WO2001050957A1 - Indicateur de position et dispositif de controle de l'activite - Google Patents

Indicateur de position et dispositif de controle de l'activite Download PDF

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Publication number
WO2001050957A1
WO2001050957A1 PCT/US2001/000457 US0100457W WO0150957A1 WO 2001050957 A1 WO2001050957 A1 WO 2001050957A1 US 0100457 W US0100457 W US 0100457W WO 0150957 A1 WO0150957 A1 WO 0150957A1
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WO
WIPO (PCT)
Prior art keywords
recited
orientation
transmitter
sensor
individual
Prior art date
Application number
PCT/US2001/000457
Other languages
English (en)
Inventor
Paul B. Kelly, Jr.
Donald W. Schoendorfer
Jeffrey L. Simmons
Original Assignee
Kelly Paul B Jr
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kelly Paul B Jr filed Critical Kelly Paul B Jr
Priority to AU27680/01A priority Critical patent/AU2768001A/en
Publication of WO2001050957A1 publication Critical patent/WO2001050957A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
    • A61B5/6843—Monitoring or controlling sensor contact pressure
    • 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
    • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb
    • A61B5/1116—Determining posture transitions
    • A61B5/1117—Fall detection
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C9/00—Measuring inclination, e.g. by clinometers, by levels
    • G01C9/02—Details
    • G01C9/06—Electric or photoelectric indication or reading means
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B21/00—Alarms responsive to a single specified undesired or abnormal condition and not otherwise provided for
    • G08B21/02—Alarms for ensuring the safety of persons
    • G08B21/0202—Child monitoring systems using a transmitter-receiver system carried by the parent and the child
    • G08B21/0205—Specific application combined with child monitoring using a transmitter-receiver system
    • G08B21/0211—Combination with medical sensor, e.g. for measuring heart rate, temperature
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B21/00—Alarms responsive to a single specified undesired or abnormal condition and not otherwise provided for
    • G08B21/02—Alarms for ensuring the safety of persons
    • G08B21/0202—Child monitoring systems using a transmitter-receiver system carried by the parent and the child
    • G08B21/0288—Attachment of child unit to child/article
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B21/00—Alarms responsive to a single specified undesired or abnormal condition and not otherwise provided for
    • G08B21/02—Alarms for ensuring the safety of persons
    • G08B21/0202—Child monitoring systems using a transmitter-receiver system carried by the parent and the child
    • G08B21/0294—Display details on parent unit
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2560/00—Constructional details of operational features of apparatus; Accessories for medical measuring apparatus
    • A61B2560/02—Operational features
    • A61B2560/0204—Operational features of power management
    • A61B2560/0209—Operational features of power management adapted for power saving
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2560/00—Constructional details of operational features of apparatus; Accessories for medical measuring apparatus
    • A61B2560/04—Constructional details of apparatus
    • A61B2560/0406—Constructional details of apparatus specially shaped apparatus housings
    • A61B2560/0412—Low-profile patch shaped housings

Definitions

  • a preferred application of the attitude indicating device is that of detecting intended egress by an individual.
  • an attitude transmitter unit is integrated within an appliance that is preferably attached to the posterior thigh, of the individual being monitored.
  • An attitude receiver unit is located within range of the attitude transmitter unit to receive alert conditions and generate an indication of the alert in a form that may include, audio, visual, or tactile information.
  • the transmitter generates radio-frequency alert transmissions in response to changes in transmitter attitude that are characteristic of specific conditions.
  • the alert transmissions are received by a receiver unit that generates audio alerts to attendants, or other nearby personnel.
  • the receiver unit may be configured to provide attitude, or activity, indication in a variety of forms, such as audible tones and/or words, discrete visual indicators, such as LEDs, various displays such as an alphanumeric LCD, or by remotely conveying attitude, or activity, information to another system.
  • An example of conveying the information to a remote system may involve interfacing the attitude indication signals with an institutional monitoring system, such as a nurse's station capable of displaying the attitude information as status information, of generating audible alerts, of dispatching personnel, of generating a page, and so forth.
  • the receiver unit may comprise more than one device; for example, a receiver positioned at a first location and operably connected to circuitry at a second location that performs the processing of the received signals. The circuitry at the second location may in turn be operably connected to another unit, and so forth. Any combination or level of integration can be supported insofar as one or more of the units, or devices, is capable of generating alerting signals that are responsive to the transmitter unit.
  • the attitude, and activity, indicating device of the present invention allows physical orientation to be indicated as a set of measurements, or by way of orientation alerts generated in response to attitude threshold conditions.
  • Attitude and activity are preferably detected within the transmitter by utilizing an acceleration sensor that is capable of detecting attitude (tilt), and positional rate of change.
  • An attitude transmitter configured to provide attitude measurements may transmit measured orientation information either in response to status changes or on a periodic basis.
  • Alerting signals may be generated upon the measured conditions meeting one or more alert validation criteria.
  • the receiver unit is capable of responding to the transmitted signals in a manner consistent with the application. For example, the receiver may generate an audio output in response to the alert signal, or it may record, display, communicate, and/or analyze the attitude or acceleration data contained within a transmission.
  • the attitude indicator device of the present invention may be utilized within a variety of diverse medical applications, which include but are not limited to: preventing/detecting patient egress, preventing/detecting patient falls, monitoring infants, detecting the onset of labor in horses, tracking physiological activity of patients, use in physical therapy, detecting range of motion, monitoring epileptics for seizures, limiting post surgical patient movement, limiting the motion of unconscious patients recovering from surgery, monitoring for sleep apnea and snoring, alerting employers of unsafe worker activity, detecting improper standing sleeping or lifting posture, and detecting lapses of consciousness.
  • Another object of the invention is to provide a device that is waterproof and shockproof.
  • Another object of the invention is to provide an attitude monitoring system that provides a wireless connection between an attitude detector and a remote attitude indication unit so that wearers need not be “tethered” by an electrical cord to an electrical device.
  • Another object of the invention is to provide an attitude transmitter unit configured to detect when it is being removed from a subject, whereupon it responds by generating an alerting signal.
  • Another object of the invention is to provide a monitoring device that can be readily manufactured at low cost.
  • FIG. 2A is a diagram of the attitude-monitoring device according to the present invention adhesively attached to the thigh of an individual shown lying in a generally horizontal position.
  • FIG. 2B is a diagram of the attitude indicator device of FIG. 2A shown angled as the leg of the individual moves downwardly.
  • FIG. 4 is a cross-sectional view of an attitude transmitter unit according to the present invention shown integrated within a moisture sealed adhesive medical appliance which is being retained adjacent the skin of an individual.
  • FIG. 10 is a flowchart of program flow within an attitude transmitter unit according to the present invention that exemplifies the process of attitude detection.
  • FIG. 1 the attitude indication device 10 of the present invention is shown, byway of example, being worn on the posterior thigh region 12 on the leg 14 of an individual 16 (shown in phantom).
