CA1314993C - Process for the location of an object and the determination of its orientation in space and apparatus for performing the same - Google Patents
Process for the location of an object and the determination of its orientation in space and apparatus for performing the sameInfo
- Publication number
- CA1314993C CA1314993C CA000515137A CA515137A CA1314993C CA 1314993 C CA1314993 C CA 1314993C CA 000515137 A CA000515137 A CA 000515137A CA 515137 A CA515137 A CA 515137A CA 1314993 C CA1314993 C CA 1314993C
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- Canada
- Prior art keywords
- dipole
- measuring
- magnetic
- frequency
- process according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V15/00—Tags attached to, or associated with, an object, in order to enable detection of the object
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/033—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor
- G06F3/0346—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor with detection of the device orientation or free movement in a 3D space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/033—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor
- G06F3/0354—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor with detection of 2D relative movements between the device, or an operating part thereof, and a plane or surface, e.g. 2D mice, trackballs, pens or pucks
- G06F3/03545—Pens or stylus
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Human Computer Interaction (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geophysics (AREA)
- Geophysics And Detection Of Objects (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Process for locating an object and determining its orientation in space and apparatus for performing this process.
The object to be located is provided with one or more magnetic dipoles. With the aid of measuring systems, each constituted by directional magnetometers, the magnetic field is measured and from it is deduced the position of the origin of the vector integral with the object and the orientation of said vector.
Application to the production of contour or notation acquisition means and to the characterization of the movements of mock-ups of elements constituting seawalls.
B 8785.3 RS
Process for locating an object and determining its orientation in space and apparatus for performing this process.
The object to be located is provided with one or more magnetic dipoles. With the aid of measuring systems, each constituted by directional magnetometers, the magnetic field is measured and from it is deduced the position of the origin of the vector integral with the object and the orientation of said vector.
Application to the production of contour or notation acquisition means and to the characterization of the movements of mock-ups of elements constituting seawalls.
B 8785.3 RS
Description
1 3 1 ~9~3 PROCESS FOR THE LOCATION Ol; AN OBJECT AND THE DETERMINhTION
__ ~_ _ _ _ OF ITS ORIENTATION N SPACE AND
APPARATUS FOR PERFOR~fING THE SAr~E
BACKGROUND OF THE INVENTION
The present invention relates to a process for locating an object and determining its orientation in space and to an apparatus for performing the same.
The problem of locating an object and investigating its orientation in space frequently occurs in widely ~arying fields, such as the control of the displacements of moving members, models or mock-ups (e.g. of ships or seawalls), the scanning or acquisition of notations or contours, robotics, etc.
For solving -this p~oblem, use has already been made of optical or ultrasonic processes. Processes are also known which use accelerometers, capacitive or resistive sensors, etc.
Certain of these methods are difficult to perform, particularly when several media are involved. This is more particularly the case with obJects ~hich are partly submerged in the water (ships, seawalls, etc.), the immersion in the water greatly disturbing the propagation conditions of the optical or sound waves used. In the case of contour or notation acquisition or scanning tables, the pressure of the hand on the table can also lead to operating difficulties.
SUMMARY OF THE INVENTION
The obJect of the present invention is to obviate these B 8785 . 3 RS
1 31 4~93 disadvantages. For this p~rpose, it proposes a process and an apparatus based on a completely novel principle consisting of providing the object to be investigated with at least one magnetic dipole and locating or spotmarking the position of said dipole or dipoles by a measurement of the magnetic field which it produces. The position of the ob3ect and its orientation in space are deduced from this measurement, More specifically, the present invention relates to a process for locating an object and for determining its position in space, wherein it comprises equipping the object with at least one magnetic dipole constituted by a winding excited by an alterna-ting current generator having a given frequency, such a dipole having an origin and a magnetic moment, placing at least one measuring system in the space where the object is assumed to be, each system having directional magnetometers able to measure the component along an axis of the ambient magnetic field, measuring with the aid of said system or systems the components of the field along a~es at said given frequency and as a function of -the result of these measurements, calculating the coordinates of the origin of the dipole with respect to the measuring system, which locates the object and orientation ansles of the dipole moment with respect to the measuring axes, which gives it sorientation.
According to an advantageous embodiment, the object is provided with a single dipole and use is made o~ at least two measuring trihedrons~ However, according to another variant, B 8785~3 RS
_ 3 _ t 31 ~9q3 the object is provided with three trihedron dipoles and only one measuring sy.stem is used. Preferably, each measuring system comprises three magnetometers, whereof the three measuring axes are oriented according to a trirectangular trihedron~
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in greater detail hereinafter relative to non-limitative embodiments and the attached drawings, wherein show:
Fig. 1 Diagrammatically the principle of the invention, 10 Fig. 2 An example of windings making it possible to form a measurement trirectangular trihedron.
Fig. 3 The notations making it possible to locate or spotmark a point in a reference system with two trirectangular trihedrons.
15 Fig. 4 The notations making it possible to locate or spotmark the orientation of a dipole moment.
Fig. 5 Diagrammaticall~ a contour or notation acquisition system according to the invention.
Fig. 6 The location of two reference trihedrons with respect to a three dimensional acquisition support.
Fig. 7 The general organisation of an acquisition apparatus according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Fig. 1 illustrates the principle of the process accordins to the invention in the more general case where the object has six degre0s o~ freedom. The object, whose position and/or B 8785.3 RS
~ 1 3 1 1Ir993 orientation is to be determined is designated 10. A magnetic dipole is made integral with this object. It is constituted by a winding 12 and a magnetic core 14, which is preferably laminated to prevent eddy currentsO However~ the ferromagnetic core is not obligatory. It merely makes it possible to amplify the signal without increasing the dimensions of the exciting coil. This dipole has an origin A and a dipole moment M.
