EP2102590A1 - Dispositif et procédé de détermination de l'orientation d'un plan dans l'espace - Google Patents

Dispositif et procédé de détermination de l'orientation d'un plan dans l'espace

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Publication number
EP2102590A1
EP2102590A1 EP07857024A EP07857024A EP2102590A1 EP 2102590 A1 EP2102590 A1 EP 2102590A1 EP 07857024 A EP07857024 A EP 07857024A EP 07857024 A EP07857024 A EP 07857024A EP 2102590 A1 EP2102590 A1 EP 2102590A1
Authority
EP
European Patent Office
Prior art keywords
data set
angle
sensor
indicative
transformation
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.)
Withdrawn
Application number
EP07857024A
Other languages
German (de)
English (en)
Inventor
Fritz K. Brunner
Fritz Zobl
Andreas Wieser
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Technische Universitaet Graz
Forschungsholding TU Graz GmbH
Original Assignee
Technische Universitaet Graz
Forschungsholding TU Graz GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Technische Universitaet Graz, Forschungsholding TU Graz GmbH filed Critical Technische Universitaet Graz
Priority to EP07857024A priority Critical patent/EP2102590A1/fr
Publication of EP2102590A1 publication Critical patent/EP2102590A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C17/00—Compasses; Devices for ascertaining true or magnetic north for navigation or surveying purposes
    • G01C17/02—Magnetic compasses
    • G01C17/04—Magnetic compasses with north-seeking magnetic elements, e.g. needles
    • G01C17/10—Comparing observed direction with north indication
    • G01C17/16—Comparing observed direction with north indication by clinometers, e.g. for determining dip or strike of geological strata
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C17/00—Compasses; Devices for ascertaining true or magnetic north for navigation or surveying purposes
    • G01C17/02—Magnetic compasses
    • G01C17/28—Electromagnetic compasses

