Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/0002—Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
  • A61B5/1036—Measuring load distribution, e.g. podologic studies
  • A61B5/1038—Measuring plantar pressure during gait
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L1/00—Measuring force or stress, in general
  • G01L1/14—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
  • G01L1/142—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators using capacitors
  • G01L1/148—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators using capacitors using semiconductive material, e.g. silicon
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L1/00—Measuring force or stress, in general
  • G01L1/16—Measuring force or stress, in general using properties of piezoelectric devices
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L1/00—Measuring force or stress, in general
  • G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
  • A61B2562/02—Details of sensors specially adapted for in-vivo measurements
  • A61B2562/0247—Pressure sensors
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
  • A61B2562/04—Arrangements of multiple sensors of the same type
  • A61B2562/046—Arrangements of multiple sensors of the same type in a matrix array
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
  • A61B5/7232—Signal processing specially adapted for physiological signals or for diagnostic purposes involving compression of the physiological signal, e.g. to extend the signal recording period

Definitions

• the present invention in its disclosed embodiments is related generally to pressure sensing systems, methods, and computer-program products, and more particularly to such systems, methods, and computer-program products for sensing pressure along the bottom of a user's foot during sports training and monitoring applications, electronic games, and diagnostic systems as will become more apparent hereinafter.
• pressure sensing systems methods, and computer-program products
• computer-program products for sensing pressure along the bottom of a user's foot during sports training and monitoring applications, electronic games, and diagnostic systems as will become more apparent hereinafter.
• the following embodiments may also be applicable to the other pressure sensing applications.
• Athletes utilize various metrics to measure their performance and chart their workouts.
• the metrics are recorded and analyzed both during and after workouts.
• interval type workouts typically involve multiple sets of intense activity, semi-intense activity, and rest.
• the intense activity may be characterized by a range of metrics which correlate to the desired intensity for a particular athlete.
• the rest or semi-intense activity periods may be characterized by a range or metrics which correlate to the desired restful state for a particular athlete.
• the human foot combines mechanical complexity and structural strength.
• the ankle serves as foundation, shock absorber, and propulsion engine.
• the foot can sustain enormous pressure (i.e., in the range of about several tons over the course of a one-mile run) and provides flexibility and resiliency.
• the foot and ankle contain 26 bones (i. e., nearly one-quarter of the bones in the human body are in the feet); 33 joints; more than 100 muscles, tendons (i.e., fibrous tissues that connect muscles to bones), and ligaments (i.e., fibrous tissues that connect bones to other bones); and a network of blood vessels, nerves, skin, and soft tissue.
• Embodiments of the present invention help sense the pressure exerted at a plurality of points of the user's feet to help alleviate such problems.
• the foot has three main parts: the forefoot, the midfoot, and the hindfoot.
• the forefoot as shown in FIGS. 2A and 2B is composed of the five toes (called phalanges) and their connecting long bones (metatarsals).
• Each toe (phalanx) is made up of several small bones.
• the big toe also known as the hallux
• the big toe articulates with the head of the first metatarsal and is called the first metatarsophalangeal joint (MTPJ for short). Underneath the first metatarsal head are two tiny, round bones called sesamoids.
• the other four toes each have three bones and two joints.
• the phalanges are connected to the metatarsals by five metatarsal phalangeal joints at the ball of the foot.
• the forefoot bears half the body's weight and balances pressure on the ball of the foot.
• the midfoot has five irregularly shaped tarsal bones, forms the foot's arch, and serves as a shock absorber.
• the bones of the midfoot are connected to the forefoot and the hindfoot by muscles and the plantar fascia (arch ligament).
• the hindfoot is composed of three joints and links the midfoot to the ankle (talus).
• the top of the talus is connected to the two long bones of the lower leg (tibia and fibula), forming a hinge that allows the foot to move up and down.
• the heel bone (calcaneus) is the largest bone in the foot. It joins the talus to form the subtalar joint.
• the bottom of the heel bone is cushioned by a layer of fat.
• a network of muscles, tendons, and ligaments supports the bones and joints in the foot.
• the main muscles of the foot are: the anterior tibial, which enables the foot to move upward; the posterior tibial, which supports the arch; the peroneal tibial, which controls movement on the outside of the ankle; the extensors, which help the ankle raise the toes to initiate the act of stepping forward; and the flexors, which help stabilize the toes against the ground. Smaller muscles enable the toes to lift and curl.
• tendons elastic tissues in the foot that connect the muscles to the bones and joints.
• Achilles tendon which extends from the calf muscle to the heel. Its strength and joint function facilitate running, jumping, walking up stairs, and raising the body onto the toes.
• Ligaments hold the tendons in place and stabilize the joints.
• the longest of these, the plantar fascia forms the arch on the sole of the foot from the heel to the toes. By stretching and contracting, it allows the arch to curve or flatten, providing balance and giving the foot strength to initiate the act of walking.
• Medial ligaments on the inside and lateral ligaments on outside of the foot provide stability and enable the foot to move up and down. Skin, blood vessels, and nerves give the foot its shape and durability, provide cell regeneration and essential muscular nourishment, and control its varied movements.
• Pressure sensing methods, systems, and computer-program products in particular may be used to sense pressure at a plurality of points of a user's foot, including its bones, joints, muscles, tendons, and ligaments.
• a sensing system generally comprising a transducer having a plurality of points of interest, first means for collecting and transmitting data sensed at the plurality of points of interest, first means for coupling that data across a network by way of second means coupling same to a collector node and then to a computer for analysis.
