Data processing: measuring – calibrating – or testing – Measurement system – Measured signal processing
Reexamination Certificate
2001-02-08
2004-02-10
Barlow, John (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system
Measured signal processing
C702S190000
Reexamination Certificate
active
06691074
ABSTRACT:
REFERENCE TO COMPUTER PROGRAM LISTING APPENDIX
Computer program listing appendices are submitted herewith on one compact disc and one duplicate compact disc. The total number of compact discs including duplicates is two. The files on the compact disc are ASCII text files in which the characters are displayed as their corresponding values in hexadecimal format. Their names, dates of creation, directory locations, and sizes in bytes are:
1. Directory appndxI containing file 36725aI.HEX (Appendix I) of Jan. 16, 2001 and of length 55,519 bytes.
2. Directory appndxII containing file 36725aII.HEX (Appendix II) of Jan. 16, 2001 and of length 8,260 bytes.
The files are referred to herein as appendices I and II respectively. The material on the compact discs is incorporated by reference herein.
FIELD OF THE INVENTION
The present invention relates generally, to positioning systems and more particularly to positioning systems employing alternating electromagnetic fields and acceleration measurements, as well as to an apparatus for localization and tracking using an extended Kalman filter.
BACKGROUND OF THE INVENTION
Various types of positioning systems which employ alternating electromagnetic fields are known. The following U.S. Patents and foreign patent documents are believed to represent the state of the art for positioning systems:
U.S. Pat. Nos. 4,054,881 and 4,314,251 to Raab; U.S. Pat. Nos. 4,622,644, 4,642,786, 5,742,394, 5,744,953, 5,767,669, 5,831,260 and 5,953,683 to Hansen; U.S. Pat. No. 4,737,794 to Jones; U.S. Pat. Nos. 4,613,866, 4,945,305 and 4,849,692 to Blood; U.S. Pat. Nos. 3,868,565, 3,983,474, 4,017,858, 4,298,874 and 4,742,356 to Kuipers; U.S. Pat. Nos. 5,168,222 and 5,172,056 to Volsin et al; U.S. Pat. No. 5,0170,172 to Weinstein; U.S. Pat. Nos. 5,453,686 and 5,640,170 to Anderson; U.S. Pat. No. 5,767,960 to Orman; U.S. Pat. No. 5,600,330 to Blood; U.S. Pat. No. 5,307,072 to Jones; U.S. Pat. No. 4,710,708 to Rorden; U.S. Pat. No. 4,346,384 to Raab; U.S. Pat. No. 4,328,548 to Crow; U.S. Pat. No. 5,558,091 to Acker; U.S. Pat. No. 5,592,939 to Martinelli; U.S. Pat. No. 6,073,043 to Schnieder; U.S. Pat. No. 3,644,825 to Davis; U.S. Pat. No. 5,377,678 to Dumoulin; U.S. Pat. Nos. 4,287,809 and 4,394,831 to Egli; U.S. Pat. No. 4,396,885 to Constant WO 96/05768 to Ben-Haim and WO 94/04938 to Bladen;
U.S. Pat. No. 4,710,708 to Rorden describes a positioning system which employs only one electromagnetic coil.
A description of accelerometer technology may be found in
Capacitive Sensors,
L. K. Baxter, 1998 ISBN 0-7803-5351-X;
U.S. Pat. No. 5,592,401 to Kramer, U.S. Pat. No. 5,657,226 to Shin, U.S. Pat. No. 5,615,116 to Gudat, U.S. Pat. No. 5,615,132 to Horton, U.S. Pat. No. 5,956,250 to Gudat, U.S. Pat. No. 5,902,351 to Streit, U.S. Pat. No. 5,991,692 to Spencer, U.S. Pat. No. 4,506,979 to Rogers, U.S. Pat. No. 5,051,751 to Gray and U.S. Pat. No. 5,930,741 to Kramer, all describe positioning systems which may employ Kalman filtering and acceleration measurements.
Phase Locked Loop technology is described in “Phase locked loop: simulation and applications”, by Roland E. Best, McGraw-Hill Book Company, ISBN 0070060517.