Definitions

  • the invention relates to a device for determining the orientation of a plane in space.
  • the invention relates to a method of determining the orientation of a plane in space.
  • the invention relates to a geological compass for determining the orientation of a plane in space, in particular of a geological surface.
  • the invention relates to a computer-readable medium.
  • the invention relates to a program element.
  • the study of three-dimensional (3-D) structures and regions is essential for investigating a geological environment, estimating the tectonic history, and assessing deformation processes.
  • the key data for studies in structural geology as well as in engineering geology are the dip angle ( ⁇ ) and the dip azimuth ( ⁇ ) of geological features. Numerical values of these measures are derived from field-measurements using a so-called geological compass (GC) which is still the fundamental instrument used in geological field work.
  • GC geological compass
  • the shown geological compass 600 comprises a main body 601 having a compass 602 implemented therein.
  • the geological compass 600 comprises a Bull's eye level 603 in order to indicate whether the geological compass 600 is levelled or not, and a test plate 604 which can be swivelled and is used to be abutted on a geological feature which is schematically shown in Fig. 6 and labelled 605. Furthermore, the geological compass 600 comprises a scale 606 interacting with the test plate 604 in order to determine the dip angle, i.e. the inclination with respect to the gravity field.
  • a conventional geological compass has graduation lines every 2° for the horizontal circle and every 5° for the dip angle.
  • the standard deviation of the raw readings can be estimated as about one third of the respective graduation interval. Due to the limited accuracy of representing a geological feature by locally attaching a rather small test plate the attainable precision of the dip angle ( ⁇ ) and the dip azimuth ( ⁇ ) is typically no better than 2°. Further sources of possibly much larger errors are inadequate levelling due to difficult geological compass handling, visual observation of the Bull's eye level, visual reading of the graduation, and the subsequent manual recording of the compass data.
  • a device for determining the orientation of a plane in space comprising a first unit adapted to receive a first data set indicative of a first physical parameter, and a second unit adapted to receive a second data set indicative of a second physical parameter. Further the device comprises a calculation unit adapted to calculate a transformation array for a transformation based on the first data set, a transformation unit adapted to transform the second data set by using the transformation array, and a determination unit adapted to determine a first angle indicative of an angular orientation of the object in space based on the transformed second data set.
  • the first unit and the second unit may be formed or housed by a single unit or by two different units.
  • a geological compass comprises a device according to an exemplary embodiment, comprising a first sensor, and a second sensor, wherein the first sensor is adapted to measure the first data set and wherein the second sensor is adapted to measure the second data set.
  • the first sensor and the second sensor may be formed or housed by a single sensor or by two different sensors with known relative orientation.
  • a method of determining an orientation of a plane in space comprises receiving a first data set indicative of a first physical parameter, receiving a second data set indicative of a second physical parameter, calculating a transformation array for a transformation based on the first data set. Further, the method comprises transforming the second data set by using the transformation array, and determining a first angle indicative of an angular orientation of the object in space based on the transformed second data set.
  • a program element which, when being executed by a processor, is adapted to control or carry out a method of determining an orientation of a plane in space, wherein the method comprises receiving a first data set indicative to a first physical parameter, receiving a second data set indicative of a second physical parameter, and calculating a transformation array for a transformation based on the first data set. Further, the method comprises transforming the second data set by using the transformation array, and determining a first angle indicative of an angular orientation in space based on the transformed second data set.
  • a computer-readable medium in which a computer program is stored, which, when being executed by a processor, is adapted to control or carry out a method of determining an orientation of a plane in space, wherein the method comprises receiving a first data set indicative of a first physical parameter, receiving a second data set indicative of a second physical parameter, and calculating a transformation array for a transformation based on the first data set. Further, the method comprises transforming the second data set by using the transformation array, and determining a first angle indicative of an angular orientation in space based on the transformed second data set.
  • a gist of an exemplary embodiment may be seen in the fact that a determination or evaluation device is provided which can be used in connection with a geological compass.
  • a geological compass using such an evaluation device or unit may be called digital geological compass since the evaluation is done electronically, e.g., by using a computer program implemented as software in the evaluation unit or by using a hard wired circuit or a specialized integrated circuit.
  • a digital geological compass may not require physical levelling; rather the levelling may be performed mathematically as part of the evaluation algorithm.
  • Such a digital geological compass may thus be called a mathematically self-levelling geological compass (GC-MSL).
  • a GC-MSL may overcome some of the problems associated with a conventional geological compass (GC).
  • a GC-MSL may not need a swivelling test plate to represent the surface of the feature whose orientation in space is to be determined.
  • any surface of the GC-MSL housing may be used as the test plate. Measurements may be taken electronically and may internally be recorded in the device, i.e., the determination device or the GC-MSL.
