Abstract: A coordinate measuring machine has a probe head, a calibrating body and an apparatus for recording and correcting measured values obtained by the probe head. A mechanical flexibility at predetermined points on the surface of the calibrating body is determined. The mechanical flexibility is stored in the apparatus in the form of a data record. The calibrating body is scanned point by point by means of the probe head in order to obtain the measured values. Thereafter, the probe head is calibrated by correcting the measured values using the data record. A similar approach can also be used on workpieces having a known mechanical flexibility.

Abstract: A method for measuring a surface profile using a surface sensing device mounted on an articulating probe head in which the probe head is moved along a nominal path relative to the surface profile, an at least approximation of the surface normal of the surface profile, the surface profile is sensed with the surface sensing device and the distance or force of the surface sensing device relative to the surface profile substantially in the direction of the surface normal. The surface normal may be determined by approximating at least one section to a curved profile which can be mathematically parameterised.

Abstract: A process in which a white light scanner and a CMM are integrated into one inspection tool. The white light scanner and CMM will be tied to the same table and articulate using the same mechanism. Both inspection processes use the same absolute point to take measurements. The white light data will be modified using the CMM inspection data. Ultimately, the output of the inspection process will be a surface created by the white light inspection with the accuracy of a CMM. The white light scanner first scans the part to determine the surface topography within a first predetermined tolerance. The CMM scanner then scans the part using the coordinates from the white light scanner to position the probe close and fast, and then scans the surface topography of the part with a better tolerance than the white light scanner.

Abstract: An ultra-precision machine tool capable of accurately detecting a machining start position, in which movable axes are supported by fluid bearings. A workpiece is mounted on a rotary table of a B axis, and the rotary table is mounted on an X axis that is a linear motion axis. A tool is mounted on a Y axis. The Y axis is mounted on a Z axis. The X axis is moved reciprocally each time the Z axis is moved a predetermined amount, a machining surface of the workpiece is scanned, and it is determined whether or not position deviation of the X, Y and B axes reaches or exceeds a reference value. The Y axis is driven and the tool is moved toward the workpiece a predetermined amount, and the above-described scan is performed.

Abstract: A method for calculating coordinate values of a measuring machine is provided. The method includes receiving signals in three dimensions from a raster ruler signal generator, identifying a direction of each signal and multiply a frequency of each signal. The method further includes counting each of multiplied signals in each dimension, sending the counted data to the MCU. The method further includes adding the counted data of each of the multiplied signals in each dimension to obtain an accumulated number in each dimension and calculating coordinate values of the measuring machine according to the accumulated number in each dimension and a proportionality factor of the raster ruler signal generator.

Abstract: A method of calibrating a measurement probe (10) mounted on a machine is described. The measurement probe (10) has a stylus (14) with a workpiece contacting tip (16). The method comprises determining a probe calibration matrix that relates the probe outputs (a,b,c) to the machine coordinate system (x,y,z.). The method comprising the steps of scanning a calibration artefact (18) using a first probe deflection (d1) to obtain first machine data and using a second probe deflection (d2) to obtain second machine data. The first and second machine data are used to obtain a pure probe calibration matrix in which any machine errors are substantially omitted. Advantageously, the method determines the pure probe matrix numerically based on the assumption that the difference between the first and second machine position data is known.

Abstract: A method of compensating the measurement errors of a measuring machine deriving from the deformations of a machine bed of the machine caused by the load exerted by a mobile unit of the machine on the machine bed, comprising a first acquisition step in which first data regarding the conditions of resting mode of a workpiece on the machine bed are acquired, a second acquisition step in which second data regarding the deformation of the machine bed as the position of the mobile unit of the machine varies are acquired, and a third calculation step in which correction values depending upon said first and second data are calculated.

Abstract: A hoist positioning system includes an accelerometer attached to a hoist, a control unit for processing signals from the accelerometer and comparing the processed signals with reference data to determine a position of the hoist, a drive system for moving the hoist up and down, and a relay that is switched ON and OFF by a control signal from the control unit. When the relay is switched ON, power is supplied to the drive system from a high-voltage power source and the hoist is driven up or down. When the relay is switched OFF, power from the high-voltage power source to the drive system is cut off and the hoist stops moving up or down.