  • the preferred apparatus comprises an orientation sensor within an attitude transmitter unit that is worn as a medical appliance, or patch, on the individual's thigh and that is operatively coupled for communication with a remote attitude-receiving unit.
  • the attitude transmitter unit may be attached to the individual's body at any location consistent with its intended application, however, it has been determined that by properly configuring the attitude indicator and mounting it on the thigh, an example of which is shown in FIG. 1 , patient egress may be detected prior to ambulation while false alarms may be minimized.
  • the orientation sensor within the attitude transmitter unit is responsive to the downward angle of the thigh, and according to one embodiment of the invention, the attitude indication device generates a signal if the thigh of the individual is oriented downwardly at an angle that indicates that the individual is in an undesired orientation.
  • the attitude indication device is configured to prevent the generation of alert signals in response to any angle above the horizontal as exemplified by angle 30. As the thigh is inclined downwardly, the angle at which the thigh must be oriented in order for a signal to be generated by the attitude detector varies depending on how the attitude transmitter unit has been configured for the applicable circumstances.
  • the attitude transmitter unit when the attitude transmitter unit is attached to a comatose individual that is unlikely to move, it may be desirable to generate an alert signal for even slightly downward displacements of thigh 12 from horizontal plane 24.
  • the orientation sensor may generate a signal if the individual's thigh is at a slight downward angle 32 that preferably exceeds about five to fifteen degrees from horizontal plane 24.
  • the attitude transmitter unit is configured to ignore all upward angular displacements of the thigh, such as frequently may occur when an individual props up a knee, or elevates one leg.
  • a downward threshold angle 38 of about seventy degrees is highly preferred as a detection threshold.
  • This highly preferred detection threshold can range from between sixty degrees up to eighty degrees.
  • the device may be attached to the individual's head, neck, shoulder, arm, chest, abdomen, waist, lower back, calf, or any other body part consistent with its intended use.
  • the device may be attached to the individual using any of the means familiar to those skilled in the art.
  • the attitude transmitter unit 10 is sealed and then adhesively attached to the individual, such as on the posterior thigh.
  • the attitude transmitter unit is preferably adapted into a medical appliance that is both waterproof and shockproof, whereby individuals may shower, bathe, or perform additional common tasks over an interval that may exceed one or more weeks without needing to remove the device.
  • the circuitry of the attitude transmitter unit may be sealed by various means that may be used singly or in combinations thereof, and is inclusive of potting compounds, sealants, encapsulation, pouches, or material overlays. It will be further appreciated that other moisture resistant packaging may be utilized, such as implementing the device with high levels of integration, preferably single chip, coupled with the use of waterproof connections.
  • Attitude transmitter unit 10 of FIG. 4 is shown having a printed circuit board 50 upon which are mounted several electronic components, such as integrated circuit 52.
  • the circuit of the device is preferably sealed against moisture, such as with an insulating sealer 54 applied to the portions of the circuit that require environmental protection.
  • the transmitter unit may be attached to a bottom adhesive layer 56, such as 9776 Foam Medical TapeTM produced by 3MTM, for attachment to the skin 58 of an individual and covered by a top layer 60 of material. It is advantageous if the bottom adhesive layer 56 is fabricated of a material that is capable of maintaining skin adhesion for a period of days, or weeks, and is not subject to a loss of adherence as a result of bathing or similar normal activities. If longer monitoring is required, the tape may be replaced, or a reinforcing band (e.g., CobanTM wrap by 3MTM) may be employed. Where no adhesive contact is desirable, the attitude transmitter unit may be attached by means of an Ace bandageTM or the like.
  • a reinforcing band e.g., CobanTM wrap by 3MTM
  • top layer 60 may comprise any of various materials, such as 9776 Foam Medical TapeTM.
  • top layer 60 may be fabricated, for example from a layer of AveryTM Medical 5020 Urethane TapeTM over which is placed a second layer of opaque material, such as foam tape that may be configured with apertures, or as a frame, for viewing.
  • Optional temperature sensors are shown attached to the circuit board 50, which is shown configured with an outer sensor 62 and inner sensor 64. The temperature sensors can provide additional patient related statistics, while the use of dual sensors further provides for detecting temperature differentials indicative of attitude transmitter patch removal.
  • an attitude transmitter unit 70 comprising an orientation sensor, a controller, an RF transmitter, and a power supply. It will be appreciated that various receivers can be implemented for receiving the signals from the device and for the subsequent display and/or annunciating of corresponding information and alerts.
  • An orientation sensor 72 is capable of sensing the orientation of the portion of an individual's body to which it is attached. Subject orientation is sensed in relation to the downward force of gravity and may be sensed as an acceleration, inclination, tilt, roll, or similar force that is indicative of orientation for that portion of the individual to which it is attached.
  • the output of the orientation sensor should be largely immune to influence from nearby circuitry, mechanical oscillation, and sensor inertia.
  • the orientation sensor is preferably capable of sensing from one to three dimensions of orientation, the larger number of axes being used to increase event discrimination, reduce false triggering, and facilitate more complex attitude monitoring applications.
  • the orientation sensor in combination with the circuit should provide substantially linear output in response to orientation and be configured to dampen transient responses that could otherwise lead to false triggering.
  • the use, therefore, of mechanical position switches is not preferred within the present invention because of their step-wise output and the significant debouncing (in hardware or software) required before the output can be utilized.
  • the orientation sensor 72 in a preferable configuration comprises an acceleration sensor having corresponding outputs 74.
  • the incorporation of an acceleration sensor provides numerous advantages, which include the ability to sense static orientation in relation to gravity and the simultaneous ability to sense the changes in movement rates, so that subject activities may be accurately discriminated to provide improved differentiation of events to reduce false alarms. If the orientation sensor draws significant amounts of operating current, the circuit should be configured to periodically shut down the sensor, so as to conserve the power source of the portable transmitter.
  • a sleep input line 76 is shown connected to the orientation sensor 72. Any of various control circuits 78 may be utilized for controlling circuit operation within the attitude transmitter unit.
  • control circuit may utilize any combination of circuitry including application-specific integrated circuits (ASICs), semi-custom integrated circuits (ICs), programmable logic arrays (PLAs), gate arrays, microcontrollers, microprocessors, neural net circuits and assorted discrete circuits.
  • ASICs application-specific integrated circuits
  • ICs integrated circuits
  • PLAs programmable logic arrays
  • gate arrays microcontrollers
  • microprocessors neural net circuits and assorted discrete circuits.
  • the control circuit 78 coordinates the activities of the orientation sensor 72 and the generation of the output signal, while it can additionally provide for signal processing, event differentiation, the maintenance of event history to provide improved differentiation, signal transmitter control, coordination of auxiliary functions such as temperature measurement, patch removal detection, on/off control, and so forth.
  • the control circuit 78 is preferably implemented as a low-cost, low-power integrated microcontroller that is capable of performing extended levels of processing on the input signals and of generating complex outputs.
