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Flexible monitoring of location and motion

  • US 6,181,253 B1
  • Filed: 02/05/1998
  • Issued: 01/30/2001
  • Est. Priority Date: 12/21/1993
  • Status: Expired due to Fees
First Claim
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1. A method for monitoring the location of a monitored person (MP) with reference to a permitted site, the method comprising the steps of:

  • (1) designating a site, having a connected and closed curve or surface of arbitrary shape as a site boundary, as a permitted site;

    (2) permitting an MP to move on the permitted site;

    (3) receiving location determination (LD) signals at an LD unit attached to the MP that allow determination of the present location of the MP;

    (4) determining the present location of the MP, using the LD unit;

    (5) when the MP is not on the permitted site at one or more of the location determination times, transmitting an alarm signal number 1;

    (6) providing a signal generator that is attached to the MP'"'"'s body and that, when activated, transmits a distinguishable electromagnetic signal;

    (7) providing the MP with a motion sensor that, when the sensor is substantially motionless, issues a stationarity signal;

    (8) when the MP is on the permitted site;

    (8A) determining whether the LD unit is receiving LD signals;

    (8B) when the LD unit is receiving LD signals, returning to step (4), and when the LD unit is not receiving LD signals, proceeding to step (8C);

    (8C) issuing an advisory signal number 1 and causing a first timer to begin a countdown from an initial time Δ

    t1=Δ

    t1, max;

    (8D) determining whether the motion sensor is issuing a stationarity signal;

    (8E) when the first timer reaches the maximum accumulated time Δ

    t1=Δ

    t1, max and the motion sensor has not yet begun issuing a stationarity signal, transmitting an alarm signal number 2 and returning to step (8A);

    (8F) when the motion sensor begins issuing a stationarity signal before the first timer reaches the maximum accumulated time Δ

    t1=Δ

    t1, max deactivating the LD unit, deactivating the first timer, resetting the first timer accumulated time to Δ

    t1=0, activating the signal generator and causing the signal generator to transmit a distinguishable signal;

    (8G) providing a signal sensor, positioned at a selected location, that receives the distinguishable signal from the activated signal generator and that assigns a range attribute value A, having a real number value, to the received signal that is an approximate measure of the distance between the signal generator and the signal sensor;

    (8H) determining whether the range attribute value A for the distinguishable signal, received from the signal generator, is less than a selected range attribute threshold value Athr, at a sequence of at least two times;

    (8I) when A≧

    Athr, continuing to compare the range attribute value A with the threshold value Athr and (8J) when A<

    Athr (8J-1) transmitting an advisory signal number 2 and causing a second timer to begin a second countdown from a time Δ

    t2=0 to a second selected maximum accumulated countdown time of Δ

    t2=Δ

    t2, max;

    (8J-2) when the second countdown has begun, the motion sensor is issuing a stationarity signal, and Δ

    t2<

    Δ

    t2, max continuing to compare the range attribute value A with the threshold value Athr;

    (8J-3) when the second countdown has begun, the motion sensor is issuing a stationarity signal, and Δ

    t2<

    Δ

    t2, max transmitting an alarm signal number 3, returning to step (8H);

    (8J-4) when the second countdown has begun and the motion sensor is not issuing a stationarity signal, deactivating the second timer and resetting the second timer accumulated time to Δ

    t2=0;

    (8J-5) when the second countdown has begun and the motion sensor is not issuing a stationarity signal, activating the LD unit and causing a third timer to begin a countdown from an initial time Δ

    t3=0 to a third selected maximum accumulated countdown time Δ

    t3=Δ

    t3, max;

    (8J-6) when the second countdown has begun, the motion sensor is not issuing a stationarity signal and Δ

    t3≦

    Δ

    t3, max determining if the LD unit has acquired LD signals;

    (8J-7) when the second countdown has begun, the motion sensor is not issuing a stationarity signal and Δ

    t3≦

    Δ

    t3, max and the LD unit has acquired LD signals, initializing and deactivating the third timer and returning to step (8A);

    (8J-8) when the second countdown has begun, the motion sensor is not issuing a stationarity signal and Δ

    t3≦

    Δ

    t3, max, and the LD unit has not acquired LD signals, returning to step (8J-6)]; and

    (8J-9) when the second countdown has begun, the motion sensor is not issuing a stationarity signal and Δ

    t3≦

    Δ

    t3, max and the LD unit has not acquired LD signals, deactivating and initializing the third time counter, transmitting an alarm signal number 4 and returning to step (8A).

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