification, retinal identification, face identification, fingerprint identification, or brainwave-based identification), etc. The motion component 1434 may include motion sensors 324, including an acceleration sensor component (e.g., an accelerometer), a gravity sensor component, a rotation sensor component (e.g., a gyroscope), etc. The environmental components 1436 include, for example, an illuminance sensor component (e.g., a photometer), a temperature sensor component (e.g., one or more thermometers that detect ambient temperature), a humidity sensor component, a pressure sensor component (e.g., a barometer), an acoustic sensor component (e.g., one or more microphones that detect background noise), a proximity sensor component (e.g., an infrared sensor that detects nearby objects), a gas sensor (e.g., a gas detection sensor that detects concentrations of harmful gases for safety purposes or measures pollutants in the air), or other components that can provide an indication, measurement, or signal corresponding to the surrounding physical environment. The location components 1438 include a location sensor component (e.g., a GPS receiver component), an altitude sensor component (e.g., an altimeter or barometer that detects air pressure from which altitude can be derived), an orientation sensor component (e.g., a magnetometer), etc.

[0137] Communication can be implemented using a variety of technologies. I / O component 1442 further includes a communication component 1440 operable to couple machine 1400 to network 1420 or device 1422 via coupling 1424 and coupling 1426. For example, communication component 1440 may include a network interface component or another suitable device for interfacing with network 1420. In further examples, communication component 1440 may include a wired communication component, a wireless communication component, a cellular communication component, a near field communication (NFC) component, a Bluetooth® component (e.g., Bluetooth® Low Energy), a Wi-Fi® component, and other communication components for providing communication via other manners. Device 1422 may be another machine or any of a variety of peripheral devices (e.g., a peripheral device connected via USB).

[0138] Additionally, the communications component 1440 may include a component that detects or is operable to detect an identifier. For example, the communications component 1440 may include a radio frequency identification (RFID) tag reader component, an NFC smart tag detection component, an optical reader component (e.g., an optical sensor that detects one-dimensional barcodes such as Universal Product Code (UPC) barcodes, multidimensional barcodes, or other optical codes), or an acoustic detection component (e.g., a microphone that identifies tagged audio signals). Additionally, various information may be obtained via the communications component 1440, such as location information via Internet Protocol (IP) geolocation, location information via Wi-Fi signal triangulation, location information via detection of NFC beacon signals that may indicate a particular location, etc.

[0139] Various memories (e.g., memory 1404, main memory 1412, static memory 1414, and / or memory of processor 1402) and / or storage unit 1416 may store one or more sets of instructions and data structures (e.g., software) that embody or use any one or more of the methodologies or functions described herein. These instructions (e.g., instructions 1408), when executed by processor 1402, cause various operations to implement the disclosed embodiments.

[0140] The instructions 1408 may be transmitted or received over the network 1420 using a transmission medium via a network interface device (e.g., a network interface component included in the communications component 1440) and using any of a number of well-known transfer protocols (e.g., Hypertext Transfer Protocol (HTTP)). Similarly, the instructions 1408 may be transmitted or received using a transmission medium via a coupling 1426 (e.g., a peer-to-peer coupling) to the device 1422.

[0141] Various embodiments of the present disclosure can help provide solutions to problems related to body presence detection identified herein. Example 1 can include a footwear sensor system including: a first capacitance sensor within the footwear item, the first capacitance sensor configured to provide a first electric field at least partially within the interior of the footwear item using a first excitation signal; a second capacitance sensor within the footwear item, the second capacitance sensor configured to provide a second electric field at least partially within the interior of the footwear item using a second excitation signal; a signal generator configured to provide the first excitation signal and the second excitation signal; and a processor circuit configured to provide a foot presence indication based on information received from the first capacitance sensor and the second capacitance sensor regarding interruptions of the first electric field and the second electric field.

[0142] In Example 2, the subject matter of Example 1 can include a first electrode pair including a ring electrode and a reference electrode.