  • the microcontroller may also be serialized with an included identification number 80 which can be decoded by a remote attitude receiver unit for discerning one attitude transmitter unit from another.
  • numerous microcontrollers provide low- power/sleep circuits 82 which allow the processor itself to enter a low power mode, and to return to conventional power mode upon the detection of an event or upon the expiration of a time interval.
  • Use of a microcontroller as the control circuit provides the additional advantage that attitude detection devices may be custom programmed for specific applications, while the program itself may be periodically updated to include new system enhancements.
  • attitude transmitter units may be custom programmed for various inclination thresholds to suit a variety of applications, such as detecting slight movements of a postoperative or comatose patient.
  • Switch 84 connected to the control circuit 78 provides an activation signal, or wakeup signal, which is responsive to the orientation of the transmitter patch and can provide for further reductions in power dissipation.
  • Switch 84 may comprise a tilt sensor whose contacts change state when subject to a slight angle, such as a tilt exceeding approximately twenty degrees from the horizontal. The tilt sensor in this situation senses that the patient is no longer in a quiescent, non-inclined state. It will be appreciated that if the patient is not moving enough to trigger the tilt sensor, then attitude readings need not be taken and power savings may be accrued by shutting down the orientation sensor 72 and the control circuit 78.
  • a variety of mechanical vibration or pendulum-style devices may be utilized to sense a quiescent state, and/or a non-tilting state, so as to condition the processor and/or the associated orientation sensor into a desired operating mode.
  • a mechanical inclination switch such as a series 0732 On/Off switch produced by the Fredericks CompanyTM of Huntington Valley, Pennsylvania, is one example of a tilt switch that may be utilized to condition the operating mode of the transmitter unit.
  • the switch angle between “off' and “on” is configured so that at zero degrees inclination the switch is “off (non-conductive), and at a tilt angle in excess of twenty-two degrees the switch is activated to an "on” state (conductive).
  • a mechanical switch does not provide a linear output for accurately detecting attitude; however, it may be safely utilized to awaken the circuitry from a low power mode upon the occurrence of a prospective event.
  • a simple tilt sensor does not have the specificity to distinguish pitch from roll, and as a result the orientation sensor may remain activated with a concomitant level of power dissipation. It is anticipated that an individual, such as a medical patient, shall spend a far greater percentage of their time in a lying position, or a sitting position, therefore, operation of the orientation sensor while a patient lies on one side should not substantially reduce the longevity of the power source within the attitude transmitter unit.
  • the control circuit 72 is operably connected to an RF transmitter circuit 86 whose output is coupled through an antenna 88.
  • RF transmitter 86 may be constructed from various off-the-shelf RF modules, or from discrete components.
  • a periodic ALIVE signal is broadcast from the device to the remote receiver.
  • the ALIVE signal provides assurance that the associated transmitter is operational and within the range of the receiver.
  • the ALIVE signal will be periodically generated if the transmitter has not otherwise generated a signal within the given time interval.
  • the associated receiver thereby anticipates, and is conditioned upon the receipt of a periodic signal, which may consist of a measurement, an alert, or the ALIVE signal. If the signal is not received within a predetermined interval, the receiver generates an alert indicative of a non-responsive attitude transmitter unit. It is further preferable that transmission of the ALIVE signal be conditioned upon obtaining a proper result from a self-test routine so that problems within the transmitter unit may be detected by the remote receiver as a fault indication or missing ALIVE signal.
  • a power supply 90 provides conditioned power to the circuitry from battery 92 such as a lithium battery.
  • the preferred use of power conditioning circuitry in contrast to the direct connection of battery 92 to the circuitry, provides a regulated circuit supply voltage to maintain unit accuracy, while it additionally provides for the detection and control of power drain from the battery source.
  • the power supply includes a regulator that controls the output voltage for the circuit, and preferably provides a low battery signal 94 to the control circuit. In response to the low battery signal, the control circuit generates an alert to the remote attitude receiver unit that provides an audible or visual indication to personnel so that battery replacement may be initiated.
  • a momentary switch 96 is shown on the power supply to control the application of power to the device.
  • the switch is preferably implemented to engage and latch power to the transmitter unit while providing security from inadvertent engagement.
  • the optional switch may be implemented in a variety of forms, or left off altogether with circuit activation being contingent upon insertion of the battery into the battery holder of the transmitter unit.
  • another form of activation switch can be configured utilizing a magnetically sensitive bi-stable switch, wherein proximal application of a sufficient magnetic field causes the switch to change states. Utilizing the push-button style momentary switch 96, as shown in FIG. 5, provides compatibility with the preferably sealed nature of the device.
  • the momentary switch 96 may be used in concert with the microcontroller in a power activation loop, wherein the momentary switch is pressed for a period of time to exceed the activation loop period in order that power is latched into a permanent "On" state.
  • the state of power activation may be controlled within a properly configured device by means of a radio transmitter, infrared source, or similar signal.
  • the attitude detector may be optionally configured with sensors 98 to register one or more vital signs of the individual, for example temperature, heart rate, and/or blood pressure.
  • the attitude indicator provides for the detection of the physiological attitude of a portion of an individual, it may in addition provide for the communication of an individual's vital statistics, or the generation of alerts based on those vital statistics, to facilitate directing proper attention to those individuals in distress or possible danger.
  • the transmitter unit preferably is configured with a detector 100 that is responsive to the removal of the patch from the individual.
  • the appliance containing the attitude indicator may become separated from the patient if the retention mechanism, such as the adhesive layer, which holds the appliance to the patient's body fails, or if the patient accidentally or purposely removes the appliance.
  • a preferred embodiment utilizing an acceleration sensor can be configured to monitor acceleration conditions which are indicative of not only the orientation, but of events relevant to the status of the device, such as monitoring for device removal. It will be recognized that the device, during and after removal, is subject to increased levels of acceleration, and fluctuations thereof, due to its minimal mass in comparison to the mass of an individual's thigh to which it is preferably retained.
  • a temperature sensor may be utilized to sense patch removal, as the temperature of the surroundings is generally lower than skin temperature, whereby a drop in temperature is characteristic of device removal.
  • the combination of two temperature sensors is preferred, with one near the exterior of the patch and one near the interior of the patch to improve patch removal detection based on a temperature differential.
  • the combination of acceleration sensing and patch removal detection can provide an extremely accurate and rapid removal detection mechanism, such that a responsive action may be quickly taken.
  • sensors that operate according to any of various operating principles may be utilized within the present invention to detect the removal of the transmitter from the individual.
  • a pair of differential humidity sensors could be utilized instead, with an inner humidity sensor generating a higher level of humidity than the outside sensor while the attitude indicator remains attached to the individual.
  • Alternative detection mechanisms include monitoring for conductivity changes that are characteristic of the transmitter being removed from the patient. Conductivity may be measured between electrodes placed proximal to the skin of the wearer. Alternative mechanisms may be utilized for sensing characteristics associated with device removal, such as changes in applied pressure, inductance changes, capacitance changes, in addition to further mechanisms capable of sensing the removal of the attitude detector from the individual.