• a "computer” may refer to one or more apparatus and/or one or more systems that are capable of accepting a structured input, processing the structured input according to prescribed rules, and producing results of the processing as output.
• Examples of a computer may include: a computer; a stationary and/or portable computer; a computer having a single processor, multiple processors, or multi-core processors, which may operate in parallel and/or not in parallel; a general purpose computer; a supercomputer; a mainframe; a super mini-computer; a mini-computer; a workstation; a microcomputer; a server; a client; an interactive television; a web appliance; a telecommunications device with internet access; a hybrid combination of a computer and an interactive television; a portable computer; a tablet personal computer (PC); a personal digital assistant (PDA); a portable telephone; application-specific hardware to emulate a computer and/or software, such as, for example, a digital signal processor (DSP), a field-programmable gate array (FPGA), an application specific integrated
• Software may refer to prescribed rules to operate a computer.
• Examples of software may include: code segments in one or more computer- readable languages; graphical and or/textual instructions; applets; precompiled code; interpreted code; compiled code; and computer programs.
• a "computer-readable medium” may refer to any storage device used for storing data accessible by a computer. Examples of a computer-readable medium may include: a magnetic hard disk; a floppy disk; an optical disk, such as a CD-ROM and a DVD; a magnetic tape; a flash memory; a memory chip; and/or other types of media that can store machine-readable instructions thereon.
• a "computer system” may refer to a system having one or more computers, where each computer may include a computer-readable medium embodying software to operate the computer or one or more of its components.
• Examples of a computer system may include: a distributed computer system for processing information via computer systems linked by a network; two or more computer systems connected together via a network for transmitting and/or receiving information between the computer systems; a computer system including two or more processors within a single computer; and one or more apparatuses and/or one or more systems that may accept data, may process data in accordance with one or more stored software programs, may generate results, and typically may include input, output, storage, arithmetic, logic, and control units.
• a "network” may refer to a number of computers and associated devices that may be connected by communication facilities.
• a network may involve permanent connections such as cables or temporary connections such as those made through telephone or other communication links.
• a network may further include hard-wired connections (e.g., coaxial cable, twisted pair, optical fiber, waveguides, etc.) and/or wireless connections (e.g., radio frequency waveforms, free-space optical waveforms, acoustic waveforms, etc.).
• Examples of a network may include: an internet, such as the Internet; an intranet; a local area network (LAN); a wide area network (WAN); and a combination of networks, such as an internet and an intranet.
• Exemplary networks may operate with any of a number of protocols, such as Internet protocol (IP), asynchronous transfer mode (ATM), and/or synchronous optical network (SONET), user datagram protocol (UDP), IEEE 802.x, etc.
• IP Internet protocol
• ATM asynchronous transfer mode
• SONET synchronous optical
• Embodiments of the present invention may include apparatuses for performing the operations disclosed herein.
• An apparatus may be specially constructed for the desired purposes, or it may comprise a general-purpose device selectively activated or reconfigured by a program stored in the device.
• Embodiments of the invention may also be implemented in one or a combination of hardware, firmware, and software. They may be implemented as instructions stored on a machine-readable medium, which may be read and executed by a computing platform to perform the operations described herein.
• computer program medium and “computer readable medium” may be used to generally refer to media such as, but not limited to, removable storage drives, a hard disk installed in hard disk drive, and the like.
• These computer program products may provide software to a computer system. Embodiments of the invention may be directed to such computer program products.
• references to "one embodiment,” “an embodiment,” “example embodiment,” “various embodiments,” etc., may indicate that the embodiment(s) of the invention so described may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Further, repeated use of the phrase “in one embodiment,” or “in an exemplary embodiment,” do not necessarily refer to the same embodiment, although they may.
• connection along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, “connected” may be used to indicate that two or more elements are in direct physical or electrical contact with each other. "Coupled” may mean that two or more elements are in direct physical or electrical contact. However, “coupled” may also mean that two or more elements are not in direct contact with each other, but yet still cooperate or interact with each other.
• An algorithm is here, and generally, considered to be a self-consistent sequence of acts or operations leading to a desired result. These include physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers or the like. It should be understood, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities.
• processor may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory.
• a “computing platform” may comprise one or more processors.
• FIG. 1 illustrates a sensing system according to a first embodiment of the present invention
• FIGS. 2A and 2B illustrate parts of the human foot, some of which may be sensed by the sensing system shown in FIG.1 ;
• FIG. 3 illustrates a portion of the sensing system shown in FIG. 1 , with an exploded view of a transducer according thereto;
• FIG. 4 illustrates in schematic format electrode grid selector mapping means which may be used with the transducer shown in FIG. 3;
• FIG. 5 illustrates in schematic format a controller which incorporates the electrode grid selector mapping means shown in FIG. 4;
• FIG. 6 illustrates a graph showing the dependency of the resistance of the transducer as a function of pressure sensed by same
• FIG. 7 illustrates a flowchart of the transmission of data sensed by the sensing system of FIGS. 1 and 3-6;
• FIG. 8 illustrates a first electrode grid layer of a transducer according to another embodiment of the present invention.
• FIG. 9 illustrates a second electrode grid layer which may be used with the first electrode grid layer of a transducer according to another embodiment of the present invention.