Abstract: A system and method for calculating an observational error of a coordinate measuring machine includes receiving measuring parameters input by a user, obtaining observational errors of the ruler from a storage system, and identifying the zero mark of the ruler. A direction of the ruler is adjusted to be substantially parallel to the measuring direction of the measuring parameters, controlling the coordinate measuring machine to measure the ruler according to the measuring parameters, obtaining measured data. Observational error of the coordinate measuring machine is calculated according to the measured data, which is stored in the storage system.

Abstract: Methods are disclosed wherein the structural health of a civil structure, such as, but not limited to, a bridge or the like is measured by electronic distance measurement from a plurality of stable locations to a plurality of cardinal points on the structure in a methodical manner. By measuring the coordinates of the cardinal points, the dynamic and long-term static behavior of the structure provide an indication of the health of the structure. Analysis includes; comparison to a Finite Element Model (FEM), comparison to historical data, linearity, hysteresis, symmetry, creep, damping coefficient, and harmonic terms.

Abstract: A reference measurement object having known properties is used for the purpose of calibrating a coordinate measuring machine. A plurality of reference measured values are picked up on the reference measurement object. Calibration data are determined using the reference measured values and using the known properties of the reference measurement object. The calibration data comprises a first number of polynomial coefficients that are selected to correct nonlinear measuring errors using at least one polynomial transformation. The first number of polynomial coefficients is reduced in an iterative method to a lesser second number, with a plurality of pairs of polynomial coefficients being formed and with a polynomial coefficient of a pair being eliminated in each case when a statistical dependence between the polynomial coefficients of the pair is greater than a defined threshold value.

Abstract: A method of calibrating a probe is disclosed said probe being mounted on a machine and having a stylus with a workpiece contacting tip, comprising calculating calibration information for the probe for a first orientation of the probe, and rotating the calibration information by an angle to obtain a probe calibration information for when the probe is oriented by that angle with respect to the first orientation. Also disclosed is a method of calibrating a probe during a measurement process. The calibration information may include a vector which relates probe head axes to machine axes; a calibration matrix; datum data; an inertial matrix. The stylus tip may be datumed at the orientation of the probe or inferred from datum information obtained at different orientations. The rotation step may be carried out by a software/computer program which may be stored on a controller for the machine.

Abstract: A portable coordinate measurement machine for measuring the position of an object in a selected volume comprises includes an a positionable articulated arm having a plurality of jointed arm segments. The arm includes a measurement probe having an integrated line laser scanner mounted thereon. The laser may be a fiber coupled laser. Wireless data transfer and communication capability for the CMM is also possible.

Abstract: A camera coordinate calibration system and method are provided. The system includes a calibration contactor having at least two fiducials. The system also includes a double sided visible calibration target. A pick and place handler is provided with a device holder having at least two fiducials, where the device holder is configured to pickup the double sided visible calibration target and place the target onto the calibration contactor. The system includes a device view camera configured to image a first side of the double sided visible calibration target inserted into the device holder, and a contactor view camera configured to image a second side of the target inserted into the calibration contactor. A processor is provided that calculates a common coordinate system for the device view camera and the contactor view camera based on the images of the first and second sides of the double sided visible calibration target.

Abstract: A probe straightness measuring method includes: placing a measurement jig having a measurement reference surface with a known profile error on a stage surface of an XY stage so that the measurement reference surface is slanted in a moving direction of the XY stage; measuring a displaced position of the measurement piece by a displacement detector of the probe each time the XY stage is moved for a predetermined distance while controlling a driving actuator so that the measurement piece of a probe touches the measurement reference surface at a constant pressure; and calculating a straightness error of a measurement-piece moving mechanism on a basis of a measured position of the measurement piece obtained in the measuring, a nominal position of the measurement piece obtained by a calculation and a slant angle of the measurement reference surface.

Abstract: A defect review apparatus for reviewing a specimen by moving the specimen to pre-calculated coordinate includes: a function to measure a deviation amount between the pre-calculated coordinates and coordinates of an actual position of the specimen; a function to optimize a coordinate correcting expression to minimize the measured deviation amount; and a function to determine that the deviation amounts have converged. When the deviation amounts have converged, the measurement for the coordinate-correcting-expression optimization is terminated, minimizing a reduction in throughput. field of view (FOV) necessary for the specimen to be within the FOV is set according to a convergence value of the calculated deviation amount.