  • the attitude transmitter unit is worn by an individual, preferably against the skin as a medical appliance, or transmitter patch, wherein attitude related information is transmitted from the attitude transmitter unit to a remote receiver.
  • Transmitter range is configured for approximately fifty feet as measured in an open room and the range is independent of relative orientation between the transmitter and its respective receiver.
  • the range of the transmitter may be alternatively adapted to suit other applications, the fifty-foot range being provided by way of example based on testing of the attitude indication device utilized as an egress detector within a room containing a single receiver.
  • an ALIVE signal is sent from the attitude transmitter unit to the attitude receiver unit approximately every one to ten minutes, so that the remote receiver unit can detect if the attitude transmitter unit is positioned out of range or is no longer serviceable.
  • Operational life of the transmitter battery was found to exceed one week under circumstances in which the attitude transmitter unit was exposed to twenty, or fewer, minutes per day in an alert generating state, e.g., positioned vertically.
  • An alert signal is generated by the attitude transmitter unit as it detects a possible patient egress condition triggered by a downward pitch of the device exceeding about seventy degrees from the horizontal.
  • the embodied single axis transmitter is insensitive to patient roll and therefore does not generate alert signals when the patient shifts to a position lying on their side or raises a leg toward the ceiling instead of the floor.
  • the attitude indicating device of FIG. 6A through FIG. 6C for detecting patient egress can be broken down into four major sections: orientation sensor circuit 112 of FIG. 6A, microcontroller circuit 114 and RF transmitter circuit 116 of FIG. 6B, and the power supply circuit 118 of FIG. 6C.
  • Table 1 contains a list of the components utilized within the exemplified embodiment.
  • the orientation sensor circuit 112 within the attitude indication device is shown as being implemented using an ADXL202E acceleration sensor (U4) 120 from Analog DevicesTM.
  • U4 ADXL202E acceleration sensor
  • Two axis outputs are provided, with the X-axis being utilized within the attitude transmitter unit for measuring tilt, while the second output, if used, corresponds to the measurement of roll.
  • Each of the two outputs from acceleration sensor 120 is independent and directly proportional to the acceleration in each of the two sensitive axes.
  • the outputs are pulse-width modulated (PWM), wherein continuous pulse trains are generated in which the duty cycles represent the present level of acceleration to which the sensor is subject. Only a single channel of the acceleration sensor is utilized for sensing the tilt within this particular embodiment to which the portion of the body upon which it has been attached is subjected.
  • PWM pulse-width modulated
  • the operation of the acceleration sensor 120 shown in FIG. 6A is herein controlled by three components associated with the ADXL202E.
  • the first component R1 is a resistor 122 that in combination with a parallel resistance comprising a fixed resistor R14 124 in series with an adjustable resistor R15 126, sets the output periods of both tilt and roll for the acceleration sensor, which is preferably adjusted to yield a square wave output having a period 72 ranging from approximately one-half to one millisecond.
  • a pair of capacitors, C2 128 and C3 130, is utilized as filter capacitors by the ADXL202E to establish the bandwidth of the acceleration sensor.
  • the duty cycle of either axis for the acceleration sensor is approximately fifty-percent when no gravity force is being registered within that axis, and the duty cycle changes by approximately twelve-point-five percent per gravitation unit (G).
  • the acceleration sensor bandwidth determines the maximum measurement resolution that thereby defines the smallest detectable acceleration change.
  • capacitors C2 128, and C3 130 are set to provide a resolution of approximately fifty Hertz.
  • the supply voltage V cc is bypassed by a capacitor C1 132.
  • the X output of the accelerometer is connected directly to the microcontroller circuit 114 that determines acceleration based on the duty cycle of the received PWM square wave.
  • the microcontroller circuit 114 contains a PIC12C508 eight-bit, eight-pin microcontroller chip U2 134 from Microchip SemiconductorTM which provides low power consumption, internal peripherals, a counter/timer with prescaler, 25 bytes of RAM memory, and 512 bytes of non-volatile (program) memory.
  • the microcontroller 134 within the depicted embodiment performs reading and interpretation of accelerometer output signals, the latching of circuit power, the control of power to the acceleration sensor, and the modulation of the RF transmitter with data to be transmitted to the remote attitude receiver unit.
  • the use of a microcontroller 134 within the attitude transmitter unit provides significant advantages over the use of simple thresholding circuits.
  • the microcontroller is capable of complex circuit control and of performing simple signal processing functions that for instance utilize historical signal information so that the number of false alarms may be reduced.
  • firmware programming of the microcontroller may be adapted to suit different applications of the sensor, and to accept firmware updates thereupon.
  • Microcontroller 134 may be programmed with various firmware settings and operating features to support a wide range of alert configuration and applications.
  • the firmware may be programmed to detect a declination other than seventy degrees, or the tilt may be qualified with additional metrics to suit other applications.
  • the microcontroller should preferably be reprogrammable (for example, utilizing FLASH ROM) and be configured to receive off-board programming signals to allow for the updating of firmware.
  • the microcontroller 134 receives a single axis input from the acceleration sensor 120 on general-purpose I/O pin GP3 and outputs a single bit from I/O pin GP2 to modulate the RF transmitter circuit 116.
  • the microcontroller circuit 114 additionally provides an output GPO for latching the battery power for the device, while I/O pin GP1 is utilized for controlling the operational state of acceleration sensor 120.
  • the microcontroller must configure GP1 into a Low state output capable of sinking operating current from the acceleration sensor to thereby activate the sensor.
  • a pair of bypass capacitors C8 136 and C9 138 is provided to filter voltage transients created by microcontroller 134.
  • the frequency of oscillation within microcontroller 134 is established by quartz crystal Y1 140 that is configured with a pair of capacitors C10 142 and C11 144 and an overdrive- limiting resistor R3 146.
  • the control and operational characteristics of the attitude indication device of the depicted embodiment of the present invention are preferably embedded within the microcontroller firmware.
  • the individual microcontroller chips within individual attitude transmitter units be configured, or programmed, with a unique identification code that may be utilized by the firmware for encoding an identifier within the RF output so that individual attitude indication devices may be distinguished from one another.
  • the radio-frequency (RF) transmitter circuit 116 provides a pulse code modulated (PCM) transmitter that receives data input from the microcontroller circuit 114.
  • PCM pulse code modulated
  • a broadcast signal of approximately 302 MHz is generated through an RF switching transistor Q1 148, feedback capacitor C5 150, an inductive choke L1 152 and LC tank circuit comprising capacitors C6 156 in parallel with series combination C4 154 and C7 158, which is in parallel with antenna ANT1 160 that is configured as a trace on the printed circuit board (PCB).
  • PCB printed circuit board
  • the antenna ANT1 160 is implemented as a PCB trace that is 100 millimeters thick and is configured in a rectangular form factor to reduce the requisite area of the printed circuit board (PCB), although antenna geometry is not critical due to the short-distance over which the data is to be communicated and the low data rate involved.