Winding 12 is supplied by a generator 16 supplying an alternating current at a given frequency. As a function of the size of object 10, generator 16 can be incorporated into the object (as will be shown hereinafter) or can be separated therefrom and connected thereto by connecting wires. A
resistor 18 optionally makes it possible to tap a voltage, whose ~requenc~ is equal to the exciting frequency for reasons which will become apparent hereinafter.
The eans for determining the position of A and -the orientation of M in space comprise t~o systems El and E2, each constituted by three directional magnetometers oriented as *rirectangular trihedrons, respectively Ml , Mly, Ml for the first and M2X, M2y and M2z for the second. These trihedrons have the respective origins points l and 2 The signals emitted by these measuring systems (3 for each ~stem) are addressed to a processing system 22 which can fulfil various functions, i.e~ calculating, storing, displaying, transmitting, etc.
B 8785.3 RS
- 5 - 1 31 ~3 A directional magnetometer which can be used in the invention is described in ~R-A-2 198 146. It uses a thin ferromagnetic film deposited on a cylinder and gives the value of the compo~ent of the ambient magnetic field along the cylinder axis. Three magnetometers of this type can be grouped as a trirectangular trihedron. In the case of a ver~ precise location, it is necessary to take account o-f the distances between the measuring axes because the measurement is not performed at the same point for each axis.
The windings of the -trihedrons can be coiled, as shown in fig. 2, onto a cube 25, in accordance with three coils 25x, 25y, 25z.
Figs. 3 and 4 make it possible to define the notatlons used for calculat:ing the coordinates of point A and the orientation of vector M on the basis of the measurement of the magnetic ~ields.
In trihedron lxyz (fi~. 3), the vector OlA is spotmarked b~
a unit vector ul, whose spherical coordinate angles are ~'1 and ~1- Thus, point A has as spherical coordinates ~1' ~ and Rl and in the same ~ay in 2 in which the unit vector u2 has as angles ~2 and ~'2 and point A the spherical coordinate 2~ ~2 and R2- l and 2 being spaced b~ d.
On assuming a position in a trirectangular trihedron ha~ing as its origin point A, the magnetic dipole moment M can be B 8785.3 RS
6 1 31 ~(13 spotmarked by the angles ~ and ~, its modulus being designated ¦M ¦.
The fields measured at l and 2 comprise three components, Y lx' ly' ~lz and h2x~ h2y- h2 directed along three axes of the trihedrons. In order to simplify the notations, a matrix notation system is adopted, a ~atrix magnitude being designated by an underlined letter. Thus, the fields measured by El and E2 have as their values:
10 hl = h y and h2 = ¦h2 In the same way a matrix M is obtained characterizing the magnetic dipole moment, whose modulus is M
c os ~ . c osY
M = ¦M¦ COS~ .sinY
sin~
For the unit vectors ul and u2, we obtain:
~cos ~l~cos ~ 1~ cos ~2~cos ~2 ul cos~ sin ~1u2 cos ~ 2.sin ~2 20sin ~1 sin ~ 2 and we also have:
'~llx l U2 = U2Y 1 lUlZ ~ -- LU~Z~ ~
B 87~5.3 RS
1 3 1 llr9q3 A standard calculation makes it possible to determine the field h at a point in space created by a ma~netic dipole M
defined by a vector u and located at distance R:
1 3u ut ~ I
h = ~ M
in which u is the transposed matrix of u, I is the unit matrix:
. '~. O O' .
I = O 1 0 This equation corresponds to three equations for lxy and three equations for 2xyz' i.e. respectively:
1 3ul ul - I
~ R3 M (1, 2, 31 15 in which Rl = ¦01A¦
h2 ~ R~ ~4, 5, 6) in which R2 = ¦02A ¦
we also obtain:
d = RlUly -R2U2y RlUlz = ~2u2 ~8) Rlulx = R2U2X
Thus, there are in all nine equations with nine unknowns, ~len B 8785.3 RS
1 31 ~qC)3 the modu]us of ~ is not known the problem can be reduced to the sol~ing of th~ee equations with three unknowns by a careful choice o~ the fixed reference of the coordinates and a few mathematical operations. Computer 22 has the ~unction of solving these equations and giving the value of these ~ 1' ~1' Rl and ~2' ~2' R2 making it possible to locate point A, i.e. the object, and ~, r make it possible to spotmark its orientation.
It is possible to use a third measuring system E3 forming a 1~ supplementary trirectangular trihedron. Then 3=3=6 supplementary equations are obtained for only three unknowns more, namely ~3, ~3, R3, so that there is a certain redundancy in the informations, which can be use~ul.
It is also possible to equip the object with one or two supplementary dipoles (at different frequencies~, which contribute to supplying more informations on the same trihedron. The maximum three dipoles can be perpendicular and form a trirectangular trihedron. The reverse problem is then relatively simple for a single measuring trihedron.
In certain cases, on ~nowing the position of the object in a certain direction, it is possible not to use the measuring axis parallel to said direction and reduce the trihedron to a dihedron. This is more particularly the case if the ob~ect is mobile in one plane~ two axes only defining said plane being useful. This reduction of the measuring means was stressed hereinbefore.
