WO2000017603A1 - Systeme de detecteurs magnetiques de mesure de positions en trois dimensions a reponse rapide, haute resolution et haute precision - Google Patents

Systeme de detecteurs magnetiques de mesure de positions en trois dimensions a reponse rapide, haute resolution et haute precision Download PDF

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Publication number
WO2000017603A1
WO2000017603A1 PCT/US1999/021240 US9921240W WO0017603A1 WO 2000017603 A1 WO2000017603 A1 WO 2000017603A1 US 9921240 W US9921240 W US 9921240W WO 0017603 A1 WO0017603 A1 WO 0017603A1
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WIPO (PCT)
Prior art keywords
magnetic field
transmitters
sensor system
reference frame
velocity
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Application number
PCT/US1999/021240
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English (en)
Inventor
Carl V. Nelson
Bryan C. Jacobs
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The Johns Hopkins University
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Publication date
Application filed by The Johns Hopkins University filed Critical The Johns Hopkins University
Priority to EP99949668A priority Critical patent/EP1131597A4/fr
Priority to AU22514/00A priority patent/AU2251400A/en
Publication of WO2000017603A1 publication Critical patent/WO2000017603A1/fr

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    • 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
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/003—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring position, not involving coordinate determination
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/004—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring coordinates of points

Definitions

  • the invention relates generally to sensor systems and, more particularly, to a system capable of fast-response, high resolution, high accuracy three-dimensional position measurement using magnetic sensors.
  • the transmitters may be identical to one another but disposed at different locations or in different orientations.
  • the field patterns of the transmitters are thus displaced or rotated relative to one another, and relative to the fixed frame of reference.
  • the sensor on the object detects the parameters of the field prevailing at the location of the object as, for example, the magnitude and/or direction of the field at the object or the magnitude of individual components of the field at the object in _ one or more pre-selected directions.
  • the transmitter may be actuated in a predetermined sequence so that at any time only one transmitter is active and therefore the field prevailing at the object is only the field contributed by one transmitter, plus a background field due to the Earth's magnetic field and other environmental sources.
  • the transmitters can be driven at different frequencies so that components of the signal from the sensor varying at different frequencies represent contributions to the field at the object from different transmitters simultaneously.
  • a computer system Based upon the detected parameters of the fields from the individual transmitters, and the known pattern of variation of the field from each transmitter, a computer system calculates the position and orientation of the sensor, and hence the position of the object bearing the sensor, in the fixed frame of reference of the transmitters.
  • the object to be located carries the transmitters, whereas a plurality of sensors are disposed at various locations or orientations in the fixed frame of reference. The location and/or orientation of the object is deduced from signals representing the parameter of the field prevailing at the various sensors.
  • U.S. Patent No. 4,054,881 to Raab discloses three mutually orthogonally radiating antennas each of which transmits electromagnetic radiation to three mutually orthogonal receiving antennas.
  • the receiving antennas measure the radiated signals and produce nine parameters which enable the calculation of the position and orientation of the receiving antennas. No mention is made of determining the velocity or acceleration of the sensor.
  • U.S. Patent No. 4,622,644 to Hansen discloses a system which enables the measurement and position of a permanent magnet within a three-dimensional region in five degrees of freedom.
  • the system uses three antennas each composed of three mutually orthogonal Hall effect devices.
  • the output voltages from the nine Hall effect devices are inputted into a microprocessor device which first calculates an estimate of the position using a nonlinearized algorithm. Subsequently, the microprocessor uses a linearized algorithm to calculate the precise position and orientation of the permanent magnet.
  • Hansen's device uses Hall sensors, rather than transmitter coils, as the primary sensors.
  • U.S. Patent No. 5,729,129 to Acker discloses a system utilizing three electromagnetic transmitters arranged about an electromagnetic detector positioned in the chest of a patient (Fig. 1). The transmitting coils are all arranged in a common plane.
  • U.S. Patent No. 5,71 ,478 to Ollson discloses a system of general interest which utilizes three transmitting and three receiving means. Ollson's system is used to measure the position of a ball joint.