Abstract: A first method determines a position of a point of interest on a target object surface in a target object coordinate system using orientation and distance measurements of a pointing instrument in an instrument coordinate system. A second method determines an orientation of a pointing instrument in an instrument coordinate system for the instrument to be aligned with a point of interest on a target object surface having a target object coordinate system, wherein a position of the point of interest in the target object coordinate system is known. A third method controls orientation of a laser beam of a laser in an instrument coordinate system for the laser beam to trace an image on a target object surface having a target object coordinate system, wherein positions of points for the image on the surface of the target object in the target object coordinate system are known.

Abstract: A method is disclosed whereby a laser-based spherical coordinate measurement system is dynamically calibrated. A mechanical oscillator, such as, but not limited to, a Foucault pendulum is used to generate periodic motions which can be fitted to Fourier series models. The residuals between the experimental measurements and the model can provide information which can be used to calibrate the instrument. The calibration information is used to augment the ASME B89.4.19-2006 standard to improve sensitivity to cyclic errors and include the servo systems.

Abstract: A method for correcting software keyboard input includes the following steps. A first set of touch coordinates from a user is obtained. The first set of touch coordinates includes a first horizontal touch coordinate and a first vertical touch coordinate. A horizontal calibration model and a vertical calibration model are obtained from a calibration database. The first horizontal touch coordinate and the first vertical touch coordinate are substituted into the horizontal calibration model and the vertical calibration model respectively to calculate a set of calibrated coordinates. The set of calibrated coordinates is compared with a set of center coordinates to determine a desired user input. A computer program product using the method and a system for correcting software keyboard input are also disclosed herein.

Abstract: An information processing method for obtaining placement information of a first position and orientation sensor attached to an object with respect to the object includes an image input step of inputting an image of the object captured by an image capturing device, and a sensor measurement value input step of inputting a first measurement value of the first position and orientation sensor and a second measurement value of a second position and orientation sensor attached to the image capturing device. An index detecting step detects information about image coordinates of an index attached to the object from the image, and a placement information calculating step calculates the placement information by using the first and second measurement values of the first and second position and orientation sensors and the information about the image coordinates of the index.

Abstract: A shooting-location acquiring unit acquires a current location, and stores acquired current location as a shooting location. A distance acquiring unit acquires a distance between a subject and the current location, and stores acquired distance as an imaging subject distance. An orientation acquiring unit acquires an orientation of the subject, and stores acquired orientation as an imaging subject orientation. A subject-location calculating unit calculates an imaging subject location, based on the shooting location, the imaging subject distance, and the imaging subject orientation. An information recording unit records an image with calculated imaging subject location.

Abstract: A thermal deformation error compensation method for a coordinate measuring machine creates thermal deformation and geometric error data at different ambient temperatures including temperatures and machine kinematic parameters to obtain a thermal deformation and geometric error model, and inputs the model into central control unit of the coordinate measuring machine, and converts a 3D error compensation to obtain a thermal deformation and geometric error compensation model, and uses the thermal deformation and geometric error compensation model for performing compensations, so as to complete a thermal deformation and geometric error compensation of the coordinate measuring machine.

Abstract: Real time performance comparison involves identifying predefined route data corresponding to a route. Measured locations are detected while a user traverses the route carrying a mobile device. The measured locations are sent via a network synchronously with the detection of the respective measured locations. Comparative data points are derived based on the predefined route data and the measured locations in response to receiving the measured locations. The comparative data points are sent, via the network, in response to measured locations. The comparative data points allow the user to measure relative performance during the route traversal.

Abstract: An inspection artifact includes a central portion and multiple optical and coordinate measurement machine (CMM) alignment features arranged on the central portion. The optical and CMM alignment features are configured to align the coordinates for an optical or a CMM measurement system to a common coordinate system. Another inspection artifact includes a central portion and multiple computed tomography (CT) alignment features arranged on the central portion. The CT alignment features are configured to align the coordinates for a CT system to a common coordinate system.