~ 878~.~ RS
9 1 31 4~3 The process described hereinbefore is not limited to the detection of a single object. It is very easily possible to work on a plurality of objects, provided that the winding of the object of order or rank i is excited to a frequency fi, which is its own. It is obviously necessary to avoid any harmonics of the frequency fi, i.e. close to a frequency fj of another object of order or rank j, or one of its harmonics and ensure that the various frequencies are sufficiently different from one another. These e~perimental conditions are clearly dependent on the desired precision, the integration time of the measurement signals, the speed of the movements of the object, etc.
Thus, as each object is to a certain extent located b~ a frequency, the measurement of the magnetic field of said object takes place at said frequency. This means that the sisnal supplied by the magnetometers of systems El and E2 must be successively analysed at the different frequencies fi allocated to the different objects. For this purpose, a first solution consists of carrying out a s~nchronous detection with the aid of a reference signal charac*erizing the natural frequency of the sought object ~e.g. by means of a voltage tapped at the terminals of the aforementioned resistor 18).
This voltage can be transmitted to the magnetometers by wire or radio. Behind said magnetometers, a successive synchronous detection takes place on the ~arious frequencies used. It is even possible not to transmit the voltage if the same crystal is used on transmission and reception.
B 8785.3 RS
" 1 31 ~q3 It is also possible to carry out a spectral analysis by Fourier transformation. In the case where the measurement signals are sampled, use is made of the discrete Fourier transform and certain known algorithms called fast Fourier transforms.
Using the type of magnetometer referred to hereinbefore, the Applicant has been able to locate objects ~ith an accuracy of 1 mm for distances below 1 metre and spotmark their orientations with an accuracy of approximately 1. The dipole used was constituted by a ferrite bar excited at low frequency of 129 Hz.
Its length was 100 mm, i-ts diameter 10 mm, its permeability 1600, its n~nber of turns 1345 and its exciting current 65 mA.
This bar can be replaced by a stack of thin mumetal plates (thickness between 0.05 and 0.2 mm), which are parallel to the generatrixes of the cylinder. The source signal gain can then be 10 for frequencies below 100 Hz.
An optimization of all the parameters (ma~netic ~ment of the dipole, choice of the exci*ing frequencies, choice of magnetometers, minimization of the external effects) makes it possible to improve these performances by a factor of 10 either in accurac~ for a given distance, or in range for a given accuracy.
The present invention also relates to an apparatus for performing theaforementioned process. This is in ~act a notation and/or contour acquisition or scannin$ appara*us shown in fig~ 5 and which comprises:
B o705.3 RS
~ 3 1 ~ q '~ 3 a bidi~lensional acquisition support 28, which is neither electrically conducti~e, nor magne*ic (it can e~g~ be a glass or plastic plate), a pen 30 having a magnetic dipole 32 constituted by a winding excited by an alternating current generator 34 having a given frequency, said generator being supplied b~ a battery or cell 36, two measuring systems El, E2 located on either side of the acquisition support 28 and each having three directional magnetometers able to measure the component along one RXiS of the ambient magnetic field, the three axes of the three magnetometers forming a trirectangular trihedron, each system being able to measure the components of the field at the given frequency belonging to the pen used, a calculating or computing member 38 able to determine the coordinates of the origin A of the magnetic dipole and the orientation angles of said dipole and deduce the coordinates from the pen end 40, which follows a contour 42 or writes characters or punches coordinates, which are in this way acquired or scanned by member 38.
The only difference compared with the process described relative to fig. 1 is that the location of origin A is not an end in itself, but merely serves to determine the position of the pen point or tip 40. This determination is possible on knowing the direction of the magnetic moment (and therefore the orientation of the pen) and the distance separatin~ the origin or centre A of the dipole from the pen tip.
B 87~5.3 RS
- 12 - ~ 3 ~ ~ 9 9 3 According to an advantageous arrangement, the apparatus comprises seve~al pens operating at different frequencies.
It can be agreed that each pen corresponds to a particular "colour" of the graphics which it follows or traces. The frequency can optionally be regulatable from the body or cap of the pen, e.g. by means of a knurled wheel 35 connected to a frequency divider located in oscillator 34. Thus, at any time, the operator can allocate a "colour" to the pen being used, for distinguishing different traces or graphics.
More specifically, each pen can e.g. comprise a non-magnetic cylindrical body, at one end of which is positioned the ferromagnetic ma*erial cylinder surrounded by its exciting winding. At the other end are located the current generator 34, e.g. a quartz oscillator and a supply battery or cell 36.
Naturally, each pen can also be an inking pen.
If the space in which the tip is moved is three-dimensional, as illustrated in fig. 6 under reference 50, the t~o measuring systems El and E2 are located on either side thereof, e.g.
in the centre oE the two side faces of parallelepiped 50.
Thus, pen 30 can make it possible to punch these precise coordinates on a mock-up, e.g. of a nuclear power station, in order to control an intervention robot or authorize the acquisition of forms or shapes in space. In the case of a planar support, these two systems are preferably located along sides, or along a diagonal.
As stated in connection with the general principle of the B 8785. 3 RS
1 31 1l,q93 invention, it is possible to use a third measuring system, which gives the overall system a certain redundancy.
Fig. 7 shows an overall diagram of an acquisition or scanning apparatus according to the invention. It comprises a pen holder 52 with pens 30a, 30b and 30c having different colours, a table 54 having, on the upper face, an acquisition support 28 and, in its volume, the measuring trihedrons. From this table emanates a cable constituted by six identical channels coming Prom six magnetometers. These six channels are addressed to a digitization and synchronous detection circuit 58. The cligital signals are processed by a processor 60 connected to a bull~ memory 62, a display means 6~ and a terminal 66~
Such a system has numerous advantages compared with the prior art systems (based on a variation of resistivity, or on conventional capacitive, acoustic or electromagnetic processes), namely:
it requires no wire connecting the pen to the acquisition system, it is completel~ insensitive to the pressure which may be exerted by the hand on the acquisition table, it gives the possibility of carrying out several acquisitions simultaneously by frequency differentiation, it can operate ~ith both 2 and 3 dimensions.