[0143] In Example 3, the subject matter of Example 2 can include a ring electrode occupying a first plane and a reference electrode occupying a second plane, the first plane and the second plane being spaced apart by at least a distance.

[0144] In Example 4, the subject matter of one or more of Examples 2-3 can include a reference electrode including a conductor having a planar surface area that exceeds a surface area of ​​the ring electrode.

[0145] In Example 5, the subject matter of any one or more of Examples 2-4 can include a second electrode pair including a planar electrode and a reference electrode.

[0146] In Example 6, the subject matter of Example 5 can include a planar electrode disposed coaxially with the ring electrode, and the planar electrode and the ring electrode can be spaced apart.

[0147] In Example 7, the subject matter of any one or more of Examples 5-6 can include a planar electrode and a ring electrode that share a substrate in the first plane (ie, include a common substrate).

[0148] In Example 8, the subject matter of Example 7 can include a reference electrode occupying a second plane that can be spaced apart from the first plane.

[0149] In Example 9, the subject matter of one or more of Examples 1-8 can include a first electrode pair including a first electrode and a reference electrode, a second electrode pair including a second electrode and a reference electrode, and the signal generator can be configured to provide a third excitation signal between the first electrode and the second electrode. In response, a third electric field can extend between the first electrode and the second electrode and into the foot-receiving cavity of the article of footwear.

[0150] In Example 10, the subject matter of Example 9 includes an article of footwear, wherein the electrodes of the first capacitance sensor and the second capacitance sensor include respective planar electrode portions disposed parallel to a footbed of the article of footwear.

[0151] In example 11, the subject matter of example 10 includes a sensor housing configured to be positioned in an arch region or a central region of a footbed of an article of footwear.

[0152] In Example 12, the subject matter of one or more of Examples 1-11 can include a first excitation signal and a second excitation signal each having a different frequency characteristic.

[0153] In Example 13, the subject matter of any one or more of Examples 1-12 can include a first excitation signal and a second excitation signal each having a different amplitude characteristic.

[0154] In Example 14, the subject matter of one or more of Examples 1-13 can include a signal generator configured to provide the first excitation signal and the second excitation signal in a time-multiplexed manner.

[0155] In Example 15, the subject matter of one or more of Examples 1-14 can include a signal generator configured to simultaneously provide the first excitation signal and the second excitation signal.

[0156] In Example 16, the subject matter of one or more of Examples 1-15 can include a processor circuit configured to receive a first response signal from the first capacitance sensor in response to the first excitation signal and a second response signal from the second capacitance sensor in response to the second excitation signal, and the processor circuit can be configured to provide a foot presence indication based on a sum of the first response signal and the second response signal.

[0157] In Example 17, the subject matter of one or more of Examples 1-16 can include a processor circuit configured to receive a first response signal from the first capacitance sensor in response to the first excitation signal and a second response signal from the second capacitance sensor in response to the second excitation signal, and the processor circuit can be configured to provide an indication of foot presence based on a difference between the first response signal and the second response signal.

[0158] In Example 18, the subject matter of Example 17 is further characterized in that the first electrode pair of the first capacitance sensor can include a reference electrode and a composite electrode, the composite electrode including a coplanar and coaxial main electrode and a ring electrode, and the second electrode pair of the second capacitance sensor can include a reference electrode and a ring electrode. In Example 18, the signal generator can be configured to provide a first excitation signal to the composite electrode during a first excitation interval and a second excitation signal to the ring electrode during a second excitation interval, and the main electrode can be electrically isolated from the ring electrode during the second excitation interval.

[0159] In Example 19, the subject matter of any one or more of Examples 1-18 includes a processor circuit configured to determine a liquid saturation level of one or more portions of the article of footwear based on information received from the first capacitance sensor and the second capacitance sensor, and the processor circuit can be configured to provide a foot presence indication using the determined liquid saturation level.

[0160] Example 20 is a footwear system including a first electrode, a second electrode, a third electrode, a signal generator configured to provide excitation signals to each of the first electrode, second electrode, and / or third electrode groups at different times, and a processor circuit configured to receive electric field information from each of the electrode groups and, in response thereto, determine the presence or absence of a foot within a foot-receiving cavity of the footwear article.

