Classifications

• • 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
• • 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
  • G08B21/04—Alarms for ensuring the safety of persons responsive to non-activity, e.g. of elderly persons
  • G08B21/0438—Sensor means for detecting
  • G08B21/0446—Sensor means for detecting worn on the body to detect changes of posture, e.g. a fall, inclination, acceleration, gait
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
  • G01P3/62—Devices characterised by the determination or the variation of atmospheric pressure with height to measure the vertical components of speed
• • 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
  • G01C5/00—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels
  • G01C5/06—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels by using barometric means
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L13/00—Devices or apparatus for measuring differences of two or more fluid pressure values
• • G—PHYSICS
  • G08—SIGNALLING
  • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
  • G08B25/00—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems
  • G08B25/01—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems characterised by the transmission medium
  • G08B25/08—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems characterised by the transmission medium using communication transmission lines
• • 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
  • A61B2560/0242—Operational features adapted to measure environmental factors, e.g. temperature, pollution
  • A61B2560/0247—Operational features adapted to measure environmental factors, e.g. temperature, pollution for compensation or correction of the measured physiological value
  • A61B2560/0257—Operational features adapted to measure environmental factors, e.g. temperature, pollution for compensation or correction of the measured physiological value using atmospheric pressure
• • 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

Definitions

• the present invention relates to a method and system for determining a change in height of a first object being moved in a room where the background pressure fluctuates.
• the interference voltage from such sensors corresponds to an altitude variation of about 1 cm.
• Many applications only use a small part of the available measurement range, and such measurements would be more accurate if a differential pressure sensor could be used.
• a method of using a pressure change measurement for the accurate determination of a change in height of an object being moved in a room where the background pressure fluctuates in that, instead of basing the measurement on the pressure change from a single sensor attached to the object, the measurement is based on a difference between the signals from two pressure change sensors, one being attached to the object and the other being fixedly installed in the room where the measurements are carried out.
• a method of using a pressure change measurement for the accurate determination of a difference in height change between two objects which are both being moved in a room where the background pressure fluctuates in that the fixedly installed sensor is also made movable and is attached to one of the objects.
• a method of registering that a person, who is staying indoors or outdoors, suffers a fall in which a change in the vertical positions of two or more body parts of the person being characteristic of a fall is obtained from the difference between the pressure change measured by sensors attached to each of the body parts concerned.
• a method for eliminating ambiguity in fall detection in that the correlation between each of the sensor signals measured by sensors attached to each of the body parts concerned and the difference signal is calculated, to thereby determine to what extent each of the sensor signals contributes to the difference signal.
• Fig. 1 shows how background noise is removed using a stationary and a moveable sensor
• Fig. 2 shows how background noise is removed using two moveable sensors. The measurement signal indicates the difference in height between the sensors
• Fig. 3 shows a principle of a fall detector based on a sensor carried by a user and a stationary sensor
• Fig. 4 shows a principle of a fall detector based on two sensors which are both carried by a user.
• barometric pressure sensors that is, absolute pressure sensors having an operating range slightly above normal atmospheric pressure
• the method has since long been used in different forms of navigation.
• Pressure sensors have evolved considerably in recent years. Improved micromachining technology and the development of analogue and digital microelectronics have resulted in increasingly better and less expensive sensors. The development will continue, but when it comes to resolution and sensitivity, however, much of the noise that limits the achievable improvements is caused by fundamental, physical processes. It does not seem realistic to expect major improvements in these properties.
• the atmospheric pressure is determined by a number of meteorological factors besides vertical position, and an accurate pressure measurement alone is unable provide an accurate value of the vertical position of the sensor. Since the meteorological conditions vary relatively slowly with time, however, we can use an accurate measurement of the atmospheric pressure to determine rapid changes in vertical position. These are changes occurring on a considerably shorter time scale than the
• a sensitive differential pressure sensor of which one port is connected to a chamber that is vented to the surroundings through a large flow resistance element may be used.
• a capillary tube is suitable.
• vol ref is the reference volume
• P ref is the ambient