Abstract: A method of compensating the measurement errors of a measuring machine that derive from the deformations of the machine bed caused by the load exerted by the workpiece to be measured on the machine bed, comprising a first acquisition step in which data regarding the weight of the workpiece and the modes of resting of the workpiece on the machine bed are acquired, and a second calculation step in which correction values depending upon said data are calculated.

Abstract: Stage orthogonal error and position errors caused by mirror distortion are reduced. A CPU 10-2 calculates a coordinate error (?x,?y) between a measured XY coordinate (x,y) of each of arbitrary reference points on a wafer W0 loaded on a XY stage 10-1 which is measured by a laser interferometer 10-4 and a calculated ideal position XY coordinate of the reference point, calculates an orthogonal error of the XY coordinates on the bases of the calculated coordinate errors (?x,?y) and an error due to mirror distortion, and stores them in a storage device 10-5. When a wafer W is actually inspected, the CPU 10-2 corrects the measured position coordinates (x,y) from the laser interferometer 10-4 on the basis of the calculated orthogonal error, and corrects beam deflector 10-7 for deflection on the basis of the calculated error due to mirror distortion.

Abstract: A process and a device are provided for determining the pose as the entirety of the position and the orientation of an image reception device. The process is characterized in that the pose of the image reception device is determined with the use of at least one measuring device that is part of a robot. The device is characterized by a robot with an integrated measuring device that is part of the robot for determining the pose of the image reception device.

Abstract: A corrected ball diameter calculating method includes: preparing a reference gauge that has at least one reference peripheral surface of an outer peripheral surface and an inner peripheral surface; valuing of diameter values of the reference peripheral surface at a plurality of different height positions from a bottom surface of the reference gauge; calculating calibrated diameter values per each of the height positions; placing the reference gauge on the rotary table and causing the stylus tip to touch a plurality of measurement sites on the reference peripheral surface at each of the height positions to calculate measured diameter values that are diameter values of a circle passing through the neighborhood of center points of the stylus tip; and calculating the corrected ball diameters per each of the height positions from the calibrated diameter values and the measured diameter values that are calculated per each of the height positions.

Abstract: A method and system are for measuring and correcting shifts in the boresight, effective focal length, and focus of an optical system that are caused by temperature variations. The method can be used for systems which can be expected to operate in situations where the temperature variations are large, e.g. a FLIR system of a fighter plane, and also where the temperature variations can be very small however high accuracy is needed. The invention is based on placing radiation emitting sources before and as close as possible to the first optical element of the optical system and measuring the thermally induced shifts of the locations of the images of the radiation emitting sources on the surface of the detector of the optical system.

Abstract: The present invention provides a method of correcting coordinates so as to quickly and properly arrange a sample in a field of view in a review apparatus for moving a sample stage onto the specified coordinates to review the sample. A review apparatus according to the present invention, which is a review apparatus for moving a sample stage onto coordinates previously calculated by a checking apparatus to review the sample, has a function of retaining a plurality of coordinate correction tables to correct a deviation between a coordinate value previously calculated by a checking apparatus and an actual sample position detected by the review apparatus. The review apparatus evaluates correction accuracy of the plurality of coordinate correction tables and applies one of the coordinate correction tables with the maximum evaluation value.

Abstract: Some embodiments of the present invention provide a system that generates a simulated vibration pattern in a computer subsystem. During operation, a vibration pattern is monitored at a location in the computer subsystem, wherein the vibration pattern is monitored while the computer subsystem is incorporated into the computer system and the computer system is operating. Then, the vibrations of the computer subsystem are mimicked by generating the simulated vibration pattern at the same location in the computer subsystem based on the monitored vibration pattern.

Abstract: A probe for measuring the dimensions of objects on a coordinate positioning machine such as a machine tool has a workpiece-contacting stylus 20. This is suspended via a sensor mechanism 30, including strain gauges 34 which provide an output when the stylus contacts a workpiece. A processor 16 processes the strain gauge outputs to produce a trigger signal. It does so in accordance with an algorithm or equation or look-up table which ensures equal sensitivity in all possible directions of approach to the workpiece in the three dimensions X, Y, Z.