  • received signals from a sensor are time-averaged to reduce environmental and electronic noise effects.
  • the time-averaging increases the signal to noise ratio (SNR), yielding improved range, resolution, or accuracy (or all of the above).
  • SNR signal to noise ratio
  • the trade-off is that such time-averaging slows the sensor's response time, so that the sensor cannot respond to sudden positional changes (i.e., velocity or acceleration).
  • the desired parameter is not just position, but speed and/or acceleration of the test object.
  • speed and/or acceleration one must differentiate the position data resulting in noisy data or reduced accuracy/resolution.
  • a magnetic sensor system for determining the three-dimensional position, velocity and acceleration of an object utilizing magnetic field currents, said sensor system being capable of operating within close proximity to metal surfaces and metal objects, comprising an object, the position, velocity and acceleration of which are to be determined; a three-dimensional fixed reference frame of known dimensions, wherein said object is located within said fixed reference frame; a power source capable of generating a magnetic field within said fixed reference frame; a plurality of magnetic field transmitters, said transmitters operatively interconnected to said power source and capable of being geometrically arbitrarily oriented relative to said fixed reference frame; at least one magnetic field receiver, said receiver capable of receiving electronic signals from said transmitters and further capable of being geometrically arbitrarily oriented relative to said fixed reference frame; a programmed computer, said computer capable of receiving said signals from said receiver and further capable of calculating the position, velocity and acceleration of said object based upon said signals.
  • a method for determining the position, velocity and acceleration of an object comprising providing a three dimensional fixed reference frame of known dimensions; providing an object, the position, velocity and acceleration of which are to be measured; generating electrical current from an oscillator; delivering said current from said oscillator to a power amplifier; directing said amplified current from said amplifier to a plurality of transmitters; generating a magnetic field from said transmitters in said reference frame; receiving said magnetic field signal from said transmitters into at least one receiver; demodulating and amplifying said received magnetic field signal into magnetic field components from said receiver signal, wherein said output from said amplifier is proportional to said magnetic field components; applying a mathematical filter to said demodulated and amplified signal; and applying a mathematical algorithm to calculate the position, velocity and acceleration of said object.
  • FIG 1 shows the general features of the invention.
  • FIG. 2 shows several potential embodiments or applications of the invention.
  • Figure 3 shows a proof-of-concept, reduction to practice invention block diagram using three transmitters mounted on a plane and three orthogonal receiver coils mounted on a plastic cube for use in the invention.
  • Figure 4 shows a simplified diagram of the signal processing used with the total magnetic field processing approach for use in the invention.
  • the present invention is a three-dimensional (3-D) position measuring sensor based on magnetic field measurements.
  • the present invention includes several advantages, as follows.
  • the sensor system can use an arbitrary number of magnetic field transmitters and magnetic field receivers.
  • the transmitters and receivers can be oriented in an arbitrary geometry relative to a fixed reference frame of the object whose position is being measured. Because multiple transmitters and receivers can be used in the sensor system, two major advantages are realized. First, multiple transmitters can be used to provide signal coverage in a large sensing volume, while most magnetic position sensing systems are limited by the range of the magnetic transmitters and the sensitivity of the magnetic field receivers. Second, the sensor system can operate in close proximity to metal surfaces and objects.
  • eddy currents generated in the metal by the magnetic transmitter can be modeled and accounted for in the processing algorithm, i.e., the nearby metal generates 'virtual' magnetic field transmitters that can be treated as additional transmitters with their own unique position and orientation.
  • the sensor system can operate with DC, AC, pulsed DC, or combinations of these magnetic fields.
  • the processing algorithm needs only the magnetic field components of the transmitters and is insensitive to how those measurements are obtained. By placing calibrated magnetic field receivers at a known location in an uncalibrated transmitter geometry, the processing algorithm can determine the transmitter's location in the fixed reference frame. This is an important feature where absolute position measurements are required.
  • the transmitters are modeled as dipoles in the processing algorithm and the sensor system can also be made to be self-calibrating.
  • the invention can use total field and vector magnetic field components to calculate position.
  • the magnetic field transmitters can include, but are not limited to, induction loops (AC magnetic field generator) and permanent magnets or combinations thereof.