B 8785.3 RS
__ ~_ _ _ _ OF ITS ORIENTATION N SPACE AND
APPARATUS FOR PERFOR~fING THE SAr~E
BACKGROUND OF THE INVENTION
The present invention relates to a process for locating an object and determining its orientation in space and to an apparatus for performing the same.
The problem of locating an object and investigating its orientation in space frequently occurs in widely ~arying fields, such as the control of the displacements of moving members, models or mock-ups (e.g. of ships or seawalls), the scanning or acquisition of notations or contours, robotics, etc.
For solving -this p~oblem, use has already been made of optical or ultrasonic processes. Processes are also known which use accelerometers, capacitive or resistive sensors, etc.
Certain of these methods are difficult to perform, particularly when several media are involved. This is more particularly the case with obJects ~hich are partly submerged in the water (ships, seawalls, etc.), the immersion in the water greatly disturbing the propagation conditions of the optical or sound waves used. In the case of contour or notation acquisition or scanning tables, the pressure of the hand on the table can also lead to operating difficulties.
SUMMARY OF THE INVENTION
The obJect of the present invention is to obviate these B 8785 . 3 RS
1 31 4~93 disadvantages. For this p~rpose, it proposes a process and an apparatus based on a completely novel principle consisting of providing the object to be investigated with at least one magnetic dipole and locating or spotmarking the position of said dipole or dipoles by a measurement of the magnetic field which it produces. The position of the ob3ect and its orientation in space are deduced from this measurement, More specifically, the present invention relates to a process for locating an object and for determining its position in space, wherein it comprises equipping the object with at least one magnetic dipole constituted by a winding excited by an alterna-ting current generator having a given frequency, such a dipole having an origin and a magnetic moment, placing at least one measuring system in the space where the object is assumed to be, each system having directional magnetometers able to measure the component along an axis of the ambient magnetic field, measuring with the aid of said system or systems the components of the field along a~es at said given frequency and as a function of -the result of these measurements, calculating the coordinates of the origin of the dipole with respect to the measuring system, which locates the object and orientation ansles of the dipole moment with respect to the measuring axes, which gives it sorientation.
According to an advantageous embodiment, the object is provided with a single dipole and use is made o~ at least two measuring trihedrons~ However, according to another variant, B 8785~3 RS
_ 3 _ t 31 ~9q3 the object is provided with three trihedron dipoles and only one measuring sy.stem is used. Preferably, each measuring system comprises three magnetometers, whereof the three measuring axes are oriented according to a trirectangular trihedron~
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in greater detail hereinafter relative to non-limitative embodiments and the attached drawings, wherein show:
Fig. 1 Diagrammatically the principle of the invention, 10 Fig. 2 An example of windings making it possible to form a measurement trirectangular trihedron.
Fig. 3 The notations making it possible to locate or spotmark a point in a reference system with two trirectangular trihedrons.
15 Fig. 4 The notations making it possible to locate or spotmark the orientation of a dipole moment.
Fig. 5 Diagrammaticall~ a contour or notation acquisition system according to the invention.
Fig. 6 The location of two reference trihedrons with respect to a three dimensional acquisition support.
Fig. 7 The general organisation of an acquisition apparatus according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Fig. 1 illustrates the principle of the process accordins to the invention in the more general case where the object has six degre0s o~ freedom. The object, whose position and/or B 8785.3 RS
~ 1 3 1 1Ir993 orientation is to be determined is designated 10. A magnetic dipole is made integral with this object. It is constituted by a winding 12 and a magnetic core 14, which is preferably laminated to prevent eddy currentsO However~ the ferromagnetic core is not obligatory. It merely makes it possible to amplify the signal without increasing the dimensions of the exciting coil. This dipole has an origin A and a dipole moment M.
Winding 12 is supplied by a generator 16 supplying an alternating current at a given frequency. As a function of the size of object 10, generator 16 can be incorporated into the object (as will be shown hereinafter) or can be separated therefrom and connected thereto by connecting wires. A
resistor 18 optionally makes it possible to tap a voltage, whose ~requenc~ is equal to the exciting frequency for reasons which will become apparent hereinafter.
The eans for determining the position of A and -the orientation of M in space comprise t~o systems El and E2, each constituted by three directional magnetometers oriented as *rirectangular trihedrons, respectively Ml , Mly, Ml for the first and M2X, M2y and M2z for the second. These trihedrons have the respective origins points l and 2 The signals emitted by these measuring systems (3 for each ~stem) are addressed to a processing system 22 which can fulfil various functions, i.e~ calculating, storing, displaying, transmitting, etc.
B 8785.3 RS
- 5 - 1 31 ~3 A directional magnetometer which can be used in the invention is described in ~R-A-2 198 146. It uses a thin ferromagnetic film deposited on a cylinder and gives the value of the compo~ent of the ambient magnetic field along the cylinder axis. Three magnetometers of this type can be grouped as a trirectangular trihedron. In the case of a ver~ precise location, it is necessary to take account o-f the distances between the measuring axes because the measurement is not performed at the same point for each axis.
The windings of the -trihedrons can be coiled, as shown in fig. 2, onto a cube 25, in accordance with three coils 25x, 25y, 25z.
Figs. 3 and 4 make it possible to define the notatlons used for calculat:ing the coordinates of point A and the orientation of vector M on the basis of the measurement of the magnetic ~ields.