[0161] In Example 21, the subject matter of Example 20 includes a first electrode group including a first electrode and a second electrode electrically coupled as an anode and a third electrode as a cathode; a second electrode group including the first electrode as an anode and the third electrode as a cathode, the second electrode being electrically isolated from the first electrode and the third electrode; and a signal generator configured to provide a first AC excitation signal to the first electrode group at a first time and a second AC excitation signal to the second electrode group at a different second time.

[0162] In Example 22, the subject matter of Example 21 can include a processor circuit configured to receive a first response signal from a first group of electrodes at a first time and a second response signal from a second group of electrodes at a second time, and the processor circuit can be configured to determine a liquid saturation of a portion of the footwear article using information regarding a difference between the first response signal and the second response signal.

[0163] In Example 23, the subject matter of Example 22 can include a processor circuit configured to use the determined liquid saturation to determine the presence or absence of a foot within the foot-receiving cavity of the article of footwear.

[0164] In Example 24, the subject matter of any one or more of Examples 20-23 includes a signal generator configured to provide a first AC excitation signal between the first electrode and the second electrode at a first time, and the signal generator can be configured to provide a second AC excitation signal between the third electrode and a composite electrode including the first electrode and the second electrode at a second time.

[0165] Example 25 is a method that includes providing time-multiplexed first and second excitation signals from a signal generator circuit to respective first and second electrode pairs in the article of footwear, thereby generating respective first and second electric fields within the article of footwear. Example 25 may further include receiving, with a processor circuit, respective first and second response signals from the first and second electrode pairs, and using the received first and second response signals to determine an indication of the proximity of the foot within the article of footwear (e.g., by processing the first and second response signals together, such as by adding, differencing, or otherwise manipulating the signals or information from the signals).

[0166] In Example 26, the subject matter of Example 25 includes providing a first excitation signal to a first electrode pair including providing a first AC signal between a ring electrode and a main electrode electrically coupled to the reference electrode, and providing a second excitation signal to a second electrode pair can include providing a second AC signal between the reference electrode and the ring electrode.

[0167] In Example 27, the subject matter of Example 26 can include determining a foot proximity indication using information about a difference between the first response signal and the second response signal.

[0168] In Example 28, the subject matter of one or more of Examples 25-27 includes determining a liquid saturation level of a portion of the footwear article using the first response signal and the second response signal, and determining the foot proximity indication includes using the determined liquid saturation level.

[0169] In Example 29, the subject matter of any one or more of Examples 25-28 can include providing a second excitation signal that includes electrically coupling the first conductor portion and the second conductor portion of the composite electrode, and wherein providing the first excitation signal includes electrically isolating the first conductor portion and the second conductor portion of the composite electrode.

[0170] In Example 30, the subject matter of Example 29 can include providing a second excitation signal, including electrically coupling the second conductor portion to a reference electrode.

[0171] Example 31 is a sensor signal processing method including steps of sampling sensor signal values ​​from a foot presence sensor within an article of footwear, identifying a walking state of the article of footwear using the sampled sensor signal values, updating a threshold value of the sensor signal in response to identifying the walking state, and determining a foot entering or exiting the article of footwear based on the updated sensor signal threshold value and subsequent values ​​of the sensor signal.

[0172] In Example 32, the subject matter of Example 31 can include identifying a walking state, which includes comparing one or more values ​​of the sensor signal to a reference threshold.

[0173] In Example 33, the subject matter of any one or more of Examples 31-32 may include a step of identifying a walking state, including the steps of filtering the sensor signal using a low-pass filter to provide a filtered signal, and analyzing a series of values ​​of the filtered signal to distinguish the walking state of the footwear item from a stationary state of the footwear item.