  • the magnetic field receivers should be compatible with the magnetic field transmitters, i.e., an induction loop receiver is an AC magnetic field detector and thus should have an AC magnetic field transmitter.
  • the magnetic field receivers can include, but are not limited to, induction loops, Hall effect sensors, and magneto-resistive magnetic field sensors.
  • the sensor system does not require the receiver signals to be averaged. Therefore, the measurements can be taken at high speed, thus giving the sensor the advantage of high speed response.
  • the sensor system can have high spatial resolution/accuracy by averaging the receiver signals (trade-off of speed vs. spatial resolution). For cases where there is high signal-to-noise, the sensor system provides both high speed response and high spatial resolution and accuracy.
  • the number of receivers can be reduced to less than three, and in some special cases, only one receiver may be used (this has many advantages in measurement systems where space is at a premium).
  • the processing algorithm uses a physics-based Extended Kalman Filter to solve the non-linear measurement problem and provide 3-D position, 3-D velocity and 3-D acceleration estimates of the object under test.
  • Figure 1 shows a basic overview of the system for measuring position in three dimensions.
  • the system uses an array of multiple, arbitrarily oriented magnetic field transmitters
  • the system also employs an array of multiple, calibrated, arbitrarily oriented magnetic field receivers (2), located on the test object (3) in a reference frame fixed to the test object (3), and measures the magnetic field components created by the array of transmitters (1 ).
  • the transmitter frequencies are different; for DC magnetic field transmitters, the transmitters are operated sequentially.
  • the array of magnetic field transmitters (1 ) generate a spatially varying magnetic field in the sensing volume.
  • a method is employed to sort the magnetic field components from the receiver signal (e.g., for an AC transmitter system with multiple frequencies, one can use a synchronous demodulator or notch filter to isolate the multiple frequencies).
  • a physics-based extended Kalman filter is used to solve the non-linear inverse measurement problem and provide 3-D position, 3-D velocity and 3-D acceleration of the test object (3).
  • FIG. 2 shows several embodiments of the invention. The use of coils in the
  • Figure to represent magnetic field transmitters (1) and receivers (2) is a graphical convenience and should not be construed as to limit the application of other appropriate magnetic field devices.
  • Figure 2A shows the case where the receivers
  • FIG. 2B shows the case of an array of multiple transmitters (1 ) and a single flat receiver coil (5).
  • the transmitters (1 ) are shown on a transmitter array plane (4) for simplicity and could be located in an arbitrary manner. This case is very useful for measurement systems that have severe space constraints and the receiver (5) has a limited range of motion (either rotationally or constrained in some fashion that can be physically modeled).
  • Figure 2C shows the case, with the minimum number of transmitters (1 ) and receivers (2), where all six degrees of freedom of the test object (3) can be measured (i.e., utilizing an arbitrary geometry of receivers (2) fixed to a test object (3)).
  • Figure 2D shows the case where the orientation of a pilot's helmet (6) can be measured with transmitters (1 ) located on the canopy (7) and receivers (2) which can be located on the helmet
  • FIG. 3 shows a simplified diagram of a sensor system that was constructed to demonstrate the invention. This would be one of many potential embodiments of the invention.
  • sensor system in Figure 3 includes: three dipole transmitters (1 ) mounted at known locations; transmitters (1 ) operating at three frequencies (2); three orthogonal induction coil receivers mounted on a plastic cube (3) (fixed rigid body); receiver signals are amplified (4); receiver signals are demodulated using lock-in amplifier technology (5) (alternatively, the multiple frequencies in the receiver signal could be digitally, synchronously demodulated by using a high-speed analog- to-digital converter); and employing an extended Kalman filter to solve the non-linear measurement problem and provide position, velocity and acceleration estimates.
  • the power oscillators (1) drive the magnetic field transmitters (2)
  • the magnetic field is sensed by magnetic field receivers (3) which are then amplified and synchronously demodulated by nine-channel lock-in amplifiers and filters (4)
  • the output voltage for each frequency of the lock-in amplifiers (4) is sent to the total magnetic field calculator (5) where the voltages are converted into magnetic field values.
  • An extended Kalman filter/smoother (6) uses the calibration equation of magnetic field as a function of position for each frequency and each receiver (3) to calculate position, velocity and acceleration.
  • the Biot-Savart law was integrated for the transmitter geometry and certain approximations to express the magnetic field as a sum of trigonometric functions were made. Faraday's law on induction was then applied to determine an expression for the induced pick-up coil voltages, the envelopes of which are produced by lock-in amplifiers and sampled by an analog to digital converter.
