EP0655138B1
Expired / Lapsed
EP
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Position location system
Assignee: British Telecommunications PLC
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Filing: 1993-08-16
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Granted: 1998-04-29
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Expires: 2013-08-16
Abstract
No abstract record available.
Inventors
- 👤 John Stuart Bladen
- 👤 Alan Patrick 6 The Fairway Anderson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 22:32
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/06; A61B5/061; A61B5/062; A61B90/00; A61B90/39; A61B2090/3954; A61B2090/3958; A61B2090/397; A61B2090/3975
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
216 words
A method of determining the location and/or orientation of a field sensor (7)
relative to a plurality of field generators (1) of known location, each field generator
(1) comprising a plurality of collocated field generating elements (3), each generating
element (3) being energised and a measurement being made at the field sensor (7) of
the respective field generated by the generating element (3), the method being
characterised by the steps of: 1) ) for each field generator (1) calculating, from the measurements of the field
generated by each of its generating elements (3) and an estimate of the
orientation of the sensor (7), an estimate of the distance from that
particular field generator (1) to the sensor (7), and 2) utilising the estimates of distance from step 1), and the known location of
the field generators (1) to calculate an estimate of the location of the
sensor (7); 3) employing the estimated location of the sensor (7) from step 2) and the
measurements of the field at the sensor (7) to calculate a new estimate of
the orientation of the sensor (7); 4) repeating steps 1) to 3) iteratively, with step 1) employing the new
estimate of sensor orientation from the preceding step 3), to improve the
estimates of location and orientation of the sensor (7).
Claim 2
Dependent Claim
34 words
A method as claimed in claim 1, wherein each generating element (3) of
each field generator (1) is energised in sequence so that only one generating element
(3) is energised at any given time.
Claim 3
Dependent Claim
40 words
A method as claimed in claim 1, wherein at least two generating elements
(3) are simultaneously energised, each of these at least two generating elements (3)
being energised at a different frequency from the other simultaneously energised
generating element(s) (3).
Claim 4
Dependent Claim
67 words
A method as claimed in claim 1 wherein at step 3), the estimated location
of the sensor (7) calculated in step 2) and the measurements of the field at the
sensor (7) are used to calculate, for each field generator (1), the direction of the
respective field at the sensor (7) and from these field directions calculating a new
estimate of the orientation of the sensor (7).
Claim 5
Dependent Claim
68 words
A method as claimed in claim 1 or claim 4 wherein, at step 1), the initial
estimate of the orientation of the sensor (7) is taken to be the orientation as
calculated by the immediately preceding application of the method or, if this is the
first application of the method, the axis of the sensor (7) is initially assumed to be
directed towards the respective field generator (1).
Claim 6
Independent Claim
233 words
A method of determining the location of a field sensor (7), comprising a
plurality of collocated field sensing elements (A,B,C), relative to a field generator (1)
comprising a plurality of collocated field generating elements (3), each field
generating element (3) being energised in turn and the value of the resultant field
strength being measured at the field sensor (7), the measured field strength being
dependent on the location of the sensor (7) within the respective field, the method
being characterised by the steps of: 1) calculating, by utilising all the values of measured field strength and an
estimate of the direction of the sensor (7) from the field generator (1), a
direction dependent weighting factor for each field generating element (3)
so that the calculated field strength B is equal to the field strength B that
would exist at the sensor (7) if the axis of the field were directed towards
the sensor (7), 2) iteratively altering the direction dependent weighting factors to maximise B
and thus to determine to a desired level of accuracy the direction of the
sensor (7) from the field generator (1), and 3) employing the measured values of the field strength to calculate the
distance of the sensor (7) from the field generator (1) and hence, from the
direction of the sensor (7) in step 2), the location of the sensor (7) relative
to the field generator (1).
Claim 7
Independent Claim
213 words
A method of determining the location and/or orientation of a field generator
(7) relative to a plurality of field sensors (1) of known location, each field sensor (1)
comprising a plurality of collocated field sensor elements (3), the generator (7) being
energised and a measurement being made at the field sensor elements (3) of the
respective field generated by the generator (7), the method being characterised by
the steps of: 1) for each field sensor (1) calculating, from the measurements of the field
generated at each of its sensor elements (3) and an estimate of the
orientation of the generator (7), an estimate of the distance from that
particular sensor (1) to the generator (7), and 2) utilising the estimates of distance from step 1), and the known location of
the field sensors (1) to calculate an estimate of the location of the
generator (7); 3) employing the estimated location of the generator (7) from step 2) and the
measurements of the field at the sensors (1) to calculate a new estimate of
the orientation of the generator (7); 4) repeating steps 1) to 3) iteratively, with step 1) employing the new
estimate of generator orientation from the preceding step 3), to improve
the estimates of location and orientation of the generator (7).