  • An LC tank circuit generates the 302 MHz oscillation signal, with inductive choke L1 152 providing an AC blocking choke that provides power to the oscillator.
  • the inductor, choke L1 152 in addition prevents the AC component of the oscillator from entering the DC supply unattenuated.
  • the antenna acts as the "L” in the LC tank circuit, with the "C” comprising the parallel- serial combination of C4, C7 and C6. This configuration helps offset the PCB parasitic capacitance and allows for fine-tuning of the transmission frequency.
  • a high-frequency NPN transistor with a gain bandwidth product of 10 GHz is utilized for the RF switching transistor Q1 148, rated for a maximum collector current of 35 mA which is limited by emitter resistor R4 162.
  • the transistor Q1 148 provides a high-frequency switching device which is modulated by the microcontroller circuit 114 and which receives positive feedback from the tank circuit through capacitor C5150 to maintain oscillation.
  • the base of transistor Q1 148 is modulated through a drive resistor R2 164 by an output from microcontroller 134 which switches the RF transistor Q1 148 on and off in response to the binary pattern of data being transmitted.
  • collector current flows and initially puts the transistor into saturation which in turn charges up the capacitors C4 154, C6 156, and C7158 and prepares the capacitors for energy exchange with the antenna ANT1 160 which acts as an inductor.
  • the transistor collector current is reduced to allow the LC tank circuit to oscillate with the stored capacitive energy.
  • the feedback component is implemented as a capacitor C5 150 that provides positive feedback to the base of RF switching transistor Q1 148, which in turn allows the tank circuit to continue to oscillate at the desired frequency of 302 MHz.
  • the power supply circuit 118 is responsible for supplying the attitude transmitter unit with a source of regulated power exemplified as a standard 3-Volt button cell lithium battery BT1 166 with a preferred capacity in the vicinity of 560 mAH.
  • the battery BT1 166 is switched in and out of the circuit by a pushbutton normally-open (PBNO) switch S1 168 which acts in concert with the microcontroller 134 to control pass element 172 which switches battery current on or off.
  • PBNO pushbutton normally-open
  • microcontroller 134 transitions from a reset state to begin executing firmware instructions.
  • One such instruction generates an output on GPO of microcontroller 134 which activates MOS FET Q3 174, normally pulled inactive by resistor R8 176, to thereby sustain the activation of MOS FET Q2 172 after switch S1 168 is released.
  • firmware instructions may latch the power to the circuit after any programmed period of time has elapsed following device reset, it is preferred, however, that the microcontroller latch the power on after a period of about five seconds such that inadvertent momentary activations of the power switch do not cause the device to enter an active state. Subsequent engagements of switch S1 168 have no effect on circuit power once it is latched into a power activated mode. Current for the circuit passes through MOS FET Q2 172 from battery BT1
  • the voltage converter/regulator U3 182 of the present invention is exemplified with a step-up DC-to-DC converter so that a single battery may be utilized to supply a regulated supply voltage to the entire circuit.
  • the step-up converter U3 182 shown is a MAX1675 step up DC-DC converter configured to output 3.3 volts.
  • the step-up converter additionally provides a low battery indication LBI output, which detects a low battery condition that may be utilized in additional embodiments of the transmitter unit so that caregivers may be alerted to the need to replace the battery.
  • the output of the voltage converter U3 182 is subsequently filtered by capacitors C14 184 and C13 186 which supply the regulated V cc voltage 188 to the circuitry.
  • the attitude transmitter unit exemplified in FIG. 6A through FIG. 6C was configured according to the invention to provide a reliable, yet simple and inexpensive transmitter for detecting attempted egress of an individual when not subject to immediate or direct supervision.
  • the attitude transmitter unit is preferably attached to the posterior thigh of the individual being monitored, as previously described.
  • the orientation information provided by the acceleration sensor is monitored for a transition that is characteristic of a downward inclination of the acceleration sensor upon the thigh of the patient to a downward angle that exceeds seventy degrees from the horizontal. It will be appreciated that by monitoring a single axis of motion, the exemplified device is insensitive to movement in the other two planes of motion for this particular application.
  • the microcontroller When measurements from the acceleration sensor indicate that the seventy-degree threshold has been exceeded, the microcontroller outputs data for transmission to the remote attitude receiver unit via the RF section of the circuit.
  • the RF transmission is configured for receipt by a remote attitude receiver unit (not shown) that is capable of indicating the alert condition by the use of indicators, displays, audio annunciators, and/or communications to additional circuitry that is capable of directly, or indirectly, indicating the alert condition.
  • the power for the acceleration sensor is under the control of the microcontroller that is capable of cycling the power to the acceleration sensor as attitude measurements are necessary.
  • the thigh of an individual upon which the device is attached contains a mass that will not allow it to transition from being horizontal to an inclination that exceeds the downward threshold in a short span of a few milliseconds, and that the amount of time required to move to the position where the threshold is exceeded depends upon the present downward angle. It should additionally be recognized that the determination of a downward angle exceeding the threshold need not be registered instantly; a delay of up to one second for human applications would generally be considered insignificant. Therefore, the firmware of the microcontroller selectively activates the acceleration sensor in response to the last known angular position.
  • the microcontroller can put itself into a sleep mode wherein the microcontroller enters a low power mode until a specified period of time has elapsed, and in so doing effectively "naps" during periods of low activity, and/or low angles of thigh inclination.
  • the attitude transmitter device will transmit a periodic ALIVE signal to the receiver irrespective of the downward angle threshold, such that proper operation of the attitude transmitter is continually being verified.
  • FIG. 7 exemplifies a printed wired assembly for the attitude transmitter unit shown in FIG. 6A through FIG. 6C.
  • Apparent on the printed wired assembly 190 are the lithium battery 166, the trace of the loop antenna 160, the acceleration sensor 120, the microcontroller 134, and the momentary switch 168, in addition to the various aforementioned discrete circuit components.
  • the attitude transmitter unit is fabricated as a small, lightweight device that is preferably attached to the posterior thigh of an individual whose positional attitude is to be monitored, such as for detection of egress.
  • the attitude transmitter is implemented for inclusion within a small patch to create a medical appliance which may be worn for extended periods and which may be disposed of as conventional hospital waste.
  • PCB printed circuit board
  • the attitude transmitter unit is fabricated into a package preferably devoid of sharp edges that could injure, or cause discomfort to the individual wearing the unit.
  • the corners of the PCB have been radiused to 0.125 inches, and the assembled PCB has been potted in a soft elastomer.
  • the elastomer preferably registering under 60 on a durometer with the Shore A scale, is utilized to protect the electronics while protecting the wearer from any sharp edges or protrusions within the underlying structure.
  • the elastomer should further be capable of withstanding immersion in 100 degree Fahrenheit water for three hours.
  • the push-button momentary switch of the device is mounted to allow for activation through the combination of potting layer and adhesive cover.