  • Principal innovative features may be that the compulsory levelling of the geological compass becomes obsolete, that there may be no restrictions on the three- dimensional orientation of the GC-MSL while taking readings e.g., the GC-MSL may even be used vertically or upside-down, and that all data may be readily available in digital form.
  • the term "transformation array” may be referring to a one-, two- or three-dimensional array or matrix.
  • the transformation array may be a transformation matrix which may be used to perform a coordinate transformation, i.e., a transformation which transforms values of physical parameters which are measured in a first coordinate system into a second coordinate system.
  • the first coordinate system may be a coordinate system intrinsic or body fixed to an object or a measuring unit, e.g., a geological compass
  • the second coordinate system may be a coordinate system external to the object or measuring unit, e.g., a coordinate system relating to the gravity field and/or the magnetic field of the earth.
  • the first physical parameter represents a deviation from the fall line.
  • the first data set is measured by an inclination sensor.
  • the first data set may be representative of two linearly independent inclination directions.
  • the inclination sensor may comprise two independent inclination sub-sensors.
  • One of these two independent sub-sensors may be adapted to measure an inclination in a first direction, e.g., an x-direction of a body fixed coordinate system, while the other one of the sub-sensors may be adapted to measure the inclination in a second direction, e.g., a y-direction of the body fixed coordinate system.
  • the two directions do not have to be perpendicular to each other, but preferable they are linearly independent of each other, so that from the measured two inclinations the independent inclination components in a Cartesian coordinate system can be easily derived by known calculations.
  • the first data set is measured by an acceleration sensor.
  • the first data set may representative of three linearly independent acceleration directions.
  • the acceleration sensor may comprise three independent acceleration sub-sensors.
  • One of these three independent sub-sensors may be adapted to measure an acceleration in a first direction, e.g., an x-direction of a body fixed coordinate system
  • the second one of the sub-sensors may be adapted to measure the acceleration in a second direction, e.g., a y-direction of the body fixed coordinate system
  • the third one of the sub- sensors may be adapted to measure the acceleration in a third direction, e.g., a z- direction of the body fixed coordinate system.
  • the three directions do not have to be perpendicular to each other, but preferable they are linearly independent of each other, so that from the measured three accelerations the acceleration components in a Cartesian coordinate system can be easily derived by known calculations.
  • the acceleration sensor may be implemented by using known force detectors.
  • the second data set is measured by a magnetic field sensor.
  • the second data set may be indicative of three linearly independent components of the magnetic field.
  • the magnetic field sensor may be formed by one or more known magnetometers.
  • the magnetic field sensor may comprise three independent magnetic field sub-sensors.
  • One of these three independent sub-sensors may be adapted to measure a magnetic field in a first direction, e.g., an x-direction of a body fixed coordinate system
  • the second one of the sub-sensors may be adapted to measure the magnetic field in a second direction, e.g., a y-direction of the body fixed coordinate system
  • the third one of the sub-sensors may be adapted to measure the magnetic field in a third direction, e.g., a z-direction of the body fixed coordinate system.
  • the three directions do not have to be perpendicular to each other, but preferable they are linearly independent of each other, so that from the measured three magnetic field components the magnetic field components in a Cartesian coordinate system can be easily derived by known calculations. That is, the first angle may be associated with the point of the compass, while the second angle may be associated with the zenith angle, i.e. the angular deviation from the horizon.
  • the determination unit is further adapted to determine a second angle of the object in space, wherein the second angle is linearly independent of the first angle.
  • the first angle may be the so- called dip azimuth counted from magnetic North
  • the second angle may be the dip angle counted from the horizon.
  • the first sensor is an acceleration sensor.
  • the acceleration sensor is adapted to measure three linearly independent components of the acceleration.
  • the first sensor may be a senor adapted to measure an inclination.
  • the inclination sensor is adapted to measure two linearly independent inclinations.
  • an effective way for measuring the angular orientation of the geological compass with respect to the fall line or to the gravity field of the earth may be provided.
  • the corresponding information i.e., the measured angular orientation
  • the handling of the geological compass according to an exemplary embodiment may become easier than the handling of known geological compasses.
  • the data of the acceleration sensor and/or the inclination sensor may be used to perform a coordinate transformation of the second data set, e.g., a data set representative of the azimuth of the geological compass, which may be measured by a magnetic field sensor.
  • the geological compass further comprises a temperature sensor, wherein the temperature sensor is adapted to measure a temperature, and wherein the determination unit is adapted to determine the first angle and/or the second angle under consideration of the measured temperature.
  • a temperature sensor e.g., a digital thermometer
  • the first sensor and/or the second sensor is adapted to measure the first data set and/or the second data set for a predetermined time period.
  • the determination unit may be adapted to determine the first and/or the second angle based on the first data set and/or the second data set averaged over the predetermined time period or otherwise transformed from the predetermined time period to a single epoch.