  • the measurement equation is formulated as a non-linear function of the (assumed) six degrees of freedom of the rigid body.
  • the partial derivatives of the vector measurement equation are evaluated and used by an extended Kalman filter to provide estimates of the position, velocity, and acceleration of the rigid body. In general, any problem specific constraints and dynamics can be modeled in the Kalman filter. However, it is typically assumed that the rigid body is free to experience linear and angular accelerations which are modeled as second order Gauss-Markov random processes.
  • Fig. 3 shows a detailed layout of the operation of one particular embodiment of the three-dimensional sensor system.
  • An array of transmitter coils (1 ) generates three frequencies (2) (F1 , F2, and F3).
  • the transmitters (1 ) are typically operated at frequencies in the range of 20 to 100 KHz.
  • the transmitters (1 ) are made from an IC and an IC power operational amplifier.
  • the transmitter (1 ) coils are about 3 cm in diameter and have 20 turns of a AWG #22 wire.
  • An in-phase synchronization (sync) signal from each transmitter (1 ) is obtained by a small coil of wire wound around the output wire of the power operational amplifier.
  • the sync signal is used in the lock-in amplifier (5).
  • the receiver (3) is a cube of plastic. Three coils are wound on the cube to form an orthogonal, three-axis coil system. Each of the three coils is wound with 50 turns of AWG#36 wire. The output of each coil at this point is composed of three transmitter signals plus extraneous signals from electric and magnetic noise sources (motors, light, etc.) The output of each receiver coil is amplified with an instrumentation amplifier (4) and then high-pass filtered to remove extraneous noise below 10 KHz (e.g. power line frequencies).
  • 10 KHz e.g. power line frequencies
  • the signals from the transmitter coils (1 ) are separated (de-modulated) via three lock-in amplifiers (5).
  • the sync signal for the demodulator is obtained from the coil windings on the power amplifier (4) output.
  • the outputs of the lock-in amplifiers (5) are proportional to the different magnetic field components.
  • the three-dimensional sensor system can be composed of an array of transmitters (1 ) and a three-axis receiver coil (3).
  • Each transmitter coil (1 ) operates at a different frequency (2) and creates a unique time varying magnetic field throughout space.
  • the receiver coil (3) 'sees' each of these time-varying magnetic fields.
  • the three-axis receiver (3) measures the three components of the magnetic field from each of the three (or more) transmitters (1) and using a technique similar to triangulation, the position of the receiver coil (3) can be uniquely determined.
  • a variety of transmitter coil configurations can be used. The coil configuration depends on the application and system requirement.
  • Dipole transmitters can be used in some embodiments because of their small size and the fact that an analytical solution to the magnetic field equations is possible.
  • the magnetic field from a transmitter coil approximates a magnetic dipole field.
  • the dipole field is proportional to the radial distance between the transmitter and receiver, and the angle between the dipole's axes and the receiver coil's axes.
  • the analytical solution of the magnetic field equations are used in the Kalman filtering equations that are, in turn, used for calculating the unknown position of the receiver coil.
  • the magnetic field from a single dipole transmitter can be approximated as:
  • B r is the radial and B ⁇ is the angular component of the magnetic field relative to the axis of the dipole transmitter; Kj and K 2 are variables that depend on the area of the transmitter coil and the amount of current in the coils; and ⁇ is the angle relative to the dipole transmitter.
  • Another possible embodiment is a one-dimensional version of the sensor system.
  • This version is composed of a transmitter coil and a receiver coil co-axially located on opposite ends of a telescoping plastic tube.
  • the transmitter coil generates a time-varying magnetic field via a power amplifier connected to an oscillator, which in turn induces an oscillating voltage in the receiver coil.
  • the transmitter-receiver magnetic flux coupling (and consequently the receiver output voltage) varies approximately as the inverse cube of the coil separation distance: EMF - r
  • K is a proportionality constant dependent on the system parameters and r is the separation distance between the transmitter coil and the receiver coil. From this equation, a direct measure of distance is possible.
  • the first step is integrating the Boit-Savart law and making certain approximations to express the magnetic field as a sum of trigonometric functions. Then, Faraday's law is applied to determine an expression for the induced pick-up coil voltages, the envelopes of which are produced by lock-in amplifiers and sampled by an analog to digital converter.
  • the measurement equation is formulated as a non-linear function of the (assumed) six degrees of freedom of the rigid body.
