Patent Application
20170027512
The technique introduced here relates to the field of electronic sensor systems for footwear.
The use of orthotic inserts in footwear to assist in the therapy and alignment of the wearer's neuromuscular and skeletal systems is known. One refinement to such orthotics contemplates their use in combination with electronic pressure sensors so that the wearer can be assessed and/or monitored.
Disclosed herein is an orthotic insert configured with an improved electronic sensor layer that provides feedback on important information regarding the wearer's gait mechanics (such as the force and pressure distribution on substantially the complete footprint of the wearer) during walking and other physical activities. The layer of sensors is used to assist in monitoring the wearer's health via foot pressure tracking.
Known existing sensing systems for footwear to date are limited to 8 sensors; in other words, the force/pressure signals from no more than 8 sensors (distributed around the wearer's foot) can be tracked. This is because the signals are processed through an analog-to-digital converter (ADC) device, and presently such ADC devices typically have an 8 channel limit. The technique introduced here is able to utilize 9 or more (substantially more, where appropriate) sensors on the sensor layer. At least one embodiment of the disclosed system incorporates the use of one or more 32-channel analog multiplexers (or multiplexer switches) and Bluetooth 4.0 low-energy technology (the latter being used to transmit/communicate the data), to significantly increase the number of sensors that can be handled. Using a large quantity of standardized sensors allows the sensor layer to be more readily customizable and robust to different foot and gait biomechanics.
Furthermore, existing sensing systems that are used with footwear are generally either impractically thick or not customizable. The manufacturing process disclosed, coupled with the selection of suitable sensors and materials, enables sensor layers having a thickness of less than 2.6 mm to be produced.
The technique introduced here relates to an insert for footwear and to a composite orthotic insole comprising said insert, wherein the insert (or sensor layer) is embedded with a plurality of force (or pressure) sensors, and may be used to gather the wearer's foot pressure data (such as gait biomechanics) during various physical activities. The insert can include 9 or more embedded sensors, which together will provide broad coverage and precise sensing of the human foot impact area. In at least one embodiment, the insert comprises a polydimethylsiloxane (PDMS) covering to seal and protect the layer of sensors, thus providing flexibility, durability and waterproofing of the insert. The applicable data collected from the sensors will be passed to a proximally-located, battery-powered microcontroller (which may be concealed within or beneath the orthotic insole, such as in the area of the foot arch) which can use standard Bluetooth (4.0) communications technology to communicate such data to external devices.
Embodiments of teachings introduced here are described below with reference to the accompanying drawings in which:
Each of the active sensors 26 is shown as having a hexagonal shape (although it should be understood that other shapes of sensors are also possible, such as circular). The general layout of the sensors 26 in relation to a wearer's foot shape is shown in
An embodiment of the technique introduced here is described herein in the form of a sensor layer 22 of an orthotic insert 10. However, it should be understood that the sensor layer could instead be used in combination with a regular insole or insert, or by itself as an insert for footwear.
Below the sensor layer 22 are electronic components. The electronic components include a microcontroller 32, and a wireless communicator 34. Optionally a multiplexer 36 is connected to the microcontroller 32. The sensors 26 are connected to either the microcontroller 32 or the multiplexer 36. There is also a differential contact 38 that runs between the microcontroller 32 and the PSR layer 28 that completes the circuit. The circuit is powered by a battery 40. The battery 40 may be rechargeable or replaceable.
The general functionality of the layers is as follows. The differential contact 38 carries the voltage difference from the battery 40 to the PSR layer 28. The PSR layer 28 changes its resistance when bent, compressed or is otherwise deformed by external forces (in this case, foot impact). The air gap layer 30 is placed below the PSR layer 28 to provide cushioning and support for the PSR layer 28, and therefore regulate how much pressure is required to alter the shape of the PSR layer 28. In other words, The air gap layer 30 regulates how much force or pressure is required to create the resistance difference in the circuit. Where the PSR layer 28 contacts the sensor layer 22 (the particular sensors 26) a circuit is completed. The changing resistance is measured in the microcontroller 32, and converted into digital data points for software interpretation. The recorded voltage enables calculation of the magnitude of pressure applied to the sensor as well as the timing for the applied pressure.