[0174] In example 34, the subject matter of one or more of examples 31-33 can include updating the sensor signal threshold, which can include determining a predicted value of the sensor signal based on a previous value of the sensor signal. In example 34, if the predicted value of the sensor signal meets or exceeds the reference threshold, updating the sensor signal threshold to have a threshold based in part on the predicted value of the sensor signal or the current value of the sensor signal.

[0175] In Example 35, the subject matter of Example 34 can include the reference threshold being based on a magnitude of a difference between a predicted value and a current value of the sensor signal.

[0176] In Example 36, the subject matter of any one or more of Examples 31-35 may include identifying a gait state, the step including identifying a period of the sensor signal over time, the period corresponding to a footwear drop and a footwear lift event (e.g., corresponding to one or more step events), and updating a threshold of the sensor signal may include using a characteristic of a magnitude of the sensor signal over time.

[0177] In Example 37, the subject matter of Example 36 may include a step of updating the sensor signal threshold, which step may include a step of determining a foot presence / absence threshold using a minimum value characteristic of the sensor signal, and a step of determining a foot entering or exiting the footwear article may include a step of using the foot presence / absence threshold.

[0178] In Example 38, the subject matter of one or more of Examples 36-37 includes a step of updating a footwear load threshold using a maximum value characteristic of the sensor signal and determining a footwear load state for the footwear item based on the footwear load threshold and the subsequent value of the sensor signal.

[0179] In Example 39, the subject matter of any one or more of Examples 31-38 includes processing a sensor signal from a foot presence sensor using a recursive estimation filter to provide a predicted sensor value, and determining a foot entry into or exit from the footwear article includes using an updated sensor signal threshold and using information regarding a difference between the predicted sensor value and a subsequent sensor signal value.

[0180] In Example 40, the subject matter of one or more of Examples 31-39 may include a step of sampling a value of the sensor signal, which step includes a step of sampling a value indicative of the capacitance of the sensor signal from a capacitance-based foot presence sensor.

[0181] Example 41 is a sensor signal processing method including steps of sampling sensor signal values ​​from a foot presence sensor in an article of footwear, identifying a walking state of the article of footwear using the sampled sensor signal values, updating a threshold value of the sensor signal in response to identifying the walking state, and determining a load characteristic of the article of footwear based on the updated sensor signal threshold value and subsequent values ​​of the sensor signal.

[0182] In Example 42, the subject matter of Example 41 may include the steps of processing a sensor signal from a foot presence sensor using a recursive estimation filter to provide a predicted sensor value, identifying a variance between the predicted sensor value and a subsequent value of the sensor signal from the foot presence sensor, and identifying a gait state of the footwear article in response to a variance exceeding a specified variance threshold.

[0183] In Example 43, the subject matter of Example 42 may include updating the sensor signal threshold including determining a maximum value characteristic of the sensor signal, and calculating an updated sensor signal threshold based on the maximum value characteristic and a specified scaling factor.

[0184] In Example 44, the subject matter of Example 43 includes determining a minimum characteristic of the sensor signal and calculating a foot presence threshold based on the minimum characteristic and a second specified scaling factor.

[0185] In Example 45, the subject matter of any one or more of Examples 41-44 includes processing a sensor signal from a foot presence sensor using a recursive estimation filter to provide a predicted sensor value; identifying a variation between the predicted sensor value and a subsequent value of the sensor signal from the foot presence sensor; and updating a sensor signal threshold based on a previous threshold and the identified variation.

[0186] In Example 46, the subject matter of any one or more of Examples 41-45 may include a step of determining a load characteristic of the footwear item, which step includes a step of determining that a foot is present within the footwear item, and a step of determining whether a subsequent value of the sensor signal represents a standing or sitting posture of a wearer of the footwear item.

[0187] In Example 47, the subject matter of any one or more of Examples 41-46 may include a step of determining load characteristics of the footwear item, which step includes a step of determining a relative amount of force applied by the foot to the footbed of the footwear item.

[0188] In Example 48, the subject matter of any one or more of Examples 41-47 may include a step of sampling a value of the sensor signal, which step includes a step of sampling a value indicative of the capacitance of the sensor signal from a capacitance-based foot presence sensor.