  • the first data set and the second data set is sampled for a time period between 0.1 second and 10 seconds in particular between 0.5 seconds and 5 seconds, preferably for 1 second by a rate between 1 Hz and 10 kHz, in particular at a rate between 10 Hz and 1 kHz, preferably at a rate of 100 Hz.
  • the averaging may be done over 50 measured samples, i.e. single measurements.
  • the precision of the determined orientation may be increased; sensor faults and data outliers may be detected and mitigated, and handling errors (e.g., inappropriate moving of the geological compass during the measurement period) may be detected and signalled.
  • the geological compass further comprises a wireless data communication interface which can be used to transfer data to and/or from the geological compass to another device, e.g., a personal computer, a PDA or another electronic device.
  • a wireless data communication may be based on the so-called Bluetooth technique.
  • the geological compass further comprises an analyzing unit adapted to calculate standard errors and/or confidence intervals relating to the first angle and/or second angle, and wherein the analyzing unit is preferably further adapted to create pole diagrams.
  • the method further comprises determining a second angle indicative of an angular orientation in space, wherein the second angle is linearly independent of the first angle.
  • a is the first angle, namely the dip azimuth of the plane counted from magnetic north
  • ⁇ is an angle indicating the deviation of the x -axis from the fall line
  • ⁇ represents the deviation of the plane from the horizon
  • m b represents the i th component of the second physical parameter expressed in the body-fixed coordinate system
  • ⁇ f represents the i th component of the first physical parameter expressed in the body-fixed coordinate system whose x b and y b axes are parallel to the plane i.e., whose x b anay b axes represent the test plate abutted on the plane whose orientation is to be determined.
  • the signs of the numerator and of the denominator correspond respectively to the signs of sin ⁇
  • the second angle is determined based on the equation: wherein ⁇ represents the second angle of the plane, and wherein a t h represents the i th component of the first physical parameter expressed in the body-fixed coordinate system whose x b andy b axes are parallel to the plane i.e., whose x b and y b axes represent the test plate abutted on the plane whose orientation is to be determined.
  • the signs of the numerator and of the denominator are equal to the signs of sin ⁇ and cos ⁇ , respectively, and determine the quadrant of ⁇ unambiguously.
  • the method further comprises converting the first angle from an angle relating to magnetic North to an angle relating to any chosen earth fixed reference direction, e.g., to geographical North.
  • This can be accomplished using a third data set consisting of a first data sub-set related to the magnetic field on earth, e.g., a known numerical model of the earth magnetic field, and a second data sub-set related to the position on earth, e.g., obtained from a positioning device like a GPS receiver or from user input based on a map.
  • a digital, mathematically self-levelling geological compass may be provided which may not require the physical levelling of the compass any longer.
  • the GC-MSL instead of a swivelling test plate, as used in known geological compasses, the GC-MSL according to this aspect itself is attached to the geological surface in any suitable orientation.
  • a sensor combination which may be used for the GC-MSL comprises a three-dimensional accelerometer and a three-dimensional magnetic field sensor wherein the device, e.g., the GC-MSL, is adapted to compute the dip angle and dip azimuth of the geological surface i.e., the dip angle and the azimuth of the fall line representative of the part of the geological surface to which the GC-MSL is attached.
  • Experimental results show that the dip angle and azimuth of the fall line can be obtained with a precision better than 1° using a few seconds of data from these two sensor triads.
  • Advantages of the GC-MSL according to this exemplary aspect in comparison to a conventional geological compass may be: (a) levelling of the geological compass may not be required any longer; (b) attaching the test plate of the geological compass to the geological feature may be possible in any suitable orientation; (c) the test plate may not have to be swivelling, and thus e.g.
  • one face of the housing of the geological compass can be the test plate; (d) it may allow for true one-hand operation; (e) it may allow measurements at geological features which are inaccessible or difficult to measure when using a conventional compass that needs to be visible and levelled while the readings are taken; (f) it may save time in the measurement process; (g) it may output digital data; (h) it may provide high precision and reliability.
  • the digital geological compass may be further developed by (i) using wireless communication with a (pocket) PC in the field, (ii) optionally converting azimuths from magnetic North to a different reference direction e.g., geographical North, (iii) providing the orientation of linear elements as represented e.g., by an edge of the GC-MSL housing, in addition to the orientation of the fall line of surfaces, (iv) analyzing the data on-line in the field to provide statistical information, e.g., standard errors, confidence intervals, to safeguard against undetected sensor faults and improper handling e.g., by statistical outlier detection or time series analyses, and to automatically create graphical representations of the collected data, e.g., pole diagrams.
  • statistical information e.g., standard errors, confidence intervals
  • the dip angle is referenced to the local vertical using accelerometer measurements of the local gravity vector.
  • the dip azimuth is derived from magnetometer measurements of the local magnetic field vector.
  • the adaptation of such a sensor assembly for geological measurements and the derivation of the required data processing algorithms may represent a new and inventive novel approach.
  • a geological compass a digital, mathematically self-levelling geological compass may be provided that does not require physical levelling any longer; that may be manufactured small and lightweight, and that may yield accurate dip angle and dip azimuth measures within less than a few seconds.