• FIGS. 10A-10F illustrate in schematic format portions of an RF module which may be used with the first and second electrode grid layers shown in FIGS. 8 and 9;
• FIGS. 11 and 12 illustrate a first and a second algorithm which may be used with transducers according to FIGS. 8, 9 and 10A-10F. Detailed Description of the Embodiments
• FIG. 1 a sensing system 100 according to a first embodiment of the present invention.
• System 100 generally comprises a transducer 102 having a plurality of points of interest 104a, 104b, 104c, 104d, 104e, an insole node 106 for collecting and transmitting data sensed at the plurality of points of interest 104a through 104e, first means 108 for coupling that data across a network 110, by way of second means 112 for coupling same to a collector node 114, and then to a computer 1 16.
• FIG. 3 illustrates a portion of the sensing system 100 shown in FIG. 1 , with an exploded view of a transducer 300 according thereto.
• the insole of sensing system 100 comprises a foot force transducer 300 which may include a continuous capacitance pressure sensor system.
• Conventional foot force transducers have discrete arrays of capacitors formed by overlapping two sets of conducting strips laid in orthogonal directions on opposite sides of a center layer in a three-layer configuration.
• the continuous capacitance pressure sensor elements of the insoles are made using a pressure sensitive variable conductive polymer 302 between conductive traces 304, 306 on sheets 308, 310 of flexible circuit made of a flexible polymer film laminated to a thin sheet of copper that is etched to produce the conductor patterns.
• This polyimide film is high heat resistance, has dimensional stability, good dielectric strength, with high flexibility, which allows it to survive hostile environments.
• the continuous resistive/capacitive sensor layer may be an extruded electrostatic discharge (ESD) type ultra high-density conductive XPU foam. This is used to protect against very-high voltage ESD and provide a compressible form factor for physical device protection against movement shock.
• ESD electrostatic discharge
• the material provides linear resistive and capacitive characteristics through a range of compression forces (0 - 30 psi) as shown in FIG. 6.
• the XPU foam used in layer 302 is a semiconductor that changes its characteristic impedance as a function of applied pressure or compression. As FIG. 6 shows, the impedance characteristics of the material are non-linear at low applied pressures (e.g., less than 10 psi) or compression, and become linear as the applied pressure or compression increases. Thicknesses of the XPU material is also a determining factor of characteristic XPU material impedance.
• the impedance function is characterized by:
• the characteristic impedance of the XPU material may be profiled algorithmically with embedded software running on a processor of sensing system 100.
• variable pressure analysis point techniques may be used to dynamically map a plurality of points/regions of interest for the foot pressure measurement. For instance, and referring again to FIG. 1 , a portion of the heel area 104a and the toe areas 104c, 104d may be measured for approximately 10 milliseconds, while an arch area 104e may be measured for 25 milliseconds. This would allow for pattern measurements, for instance, in the case of persons with diabetes, where the nerve damage as a result of the disease does not allow the person to become aware of the fact that certain areas of the feet are swelling. By using targeted pattern measurement, alerts to changes in plantar foot pressure variations may be provided.
• piezoceramic materials which may provide capacitive, piezoelectric, and/or resistive effects may also be used.
• the transducer 300 of sensing system 100 incorporates these modular lightweight, high resolution, continuous pressure sensing shoe insoles, which may be reconfigurable for varying arrangements, to wirelessly transmit through an RF module 312, detailed pressure data to a computer 1 16, where the data may be collated and collectively displayed.
• Sensing system 100 may be integrated with other systems (e.g., vision based sensing systems) to provide robust multi-modal sensing capabilities. Sensing system 100, thus, not only provides a series of applications for data analysis/visualization, data recording and playback, but also may be grouped together to form clusters of sensing systems that send real-time data to computers.
• Sensing system 100 detects the changes in the electrical properties of continuous capacitance pressure sensors, caused by the mechanical deformation of its material. It may have typical recording durations of about one second at a sampling rate of 50 Hz for a transducer 300 comprising 200 elements, which results in about 10,000 pressure data points per transducer per second. With this volume of information, visual presentation and data reduction techniques may be used.
• the graphical representation of pressure distribution may be through wire frame diagrams 314. These pressure maps are obtained for each sampling interval or at specific instants during the foot- ground contact.
• a peak pressure graphical representation 316 may also be used to illustrate individual foot contact behavior with the ground. This image may be created by presenting the highest pressures under the foot, as they have occurred at any time during the ground contact.
• Sensing system 100 is able to measure plantar pressure during bipedal standing, which results in about 2.6 times higher heel against forefoot pressures. The highest forefoot pressures are located under the second and third metatarsal heads. There is almost no load sharing contribution of the toes during this standing period. The peak plantar pressures indicate no substantial relationship to body weight. Sensing system 100 measures foot pressures during bipedal standing, walking, and running and shows the highest pressures under the forefoot are found under the third metatarsal head. For bipedal standing as well as walking, peak pressures beneath the third metatarsal head are substantially higher than under the other metatarsal heads.
• sensing system 100 When running, during the impact phase of the ground reaction force, the momentum from the decelerating limb rapidly changes as the foot collides with the ground, resulting in a transient force transmitted up the skeleton. These forces reach magnitudes of up to three times body weight. The repetitive transmission of these forces contributes to degradation and overuse injuries.
• sensing system 100 to measure plantar pressure distributed over the sole of a foot during running allows for an early determination of potential degradation and overuse injury by profiling the foot's biomechanical characteristics as a result of the impact phase of the ground reaction force.
• FIG. 4 illustrates in schematic format electrode grid selector mapping means 400 which may be used with the transducer shown in FIG. 3.