[0189] Example 49 is an article of footwear comprising: a foot presence sensor including a plurality of electrodes configured to generate and detect changes in an electric field within the article of footwear, the changes indicating the presence or position of a foot within the article of footwear; and a processor circuit, wherein the processor circuit is configured to receive a foot position indication signal from the foot presence sensor, process the signal using a recursive estimation algorithm to provide a predicted sensor value, compare the predicted sensor value with a subsequent value of the foot position indication signal from the foot presence sensor to provide a comparison result, and determine at least one of the presence of a foot in the article of footwear, the absence of a foot, or a load characteristic of the article of footwear based on the comparison result.

[0190] In example 50, the subject matter of example 49 can include a foot presence sensor including a plurality of electrodes disposed in or on a footbed of the article of footwear.

[0191] In Example 51, the subject matter of Example 50 includes a dielectric member interposed between the foot presence sensor and the foot-receiving cavity of the article of footwear, the dielectric member having a dielectric constant greater than the dielectric constant of air.

[0192] In example 52, the subject matter of any one or more of examples 49-51 may include a processor circuit configured to modify a foot presence / absence threshold or a footwear load threshold based on minimum or maximum amplitude characteristics of the foot position indication signal.

[0193] In Example 53, the subject matter of any one or more of Examples 49-52 can include a foot presence sensor, the foot presence sensor including a capacitance-based foot presence sensor configured to provide information corresponding to a changing capacitance measured by the foot presence sensor to a foot position indication signal.

[0194] Example 54 is at least one machine-readable medium comprising instructions that, when executed by a processing circuit, cause the processing circuit to perform operations to implement any of Examples 1-53.

[0195] Example 55 is an apparatus equipped with means for carrying out any one of Examples 1 to 53.

[0196] Example 56 is a system that implements any one of Examples 1 to 53.

[0197] Example 57 is a method for implementing any of Examples 1 to 53.

[0198] These embodiments may stand alone or may be combined in various permutations or combinations with one or more of the other aspects, embodiments, or features described elsewhere herein.

[0199] The above description includes references to the accompanying drawings, which form a part of the detailed description. The drawings illustrate specific embodiments in which the invention may be practiced. These embodiments are also referred to herein as "examples." Such examples may include elements in addition to those shown or described. However, the inventors also contemplate examples in which only the elements shown or described are provided. The inventors also contemplate examples that utilize combinations or permutations of these elements with respect to a particular example (or one or more aspects thereof), or other example (or one or more aspects thereof) shown or described herein.

[0200] In this document, as is common in patent documents, the terms "a" or "an" are used to include one or more, regardless of other instances or uses of "at least one" or "one or more." In this document, the term "or" is used to refer to a non-exclusive nature; that is, "A or B" includes "A but not B," "B but not A," and "A and B," unless expressly stated otherwise. In this document, the terms "comprises" and "in which" are used as the plain English equivalents of the terms "comprises" and "in which," respectively. Also, in the following claims, the terms "comprises" and "comprising" are open-ended, i.e., systems, devices, articles, compositions, formulations, or processes that contain elements in addition to those recited after such terms in a claim are still considered to be within the scope of that claim. Furthermore, in the following claims, terms such as "first," "second," and "third" are used merely as labels and are not intended to impose numerical requirements on their objects.

[0201] Geometric terms such as "parallel," "perpendicular," "circular," and "square" do not require absolute mathematical precision unless the context clearly dictates otherwise. Instead, such geometric terms account for variations due to manufacturing or equivalent features. For example, if an element is described as "round" or "generally round," components that are not exactly circular (such as slightly rectangular or multi-sided polygons) are also included in this description.