  • the partial derivatives of the vector measurement equation are evaluated and used by an extended Kalman filter in order to iteratively provide estimates of the position, velocity, and acceleration of the rigid body.
  • any problem specific constraints and dynamics can be modeled in the Kalman filter, however, typically it is assumed that the rigid body is free to experience linear and angular accelerations which are modeled as second order Gauss-Markov random processes.
  • V the sampled envelope
  • V Kp _3 [3p- 2 (n t - p)p - ⁇ t ]- n r
  • K is an overall coupling constant, which is a function of the pick-up coil area and amplification, and the transmitter coil dipole moment
  • fi t and ⁇ r are the normal unit vectors of the transmitting and receiving coils
  • p is the transmitter- receiver displacement vector, the magnitude of which is simply denoted by p .
  • p and n r are generally non-linear functions of the location and orientation of the rigid body relative to the transmitter, their functional relationship is no more complicated than a simple coordinate transformation.
  • X denote the six independent positional variables of the rigid body (three for the center of mass location, three for orientation), the measurement equation is of the form:
  • V is the voltage measured by the i , receiver coil due to the j ,h transmitter, K, represents the pair-wise coupling constants, R, denotes the i ,h receiver coil location and orientation in the rigid body coordinate frame, and T denotes the fixed location and orientation of the i th transmitter.
  • the extended Kalman filter iteratively refines the solution to the measurement problem by combining: 1 ) prior information about X and its first and second time derivatives; 2) the measurement equations described above; and 3) an expression for the gradient of the measurement equation.
  • the ability of this approach to converge on the solution can be understood as follows.
  • the filter starts an iteration with an estimate of the position variables, denoted byX , which is derived by propagating the previous solution forward in time via the assumed dynamics of the problem, i.e., acceleration states integrate into velocity which in turn integrate into the position states.
  • the six positional state variables, X ⁇ [x x 2 , x 3 , x 4 , x 5 , x 6 ] are typically chosen to be the Cartesian coordinates ( X j .,. 3 ) of the center of mass of the rigid body, and three Euler parameters ( x 4 ... 6 ), which completely specify the orientation relative to some fixed coordinate system.
  • the initial position estimate, X is used to predict the value of the measurement vector, Z , and the difference between the measurement and prediction is used along with the estimated gradient information, to update the estimate.
  • ⁇ X which is a linear matrix equation that can be inverted to solve for ⁇ X , which when added to X forms the estimate for the next iteration.
  • ⁇ X falls below some arbitrary value the process is terminated and the resulting X is used as a measurement by the extended Kalman filter.
  • the filter uses this new estimate, and information about the measurement noise, and information about the dynamics of the system (e.g., how fast it can accelerate), to update all of the state variables (position, acceleration, and velocity states). The entire process is then repeated for the next measurement vector.
  • transmitter coil arrangements are possible and the selection of which configuration depends on the application.
  • the transmitter coils could be made larger or a linear transmitter (approximation to a line current) could be used.
  • the magnetic field falls off approximately as r "1 .
  • the Kalman filter equations would be need to be changed.
  • receiver coil arrangements could also be used.
  • a metal core could be added to the receiver coil to increase magnetic sensitivity.
  • the shape couid also be altered to a spherical or other non-cube receiver shape.
  • the electronic system could be altered having the amplified coil signals digitized and fed directly into a computer or digital signal processing chip, and do all of the signal processing/filtering in software/firmware (i.e., replace the lock-in amplifier with software). This approach would have significant cost improvements for a mass produced system.
  • This sensor system is a position/motion capture system. Currently it is being developed for use in crash test dummies. However, many other applications are also possible.
  • the system could be used in virtual reality devices to track head and body motion in real-time at high speed.
  • the system could be used in biomechanical analysis; once mounted on the body, it could collect motion data in real-time for analysis on a computer. It could be used in computer graphics to manipulate graphics for animation or simulation.
  • the sensor system could localize surgical instruments in three-dimensional space in real-time.
  • the system could be used to develop 3-D measurements and/or the construction of non-metallic objects in 3-D CAD/CAM programs. It could be used in anatomical measurements to make three-dimensional measurements of anatomical features, body volumes, joint relationships, and body contours.
  • the sensor system could also be used to measure high-speed deflection measurements in non-metallic ship hull explosion tests.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geophysics (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

