POSITION LOCATOR

• US 3,840,726 A
• Filed: 01/15/1973
• Issued: 10/08/1974
• Est. Priority Date: 01/15/1973
• Status: Expired due to Term

• Current Assignee: Earnest R. Harrison
• Original Assignee: Earnest R. Harrison
• Inventors: Harrison, Earnest R.
• Primary Examiner(s): Gruber, Felix D.
• Application Number:
  US05/323,592
• Time in Patent Office: 631 Days
• Field of Search: 235/150.2,150.25,150.27 73/178,432 33/324-326,355-357,361,366
• US Class Current: 701/300
• CPC Class Codes: G06G 7/78 for direction-finding, locating, distance or velocity measuring, or navigation systems

Abstract

A system for determining the course of travel of a carrier or wearer of an apparatus comprised of a pair of sensor arrays adapted to vectorially measure the earth'"'"''"'"'s gravity and magnetic fields as well as the movement of the carrier which may be for example a human wearing the sensor apparatus on his leg. Analog signals representative of these vector quantities are fed to the system which includes vector operation circuitry for performing a double integration to determine the distance traveled in three coordinate directions corresponding to the orthogonal axes of the sensor apparatus while the sensor assembly is moving and thereafter performing a coordinate transformation to provide readouts corresponding to the North, East and vertcial coordinates when the sensor apparatus is stationary.

Claims

1. A position locator system mounted on a carrier and having both momentary static and moving modes of operation during each cycle of operation, comprising in combination:

first sensor apparatus and circuit means therefor providing a composite electrical output signal comprised of a gravitational force vector component signal G and an acceleration force vector component signal A, said vector component signal A being substantially equal to zero during the stationary mode of operation of said first sensor apparatus;

second sensor apparatus and circuit means therefor providing an electrical output signal corresponding to a magnetic pole force vector H;

first circuit means coupled to said first sensor apparatus, being responsive to said composite output signal and providing an output signal corresponding to the derivative of the scalor magnitude of said composite output signal;

a logic circuit coupled to the output of said first circuit means anD being responsive to the output signal thereof to generate a control signal when the derivative of said composite output signal is substantially zero;

a clamping circuit having an input coupled to said first sensor apparatus and being activated by said control signal from said logic circuit to clamp said composite signal during a moving mode of said sensor to remove the vector component signal G from said composite output signal to thereby provide substantially only said vector component signal A;

double integration circuit means coupled to said clamping circuit and being responsive to the vector component signal A, performing a double integration with respect to time on said vector component signal A to provide electrical output signal S corresponding to distance;

first vector operation circuit means coupled to said second sensor means and being responsive to the magnetic vector signal H provided thereby and to said first sensor apparatus, being responsive to said vector component signal G when said vector component signal A is substantially zero and including means for normalizing the scalor value of the signal G to unity and maintaining said unity value substantially constant and means performing the vector operation H - (G . H) G Hh and providing an electrical output signal Hh which is a component of the vector signal H along a substantially horizontal plane;

second vector operation circuit means coupled to said first vector operation circuit means and said electrical output signal Hh provided thereby and said second circuit means and said output signal S provided thereby and including circuit means performing the vector operation Hh . S SN and providing an electrical output signal SN which is a north compass coordinate component signal of S;

third vector operation circuit means coupled to said first sensor apparatus, being responsive to the vector component signal G when said vector component signal A is substantially zero and said first vector operation circuit means and said electrical output signal Hh provided thereby and said second circuit means and said output signal S provided thereby, including circuit means performing the vector operation G X Hh . S SE and providing an electrical output signal SE which is an east compass coordinate component signal of S; and

means coupled to said electrical output signals SN and SE providing a visual representation thereof.

2. The locator system as defined by claim 1 and additionally including fourth vector operation circuit means coupled to said first sensor apparatus, being responsive to said vector component signal G when said vector component signal A is substantially zero and to said double integration circuit means and said distance signal S provided thereby, said fourth vector operation circuit means including circuit means performing the vector operation G . S SV and providing an electrical output signal SV which is a vertical coordinate component signal of S.

3. The system as defined by claim 2 and additionally including means coupled to said electrical output signal SV providing a visual representation thereof.

4. The system as defined by claim 3 wherein said means coupled to said electrical output signals SV, SN and SE additionally includes analog to digital conversion means.

5. The system as defined by claim 4 and additionally including digital readout means coupled to said analog to digital conversion means.

6. The locator system as defined by claim 1 wherein said first sensor apparatus comprises:

substantially non-magnetic support means attached to said carrieR adapted for movement in selected compass directions;

a cantilevered beam member having one end rigidly attached to said support means;

a weight under the influence of the environment'"'"''"'"'s gravitational field and the moving mode of operation attached to the other end of said beam member;

an electrically powered accelerometer assembly mounted on said beam member and being responsive to the stress upon said beam member caused by said weight to generate an analog composite electrical output signal; and

wherein said second sensor apparatus comprises;

an electrically powered flux gate magnetometer assembly housed in said support means and generating an analog electrical output signal corresponding to the magnetic pole force vector H.

7. The system as defined by claim 6 and additionally including means for attaching said support means to a human limb adapted to move while walking, running and the like.

8. The system as defined by claim 7 wherein said first, second, and third vector operation circuit means comprises analog computing elements.

9. The system as defined by claim 7 wherein said human limb comprises the leg.