In trihedron lxyz (fi~. 3), the vector OlA is spotmarked b~
a unit vector ul, whose spherical coordinate angles are ~'1 and ~1- Thus, point A has as spherical coordinates ~1' ~ and Rl and in the same ~ay in 2 in which the unit vector u2 has as angles ~2 and ~'2 and point A the spherical coordinate 2~ ~2 and R2- l and 2 being spaced b~ d.
On assuming a position in a trirectangular trihedron ha~ing as its origin point A, the magnetic dipole moment M can be B 8785.3 RS
6 1 31 ~(13 spotmarked by the angles ~ and ~, its modulus being designated ¦M ¦.
The fields measured at l and 2 comprise three components, Y lx' ly' ~lz and h2x~ h2y- h2 directed along three axes of the trihedrons. In order to simplify the notations, a matrix notation system is adopted, a ~atrix magnitude being designated by an underlined letter. Thus, the fields measured by El and E2 have as their values:
10 hl = h y and h2 = ¦h2 In the same way a matrix M is obtained characterizing the magnetic dipole moment, whose modulus is M
c os ~ . c osY
M = ¦M¦ COS~ .sinY
sin~
For the unit vectors ul and u2, we obtain:
~cos ~l~cos ~ 1~ cos ~2~cos ~2 ul cos~ sin ~1u2 cos ~ 2.sin ~2 20sin ~1 sin ~ 2 and we also have:
'~llx l U2 = U2Y 1 lUlZ ~ -- LU~Z~ ~
B 87~5.3 RS
1 3 1 llr9q3 A standard calculation makes it possible to determine the field h at a point in space created by a ma~netic dipole M
defined by a vector u and located at distance R:
1 3u ut ~ I
h = ~ M
in which u is the transposed matrix of u, I is the unit matrix:
. '~. O O' .
I = O 1 0 This equation corresponds to three equations for lxy and three equations for 2xyz' i.e. respectively:
1 3ul ul - I
~ R3 M (1, 2, 31 15 in which Rl = ¦01A¦
h2 ~ R~ ~4, 5, 6) in which R2 = ¦02A ¦
we also obtain:
d = RlUly -R2U2y RlUlz = ~2u2 ~8) Rlulx = R2U2X
Thus, there are in all nine equations with nine unknowns, ~len B 8785.3 RS
1 31 ~qC)3 the modu]us of ~ is not known the problem can be reduced to the sol~ing of th~ee equations with three unknowns by a careful choice o~ the fixed reference of the coordinates and a few mathematical operations. Computer 22 has the ~unction of solving these equations and giving the value of these ~ 1' ~1' Rl and ~2' ~2' R2 making it possible to locate point A, i.e. the object, and ~, r make it possible to spotmark its orientation.
It is possible to use a third measuring system E3 forming a 1~ supplementary trirectangular trihedron. Then 3=3=6 supplementary equations are obtained for only three unknowns more, namely ~3, ~3, R3, so that there is a certain redundancy in the informations, which can be use~ul.
It is also possible to equip the object with one or two supplementary dipoles (at different frequencies~, which contribute to supplying more informations on the same trihedron. The maximum three dipoles can be perpendicular and form a trirectangular trihedron. The reverse problem is then relatively simple for a single measuring trihedron.
In certain cases, on ~nowing the position of the object in a certain direction, it is possible not to use the measuring axis parallel to said direction and reduce the trihedron to a dihedron. This is more particularly the case if the ob~ect is mobile in one plane~ two axes only defining said plane being useful. This reduction of the measuring means was stressed hereinbefore.
~ 878~.~ RS
9 1 31 4~3 The process described hereinbefore is not limited to the detection of a single object. It is very easily possible to work on a plurality of objects, provided that the winding of the object of order or rank i is excited to a frequency fi, which is its own. It is obviously necessary to avoid any harmonics of the frequency fi, i.e. close to a frequency fj of another object of order or rank j, or one of its harmonics and ensure that the various frequencies are sufficiently different from one another. These e~perimental conditions are clearly dependent on the desired precision, the integration time of the measurement signals, the speed of the movements of the object, etc.
Thus, as each object is to a certain extent located b~ a frequency, the measurement of the magnetic field of said object takes place at said frequency. This means that the sisnal supplied by the magnetometers of systems El and E2 must be successively analysed at the different frequencies fi allocated to the different objects. For this purpose, a first solution consists of carrying out a s~nchronous detection with the aid of a reference signal charac*erizing the natural frequency of the sought object ~e.g. by means of a voltage tapped at the terminals of the aforementioned resistor 18).
This voltage can be transmitted to the magnetometers by wire or radio. Behind said magnetometers, a successive synchronous detection takes place on the ~arious frequencies used. It is even possible not to transmit the voltage if the same crystal is used on transmission and reception.
B 8785.3 RS
" 1 31 ~q3 It is also possible to carry out a spectral analysis by Fourier transformation. In the case where the measurement signals are sampled, use is made of the discrete Fourier transform and certain known algorithms called fast Fourier transforms.
Using the type of magnetometer referred to hereinbefore, the Applicant has been able to locate objects ~ith an accuracy of 1 mm for distances below 1 metre and spotmark their orientations with an accuracy of approximately 1. The dipole used was constituted by a ferrite bar excited at low frequency of 129 Hz.
Its length was 100 mm, i-ts diameter 10 mm, its permeability 1600, its n~nber of turns 1345 and its exciting current 65 mA.