[0202] Method embodiments described herein may be implemented, at least in part, by a machine or computer. Some embodiments may include a computer-readable medium or machine-readable medium encoded with instructions operable to configure an electronic device to perform the methods described in the above embodiments. Such method implementations may include code, such as microcode, assembly language code, high-level language code, etc. Such code may include computer-readable instructions for performing various methods. The code may form part of a computer program product. Furthermore, in one example, the code may be tangibly stored, such as during execution or at other times, on one or more volatile, non-transitory, or non-volatile tangible computer-readable media. Examples of these tangible computer-readable media include, but are not limited to, hard disks, removable magnetic disks, removable optical disks (such as compact disks or digital video disks), magnetic cassettes, memory cards or sticks, random access memory (RAM), read-only memory (ROM), etc.

[0203] The above description is illustrative and not limiting. For example, the above examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments may also be utilized by one of ordinary skill in the art upon reviewing the above description. The Summary is provided to enable the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Additionally, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be construed as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may reside in fewer than all features of a particular disclosed embodiment. Therefore, it is contemplated that the following claims are incorporated into the Detailed Description as examples or embodiments, with each claim standing on its own as an embodiment, and that these embodiments can be combined in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. 1. A footwear sensor system, comprising: a first capacitance sensor including a first electrode pair within the footwear article, the first capacitance sensor configured to provide a first electric field at least partially within the footwear article using a first excitation signal; a second capacitance sensor including a second electrode pair within the footwear item, the second capacitance sensor configured to provide a second electric field at least partially within the footwear item using a second excitation signal; a signal generator configured to provide the first excitation signal and the second excitation signal; and a processor circuit configured to provide a foot presence indication based on information received from the first capacitance sensor and the second capacitance sensor regarding an interruption of the first electric field and the second electric field;

2. The footwear sensor system of claim 1 , wherein the first electrode pair includes a ring electrode and a reference electrode.

3. The footwear sensor system of claim 2 , wherein the ring electrode occupies a first plane and the reference electrode occupies a second plane, the first plane and the second plane being spaced apart by at least a fixed distance.

4. The footwear sensor system of claim 2 , wherein the reference electrode includes a conductor having a planar surface area that exceeds a surface area of ​​the ring electrode.

5. The footwear sensor system of claim 2 , wherein the second electrode pair includes a planar electrode and a reference electrode.

6. The footwear sensor system according to claim 5 , wherein the planar electrode is provided coaxially with the ring electrode, and the planar electrode and the ring electrode are spaced apart from each other.

7. The footwear sensor system of claim 5 , wherein the planar electrode and the ring electrode share a substrate in the first plane.

8. The footwear sensor system of claim 7 , wherein the reference electrode occupies a second plane spaced apart from the first plane.

9. the first electrode pair includes a first electrode and a reference electrode; the second electrode pair includes a second electrode and a reference electrode; 2. The footwear sensor system of claim 1, wherein the signal generator is configured to provide a third excitation signal between the first electrode and the second electrode, and in response, the third electric field extends between the first electrode and the second electrode and within a foot-receiving cavity of the footwear item.

10. 10. The footwear sensor system of claim 9, further comprising the article of footwear, wherein the electrodes of the first capacitance sensor and the second capacitance sensor include respective planar electrode portions disposed parallel to a footbed of the article of footwear.

11. The footwear sensor system of claim 10 , further comprising a sensor housing configured to be positioned within an arch region of a footbed of the article of footwear.

12. The footwear sensor system of claim 1 , wherein the first excitation signal and the second excitation signal have different frequency characteristics.

13. The footwear sensor system of claim 1 , wherein the first excitation signal and the second excitation signal have different amplitude characteristics.

14. The footwear sensor system of claim 1 , wherein the signal generator is configured to provide the first excitation signal and the second excitation signal in a time-multiplexed manner.

15. The footwear sensor system of claim 1 , wherein the signal generator is configured to provide the first excitation signal and the second excitation signal simultaneously.

16. the processor circuit is configured to receive the first response signal from the first capacitive sensor in response to the first excitation signal and the second response signal from the second capacitive sensor in response to the second excitation signal; The footwear sensor system of claim 1 , wherein the processor circuit is configured to provide a foot presence indication based on a sum of the first response signal and the second response signal.