• the grid selector mapping means 400 may comprise a combination of logic, firmware, and hardware in a suitable microcontroller.
• Transducer 300 comprises three layers of conductive foam 302 between the electrode grids (not shown in FIG. 4) on sheets 308, 310. Such three-layer configuration is electrically coupled between +V CC and ground by way of a bias resistor 402. Vfout from sheet 308 is input to a 10-bit analog-to-digital converter (ADC) 406, which outputs ten bits of digital output.
• ADC analog-to-digital converter
• FIG. 5 illustrates in schematic format a microcontroller 500 which incorporates the electrode grid selector mapping means shown in FIG. 4.
• sensing system 100 On start up, sensing system 100 first determines if it will be a collector node 114 or an insole node 106. It does this by determining first if any wired interfaces exist. This would be the case if sensing system 100 was to be a collector node 114, since a USB interface will exist to allow for attachment to computer 116.
• sensing system 100 would initialize the MCU
• MCUInit is the master initialization routine which turns off the MCU watchdog, and sets the timer module in order to use BUSCLK as a reference with a pre-scaling of 32.
• the state variable gu ⁇ RTxMode would be set to SYSTEM_RESET_MODE, and routines GPIOInit, SPIInit, and IRQInit would be called.
• the state variable gu ⁇ RTxMode would be set to RF_TRANSCEIVER_RESET_MODE and the IRQFLAG would be checked to see if IRQ is asserted.
• the RF transceiver interrupts would first be cleared, using SPIDrvRead. Then, RF transceiver would be checked for ATTN IRQ interrupts.
• MCUInit calls would be made to PLMEPhyReset (in order to reset the physical MAC layer), IRQACK (in order to ACK the pending IRQ interrupt), and IRQPinEnable (to pin Enable, IE, IRQ CLR, on signal's negative edge).
• RF packets from insole nodes 106 is ready to receive RF packets from insole nodes 106. This would be started by creating a RF packet receive queue that is driven by a call back function on RF transceiver packet receive interrupts.
• a check would first be made to determine if that packet is from a new insole node 106 or an existing one. If from an existing insole node 106, RF packet sequence numbers would be checked to determine continuous synchronization before further analyzing the packet. If from a new insole node 106, an insole node context state block would be created and initialized. Above this RF packet session level process for node- to-node communication, is the analysis of the RF packet data payload. This payload would contain the compressed plantar foot pressure profile based on the current variable pressure analysis map. The first part of the compressed data would contain a map mask array, which may be structured as follows:
• a bit in the FootMaskArray(row 1 , row 2, ... , row m) would be set to one for data that is 255 in value.
• Each row representation byte would use 6 bits ⁇ i.e., the upper two bits would be zero and reserved for future use) to refer to each analog-to-digital (A/D) channel, of which there are six in the current utility.
• the FootRowMask[k] array would be scanned for non-active values ⁇ i.e., no compression). The location in the FootRowMask[k] array where to set the no compression value bit would then be determined.
• This may be done by first finding out which byte of 16 (which represent rows) in the FootRowMask[k] array is the row that has a no compression value in it. The base value that brings in the row byte of interest would then be removed, and the remainder may be used as a bit mask and XORed with existing contents, which could be other no compression values already identified.
• the collector node 114 would use the SCITransmitArray routine to send such decompressed RF packet data (gsRxPacket .pu ⁇ Data and gsRxPacket .u ⁇ DataLength) to the connected computer 116 via the USB interface (not shown).
• the insole pressure data would then be formatted as follow:
• the 2.4 GHz Industrial, Scientific, and Medical (ISM) band Radio Frequency (RF) transceiver which may be used herein is compliant with 802.15.4. It contains a complete 802.15.4 physical layer (PHY) modem designed for the 802.15.4 wireless standard, which supports peer-to- peer, star, and mesh networking. It is combined with an MPU to create the wireless RF data link and network according to various embodiments of the present invention.
• the transceiver e.g., RF module 312) supports both 250 kbps O-QPSK data in 5.0 MHz channels and full spread-spectrum encode and decode.
• sensing system node device's RF transceiver interface port All control, reading of status, writing of data, and reading of data is done through the sensing system node device's RF transceiver interface port.
• the sensing system node device's MPU accesses the sensing system node device's RF transceiver through interface "transactions" in which multiple bursts of byte-long data are transmitted on the interface bus. Each transaction is three or more bursts long depending on the transaction type. Transactions are always read accesses or write accesses to register addresses. The associated data for any single register access is always 16 bits in length.
• Receive mode is the state where the sensing system node device's RF transceiver is waiting for an incoming data frame.
• the packet receive mode allows the sensing system node device's RF transceiver to receive the whole packet without intervention from the sensing system node device's MPU.
• the entire packet payload may be stored in RX Packet RAM and the microcontroller fetches the data after determining the length and validity of the RX packet.
• the sensing system node device's RF transceiver waits for a preamble followed by a Start of Frame Delimiter. From there, the Frame Length Indicator is used to determine the length of the frame and calculate the Cycle Redundancy Check (CRC) sequence. After a frame is received, the sensing system node device's application determines the validity of the packet. Due to noise, it is possible for an invalid packet to be reported with either of the following conditions: a valid CRC and a frame length (0, 1 , or 2) and/or an invalid CRC/invalid frame length. [0063] The sensing system node device's application software determines if the packet CRC is valid and that the packet frame length is valid with a value of 3 or greater.