This bar can be replaced by a stack of thin mumetal plates (thickness between 0.05 and 0.2 mm), which are parallel to the generatrixes of the cylinder. The source signal gain can then be 10 for frequencies below 100 Hz.
An optimization of all the parameters (ma~netic ~ment of the dipole, choice of the exci*ing frequencies, choice of magnetometers, minimization of the external effects) makes it possible to improve these performances by a factor of 10 either in accurac~ for a given distance, or in range for a given accuracy.
The present invention also relates to an apparatus for performing theaforementioned process. This is in ~act a notation and/or contour acquisition or scannin$ appara*us shown in fig~ 5 and which comprises:
B o705.3 RS
~ 3 1 ~ q '~ 3 a bidi~lensional acquisition support 28, which is neither electrically conducti~e, nor magne*ic (it can e~g~ be a glass or plastic plate), a pen 30 having a magnetic dipole 32 constituted by a winding excited by an alternating current generator 34 having a given frequency, said generator being supplied b~ a battery or cell 36, two measuring systems El, E2 located on either side of the acquisition support 28 and each having three directional magnetometers able to measure the component along one RXiS of the ambient magnetic field, the three axes of the three magnetometers forming a trirectangular trihedron, each system being able to measure the components of the field at the given frequency belonging to the pen used, a calculating or computing member 38 able to determine the coordinates of the origin A of the magnetic dipole and the orientation angles of said dipole and deduce the coordinates from the pen end 40, which follows a contour 42 or writes characters or punches coordinates, which are in this way acquired or scanned by member 38.
The only difference compared with the process described relative to fig. 1 is that the location of origin A is not an end in itself, but merely serves to determine the position of the pen point or tip 40. This determination is possible on knowing the direction of the magnetic moment (and therefore the orientation of the pen) and the distance separatin~ the origin or centre A of the dipole from the pen tip.
B 87~5.3 RS
- 12 - ~ 3 ~ ~ 9 9 3 According to an advantageous arrangement, the apparatus comprises seve~al pens operating at different frequencies.
It can be agreed that each pen corresponds to a particular "colour" of the graphics which it follows or traces. The frequency can optionally be regulatable from the body or cap of the pen, e.g. by means of a knurled wheel 35 connected to a frequency divider located in oscillator 34. Thus, at any time, the operator can allocate a "colour" to the pen being used, for distinguishing different traces or graphics.
More specifically, each pen can e.g. comprise a non-magnetic cylindrical body, at one end of which is positioned the ferromagnetic ma*erial cylinder surrounded by its exciting winding. At the other end are located the current generator 34, e.g. a quartz oscillator and a supply battery or cell 36.
Naturally, each pen can also be an inking pen.
If the space in which the tip is moved is three-dimensional, as illustrated in fig. 6 under reference 50, the t~o measuring systems El and E2 are located on either side thereof, e.g.
in the centre oE the two side faces of parallelepiped 50.
Thus, pen 30 can make it possible to punch these precise coordinates on a mock-up, e.g. of a nuclear power station, in order to control an intervention robot or authorize the acquisition of forms or shapes in space. In the case of a planar support, these two systems are preferably located along sides, or along a diagonal.
As stated in connection with the general principle of the B 8785. 3 RS
1 31 1l,q93 invention, it is possible to use a third measuring system, which gives the overall system a certain redundancy.
Fig. 7 shows an overall diagram of an acquisition or scanning apparatus according to the invention. It comprises a pen holder 52 with pens 30a, 30b and 30c having different colours, a table 54 having, on the upper face, an acquisition support 28 and, in its volume, the measuring trihedrons. From this table emanates a cable constituted by six identical channels coming Prom six magnetometers. These six channels are addressed to a digitization and synchronous detection circuit 58. The cligital signals are processed by a processor 60 connected to a bull~ memory 62, a display means 6~ and a terminal 66~
Such a system has numerous advantages compared with the prior art systems (based on a variation of resistivity, or on conventional capacitive, acoustic or electromagnetic processes), namely:
it requires no wire connecting the pen to the acquisition system, it is completel~ insensitive to the pressure which may be exerted by the hand on the acquisition table, it gives the possibility of carrying out several acquisitions simultaneously by frequency differentiation, it can operate ~ith both 2 and 3 dimensions.
B 8785.3 RS
Claims (10)
- WHAT IS CLAIMED IS:
l. A process for locating an object and for determining its position in space, wherein it comprises equipping the object with at least one magnetic dipole constituted by a winding excited by an alternating current generator having a given frequency, such a dipole having an origin and a magnetic moment, placing at least one measuring system in the space where the object is assumed to be, each system having directional magnetometers able to measure the component along an axis of the ambient magnetic field, measuring with the aid of said system or systems the components of the field along axes at said given frequency and as a function of the result of these measurements, calculating the coordinates of the origin of the dipole with respect to the measuring system, which locates the object and orientation angles of the dipole moment with respect to the measuring axes, which gives its orientation. - 2. A process according to claim 1, wherein the object is equipped with a single dipole and where in at least two measuring systems are provided.
- 3. A process according to claim 1, wherein the object is equipped with three dipoles in trihedron form.
- 4. A process according to claim 2, wherein each measuring system comprises three directional magnetometers, whereof the three axes form a trihedron.
B 8785.3 RS - 5. A process according to claim 1 making it possible to locate several objects and determine their orientations in space, wherein the frequencies of the current generators of each of the objects are all different and wherein the measurements are carried out at each of these frequencies, which makes it possible to distinguish the measurements for each of the objects.
- 6. A process according to claim 1, wherein for performing the measurement at the given frequency characterizing an object, part of the alternating exciting current for producing the dipole in said object is tapped and said part is transmitted to the measuring systems, a synchronous detection being performed at this frequency.