  • Fig. 1 illustrates a body-fixed coordinate system in which sensor readings can be performed, and a coordinate system in which the orientation of a plane can be expressed.
  • Fig. 2 illustrates rotations of the body-fixed coordinate system of Fig. 1.
  • FIG. 3 schematically illustrates an experimental setup for testing an exemplary embodiment of a geological compass.
  • FIG. 4 schematically illustrates an enlarged view of the geological compass of Fig. 3.
  • Fig. 5 schematically shows testing results obtained using the experimental setup shown in Fig. 5.
  • Fig. 6 shows a known geological compass and a schematic display of the orientation of a geological feature.
  • An assembly of three accelerometers and three magnetometers can be used to determine the local gravity vector and the local earth magnetic field vector in a body- fixed coordinate system (x y z ). It can be assumed that this coordinate system is orthogonal, with its x b y b -p ⁇ ane representing the fixed test plate of a digital, mathematically self-levelling geological compass (e.g., one face of the housing).
  • the individual sensors are preferably aligned with the axes of the body- fixed coordinate system, thus forming substantially orthogonal and mutually aligned accelerometer and magnetometer triads.
  • the digital, mathematically self-levelling geological compass (GC-MSL) 100 can — without levelling — be held against a geological surface 101 and may yield accurate measures of the azimuth ⁇ 102 and the dip angle ⁇ 103, wherein the dip angle ⁇ 103 corresponds to the inclination angle and can be measured between the geological surface 101 and a horizontal plane schematically depicted by the line 104 in Fig. 1.
  • ⁇ and ⁇ can be computed from the sensor output by exploiting the relation between the body-fixed coordinate system, shown as 105 in Fig. 1, and the local-level coordinate system, formed by the magnetic North 106, the magnetic East 107 and the vertical 108.
  • the local-level coordinate system is defined by the local vertical, i.e., the direction "up", the opposite to the gravity vector, and by the local magnetic North direction, see Fig. 1.
  • the GC-MSL is being attached to the geological feature with the x b y b plane parallel to the feature (see Fig. 1). So, the fall line of the geological feature is contained in the x b y b plane, but not generally aligned with either axis.
  • the body- fixed coordinate system is rotated about its z*-axis by an angle ⁇ such that the resulting x-axis (x 1 ) points along the fall line (see Fig. 2a), i.e., the angle ⁇ corresponds to the angle between the fall line and the x direction of the coordinate system 105: cos ⁇ sin ⁇ 0 y - sin ⁇ cos ⁇ 0 y (1)
  • eq. 4 with the transformation matrix R ⁇ , ⁇ ) of eq. 3 represents an equation system from which the unknown angles ⁇ and ⁇ can be computed.
  • the knowledge of g i.e., magnitude of the local gravity
  • g i.e., magnitude of the local gravity
  • ⁇ is undefined if the dip angle is 0 — there is no fall line in this case — , but that eq. 5 yields the correct value of ⁇ even in this case. It is further pointed out that eq. 6 can be derived from eq. 3 by using the second component of the vector equation 3, while eq. 5 can be derived by using the first component of eq. 3.
  • Eq. 6 shows that all three original acceleration measurements are required to compute the dip angle. It is not possible to determine ⁇ using only two accelerometers unless the magnitude of g is known and either a, b is one of the measured accelerations, or a restriction on the three-dimensional orientation of the digital geological compass is applied, e.g., that it is not used with its z*-axis pointing below the horizon. Thus, according to an exemplary embodiment it is possible to only provide two accelerometers but further impose restrictions on the orientation of the digital geological compass and provide the magnitude of the gravity field at the respective position of the digital geological compass.
  • the projection of the earth magnetic field vector onto the horizontal (x 2 y )-plane defines magnetic north in that plane, see Fig. 2c.
  • the angle a counted clockwise from that projection to the x 2 -axis is the dip azimuth that would also be measured with a levelled conventional geological compass.
  • the projection can be computed from the original magnetometer measurements (m x b , m y b ,m : b ) taken in the body- fixed frame by transforming them into the (x 2 y 2 z 2 ) system using eq. 3 — thus replacing physical levelling of the digital geological compass by mathematical levelling:
  • a can then be computed from Substituting eq. 7 into eq. 8 finally yields: m x cos ⁇ cos ⁇ + m y cos ⁇ sin ⁇ + m. sin ⁇ where the signs of the numerator and the denominator are equal to the signs of cos ⁇ and sin a , respectively, and thus indicate the quadrant of a unambiguously.
  • the so-called strike azimuth i.e., the azimuth of the intersection between the measured plane and the horizon, when preferred over the dip azimuth, can be obtained by subtracting 90° from a .
  • the azimuth a of the fall line has been derived above as rotated by 90° with respect to that intersection.
  • eq. 9 yields a value that correctly represents the orientation of the plane even if the plane is vertical i.e., even if the azimuth of the fall line is undefined.
  • the strike azimuth will not be considered further in this application. If the geological feature to be measured is horizontal, then of course its azimuth a (like ⁇ ) is undefined. This is a fundamental geometric property rather than a weakness of the GC-MSL, and affects all compasses.
  • Eq. 9 clearly shows that all three components of the magnetic field vector must be measured in the body-fixed coordinate system in order to determine the dip azimuth. It may be possible to determine the dip azimuth using less than three measured components of the magnetic field if the local magnitude and direction of the field are known and restrictions on the orientation of the body-fixed frame apply.
  • the three acceleration sensors and the three magnetometers are perfectly orthogonal and perfectly aligned with the body-fixed coordinate system, the x y -plane of which was chosen to define the test plate in the exemplary embodiment of a GC-MSL.