• the sensing system node device's MPU determines the validity of the frame by reading and checking valid frame length and CRC data.
• the receive packet RAM port register is accessed when the sensing system node device's RF transceiver is read for data transfer.
• the sensing system node device's RF transceiver transmits entire packets without intervention from the Invention node device's MPU.
• the entire packet payload is pre-loaded in TX Packet RAM, the sensing system node device's RF transceiver transmits the frame, and then the transmit complete status is set for the sensing system node device's MPU.
• a transmit interrupt routine that runs on the sensing system node device's MPU reports the completion of packet transmission.
• the sensing system node device's MPU reads the status to clear the interrupt and check successful transmission.
• SPI Serial Peripheral Interface
• a singular SPI read or write transaction comprises an 8-bit header transfer followed by two 8-bit data transfers.
• the header denotes access type and register address.
• the following bytes are read or write data.
• the SPI also supports recursive "data burst" transactions, in which additional data transfers can occur. The recursive mode is primarily intended for packet RAM access and fast configuration of the sensing system node device's RF transceiver.
• the sensing system When the sensing system determines that it is to operate in an insole mode, it will reset its state flag, FootsteppacketRecvd, and will call its MLMERXEnabieRequest routine while enabling a LOW_POWER_WHILE state.
• the insole node 106 will then wait 250 milliseconds for a response from the collector node 114 to determine whether a default full insole electrode scan will be done or a mapped electrode scan will be initiated. In the case of a mapped electrode scan, the collector node send the appropriate electrode scan mapping configuration data.
• the columns which are attached to the MCU analog signal ports will sample and read the current voltage on the column lines and convert them into digital form which is the plantar foot pressure across that selected row. All rows may be sequentially scanned and the entire process repeated until a reset condition or inactivity power-down mode.
• the plantar foot pressure data is compressed by clearing the bit map mask array, which may be structured as follows:
• FootMaskArray [k] This is where a bit in the FootMaskArray [k] is set to one for data that is no compression in value.
• Each row representation byte uses 6 bits (i.e., the upper two bits would be zero and reserved for future use) to refer to each A/D channel, of which there are six.
• a call is made to the routine FootsetMask with parameters FootRowMaskindex and Maskvaiue set accordingly. Then, based on Maskvaiue, an XOR operation is performed on FootRowMask iR] with a selected mask value ⁇ 0x01 ; 0x02; 0x04; 0x08; 0x10; 0x20; ⁇ .
• mask length setting may be updated with 2 added 2 for CRC and 2 for code bytes.
• a call is made to spiorvwrite to update the TX packet length field.
• a call to spiciearRecievestatReg is made to clear the status register followed by a call to spiciearRecieveoataReg to clear the receive data register to make the SPI interface ready for reading or writing.
• OxFF character which represents the 1st code byte.
• spiwaitTransf erDone is called to verify the send is done.
• spisendchar is called again to send a 0x7E byte, which is the second code byte and then the spiwaitTransf erDone is called again to verify the send is done.
• the rest of the packet is sent using a for loop where psTxPkt->u8Datal_ength+1 are the number of iterations to a Series Of Sequential to SPISendChar, SPIWaitTransf erDone , spiciearRecieveDataReg.
• the RF transceiver is loaded with the packet to send.
• the ANTENNA_SWITCH is set to transmit, the LNA_ON mode enabled and finally a RTXENAssert call made to actually send the packet.
• sensing system 100 in this manner, by using continuous two-dimensional pressure sensing grids with variable mapping capability, a three-dimensional, real-time plantar pressure may be obtained and wirelessly transmitted to a remote location for analysis and display. Further details regarding the programming of sensing system 100 in the manner described above may be found in Wireless Sensing Triple Axis Reference Design Designer Reference Manual, Document Number ZSTARRM, Rev. 3, 01/2007, and Simple Media Access Controller (SMAC) User's Guide. Document Number SMACRM, Rev. 1.2, 04/2005, each of which is a publication of Freescale Semiconductor, Inc. and is incorporated herein by reference.
• FIG. 8 there is shown a first electrode grid layer 800 of a transducer according to another embodiment of the present invention.
• Layer 800 is comparable to layer 308 shown in FIG. 3.
• a plurality of lateral grid members 802 are electrically coupled to RF module 312, as are a plurality of longitudinal grid members 804.
• FIG. 9 illustrates a second electrode grid layer 900 which may be used with the first electrode grid layer 800.
• Layer 900 is comparable to layer 310 shown in FIG. 3.
• the plurality of longitudinal members 902 are coupled to RF module 312, and cooperate with the first electrode grid layer 800 and conductive foam layer 302 (not shown in FIGS. 8 or 9) to sense pressure at a plurality of points of interest along the user's feet.
• FIGS. 10A-10F illustrate in schematic format portions of an RF module
• FIG. 10A a portion of the schematic relating to a flexible PCB connection 1000 is shown. Rows and columns of the electronic grids in the mapped array may be coupled to the RF module 312.
• FIG. 10B illustrates a portion of the schematic relating to a battery 1002.
• a suitable battery may comprise a Model No. BK-877, with a CR2450 Coin Cell Retainer SMD made of phosphor bronze, nickel finished contacts, and a Mylar battery insulator.
• One exemplary accelerometer 1004 may be the model MMA7260QT ⁇ 1.5g - 6g Three Axis Low-g Micromachined Accelerometer manufactured by Freescale Semiconductor, Inc. of Tempe, Arizona USA.