- 7. A process according to claim 1, wherein for performing the measurement at the given frequency characterizing an object, there is a spectral analysis at this frequency of the measuring signal for extracting the component having said frequency.
- 8. A notation and contour acquisition apparatus performing the process according to claim 1, wherein it comprises:
an acquisition support having at least two dimensions, said support being neither electrically conductive, nor magnetic, at least one pen having at least one magnetic dipole constituted by a winding excited by an alternating current generator having a given frequency, such a dipole having an B 8785.3 RS
origin and a magnetic moment, at least one measuring system located in the vicinity of the acquisition support and having three directional magnetometers able to measure the component along one axis of the ambient magnetic field, the three axes of the three magnetometers forming a trihedron, each system being able to measure the components of the field at the given frequency belonging to the pen used, a calculating or computing means able to determine the coordinates of the origin of the magnetic dipole and the orientation angles of said dipole and deduce therefrom the coordinates of the end of the pen. - 9. An apparatus according to claim 7, wherein it comprises a group of pens for which the frequencies used are all different.
- 10. An apparatus according to claim 8, wherein each pen comprises a cylindrical non-magnetic body within which is disposed a ferromagnetic material cylinder surrounded by an exciting winding and in whose upper part is located an alternating current generator, whose frequency is regulatable by means of a member accessible to the operator, said generator being connected to the winding, and finally an electric power source supplying the generator.
B 8785.3 RS
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8512327A FR2586302B1 (en) | 1985-08-13 | 1985-08-13 | METHOD FOR LOCATING AN OBJECT AND DETERMINING ITS ORIENTATION IN SPACE AND DEVICE FOR IMPLEMENTING IT |
| FR8512327 | 1985-08-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1314993C true CA1314993C (en) | 1993-03-23 |
Family
ID=9322197
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000515137A Expired - Fee Related CA1314993C (en) | 1985-08-13 | 1986-07-31 | Process for the location of an object and the determination of its orientation in space and apparatus for performing the same |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0215695B1 (en) |
| JP (1) | JP2508010B2 (en) |
| CA (1) | CA1314993C (en) |
| DE (1) | DE3669586D1 (en) |
| FR (1) | FR2586302B1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1464918B1 (en) | 2003-04-01 | 2016-11-16 | Seuffer GmbH & Co. KG | Method and apparatus for measuring the position of a magnet relative to a measuring place |
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| GB2215063A (en) * | 1988-02-18 | 1989-09-13 | Tokyo Gas Co Ltd | Detecting buried conductors |
| GB8913200D0 (en) * | 1989-06-08 | 1989-07-26 | Woodbridge Electronics Limited | Method and device for locating branches in drains |
| DE4208703A1 (en) * | 1991-06-03 | 1992-12-10 | Letron Gmbh Electronic Leheste | METHOD AND DEVICE FOR GENERATING ELECTRICAL SIGNALS THAT DETERMINE THE POSITION OF A BODY WITH REGARD TO A REFERENCE AREA, IN PARTICULAR FOR SCREEN POINT OR CURSOR CONTROL ON A SCREEN |
| FR2678090B1 (en) * | 1991-06-20 | 1996-07-05 | Pierre Mallet | DEVICE FOR WRITING MANUSCRIBED SIGNS ON ANY MEDIUM, SUITABLE FOR TRANSMITTING SIMULTANEOUSLY THESE SIGNS TO A RECEIVING SYSTEM, AND USE OF SAID DEVICE. |
| DE4307453A1 (en) * | 1993-03-10 | 1994-09-15 | Ruhrgas Ag | Method and device for locating a line |
| FR2720840B1 (en) * | 1994-06-02 | 1996-09-20 | Olivier Bardot | Method for transmitting an electromagnetic field and having a large range, transmission and localization method using said emission method, devices implementing said methods. |
| US5684396A (en) * | 1996-03-05 | 1997-11-04 | Hughes Aircraft Company | Localizing magnetic dipoles using spatial and temporal processing of magnetometer data |
| US5731996A (en) * | 1996-03-05 | 1998-03-24 | Hughes Electronics | Dipole moment detector and localizer |
| JP2001500299A (en) * | 1997-07-08 | 2001-01-09 | コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ | Input device |
| US6172499B1 (en) * | 1999-10-29 | 2001-01-09 | Ascension Technology Corporation | Eddy current error-reduced AC magnetic position measurement system |
| US6553326B1 (en) * | 2000-04-07 | 2003-04-22 | Northern Digital Inc. | Errors in systems using magnetic fields to locate objects |
| FR2812481B1 (en) | 2000-07-31 | 2002-12-13 | Commissariat Energie Atomique | SHORT DISTANCE LOCATION SYSTEM |
| JP2003004409A (en) * | 2001-06-26 | 2003-01-08 | Reideikku:Kk | Position-measuring method and position-measuring apparatus |
| JP2002054928A (en) * | 2000-08-14 | 2002-02-20 | Reideikku:Kk | Azimuth measuring method and device |