Claim 8
Dependent Claim
299 words
Apparatus for determining the location and/or orientation of a field sensor
(7) comprising: a plurality of field generators (1) each comprising a plurality of collocated
field generating elements (3), energising means (5) operable for each field generator (1) to energise each
of the plurality of field generating elements (3) to produce a field within which the
location and orientation of the sensor (7) may be determined, measurement means (8), connected to the field sensor (7), to measure and
output a parameter of the field at the sensor (7), and control means (6) to control the energising means (5), the control means
(6) comprising storing means to store parameters output by the measurement means
(8), and calculating means to calculate, from the stored measurements of the fields,
the location and orientation of the sensor (7), the apparatus being characterised in that the calculating means comprises: location estimating means being operable to calculate, from the stored
measurements of the fields and an estimate of the orientation of the sensor (7), an
estimate of the distance of the sensor (7) from each of the field generators (1) and,
using the estimates of distance and the known location of the field generators (1), to
calculate an estimate of the location of the sensor (7); orientation estimating means being operable to calculate, from the estimate
of sensor location by the location estimating means and the stored measurements of
the field, a new estimate of the orientation of the sensor (7); means to iteratively improve the estimate of the location and orientation of
the sensor (7), which means in use repeatedly employ the location and orientation
estimating means in sequence, wherein the output of the orientation estimating
means is adopted by the location estimating means as the new estimate of sensor
orientation at each iteration.
Claim 9
Dependent Claim
52 words
Apparatus for determining the location of a field sensor (7) as claimed in
claim 8, wherein the field sensor (7) comprises a single field sensing element and the
parameter of the field sensed by said single field sensing element is dependent on
the orientation of the field sensing element within the field.
Claim 10
Dependent Claim
33 words
Apparatus for determining the location of a field sensor (7) as claimed in
claim 8 or claim 9, having three field generators (1), each comprising three mutually
orthogonal collocated field generating elements (3).
Claim 11
Dependent Claim
276 words
Apparatus for determining the location of an object relative to a field
generator (1), the apparatus comprising a field generator (1) comprising a plurality of field generating elements (3), energising means (5) to sequentially energise each of the field generating
elements (3) to produce a field within which the object may be located, a sensor (7), to be attached to the object, comprising a plurality of
collocated field sensing elements (A,B,C), each able to sense a parameter of the
field, measurement means (8) to measure and output the parameter of the field
sensed by each field sensing element (A,B,C) when each field generating element (3)
is energised, and control means (6) to control the energising means (5), store the parameters
output by the measurement means (8) and calculate the location of the sensor (7),
relative to the field generator (1), the apparatus being characterised in that the control means (6) comprises weighting means to weight each of the parameters, sensed by the sensor
(7), by a direction dependent weighting factor for each field generating element (3),
so that the calculated field strength B is equal to the field strength B that would exist
at the sensor (7) if the axis of the field were directed towards the sensor (7), means to iteratively alter the direction dependent weighting factors until a
maximum value of the field strength is found, and to determine the direction of the
sensor (7) from the field generator (1) to a desired level of accuracy, and calculating means to calculate the distance of the sensor (7) from the
generator (1) and hence the location of the sensor (7) relative to the generator (1).
Claim 12
Dependent Claim
38 words
Apparatus for determining the location of an object as claimed in claim 11,
wherein the field generator (1) comprises three mutually orthogonal field generating
elements (3) and the sensor (7) comprises three mutually orthogonal field sensing
elements (A,B,C).
Claim 13
Dependent Claim
25 words
Apparatus as claimed in any one of claims 8 to 12, arranged for use in
surgery, therapy or diagnosis of a human or animal body.
Claim 14
Dependent Claim
29 words
An endoscopy system for use in the endoscopy of a human or animal body,
the endoscopy system comprising apparatus as claimed in any one of claims 8 to 12.
Claim 15
Dependent Claim
167 words
Apparatus for monitoring the position of an endoscope within a human or
animal body, the apparatus comprising a field sensor (7), a plurality of field generators (1) each comprising a plurality of field
generating elements (3), energising means (5) operable for each field generator (1) to energise each
of the plurality of field generating elements (3) to produce a field within which the
location of the endoscope may be determined, measurement means (8), connected to the field sensor (7), to measure and
output a parameter of the field at the sensor (7), and control means (6) to control the energising means (5), store parameters
output by the measurement means (8), and calculate the location of the sensor (7)
relative to the plurality of field generators (1), the apparatus being characterised in
that the control means (6) are arranged to calculate the location of the sensor (7)
relative to the plurality of field generators (1) by the method as claimed in any one of
claims 1 to 7.
Claim 16
Dependent Claim
58 words
Apparatus for determining the location and/or orientation of a sensor (7) as
claimed in any one of claims 8, 9 or 10, wherein one or more of said sensors (7) are
attached to parts of a glove, the output of said apparatus providing data defining the
location and orientation of the respective parts of a glove wearer's hand.
Claim 17
Dependent Claim
19 words
Apparatus as claimed in claim 16, wherein one or more sensors (7) are
attached to fingers of the glove.
References Cited (Backward Citations)
No citation records indexed.
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