Based on the number of sensors 26, the orthotic insert 20 makes use of the multiplexer 36. Where the microcontroller 32 is configured to accept all of the inputs on the of the sensors 26 directly, no multiplexer 36 is required. Where the number of sensors 26 is greater than the number of sensor inputs on the microcontroller 32, a multiplexer 36 enables additional sensor input to the microcontroller 32. In at least one embodiment, the sensor coverage will be such that a minimum of nine sensors 26 providing pressure data points at all times.
In at least one embodiment, the complete pressure sensors are composed of a Velostat™ layer, an air gap layer, sensor layer and electronic components. Sensors 26 can be sized as desired, possibly in the 5 mm to 40 mm range. The sensors are semi-custom, in that the sensors 26 are based on a standard set of layers, and customized in terms of shape and size to fit the design of the sensor sheet. An example of a suitable off-the-shelf complete pressure sensor that utilizes a usable pressure-sensor configuration is the Teksan™ FlexiForce™ A201.
The sensor sheet can be used in contact with a human foot and placed above an orthotic insert (which itself is preferably one that has been customized to a shape or profile to provide the wearer with specific biomechanical improvements). The sensor layer can provide gait and stride force/pressure feedback to validate these improvements, and predict future orthotic refinements. The gathered data could be used for performance analysis, performance improvement recommendation, health tracking, injury prevention, and various other biomechanical applications.
The sensors are wired through one or more multiplexer switch 36, which can be analog 32-channel switches, for example. From the multiplexer switch 36, the wiring 42 runs to a microcontroller 32, which is limited to 8 inputs. It may be preferable that a particular sensor sheet be made up of sensors 26 that are standardized and the same size, since this makes the sensor sheet more readily customizable and facilitates comparisons (and provides for uniformity) of the various sensor signals from the same foot or from different wearers; however, sensors 26 of differing sizes could be used.
The multiplexer 36 will switch between the sensors 26 rapidly, i.e., fast enough to ensure that any measurable pressure changes can be detected and recorded. The multiplexer 36 switches one of multiple inputs to the common output, determined by a unique binary address lines (samples are marked on each sensor 26).
For 9-16 sensors, a 16-channel analog multiplexer can be used, switching one of 16 inputs to one, determined by four-bit binary address lines (in this case, a 32-channel analog multiplexer could also be used). For 17-32 sensors, a 32-channel analogy multiplexer can be used, switching one of 32 inputs to one, determined by five-bit binary address lines. Alternatively, where appropriate, two or more multiplexers 36 can be used in combination. The signal from the sensors is passed to a microcontroller 32, which can include a microcontroller and associated electronic equipment (including battery unit and communication hardware).
The above-described approach involving relatively large numbers of sensors is practical in combination with the use of electronics that consume small amounts of power (such as low-power sensors) and that require low-power for communication through the wireless communicator 34. Bluetooth 4.0 standard technology, compatible with iBeacon™, for example, can be used to conserve battery life. Other forms of wireless communicators 34 are also suitable such as WiFi or cellular (GSM, CDMA, GPRS, etc . . . ) so long as the wireless communicator 34 is compact.
The production process can start with a set of standard sensor sheets 44. In some embodiments these sensor sheets 44 are categorized for one or more shoe sizes. In some embodiments, the sensor sheets 44 are suitably large to be used for all shoe sizes. The customization of the orthotic inserts 20 begins with the sizing of the sensor sheet 44. Where customized foot sized data is received by the manufacturer, a very particular foot shape may be cut into the sensor sheet 44 matching foot of the intended user as accurately as possible. This is technique is highly customizable, in part, as a result of the repeating, pattern of the sensors 26 on the sensor sheet 44, and that the wiring 42 for each of the sensors 26 is routed towards the center of the sensor sheet 44. Routing the wiring 42 to the center of the sensor sheet 44 enables large variation in the foot size cut 46 into the sensor sheet 44 while still enabling the wiring 42 to function for all remaining sensors 26.