| FR2825499B1 (en) * | 2001-06-05 | 2004-07-23 | Commissariat Energie Atomique | DEVICE AND METHOD FOR LOCATING THE TIP OF A PEN ON A SCANNING MEDIUM |
| FR2826127B1 (en) | 2001-06-19 | 2003-09-26 | Commissariat Energie Atomique | TELESURVEILLANCE INSTALLATION AND METHOD USING THE INSTALLATION |
| DE10164477A1 (en) * | 2001-12-20 | 2003-07-03 | Philips Intellectual Property | input device |
| JP2004145526A (en) * | 2002-10-23 | 2004-05-20 | Japan Aviation Electronics Industry Ltd | Position attitude sensor |
| GB2409900B (en) | 2004-01-09 | 2006-05-24 | Statoil Asa | Processing seismic data representing a physical system |
| JP4214083B2 (en) * | 2004-05-28 | 2009-01-28 | 坂田電機株式会社 | Method for investigating sediment |
| JP2006010628A (en) * | 2004-06-29 | 2006-01-12 | Hitachi Metals Ltd | Detector for detecting object |
| GB2435693A (en) | 2006-02-09 | 2007-09-05 | Electromagnetic Geoservices As | Seabed electromagnetic surveying |
| GB2439378B (en) | 2006-06-09 | 2011-03-16 | Electromagnetic Geoservices As | Instrument for measuring electromagnetic signals |
| GB2441787A (en) * | 2006-09-15 | 2008-03-19 | Electromagnetic Geoservices As | Method of determining the orientation of an electric and magnetic receiver deployed remotely |
| GB2442749B (en) | 2006-10-12 | 2010-05-19 | Electromagnetic Geoservices As | Positioning system |
| GB2445582A (en) | 2007-01-09 | 2008-07-16 | Statoil Asa | Method for analysing data from an electromagnetic survey |
| WO2008096856A1 (en) * | 2007-02-09 | 2008-08-14 | Asahi Kasei Emd Corporation | Spatial information detecting system, its detecting method, and spatial information detecting device |
| JP4958605B2 (en) * | 2007-04-02 | 2012-06-20 | ユニバーサル特機株式会社 | Moving object position estimation detection method, apparatus, and moving object position estimation detection program |
| JP5004646B2 (en) * | 2007-04-26 | 2012-08-22 | 旭化成エレクトロニクス株式会社 | Position / orientation detection system, detection method thereof, and position / orientation detection apparatus |
| US7800373B2 (en) * | 2007-11-20 | 2010-09-21 | Westerngeco L.L.C. | Method for correcting magnetic based orientation measurements for local biasing fields |
| JP5187907B2 (en) * | 2009-05-12 | 2013-04-24 | 日本写真印刷株式会社 | Position detection input device |
| JP5780696B2 (en) * | 2009-07-06 | 2015-09-16 | 協立電機株式会社 | Object detection device |
| JP5364907B2 (en) * | 2009-08-18 | 2013-12-11 | 独立行政法人土木研究所 | Deformation measurement system and deformation measurement method |
| JP5628559B2 (en) * | 2010-05-31 | 2014-11-19 | オリンパス株式会社 | Nondestructive inspection equipment |
| FR2988872B1 (en) | 2012-03-29 | 2014-03-28 | Commissariat Energie Atomique | SCREEN WITH MAGNETIC OBJECT LOCATION |
| FR2996653B1 (en) * | 2012-10-05 | 2015-01-02 | Commissariat Energie Atomique | MAGNETIC RING CAPABLE OF REMOVABLE FIXING ON A CRAYON OR ERASER |
| FR3005517B1 (en) * | 2013-05-07 | 2015-05-22 | Commissariat Energie Atomique | METHOD FOR CONTROLLING A GRAPHICAL INTERFACE FOR DISPLAYING IMAGES OF A THREE-DIMENSIONAL OBJECT |
| GB2518384A (en) * | 2013-09-19 | 2015-03-25 | Univ Barcelona Autonoma | A method and a portable rescue device for locating avalanche victims |
| JP6862322B2 (en) * | 2017-09-15 | 2021-04-21 | 株式会社東芝 | Positioning systems and equipment |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2198146B1 (en) * | 1972-09-04 | 1976-08-13 | Commissariat Energie Atomique | |
| US4029899A (en) * | 1974-11-20 | 1977-06-14 | National Research Development Corporation | Position indicator |
| US4241409A (en) * | 1977-12-30 | 1980-12-23 | Nolf Jean Marie | Hand held pen-size calculator |
| US4317078A (en) * | 1979-10-15 | 1982-02-23 | Ohio State University Research Foundation | Remote position and orientation detection employing magnetic flux linkage |
| DE3103367A1 (en) * | 1981-01-27 | 1982-08-26 | Uwe Dipl.-Ing. Blücher | Device for punctiform measurement of the distance of the boundary surfaces of objects, in particular those in human and veterinary medicine |
| US4617515A (en) * | 1984-02-22 | 1986-10-14 | Wacom Co., Ltd. | Position detecting apparatus |
-
1985
- 1985-08-13 FR FR8512327A patent/FR2586302B1/en not_active Expired
-
1986
- 1986-07-31 CA CA000515137A patent/CA1314993C/en not_active Expired - Fee Related
- 1986-08-08 EP EP19860401785 patent/EP0215695B1/en not_active Expired - Lifetime
- 1986-08-08 DE DE8686401785T patent/DE3669586D1/en not_active Expired - Lifetime
- 1986-08-12 JP JP61187937A patent/JP2508010B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1464918B1 (en) | 2003-04-01 | 2016-11-16 | Seuffer GmbH & Co. KG | Method and apparatus for measuring the position of a magnet relative to a measuring place |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0215695B1 (en) | 1990-03-14 |
| JP2508010B2 (en) | 1996-06-19 |
| EP0215695A1 (en) | 1987-03-25 |
| DE3669586D1 (en) | 1990-04-19 |
| JPS6238301A (en) | 1987-02-19 |
| FR2586302B1 (en) | 1988-02-12 |
| FR2586302A1 (en) | 1987-02-20 |
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