  • Such a sensor assembly can hardly be manufactured.
  • the individual sensor output equals exactly the projection of the corresponding vector (gravity or magnetic field) onto the sensor axis.
  • the output of such sensors may be affected by biases (non-zero output with zero input), scale factor errors, random noise and higher order errors.
  • Philips Semiconductors, Systems Lab, Hamburg, 38p which is herby incorporated herein by reference, provides useful information about the calibration of the sensor misalignment, and gives the "rule-of-thumb" that the degree of non-orthogonality will create a similar degree of error in the measured azimuth of an electronic compass. Furthermore, it is known from experimental analysis of error influences on the calibration of the magnetic compass that calibration may improve the azimuth results significantly from, e.g., 8° error without calibration to about 0.3° error when using the calibration results. These findings may be applicable to the digital geological compass.
  • the errors may additionally vary slowly over time and depend on sensor temperature. While the former effect must be included in the error budget of the digital geological compass or mitigated by selecting sensors that exhibit low drift, the latter effect can be modelled and corrected for in case also a digital temperature sensor is included in the digital geological compass.
  • a geological compass inevitable random noise can be mitigated by averaging raw sensor output, e.g., measured data sets of the acceleration sensors and/or magnetic field sensors, over a suitable time interval. This may also allow for quality control of the raw data, e.g., to detect whether the sensor is sufficiently static during the measurement period. A generally valid optimum averaging time cannot be given; a suitable time needs to be found depending on the noise characteristics of the sensors contained in the digital geological compass. An indication is given later on in this application.
  • the GC-MSL comprises three solid state accelerometers, three thin film magnetometers and one temperature sensor. All sensors fit into a small and lightweight housing.
  • the accelerometer and magnetometer outputs refer to axes aligned with the body-fixed coordinate system within about 0.3°.
  • 100 Hz raw sensor data are output by the sensor unit via its serial interface and can be recorded on a laptop computer.
  • These raw sensor data can be post-processed using a known program, e.g. MATLAB, wherein the post-processing typically consists of (i) conversion from raw data to calibrated sensor output (a x b , ..., m : b ), (ii) reducing the data rate by averaging a number of consecutive epochs, e.g. 50 epochs which yields 2Hz data, and (iii) computation of dip angle and azimuth using eqs. 5, 6, 9, and 10.
  • a non- magnetic and non-ferrous test jig can be used.
  • Fig. 3 schematically shows such a jig 301.
  • the sensor unit 302 can be rigidly attached to a first plate 303 of the jig which can be pivoted about a horizontal axis 304 which can in turn be rotated about a vertical axis 305.
  • the jig provides bolts or graduations to determine the rotation angle of the first plate 303 about the two axes 304 and 305.
  • Such a jig allows establishing well known and reproducible orientations in space and removes the uncertainty associated with abutting the digital geological compass onto a real geological feature which is identical for the conventional geological compass and for a digital geological compass and will thus not be investigated in this application.
  • the field test demonstrates the overall performance as obtained using a low-cost sensor assembly once it has been properly calibrated.
  • the field test was carried out in a quarry which is situated in non-magnetic bedrock.
  • the jig 301 was mounted on a plaster bed 306 and was carefully levelled using a precision spirit level.
  • a Suunto KB-14 sighting compass was used to determine the magnetic azimuth of the jig.
  • the orientation of this plate in terms of the angles ⁇ and a was then changed to about 140 different states involving a range of 0° ⁇ a ⁇ 360° for the dip azimuth and 15° ⁇ ⁇ ⁇ 90° for the dip angle.
  • the sensor unit 302 was static for 10-20 seconds, and raw sensor output was recorded at 100Hz.
  • the dip angle and azimuth were then computed separately from each consecutive batch of 50 epochs, corresponding to a period of 0.5 seconds of raw data.
  • Fig. 4 schematically shows an enlarged view of the jig 301 which comprises a sensor unit 302 housing the sensors, i.e. the acceleration sensors, the magnetic field sensors and the temperature sensor.
  • the sensor unit 302 is fixed to a first plate 303 which can be pivoted about a horizontal axis.
  • the first plate 303 is pivotably fixed between two plates 407 and 408 which are perpendicular to the horizontal axis.
  • the two plates 407 and 408 are fixed to a second plate 409, which can be rotated about a vertical axis.
  • the sensor unit 302 can be rotated about two perpendicular axes corresponding to the two degrees of rotation of a geological surface.
  • the plot represents more than 5000 pairs of computed values of ⁇ and a covering the full azimuth range of 360° and an inclination range of 75°.
  • the non-zero mean value of 1.3° for ⁇ a can be attributed to a bias of the jig orientation as established using the conventional Suunto compass.
  • the standard deviation (std) of ⁇ and ⁇ a is 0.1° and 0.5°, respectively. All dip angle deviations and most of the azimuth deviations are within ⁇ 1° about the respective mean value (shaded area in Fig. 5). This indicates remarkably high precision, given the short measurement time of only 0.5 seconds per sample, and the contribution of the jig (slackness, and standard deviation of graduation reading were estimated with about 0.1-0.2°).
  • a GC-MSL is provided that is suitable to achieve a precision of 1 ° for both azimuth and dip angle with various three- dimensional orientations of the sensor unit.
  • Further improvements may include the selection of optimum sensor elements, the realization of wireless data transmission between the sensor unit and/or digital geological compass and a determination device, e.g. a PC or PDA, the optimization of the calibration procedure, and an error analysis including random and systematic effects.
  • a determination device e.g. a PC or PDA