  • the assembled PCB of the attitude transmitter unit is configured for inclusion within a patch or other medical appliance, and is preferably sandwiched between two sheets, herein provided as 2.5 inches in width by 3.5 inches in length of 3MTM 9776 foam tapeTM (or equivalent), with each of the four corners rounded to a 0.5 inch radius.
  • the upper surface of the tape should contain an indicia comprising directions as to which end of the patch is to be oriented toward the feet of the patient, along with additional information regarding the location of the switch, the lot number, the trade name, and any desired trade dress.
  • the completed patch is preferably individually wrapped in a pouch with an I PA wipe.
  • the pouch itself is marked with trade name, directions for application, indications and contra-indications for use, directions for disposal or reuse, and optional elements of trade dress.
  • the pouch may be configured with a transparent window through which the lot number of the patch may be seen without opening the pouch. During manufacture, the pouch should be exposed to sufficient levels of gamma radiation to ensure sterilization.
  • the packaged attitude transmitter unit is expected to have a useful shelf life of two years when properly stored. Alerts and information generated by the attitude transmitter device are monitored by an attitude receiver unit that is capable of detecting and interpreting the signals from the attitude transmitter unit, and of generating an indication to personnel as to the status, or alert, which has been communicated.
  • the attitude receiver unit registers the attitude transmissions from the attitude transmitter and is preferably configured to meet the analysis, display, and recordation needs of a particular application.
  • the registration of attitude information comprises reception followed by identification, attitude recognition, or activity characterization, along with displaying, annunciating, or logging the transmitted conditions.
  • the attitude receiver unit may act as a repeater, or transfer node, wherein the signals from the attitude transmitter unit(s) are further communicated to subsequent system elements. For example, the signals may be interfaced with a nurse's monitoring station.
  • FIG. 8 exemplifies an attitude receiver unit 210 configured for monitoring a single nearby attitude transmitter unit.
  • the embodied receiver unit 210 is contained within a housing 212 that contains a speaker (not shown) attached behind a speaker grill 214.
  • Annunciations are generated over the speaker by the attitude receiver unit 210 in response to conditions that exist within either the attitude transmitter unit, or the attitude receiver.
  • the annunciations may take the form of various tonal patterns, such as beeps, or by way of voiced annunciations that are either computer generated or played from a memory storage device.
  • Power for the receiver unit 210 is activated with switch 216 with the source of power being either batteries (not shown), or external power that may comprise low voltage, or AC power. If the unit is powered by an external power source, it is preferable that the external power source operate to maintain a charge on an internal storage cell such that the unit may continue to operate for a period of time after the loss of the external power, such as during a power failure.
  • a connection 218 to AC power is shown, by way of example, for powering receiver unit 210.
  • the status of the receiver unit is indicated by way of status indicators, which are depicted as LEDs positioned on the front of housing 212.
  • a ready LED 220 preferably green, indicates that the receiver is active and capable of receiving signals from the associated attitude transmitter unit. It is preferable that ready LED 220 blinks in response to a loss of external power, or in response to detecting a low battery voltage.
  • a low transmitter battery LED 222 preferably red, indicates that the remaining battery capacity of the associated attitude transmitter unit is low and the battery should thereby be replaced.
  • An ALIVE LED 224 indicates that the ALIVE signal continues to be timely received from the associated attitude transmitter unit.
  • this LED be a Red/Green LED that is activated with current in a first direction to output a steady green illumination when the keep alive signal is properly received, and in response to non-receipt of the ALIVE signal, LED 224 should be activated with intermittent current in an opposing second direction to output flashing red illumination.
  • An access panel 226 is provided to allow access to a set of receiver controls, not shown, which may include volume and specific alarm-related options.
  • attitude transmitter unit depicted in FIG. 6A through FIG. 6C provides an alert output upon being subjected to a declination that exceeds approximately seventy-degrees from the horizontal.
  • Conventional RF receivers may be utilized to provide an attitude receiver unit that is capable of indicating the attitude condition of the individual as reported by the attitude transmitter unit.
  • attitude transmitter unit design was performed utilizing an RS-500 Auto Security Alarm SystemTM from Radio ShackTM, which was modified to (1) remove the motion detector so that an alarm was not generated in response to receiver motion, (2) power the unit from conventional batteries, and (3) diminish the loudness of the alarm.
  • the antenna wire was removed to desensitize the receiver, because the receiver during these tests was located in the same room as the individual whose positional attitude was being monitored. The receiver without the antenna wire could still be activated by the transmitter from a 75-foot range.
  • the Radio ShackTM receiver and other similar receiver units additionally provide the capability to receive status information, such as the ALIVE signal, and battery status, although upon channels generally designated for other functions. It should be appreciated that the functions of the attitude transmitter unit are best accommodated by a receiver that is specifically designed and configured for indicating alerts from an attitude transmitter unit.
  • FIG. 9 is an embodiment of an attitude receiver circuit 230 according to the present invention comprising a power supply circuit 232, controller circuit 234, RF receiver circuit 236, option selection inputs 238, status indicators 240, display 242, and an external communications connection 244.
  • the power supply 232 provides the operating voltage 246 for the receiver circuit, and preferable contains, primary or secondary batteries 248, and an optional external power input 250 for maintaining secondary batteries 248 in a proper state of charge.
  • the controller is capable of audio output through an audio transducer 254, such as a speaker or piezoelectric transducer, whose volume may be adjusted by the potentiometer 256.
  • the controller receives information from one or more attitude transmitter units by way of the RF receiver circuit 236 having antenna 258.
  • the operation of the controller may be set for the specific application, by a set of option inputs 238, which may be implemented as one or more DIP-switches, or any alternative form of input device.
  • the status of the system and attitude transmitter may be displayed on a set of discrete status indicators 240 and/or a text or graphical display device 242.
  • the controller is capable of communicating with additional devices by way of a communication channel 244, which may be implemented as any form of communication channel including but not limited to an embedded system signal, a serial communication channel, an infrared link, an RF link, a network connection, an Internet connection, and so forth.
  • a communication channel 244 which may be implemented as any form of communication channel including but not limited to an embedded system signal, a serial communication channel, an infrared link, an RF link, a network connection, an Internet connection, and so forth.
  • the attitude receiver unit is preferably capable of generating indications as received from more than one attitude transmitter unit. Accordingly, transmitter units may be distinguished from one another within the receiver by a variety of mechanisms, including the allocation of separate frequencies, and the inclusion of identification signals within each data transmission of an attitude transmitter.
  • the use of embedded identifiers can allow a simpler RF receiver circuit to be utilized, because the required data bandwidth is exceedingly narrow and the problem of overlapping signals may be readily overcome by configuring the transmitters to repeat a giyen data transmission a certain number of times with random temporal offsets while including a checksum within each transmission to assure ungarbled receipt.
  • Operation of the attitude indicator system of the present invention is preferably determined by the firmware contained in the transmitter unit such as shown in FIG. 5 and in the receiver as shown in FIG. 9.