• This low cost capacitive micromachined accelerometer features signal conditioning, a 1-pole low pass filter, temperature compensation and g-Select which allows for the selection among 4 sensitivities.
• Zero-g offset full scale span and filter cut-off are factory set and require no external devices. It includes a Sleep Mode that makes it ideal for handheld battery powered electronics.
• Accelerometer 1004 is a surface-micromachined integrated-circuit accelerometer.
• the device consists of two surface micromachined capacitive sensing cells (g-cell) and a signal conditioning ASIC contained in a single integrated circuit package.
• the sensing elements are sealed hermetically at the wafer level using a bulk micromachined cap wafer.
• the g-cell is a mechanical structure formed from semiconductor materials (polysilicon) using semiconductor processes (masking and etching). It can be modeled as a set of beams attached to a movable central mass that move between fixed beams. The movable beams can be deflected from their rest position by subjecting the system to an acceleration. [0079] As the beams attached to the central mass move, the distance from them to the fixed beams on one side will increase by the same amount that the distance to the fixed beams on the other side decreases. The change in distance is a measure of acceleration.
• the ASIC uses switched capacitor techniques to measure the g-cell capacitors and extract the acceleration data from the difference between the two capacitors.
• the ASIC also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratiometric and proportional to acceleration.
• the g-Select feature allows for the selection among 4 sensitivities present in the device. Depending on the logic input placed on pins 1 and 2, the device internal gain will be changed allowing it to function with a 1.5g, 2g, 4g, or 6g sensitivity (Table 1 below). This feature is ideal when a product has applications requiring different sensitivities for optimum performance. The sensitivity can be changed at anytime during the operation of the product.
• the g-Select1 and g-Select2 pins can be left unconnected for applications requiring only a 1.5g sensitivity as the device has an internal pull-down to keep it at that sensitivity (800mV/g).
• Accelerometer 1004 may provide a Sleep Mode that is ideal for battery operated products. When Sleep Mode is active, the device outputs are turned off, providing significant reduction of operating current. A low input signal on pin 12 (Sleep Mode) will place the device in this mode and reduce the current to 3 ⁇ A typ. For lower power consumption, it is recommended to set g- Selecti and g-Select2 to 1.5g mode. By placing a high input signal on pin 12, the device will resume to normal mode of operation
• Accelerometer 1004 also contains onboard single-pole switched capacitor filters. Because the filter is realized using switched capacitor techniques, there is no requirement for external passive components ⁇ i.e., resistors and capacitors) to set the cut-off frequency.
• Ratiometricity simply means the output offset voltage and sensitivity will scale linearly with applied supply voltage. That is, as supply voltage is increased, the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. This is a key feature when interfacing to a microcontroller or an A/D converter because it provides system level cancellation of supply induced errors in the analog to digital conversion process.
• the VDD line should have the ability to reach 2.2 V in ⁇ 0.1 ms as measured on the device at the VDD pin Rise times greater than this most likely will prevent start up operation. Physical coupling distance of the accelerometer to the microcontroller should be minimal. The flag underneath the package is internally connected to ground It is not recommended for the flag to be soldered down. A ground plane should be placed beneath the accelerometer 1004 to reduce noise. The ground plane should be attached to all of the open ended terminals. An RC filter with a 1.0 k ⁇ resistor 1006 and a 0.1 ⁇ F capacitor 1008 may be used on the outputs of the accelerometer 1004 in order to minimize clock noise (from the switched capacitor filter circuit). PCB layout of power and ground should not couple power supply noise.
• Accelerometer and microcontroller should not be a high current path.
• A/D sampling rate and any external power supply switching frequency should be selected such that they do not interfere with the internal accelerometer sampling frequency (11 kHz for the sampling frequency). This will prevent aliasing errors.
• PCB layout should not run traces or vias under the QFN part. This could lead to ground shorting to the accelerometer flag.
• accelerometer 1004 Further details regarding accelerometer 1004 may be found in
• FIGS. 10D-10F there are shown portions of the schematic relating to a microcontroller 1010 and transceiver 1012, including a balun 1014 and crystal oscillator 1016, which may be used according to embodiments of the present invention.
• One exemplary platform incorporating both functions may be the model MC13213 ZigBeeTM- Compliant Platform - 2.4 GHz Low Power Transceiver for the IEEE® 802.15.4 Standard plus Microcontroller manufactured by Freescale Semiconductor, Inc. of Tempe, Arizona USA.
• the MC1321x family is Freescale's second-generation ZigBee platform which incorporates a low power 2.4 GHz radio frequency transceiver and an 8-bit microcontroller into a single 9x9x1 mm 71 -pin LGA package.
• the MC1321x solution can be used for wireless applications from simple proprietary point-to-point connectivity to a complete ZigBee mesh network.
• the combination of the radio and a microcontroller in a small footprint package allows for a cost-effective solution.
• the MC1321x contains an RF transceiver which is an 802.15.4 compliant radio that operates in the 2.4 GHz ISM frequency band.
• the transceiver includes a low noise amplifier, 1mW nominal output power, PA with internal voltage controlled oscillator (VCO), integrated transmit/receive and decoding
• the MC1321x also contains a microcontroller based on the HCS08 Family of Microcontroller Units (MCU), specifically the HCS08 Version A, and can provide up to 60KB of flash memory and 4KB of RAM
• MCU Microcontroller Unit
• the onboard MCU allows the communications stack and also the application to reside on the same system-in-package (SIP)
• the MC13213 contains 6OK of flash and 4KB of RAM and is also intended for use with the Freescale fully compliant 802 15 4 MAC and the fully ZigBee compliant Freescale BeeStack
• FIGS. 11 and 12 illustrate a first and a second algorithm which may be used with transducers according to FIGS. 8, 9 and 10A-10F.