• measurement signals representative of changes in height can be completely or partially eliminated if two or more pressure sensors are used. Considering, for simplicity, two pressure sensors and looking at the difference between the pressures measured by these two pressure sensors, then the ambient pressure noise will be completely or partially cancelled and the measurement signal will indicate the variation in height between the two pressure sensors with the contribution from pressure noise being completely or partially eliminated. If one sensor is fixedly located in a room and the other sensor is attached to a body movable in a vertical direction, then it is possible to measure a change in height of the second sensor. Scenarios can also be envisioned where both sensors are movable. This is illustrated in Figs. 1 and 2.
• the darker curve, 1 represents the difference signal, that is, a measurement signal compensated for pressure noise
• the two more faint curves, 2 and 3 represent pressure signals from two sensors.
• the sensor represented by curve 2 is kept stationary and the sensor represented by curve 3 is raised and lowered. It can be seen that significant background fluctuations are completely eliminated in curve 1 , i.e. the difference signal.
• both sensors are being moved. In this case, when starting from the same height, the difference signal will indicate the difference in height between the two pressure sensors.
• a measurement principle with two or more sensors where background noise is completely or partially cancelled can be used as a fall detector or an apparatus for detecting if persons or animals have suffered a fall.
• an apparatus for detecting and notifying that a user has fallen and remained lying without being able to stand up The user wears or carries a pressure sensor.
• the pressure sensor and associated necessary components may be wirelessly connected to a stationary part, e.g. the sensor installed in the room, which also includes a pressure sensor.
• the stationary part may perform any signal processing required to detect a fall based on the pressure changes measured, i.e. the stationary part can make comparisons between stored signal sequences and detected signal sequences, that is, it can discriminated between signal sequences known to indicate a fall and signal sequences that may be due to other events. It is conceivable to build a "library" of known signal sequences through simulations, for example, which known signal sequences are stored in a memory unit of the stationary part. In another embodiment, it is possible to include a remote database in which known signal sequences are stored. In this case, the stationary part may send signal sequences to the remote database, where comparisons are made between stored signal sequences and detected signal sequences (measurement signals) and the results are transferred back to the stationary part.
• Such a database could build a sizable library of real life events in a dynamic/adaptive manner and thus ensure an ever more reliable fall detection.
• a distributed system in which the comparison and discrimination are accomplished in the stationary part to also include some form of library building, that is, an experience database.
• the signal sequences stored in a stationary part can be updated wirelessly, or by wire, through firmware upgrades or otherwise.
• the stationary part may be connected to a notification system for providing a notification if a user has suffered a fall and remains lying without getting up again. Rapid pressure increases representing known changes in altitude that match falls from different positions will be detected as a fall unless the pressure subsequently decreases, indicating that the user gets up again.
• Figs. 1 and 3 show signals measured by a first pressure sensor attached to a body, such as a human body, shown as curve 3 in the graph, and by a second pressure sensor with a fixed vertical position, shown as curve 2 in the graph.
• Curve 1 shows the difference between the pressure signals of the first and second sensors - that is, the difference signal.
• the difference signal will ensure a complete or partial cancellation of noise for the following reason: the pressure change measured by the first sensor includes a change in pressure due to vertical displacement AND changes in pressure in the form of background noise, whereas the second detector, which does not move vertically, only outputs a noise signal, that is, a signal indicating changes in pressure that are independent of vertical displacement, and when the signal from the second sensor is subtracted from the signal from the first sensor a resultant noise-compensated signal is obtained.
• Fig. 3 shows a first sensor located in the neck region of a person and a second sensor, denoted as SPC, mounted to a wall.
• One such error source may be calibration/sensitivity of the sensors, and in addition there may be local pressure differences, background pressures within a small area, such as during aeration, for example, draught, fan usage and the like.
• the first sensor is characterized in that it includes arrangements that allow it to be mounted to a person, and the sensor must also include means for communicating with the second sensor, denoted as SPC in Fig. 3.
• the communication means may be wireless Bluetooth transmitters, wireless WiFi-transmitters or other types of wireless transmitters, including proprietary transmitters.
• the protocol will include reception acknowledgments, that is, the first sensor may also be provided with radio receivers configured for receiving signals transmitted wirelessly by a transmitter.
• the first sensor may typically comprise an element for detecting pressure changes, a converter converting the signal from the detector element and generally also an analogue-to-digital converter as well as a transceiver. Also needed is a voltage source.
• the voltage source can be implemented using conventional batteries or a rechargeable source, such as rechargeable batteries, for example.
• the second sensor like the first sensor, comprises a detector unit in the form of a detector element.
• the detector element outputs a signal which is correlated with pressure changes.