Abstract

Il est possible de déterminer la position, l'orientation, la vitesse et l'accélération de détecteurs (3) éloignés à l'aide de champs magnétiques. On place à cet effet plusieurs émetteurs (1) de champ magnétique orientés arbitrairement dans un cadre de référence (dit cadre de référence source) ainsi que plusieurs récepteurs (3) de champ magnétique orientés arbitrairement dans un deuxième cadre de référence (dit cadre de référence du corps). Les champs magnétiques, variables dans l'espace, des émetteurs du cadre de référence source sont détectés par les récepteurs (3) du cadre de référence du corps. Un algorithme d'ordinateur recourt à un filtre de Kalman étendu à base physique pour résoudre la position, l'orientation, la vitesse et l'accélération du corps par rapport au cadre de référence source. Ledit filtre de Kalman compense les effets de la présence de métaux dans les deux cadres ce qui permet de mesurer la position, l'orientation, la vitesse et l'accélération dans des conditions où d'autres systèmes magnétiques ne pourraient normalement pas en raison des courants de Foucault.
PCT/US1999/021240 1998-09-23 1999-09-23 Systeme de detecteurs magnetiques de mesure de positions en trois dimensions a reponse rapide, haute resolution et haute precision WO2000017603A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP99949668A EP1131597A4 (fr) 1998-09-23 1999-09-23 Systeme de detecteurs magnetiques de mesure de positions en trois dimensions a reponse rapide, haute resolution et haute precision
AU22514/00A AU2251400A (en) 1998-09-23 1999-09-23 Magnetic sensor system for fast-response, high resolution, high accuracy, three-dimensional position measurements

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US10153498P 1998-09-23 1998-09-23
US60/101,534 1998-09-23

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US6789043B1 (en) * 1998-09-23 2004-09-07 The Johns Hopkins University Magnetic sensor system for fast-response, high resolution, high accuracy, three-dimensional position measurements
DE102010020835A1 (de) * 2010-05-18 2011-11-24 Technische Universität Kaiserslautern Verfahren und Vorrichtung zur Ermittlung der räumlichen Koordinaten mindestens eines Sensorknotens in einem Behältnis
EP1370826B1 (fr) * 2001-03-19 2013-04-24 ELEKTA AB (publ.) Determination de la position d'objets
CN103995239A (zh) * 2014-05-09 2014-08-20 北京航空航天大学 一种磁场梯度参数测量新方法
EP2317966A4 (fr) * 2008-07-23 2015-05-20 Atreo Medical Inc Dispositif d'assistance à la réanimation cardio-respiratoire permettant de mesurer les paramètres de compression durant la réanimation cardio-respiratoire
EP3029548A1 (fr) * 2014-12-03 2016-06-08 Honeywell International Inc. Système de suivi de mouvement à l'aide d'un ou de plusieurs champs magnétiques

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6789043B1 (en) * 1998-09-23 2004-09-07 The Johns Hopkins University Magnetic sensor system for fast-response, high resolution, high accuracy, three-dimensional position measurements
EP1370826B1 (fr) * 2001-03-19 2013-04-24 ELEKTA AB (publ.) Determination de la position d'objets
EP2317966A4 (fr) * 2008-07-23 2015-05-20 Atreo Medical Inc Dispositif d'assistance à la réanimation cardio-respiratoire permettant de mesurer les paramètres de compression durant la réanimation cardio-respiratoire
US9585603B2 (en) 2008-07-23 2017-03-07 Physio-Control Canada Sales Ltd. CPR assist device for measuring compression parameters during cardiopulmonary resuscitation
US10952926B2 (en) 2008-07-23 2021-03-23 Stryker Canada Ulc CPR assist device for measuring compression parameters during cardiopulmonary resuscitation
DE102010020835A1 (de) * 2010-05-18 2011-11-24 Technische Universität Kaiserslautern Verfahren und Vorrichtung zur Ermittlung der räumlichen Koordinaten mindestens eines Sensorknotens in einem Behältnis
WO2011144325A3 (fr) * 2010-05-18 2012-02-02 Technische Universität Kaiserslautern Procédé et dispositif permettant de déterminer les coordonnées spatiales d'au moins un noeud capteur dans un contenant
CN103995239A (zh) * 2014-05-09 2014-08-20 北京航空航天大学 一种磁场梯度参数测量新方法
CN103995239B (zh) * 2014-05-09 2016-10-05 北京航空航天大学 一种磁场梯度参数测量新方法
EP3029548A1 (fr) * 2014-12-03 2016-06-08 Honeywell International Inc. Système de suivi de mouvement à l'aide d'un ou de plusieurs champs magnétiques

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EP1131597A4 (fr) 2001-11-07
AU2251400A (en) 2000-04-10
EP1131597A1 (fr) 2001-09-12

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