17. the processor circuit is configured to receive the first response signal from the first capacitive sensor in response to the first excitation signal and the second response signal from the second capacitive sensor in response to the second excitation signal; The footwear sensor system of claim 1 , wherein the processor circuit is configured to provide a foot presence indication based on a difference between the first response signal and the second response signal.

18. The first electrode pair of the first capacitance sensor a reference electrode and a composite electrode, the composite electrode including a coplanar and coaxial main electrode and a ring electrode; the second electrode pair of the second capacitive sensor includes the reference electrode and the ring electrode; 18. The footwear sensor system of claim 17, wherein the signal generator is configured to provide the first excitation signal to the composite electrode during a first excitation interval and the second excitation signal to the ring electrode during the second excitation interval, and wherein the main electrode is electrically isolated from the ring electrode during the second excitation interval.

19. 2. The footwear sensor system of claim 1, wherein the processor circuit is configured to determine a liquid saturation level of one or more portions of the footwear article based on information received from the first capacitance sensor and the second capacitance sensor, and the processor circuit is configured to provide a foot presence indication using the determined liquid saturation level.

20. 1. A footwear system comprising: a first electrode; a second electrode, third electrode, a signal generator configured to provide excitation signals to each of the first electrodes, the second electrodes, and / or the third electrodes at different times; and A footwear system including a processor circuit configured to receive electric field information from each of the electrode groups and, in response thereto, determine the presence or absence of a foot within the foot-receiving cavity of the footwear article.

21. a first electrode and a second electrode electrically coupled as an anode; a first electrode group including a third electrode as a cathode; a second electrode group including a first electrode as an anode and a third electrode as a cathode, the second electrode being electrically isolated from the first electrode and the third electrode; a signal generator configured to provide a first alternating current excitation signal to the first group of electrodes at a first time and a second alternating current excitation signal to the second group of electrodes at a different second time.

22. the processor circuit is configured to receive the first response signals from the first group of electrodes at a first time and the second response signals from the second group of electrodes at a second time; 22. The footwear system of claim 21, wherein the processor circuit is configured to use information regarding a difference between the first response signal and the second response signal to determine a liquid saturation level of a portion of the article of footwear.

23. 23. The footwear system of claim 22, wherein the processor circuit is configured to use the determined liquid saturation to determine the presence or absence of a foot within a foot-receiving cavity of the article of footwear.

24. the signal generator is configured to provide a first alternating excitation signal between the first electrode and the second electrode at a first time; 21. The footwear system of claim 20, wherein the signal generator is configured to provide the second alternating current excitation signal between the third electrode and a composite electrode including the first electrode and the second electrode at a second time.

25. 1. A method comprising: providing time-multiplexed first and second excitation signals from a signal generating circuit to respective first and second electrode pairs within the article of footwear, thereby generating respective first and second electric fields within the article of footwear; receiving, with a processor circuit, first and second response signals from the first and second electrode pairs, respectively; and The method includes determining a proximity indication of a foot within the article of footwear using the received first and second response signals.

26. Providing a first excitation signal to the first electrode pair includes providing a first alternating current signal between a ring electrode electrically coupled to a reference electrode and a main electrode; and 26. The method of claim 25, wherein providing a second excitation signal to a second electrode pair comprises providing a second alternating current signal between the reference electrode and the ring electrode.

27. 27. The method of claim 26, wherein determining the foot proximity indication includes using information about a difference between the first response signal and the second response signal.

28. 26. The method of claim 25, further comprising determining a liquid saturation level of a portion of the article of footwear using the first response signal and the second response signal, and wherein determining a foot proximity indication comprises using the determined liquid saturation level.

29. 26. The method of claim 25, wherein providing the first excitation signal comprises electrically coupling the first conductor portion and the second conductor portion of the composite electrode, and providing the second excitation signal comprises electrically isolating the first conductor portion and the second conductor portion of the composite electrode.

30. 30. The method of claim 29, wherein providing a second excitation signal comprises electrically coupling the second conductor portion to a reference electrode.

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