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  • Geophysics And Detection Of Objects (AREA)

Abstract

La présente invention concerne un dispositif de détermination d'une orientation angulaire d'un plan dans l'espace, le dispositif comprenant une première unité adaptée pour recevoir un premier ensemble de données représentant un premier paramètre physique, ainsi qu'une seconde unité adaptée pour recevoir un second ensemble de données représentant un second paramètre physique. Le dispositif comprend en outre une unité de calcul adaptée pour calculer une matrice de transformation en vue d'une transformation sur la base du premier ensemble de données, une unité de transformation adaptée pour transformer le second ensemble de données à l'aide de la matrice de transformation, et une unité de détermination adaptée pour déterminer un premier angle indiquant une orientation angulaire de l'objet dans l'espace sur la base du second ensemble de données transformé.
EP07857024A 2006-12-22 2007-12-20 Dispositif et procédé de détermination de l'orientation d'un plan dans l'espace Withdrawn EP2102590A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP07857024A EP2102590A1 (fr) 2006-12-22 2007-12-20 Dispositif et procédé de détermination de l'orientation d'un plan dans l'espace

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US87164706P 2006-12-22 2006-12-22
EP06026764 2006-12-22
EP07857024A EP2102590A1 (fr) 2006-12-22 2007-12-20 Dispositif et procédé de détermination de l'orientation d'un plan dans l'espace
PCT/EP2007/011301 WO2008077595A1 (fr) 2006-12-22 2007-12-20 Dispositif et procédé de détermination de l'orientation d'un plan dans l'espace

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EP2102590A1 true EP2102590A1 (fr) 2009-09-23

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WO (1) WO2008077595A1 (fr)

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GB2466016A (en) * 2008-12-06 2010-06-09 Natural Environment Res Inclinometer having a plate extending beyond the main body

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DE3915404A1 (de) * 1989-05-11 1990-11-15 Dinnebier Robert Dipl Min Geologenkompass
JPH06221852A (ja) * 1993-01-25 1994-08-12 Sato Kogyo Co Ltd 電子式ステレオクリノコンパス
AT1040U1 (de) * 1995-08-02 1996-09-25 Napetschnig Georg Messgerät zum bestimmen der neigung und der himmelsrichtung
KR100533106B1 (ko) * 2002-08-06 2005-12-05 삼성전자주식회사 지자계 센서의 자세 오차 보상장치 및 방법
TW200407025A (en) * 2002-08-27 2004-05-01 Vitec Co Ltd Pocket terminal device
JP4551661B2 (ja) * 2004-01-06 2010-09-29 シチズンホールディングス株式会社 電子方位計、記録媒体および方位演算プログラム

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