This is illustrated in
The optimal sized sheet is chosen, then trimmed/customized along the trim lines 46A and 46B respectively for the individual foot shape. Each standard sheet size could be produced in bulk using a packaging machine, or produced using additive manufacturing with a modified 3D printer. It also may be preferred to determine sensor spacing based on foot size. For example, relatively smaller foot sizes may require less spacing between sensors than larger sizes. In cases where a standardized sensor sheet 44 is used, there is a positive correlation between a number of sensors 26 to the foot size trim lines 46. Further, in those embodiments there is a static density of sensors 26 despite variance to the foot size trim lines 46.
In some embodiments, the additional instruments 48 are socketed into an insole without the pressure sensors. Rather than use a layered pressure sensor, the additional instruments 48 are inserted into sockets in the surface layer 24. Between the sockets wiring connects the microcontroller 32 and the wireless communicator 34 and the battery 40.
Processed data and signals 49 are either used directly by the external device 50, or forwarded to an applications server 52. The external device 50 may be connected to the application server 52 through wireless, network, or wired connections. In some embodiments, the processed data and signals 49 are used to construct analytical models of the wearer's gait, physical stresses, and body health.
Another possible application for the disclosed system is for entertainment purposes. For example, the foot pressure on the wearer may be tracked through the layer of sensors and used as inputs to a connected user-interactive processing device (such as a video game system or a virtual reality hardware device). The wearer can provide instructions to or otherwise control the processing device, at least in part, via the foot pressure communicated (e.g. the wearer may represent/simulate actions such as jumping, walking, hopping, balancing, etc.).
In step 906, the insole manufacturing station cuts the sensor sheet to the foot size parameter. In doing so, extraneous sensors 26B and wiring 42 for those sensors are stripped away leaving only the sensors 26A which will remain in the sensor layer 22. In step 908, the remainder of the sensor matrix is completed: the PSR layer 28 and the air gap layer 30 are formed. The electronic components (microcontroller 32, multiplexer 36, and wireless communicator 34) are connected to the wiring 42 and the differential contact 38 is connected to the PSR layer 28.
In step 910, any additional instruments 48 are added as suitable. In step 912, the layers, including the surface layer 24 are fixed into positon and a completed custom orthotic insert 20 is ready to ship to the customer.
In step 1008, the orthotic insert 20 completes one or more circuits between the one or more sensors 26 and the PSR layer 28. In step 1010, each completed circuit delivers a signal to a microcontroller 32, each signal including a unique identifier associated with each of the one or more sensors that complete the one or more circuits. In inserts 20 with a multiplexer 36 the unique identifier is determined by a binary code corresponding to the input on the multiplexer 36. In inserts 20 without a multiplexer, the unique identifier is indicated by the input used on the microcontroller 32.
In step 1012, the microcontroller 32 processes the received signals. In step 1014, the microcontroller 32 delivers the processed signals to the wireless communicator 34 for transmission. In step 1016, the signals are analyzed with a measured voltage to determine the magnitude of the pressure supplied by the footfall across each sensor 26 receiving pressure. Step 1016 may be performed either by the microcontroller 32 prior to step 1014, or after step 1014 by an external device 50 or an application server 52.
Depending on how the transmitted data is to be used by the external device 50 or application server 52, the method proceeds to step 1018 or 1020. In step 1018, the external device 50 or application server 52 uses the transmitted signals to develop analytical models of footfalls. In step 1020, the transmitted signals provide user input to an entertainment apparatus such as a game system or virtual/augmented reality apparatus.
The embodiments described herein are not, and are not intended to be, limiting in any sense. One of ordinary skill in the art will recognize that the disclosed technique(s) may be practiced with various modifications and alterations, such as structural and logical modifications. Although particular features of the disclosed technique(s) may be described with reference to one or more particular embodiments and/or drawings, it should be understood that such features are not limited to usage in the one or more particular embodiments or drawings with reference to which they are described, unless expressly specified otherwise.
This application claims the benefit of U.S. Provisional Application No. 62/199,818 of the same title and filed on Jul. 31, 2015, which is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 62199818 | Jul 2015 | US |