• Sensing system 100 may use an exponential moving average filter in conjunction with a sliding window boxcar style integrator to per-process digitize real-time acceleration data for all three dimensions Ax, Ay, Az.
• the accumulated acceleration data may be analyzed to identify unique motion artifacts such as strides and steps and their respective directions.
• Reference frames may be created to provide variable time sequences of motion artifacts.
• the XPU conductive foam allows for gating reference frames such as the start of step (i.e., a standing position - rising foot to start stride) and the end of step (Ae., a falling foot - to standing position).
• Sensing system 100 is, thus, sensitive enough to measure the plantar pressures differences between adult male and female foot pressures under the longitudinal arch. Under the mid-foot, females have reduced peak foot pressures during standing. Also, for females, there is a correlation between body weight and foot pressures under the longitudinal arch of a female's feet in walking. This allows for sensing system 100 to analyze the ligamentous structure which results to some degree in collapse of the longitudinal arch during weight bearing phase of walking.
• Sensing system 100 is able to perform similar foot function analysis during running. Specifically, sensing system 100 may analyze mid-foot loading as well as the amount of rear-foot rotation which is more apparent in female runners as compared to male runners. In the case for children, contrary to adults, body weight is identified to be of major influence on the magnitude of the pressures under the feet of children and between boys and girls no differences in the foot pressure or relative load patterns are present. Sensing system 100 may be used in such cases periodically to analyze potential walking/running/gait related issues in children as they develop. This may provide data that may help in development of proper in-soles and other support structures to aid in the renormalizing walking/running/gait related issues.
• Sensing system 100 may also help determine the cause of pain and lower extremity complaints for overweight and obese persons.
• the system's ability to analyze plantar pressure analysis may provide additional insight into pain and lower extremity complaints.
• Plantar pressure differences between obese and non-obese adults during standing and walking indicates that the overweight persons have an increase in the forefoot width to foot length ratio. This is due to the broadening of the forefoot under increased weight loading conditions. Even though there is the increased load bearing contact area with the foot against the ground, overweight persons have substantially higher foot pressures under the heel, mid-foot, and forefoot during standing, walking and running.
• Sensing system 100 measures larger foot pressures under the mid-foot during standing periods for the obese women as compared to the obese men. There is a major influence of body weight on the flattening of the arch is the consequence of the inherent reduced strength of the ligaments in natively in women's feet. This may contribute to lower extremity pain and discomfort in these obese persons and their choice of footwear and predisposition to participation in activities of daily living such as walking and running. For walking, the forefoot pressures as well as the forefoot contact area are substantially increased for obese women. Sensing system 100 may analyze and monitor this increased forefoot plantar pressures, which in most cases result in foot discomfort and hinders these obese women in participating normally in physical activity.
• Sensing system 100 may also help runners manage overuse injuries.
• Biomechanical parameters such as real-time foot pressures may be identified and analyzed by sensing system 100 to help identify key properties of athletic footwear in providing overuse injury protection and performance enhancement. Such parameters may be mid- sole material properties, which may provide information about footwear production tolerances.
• Sensing system 100 may also measure and record rear-foot rotation, foot pressure patterns, and shock absorption properties running shoes/athletic footwear to analyze shoe characteristics which may help reduce the risk of overuse injuries. Thus, sensing system 100 may be used to evaluate shoe fit and comfort during running on various terrain types. The system's long term monitoring and archive capability allows for analyzing deterioration of shoe properties over time and use.
• Sensing system 100 may also record in real-time in-shoe pressure during running and training and provides information of the interaction between footwear and foot mechanics of the person wearing them. Over rotation during running and training is responsible for many overuse injuries. Typically, restriction of excessive rear-foot motion and improved shock absorption may reduce the risk of running and training injuries. The determination and measurement of subtalar joint rotation are critical the evaluation of running and training shoes. Capturing real-time subtalar joint rotation measurement data is one of the main features of the sensing system.
• Sensing system 100 may also determine wear and tear with the assessment monitoring and recording features. It has the ability to detect, capture and analyze foot pressure data wirelessly and in real-time variations in rear-foot motion combined with the differences in mid-sole properties to determine shoe cushioning differences to categorize overall stiffness of the shoe. These stiffness characteristic tend to alter the wears landing patterns to elicit lower impact forces. This allows for constructing biomechanical assessments that are beneficial for the wearer using such shoes to minimize injuries resulting from repeated impact loading. The wear of the insole will be displayed outside the shoe as green, yellow, red graphic display indications to illustrate the degree of shoe wear.
• Sensing system 100 may also perform weight and power assessment by foot zones (e.g., heel, mid-foot, and forefoot). Sensing system 100 has capability to detect, capture and analyze foot pressure data wirelessly and in real-time relating to vertical ground reaction force patterns and materials characterization of running shoes with advanced cushioning column systems during walking, running, and/or training.
• foot zones e.g., heel, mid-foot, and forefoot.
• Sensing system 100 has capability to detect, capture and analyze foot pressure data wirelessly and in real-time relating to vertical ground reaction force patterns and materials characterization of running shoes with advanced cushioning column systems during walking, running, and/or training.