The theory of non-linear filtering and its applications is discussed in:
H. J. Kushner, “Approximations to Optimal Nonlinear Filters”. IEEE Trans. A.C., Vol. AC-12, No. 5, October 1967;
A. Gelb, J. F. Kaspar, Jr., R. A. Nash, Jr., C. E. Price, and A. A. Southerland, Jr., “Applied Optimal Estimation”, M.I.T. Press, Cambridge, Mass., 1974;
B. D. O. Anderson, and J. B. Moore, “Optimal Filtering”, Prentice-Hall, Englewood Cliffs, N.J., 1979;
A. H. Jazwinski, “Stochastic Processes and Filtering Theory”, Academic Press, New York, 1971; and
M. S. Grewal, and A. P. Andrews, “Kalman Filtering”, Prentice-Hall, Upper Saddle River, N.J., 1993.
The Electromagnetic field equation laws are discussed in:
J. D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, New York, New York, 1975.
The application of Extended Kalman filters (EKF) to tracking in the context of radar is discussed, for example, in U.S. Pat. Nos. 5,075,694, 4,179,696, 3,952,304 and 3,935,572. Other tracking systems are discussed, for example, in U.S. Pat. Nos. 5,095,467 and 4,855,932.
The Kalman filter is a standard tool for “data fusion” of different sensors. In U.S. Pat. No. 5,416,712, Global Positioning System (GPS) signals and dead reckoning are combined by a Kalman filter, where the gyro bias is also calibrated. In U.S. Pat. No. 5,645,077 automatic drift compensation is discussed.
Reference is also made to positioning and tracking systems described in the following U.S. patent and patent applications assigned to the assignee of the present invention, which are herein incorporated each in its entirety, by reference. U.S. Pat. No. 6,141,293 to Moriya at el.; U.S. patent application Ser. No. 09/345,189 entitled “A system and method for three dimensional positioning and tracking”, filed on Jun. 30, 1999 to Moriya and Itzkovich; U.S. patent application Ser. No. 09/384,314 entitled “A localization and tracking system”, filed on Aug. 27, 1999 to Moriya and Albeck; and U.S. patent application Ser. No. 09/503,436 entitled “A system for three dimensional positioning and tracking with dynamic range extension”, filed on Feb. 14, 2000 to Moriya.
The disclosures of all publications mentioned in the specification are hereby incorporated in their entirety by reference.
SUMMARY OF THE INVENTION
Preferred embodiments of the present invention provide an improved apparatus and method for positioning and tracking objects, particularly using a non-linear Kalman Filter tracker, where electromagnetic field data and acceleration information are used simultaneously for the determination of the position and orientation of a remote sensing device.
An acceleration measuring device is typically used to provide acceleration information of the moving object. A particular advantage of a preferred embodiment of the present invention is the fusion of the acceleration information in the tracking in order to increase the location, i.e. position and orientation, accuracy.
In a preferred embodiment of the present invention, the axial rotation of a probe sensor around at least one direction in space can be monitored.
Preferably, a periodic comparison between the position data based on electromagnetic field information and both electromagnetic and acceleration data is obtained. The results of the comparison is then used in order to indicate electromagnetic disturbances in the operating environment.
Preferably, a system constructed and operative in accordance with a preferred embodiment of the present invention comprises N transmitters and M receiving elements in the probe sensor which detects at least 6 electromagnetic signals, each of the transmitters is characterized by its own frequency and at least one linear multi-axial acceleration detector which detects the actual acceleration components in the direction perpendicular to its prime axis that are connected to a digital signal processing circuit. The analog output of the electromagnetic signal detector is a voltage signal proportional to the superposition of the N electromagnetic field transmitters at the coordinates x
i
, y
i
, z
i
&phgr;
I
, &thgr;
i
, and &psgr; where the index i denotes the position of the electromagnetic source i. The output of the acceleration detecting components are voltage signals which are functions of the actual acceleration components in the direction perpendicular to its prime axis.
It is a particular feature of a preferred embodiment of the present invention that the antenna coils need not be exactly mutually orthogonal and certainly need not be arranged such that the centers of the antenna coils coincide.
Preferably, analog signals of both electromagnetic field detectors and the acceleration components are digitized and are introduced to an integrated digital signal processor block, as an input data. The digitized input data from the sensor is then used by a digital signal processor, to compute the position and orientation coordinates of the sensor. The
Itzkovich Moti
Moriya Netzer
Primak Harel
Barlow John
Lau Tung
Netmore Ltd.
Nixon & Vanderhye P.C.
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