  • the firmware of the microcontroller within the attitude transmitter unit controls the numerous functions that may be performed within the system, including power-on initialization, battery status checking, acceleration sensor signal processing, ALIVE signal processing and generation, patch removal processing, temperature processing, and the transmission of data to a remote receiver.
  • FIG. 10 exemplifies process flow 300 within a transmitter unit embodiment of the present invention.
  • the process flow generally describes functionality according to the system depicted in FIG. 5, and contains a superset of functions in relation to the embodiment as shown in FIG. 6A through FIG. 6C.
  • the process is entered and the microcontroller, or processor, is powered-up and reset, whereupon it begins executing programmed instructions from firmware at block 304 and initializes both the hardware and microcontroller.
  • Initialization includes setting the modulation signal to the RF section to an inactive state and clearing all timer variables and flags.
  • Timers and clocks are initialized at block 306 and a five- second power-on timer is set at block 308.
  • a delay loop is entered at block 310 pending the expiration of the timer.
  • the five-second timer is utilized to differentiate an intentional activation of a momentary power-switch from an inadvertent activation. If the user releases the momentary button after holding it activated for less than five seconds, the attitude transmitter unit will return to a powered-off state. If the momentary button is held for greater than five seconds, the controller and power circuit hardware operate in concert to latch the transmitter unit into an active-on state such that power will remain on until the battery is removed or battery voltage drops below that required by either the power supply circuits or microcontroller circuits.
  • attitude transmitter power has been latched to an active-on state
  • a low battery check is performed at block 312, which additionally provides the entry point for the main loop.
  • a simple linear program is most readily created comprising an initialization series, blocks 302 through 310, followed by a main loop, blocks 312 through 334, which perform all recurrent processing. If a low battery condition is detected in block 312, a low battery condition is transmitted to the receiver as indicated by block 314. Once a low battery condition has been detected, it is preferably transmitted on a periodic basis until the battery is replaced.
  • the signals from the orientation sensor are processed by first initializing the circuits for each axis, such as the timers utilized for pitch, roll, and/or yaw as shown in block 316.
  • the orientation output is then registered, for instance as pitch, roll, and yaw measurements in either block 318a, or in the alternative block 318b.
  • Block 318a conveys a version of firmware that provides alerts in response to the angular orientation.
  • Block 318b in contrast, exemplifies the storage of a value in accord with the orientation measurement, so that a measurements may be conveyed, either upon change, request, or periodically, to the remote attitude receiver unit for display. Referring again to block 318a, registered measurements are compared with predetermined thresholds to determine if alert conditions exist.
  • attitude thresholds may comprise heuristic algorithms that take a number of parameters into account, such as the recent measurement history, or interrelations between the measurements being taken. For example, since the movement of the subject is relatively slow in comparison to the rate at which measurements may be taken, a series of transitory values may be retained in a circular queue. Upon a threshold condition being reached, the queue values may be used to corroborate the received threshold condition, whereby the condition may be verified or rejected.
  • an acceleration sensor is capable of detecting static orientation, it will still register all manner of accelerations to which the transmitter unit is subjected. Without proper discrimination routines in firmware, spurious accelerations and electrical noise will be indistinguishable from the attitudes for which detection is being sought. For example, false triggering can occur in response to physical oscillations (such as "jiggle") and electromagnetic disturbances (such as the 60 Hz of fluorescent lighting). In order to reduce false triggering caused by the effects of these accelerations, as well as spurious electrical noise, a series of measurements may be taken at intervals, for example 1/120 second, and examined for characteristic threshold conditions. Utilizing a historical series leads to a reduced susceptibility to both mechanical and electrical disturbances, without impairing the effectiveness of detection. In addition, the use of various microcontrollers may provide for utilizing principles of digital signal processing that may include Fourier analysis, to eliminate or further reduce the probability of false alarms.
  • the orientation signal can be processed as follows. The tilt signal is polled until a first state, such as High, is detected, then a timer is started, whereupon the controller is conditioned to detect a second alternate state, such as a Low state.
  • the timer Upon encountering the Low state signal, the timer is stopped and the angle associated with the time value determined, such as by threshold, calculation, or lookup table. If a specific tilt threshold is being detected, such as the aforementioned seventy degrees, the routine may check for a specific count as a threshold. In testing an implementation of attitude transmitter unit according to the acceleration sensor circuit of FIG. 6A, it was found that for tilt angles at or exceeding seventy degrees the elapsed time between a High to Low transition was less than 448 microseconds.
  • the process should include extended processing, such as the averaging of multiple readings, and the use of various heuristics and behavioral modeling which relate the various sensors to arrive at a verified tilt detection.
  • block 320 modifies an ALIVE signal timer, whereupon at expiration, in block 322, a flag is set to direct the transmission of an ALIVE signal later in the main loop.
  • the ALIVE signal is preferably set to be transmitted every one to ten minutes. Use of an ALIVE signal can provide a key aspect of system reliability. If for any reason the ALIVE signal is inhibited, the associated attitude receiver unit will appropriately alert personnel so that the situation may be investigated and remediated.
  • a patch removal detection routine is shown by block 324, whereupon if removal has been detected a flag is set as per block 326. Measurements are shown being registered in block 328 from temperature sensors within the device; these readings are logged for qualifying data and for subsequent transmission to a remote receiver. The temperature may be read from one or more probes strategically located on the attitude transmitter unit.
  • additional sensors such as indicators of blood pressure, consciousness, and pulse rate, may be queried to gather additional information for transmission to a remote receiver unit. If transmission flags have been set within the main loop, the routine of block 330 prepares the associated data for transmission, which is subsequently transmitted as data frames as shown in blocks 332 and 334.
  • Data transmissions are preferably tagged with an identifier that provides transmitter identification, or a receiver address.
  • the data is utilized for serially modulating the RF transmitter according to the specific modulation scheme required by the receiver.
  • the embodied transmitter utilizes OOK (On/Off Keyed) encoding, wherein the RF signal is generated by turning on and off an oscillator.
  • OOK On/Off Keyed
  • the attitude indication device of the present invention provides a mechanism for the detection and indication of positional attitude of an attitude transmitter unit that is attached to an individual.
  • Various example embodiments for the device according to the present invention have been described. Numerous features may be included within these embodiments to facilitate the use of the system for different applications, and within differing environments. The following alternate aspects of the invention are provided by way of example.
  • a number of circuits may be utilized to detect the unwarranted removal of the attitude transmitter unit from a patient, or individual. Once such circuit incorporates temperature sensing within the transmitter.
  • a pair of temperature sensors were referenced, with an outer sensor 62 configured for response to external patch temperature and an inner sensor 64 configured for response to the temperature of the individual to which the patch is attached.