• the second sensor As the second sensor is located in a fixed vertical position, e.g. secured to a wall, the detector element of this second sensor should, in principle, not provide any output signal. In practice, however, as a result of local "pressure noise", it will provide output signals.
• the second sensor comprises a means for converting signals from the detector element as well as a means for wirelessly receiving and transmitting signals from/to the first sensor.
• the solution scales well, so that one may have several "first" sensors, that is, sensors configured for being attached to persons and communicating with a fixed second sensor.
• the protocols may include information about the senders' identities, which identities can be assigned to specific persons in a lookup table that may be stored in the second sensor or in a central database.
• the second sensor may also comprise a local memory, preferably of a writeable type. Typically, a plurality of signal signatures will be stored in such a memory. It is conceivable that a person who suffers a fall will result in a specific set of output signals representative of pressure changes, and similarly it is conceivable that fans turning on and off, windows being opened and closed, doors being opened and closed, and other conditions may have output signals representative of such conditions. It is also conceivable that a person who falls or "almost falls” and then stands up again will have a specific "signal signature.” When the second sensor, continuously or intermittently, reads signals from the or each first sensor, the second sensor will first compensate the signal in that the difference signal is obtained, and then this difference signal, which should
• the second sensor may trigger an alarm. That is, the second sensor does not only comprise means for communicating with one or more first sensors, but it also comprises means for communicating with an alarm unit.
• the alarm unit may be comprised in an apparatus that includes the second sensor with detector elements and associated signal processing electronics/logic. Alternatively, the alarm unit may be external, and be connected by wire or wirelessly to the second sensor.
• the alarm unit In the case of an external alarm unit it is conceivable to have such a unit located in a guard room or at a security centre, from which a number of such second sensors can be monitored. If the alarm unit(s) is/are physically separated from the second sensor, then the alarm unit will include means for identifying the sender of received signals, either the sender in the form of the identity of the first sensor and the second sensor, or at least the identity of the first sensor. If the identity of the first sensor is known, then a lookup in a table may reveal the identity of the person who has suffered a fall, as a person's identity can be mapped to the identity of a first sensor.
• monitoring system may include statistics, adaptive learning, through which both false and true alarms are learned and stored, alarm centres can be set for different levels, e.g. locally within an institution connected to a central alarm centre that covers several institutions, etc.
• the first sensor is attached to a person in order to illustrate the use.
• the first sensor it is conceivable for the first sensor to be attached to animals or inanimate objects. For example, it could be of interest to follow products during transport or to follow products during production, etc.
• Figure 3 shows a fall detector based on a movable and a fixedly installed sensor.
• the user carries a sensor s, and this sensor communicates with a fixed unit containing the sensor s, processing means p, and a
• a fall detector can also be implemented in that a user carries or wears two first sensors.
• the sensors must be located on different body parts for which a change in height resulting from a fall are significantly different. Exemplary locations could be the neck and calf, but other places may also be suitable.
• the invention is not limited to using only two such first pressure change sensors. If more first sensors are used, we would expect increased sensitivity and fewer errors. The number of sensors used will be a trade-off between performance and complexity. [0037] When using two or more sensors attached to a user, ambiguity may arise in the difference signals since these signals indicate change in relative height between the two sensors.
• the difference in correlation between the difference signal and each of the measured signals will indicate how much of the change is attributable to each of the measured signals.
• each first sensor will communicate with a fixed unit.
• This fixed unit denoted by PC in Fig. 4, may typically correspond to the second sensor/apparatus of the first embodiment, exclusive of the detector element and the transducer.
• the fixed element receives pressure signals including background noise wirelessly from sensors attached to persons. Signals from a same person are processed and compared with "known signal patterns" and an alarm is triggered if a "fall" is detected in the comparison process.
• the second embodiment has the advantage, especially when used with live individuals, of not being dependent on where the individual carrying the detectors is located as long as it is inside a coverage area of communication between the sensors and the fixed installation, PC.
• Fig. 4 shows a fall detector based on several movable sensors.
• a user carries two sensors.
• these sensors are communicating with a fixed unit for processing p and communication c.
• This device can be fixedly installed as shown in the drawing, but it may also be carried by the user. The system then becomes completely mobile and can be used both indoors and outdoors.

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• 2015
  • 2015-10-12 NO NO20151375A patent/NO20151375A1/no not_active Application Discontinuation
• 2016
  • 2016-10-12 WO PCT/NO2016/050205 patent/WO2017065617A1/en active Application Filing

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