• Sensing system 100 may also detect changes in foot sole pressure patterns during activity so that a subjects footfall changes/patterns may be determined during a specific event and correlated against multiple events (e.g., practice versus game activity). To be able to detect slight variations of pressure over time - like the loss of fluid within a running race. The ability to transmit this information wirelessly to a collection site or monitor.
• Sensing system 100 may also detect changes in power patterns during a specific sporting event and calculate power/energy requirements against expected output. Energy vector analysis versus current and expected output.
• Sensing system 100 may also provide the monitoring and analysis required for dance and kinesiology applications, interactive dance movements (e.g., learn to dance as a game application where a subject is signaled in one way when they are taking the right steps and another when they are wrong.
• interactive dance movements e.g., learn to dance as a game application where a subject is signaled in one way when they are taking the right steps and another when they are wrong.
• Sensing system 100 may also provide the monitoring and analysis required for industrial applications to determine warehouse personnel effectiveness, such as allowable personnel movements measured against assembly efficiency, the determination of specific individuals locations (since GPS is not very effective and expensive to deploy indoors, especially in a warehouse setting), to guard against entry into certain areas where they are prohibited such as hazard and/or security areas, and in applications where there are employee health care incentives for weight loss and health maintenance.
• Sensing system 100 may also may augment gaming interfaces to supplement videogames such as PlayStation PS3 and XBox 360 gaming console. This would add an extra dimension to how one interacts with videogames running on these game consoles. Foot pressure activity detected during jumping, walking or running are combined with foot orientation and location data to provide enhance interactivity to the regular popular videogames, allowing for intuitive game play such as kicking or blocking in a fighting game.
• a backend server processing option of sensing system 100 may also be able to collect large groups of insole monitors that would represent a field of players involved in sporting games (e.g., football, soccer, basketball and the like). This may be implemented as a website for remote analysis supporting peer review type applications. Sensing system 100 may also be able to capture the data over a large field of reference (e.g., sports field, field of battle, long distance run) by a specific signature for an individual sole, by person (i.e., two soles) or by collection of individuals. Sensing system 100 would, thus, enable download of all of this information upon arrival, within a transmission zone, to a web interface that creates a post event re-simulation to be stored, compared and rated by peer web gamers.
• a large field of reference e.g., sports field, field of battle, long distance run
• Sensing system 100 would, thus, enable download of all of this information upon arrival, within a transmission zone, to a web interface that creates a post
• the backend server processing option is also able to collect large groups of the insole monitors that would represent a field of players involved in sporting games (e.g., football, soccer, basketball, and the like). This may allow for the creation of game strategy analysis program by using correlation analysis using real-time and archived in-sole data. With additional data input, such as real-time video, it would be readily apparent to those of ordinary skill in the art that enhanced dynamic game strategy adjustment programs would be possible.
• Sensing system 100 may also be able to detect slight variations of foot pressure over time caused by conditions such as the loss of fluid within a running race, the change in pressure in a medical or rehabilitation environment, the change in pressure during an operating process (e.g., driving a car) where pressure may indicate that the operator is fit to continue.
• programs may be constructed to manage long-term foot pressure variation analysis as previously mentioned.
• Sensing system 100 may also be implemented in a floor mat type arrangement for a car as the key mechanism for vehicle speed operation. It may also be used in applications to assist in small motor control where the operator is incapable, either due to injury or birth defect, of applying pressure to hand or foot operating systems. In both cases mentioned, wireless support for sensing system 100 allows for six-degrees of motion.
• sensing system 100 is one in which energy is "harvested". That is, piezoelectric fiber composites can convert mechanical energy and into electrical energy. Alternative embodiments of sensing system 100 may be used to leverage the composite nature of such piezoelectric fiber composites, because they are lighter and more flexible than bulk piezoelectric ceramics. Such piezoelectric fiber composites are capable of producing 50 V at a "stepping" frequency of 3 Hz. This could charge a battery at a 5 milliamp rate. Piezoelectric fiber composites may be shaped within insoles of various embodiments of the present invention, running from heel to toe. Piezoelectric fiber composites may also run in parallel, to accumulate the desired electric power. As a result, sensing system 100 may leverage potted and laminated implementations in conjunction with polyethylene sheets for insole design.
• Such sensing systems 100 including piezoelectric fiber composites would be very durable and have a fatigue life time which is greater than 200 million cycles, with no degradation in the piezoelectric characteristics.
• the piezoelectric fiber composites used herein are 250 microns in diameter with variable lengths.
• a charging circuit could be added to provide voltage limiting and conditioning capabilities for a battery charging application.
• the particular battery technology which would be useful for sensing system 100 would be a function of its application. For example, gaming, sports and health monitoring applications might require a rechargeable Lithium-Polymer (Li-PoIy) battery. In such cases, a 1mm insole layer of piezoelectric fiber composites would be appropriate for battery recharging implementations.
• Li-PoIy Lithium-Polymer

Applications Claiming Priority (3)

Publications (1)

Family

ID=42352596

Family Applications (1)

Country Status (4)

Families Citing this family (11)

Family Cites Families (5)

• 2008
  • 2008-11-28 EP EP08854571A patent/EP2223069A1/de not_active Withdrawn
  • 2008-11-28 WO PCT/US2008/085065 patent/WO2009070782A1/en active Application Filing
  • 2008-11-28 JP JP2010536207A patent/JP2011505015A/ja not_active Withdrawn
  • 2008-11-28 CA CA2706959A patent/CA2706959A1/en not_active Abandoned

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events