  • the inner sensor is preferably mounted directly against the skin of the wearer to minimize thermal insulation and improve the speed and accuracy of response. If the transmitter appliance remains securely in contact with the patient, the inner sensor should register a slightly higher temperature than the outer sensor. An exception would exist for high ambient temperatures that exceed body temperature, whereupon the respective temperature sense rolls would be reversed. However, it should be recognized that it would be an alert condition in itself to subject a non-ambulatory patient to such excessive ambient temperatures.
  • the readings from the two sensors Upon device removal, the readings from the two sensors will begin to equalize, which triggers an alert signal transmission for alerting personnel to the possible removal of the attitude transmitter unit.
  • Numerous temperature sensors exist, one being a DS1721 miniature digital thermometerTM manufactured by Dallas SemiconductorTM.
  • the DS1721U measures temperature in 0.1125 Fahrenheit degree increments, and thereby provides suitable precision.
  • the eight- pin device is approximately 5 mm x 5 mm and 1.4 mm high, and can thereby be comfortably configured into the printed circuit board.
  • the output from the pair of DS1721 sensors is connected to the microcontroller that monitors the difference in temperature, preferably in relation to ambient temperature.
  • this invention allows the physical positioning, or attitude, of an individual to be detected and transmitted to a remote indication device to suit a variety of medical applications.
  • the present invention provides specific advantages for detecting patient egress from a bed, or wheelchair, as sensed by the downward tilt of an attitude transmitter unit attached to the thigh of the individual whose position is being monitored. It should be appreciated that the described embodiments are provided by way of example and that numerous alternative, or additional, circuits and functionality may be provided without departing from the teachings of the present invention. Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention.

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Abstract

L'invention concerne un indicateur de position permettant de détecter, d'indiquer et/ou d'enregistrer les positions d'un individu en réaction à une déviation par rapport à un ensemble d'un ou de plusieurs angles de référence. A titre d'exemple et non de limitation, l'indicateur est monté sur la cuisse d'un patient et des mesures sont prises à partir d'un capteur d'accélération se trouvant à l'intérieur de l'indicateur. Les mesures d'accélération sont communiquées à un récepteur et lorsque ces mesures dévient de seuils acceptables, le récepteur indique une condition d'alerte. L'indicateur peut être utilisé dans de nombreuses applications liées à la médecine, par exemple, en vue de prévenir plus facilement la sortie des patients et de prévenir/détecter des chutes.
PCT/US2001/000457 2000-01-07 2001-01-05 Indicateur de position et dispositif de controle de l'activite WO2001050957A1 (fr)

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GB2396043A (en) * 2002-12-04 2004-06-09 John Phizackerley Baby alarm with tilt sensor
WO2004056263A1 (fr) * 2002-12-19 2004-07-08 Siemens Aktiengesellschaft Dispositif et procede de transmission sans fil de signaux entre des appareils medicaux
US7383728B2 (en) 2005-07-13 2008-06-10 Ultimate Balance, Inc. Orientation and motion sensing in athletic training systems, physical rehabilitation and evaluation systems, and hand-held devices
GB2452943A (en) * 2007-09-19 2009-03-25 Pawel Kisielewski Alarm device for personal security comprising a patch adherable to the body of a person
WO2009037612A3 (fr) * 2007-09-19 2009-08-20 Koninkl Philips Electronics Nv Procédé et appareil pour détecter une situation anormale
WO2011076884A3 (fr) * 2009-12-23 2011-09-09 Delta, Dansk Elektronik, Lys Og Akustik Système de surveillance
CN102542730A (zh) * 2012-02-09 2012-07-04 朱虹 婴幼儿睡眠状况监视器
EP2595707A1 (fr) * 2010-03-07 2013-05-29 Centauri Medical Inc. Systèmes, dispositifs et procédés adaptés pour prévenir, détecter et traiter des ischémies induites par la pression, des escarres de décubitus et d'autres affections
CN114241729A (zh) * 2021-12-13 2022-03-25 中国人民解放军陆军工程大学 一种振动冲击报警装置

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EP0779058A1 (fr) * 1995-12-13 1997-06-18 Alert Care, Inc. Dispositif pour surveiller l'activité d'un patient
EP0849715A2 (fr) * 1996-12-21 1998-06-24 GGT Deutsche Gesellschaft für Gerontotechnik mbH Procédé et dispositif pour détecter la chute d'une personne malade
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GB1595788A (en) * 1976-04-12 1981-08-19 Walter Barlow Warning systems
US4536755A (en) * 1983-03-07 1985-08-20 Rigi Systems, Inc. Apparatus for detecting unauthorized egress by patient from position of confinement
US5543780A (en) * 1995-06-16 1996-08-06 Secure Care Products, Inc. Monitoring tag with removal detection
EP0779058A1 (fr) * 1995-12-13 1997-06-18 Alert Care, Inc. Dispositif pour surveiller l'activité d'un patient
US5941836A (en) * 1996-06-12 1999-08-24 Friedman; Mark B. Patient position monitor
EP0849715A2 (fr) * 1996-12-21 1998-06-24 GGT Deutsche Gesellschaft für Gerontotechnik mbH Procédé et dispositif pour détecter la chute d'une personne malade

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2396043A (en) * 2002-12-04 2004-06-09 John Phizackerley Baby alarm with tilt sensor
WO2004056263A1 (fr) * 2002-12-19 2004-07-08 Siemens Aktiengesellschaft Dispositif et procede de transmission sans fil de signaux entre des appareils medicaux
US7383728B2 (en) 2005-07-13 2008-06-10 Ultimate Balance, Inc. Orientation and motion sensing in athletic training systems, physical rehabilitation and evaluation systems, and hand-held devices
GB2452943A (en) * 2007-09-19 2009-03-25 Pawel Kisielewski Alarm device for personal security comprising a patch adherable to the body of a person
WO2009037612A3 (fr) * 2007-09-19 2009-08-20 Koninkl Philips Electronics Nv Procédé et appareil pour détecter une situation anormale
GB2452943B (en) * 2007-09-19 2012-05-16 Pawel Kisielewski Alarm device for personal security
CN101802881B (zh) * 2007-09-19 2012-08-15 皇家飞利浦电子股份有限公司 检测异常情况的设备和方法
WO2011076884A3 (fr) * 2009-12-23 2011-09-09 Delta, Dansk Elektronik, Lys Og Akustik Système de surveillance
EP2595707A1 (fr) * 2010-03-07 2013-05-29 Centauri Medical Inc. Systèmes, dispositifs et procédés adaptés pour prévenir, détecter et traiter des ischémies induites par la pression, des escarres de décubitus et d'autres affections
EP2595707A4 (fr) * 2010-03-07 2014-10-22 Centauri Medical Inc Systèmes, dispositifs et procédés adaptés pour prévenir, détecter et traiter des ischémies induites par la pression, des escarres de décubitus et d'autres affections
CN102542730A (zh) * 2012-02-09 2012-07-04 朱虹 婴幼儿睡眠状况监视器
CN114241729A (zh) * 2021-12-13 2022-03-25 中国人民解放军陆军工程大学 一种振动冲击报警装置

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