Abstract: A system and method of tracking location and orientation of power tools utilized in the assembly and maintenance of complex systems is disclosed. The system can facilitate collaboration between maintenance and alert maintenance personnel to complete complex system activities.

Abstract: A method for planning the trajectory of an apparatus, such as an articulating probe head, mounted on a coordinate positioning apparatus, such as a CMM. It is determined whether for a given trajectory, the angular velocity or acceleration of the apparatus about a rotational axis of the apparatus will exceed a predetermined threshold. If so, parameters are adjusted so that the angular velocity or acceleration do not exceed the threshold.

Abstract: A position and an orientation of an image capturing device or an object to which an inclination sensor is mounted are obtained without performing iterative calculation. A position and orientation measuring method includes the steps of: inputting a measured inclination value of an inclination sensor mounted to one of an object and an image capturing device; inputting a captured image from the image capturing device; detecting an index on the object from the captured image; and calculating a position and an orientation of one of the object and the image capturing device to which the inclination sensor is mounted on the basis of the measured inclination value, an image coordinate of the detected index, and already-known positional information on the detected index without performing iterative calculation.

Abstract: A device, a method and a guiding device for setting out contours, points or works, comprising a computer-controlled measuring device provided with a movable measuring probe and a portable base unit provided with a rotatably supported elongate arm. The measuring probe is connected to the measuring device by means of a cord or a wire via the elongate arm, and the measuring device is provided with sensors for measuring a length or a change in the length of the cord or the wire and rotation of the arm in at least one degree of freedom for providing position data of the measuring probe. A guiding device communicatively connected to the measuring device is designed for providing guidance for positioning the measuring probe for the purpose of reducing a difference between a measured position of the measuring probe and a desired position of the measuring probe in accordance with a contour, point or work to be set out.

Abstract: A method for correcting the measuring errors caused by the lens distortion of an objective in a coordinate measuring machine is disclosed. For a plurality of different types of structures, the lens distortion caused by an objective is determined in an image field of the objective. The position of a type of structure is determined in the image field of the objective by a measuring window. The correction of the lens distortion required for the type of structure to be measured is retrieved from the database as a function of the type of structure to be measured.

Abstract: Optical chassis measurement of motor vehicles is carried out by a measuring arrangement equipped with at least one measuring device, in which one or more image capturing devices associated with one another in terms of their position and location record the surface geometry of a vehicle or measurement points arranged on the vehicle, carry out a referencing and/or orientation of the at least one measuring device in relation to the measuring station with reference features that are arranged at particular measuring station coordinates in the measuring station and, based on orientation data and/or association data obtained and based on measurement data obtained during execution of the axle measurement, an evaluation is carried out in an evaluation unit in order to ascertain chassis data.

Abstract: A method for measuring a dimension of a pattern formed on a semiconductor light-exposure mask includes performing a preparation arranged to form a first relationship between measured values of dimensions of opaque patterns and misalignments of detected edge positions, and a second relationship between measured values of dimensions of clear patterns and misalignments of detected edge positions, performing detection/measurement arranged to detect opposite two edge positions of a measurement target pattern, and to measure a dimension of the measurement target pattern bounded by the two edge positions and dimensions of adjacent patterns respectively adjacent to the two edge positions, and performing correction arranged to respectively correct two detected edge positions of the measurement target pattern, with reference to one or both of the first and second relationships formed in the preparation, and measured values of the dimensions obtained in the detection/measurement.

Abstract: In a capacitance type of non-contact sensor for detecting the position of an object to be detected, such as dielectric material, a detection gain is changed in a first case where the object to be detected is placed in a first position and also in a second case where the object to be detected is placed in a second position, and an offset value is adjusted for each gain to bring an output value to a predetermined value. The adjusted offset values are stored in order to define a gain and an offset value at a point, where the offset values in the first and second cases are closest, as adjustment values.

Abstract: A coordinate measuring machine includes: a probe that has a contact point capable of movement within a predetermined range; a movement mechanism for moving the probe; and a controller for controlling the movement mechanism. The controller has a measurement value calculating unit for calculating a position of the contact point based on a displacement of the movement mechanism and a displacement of the probe. The measurement value calculating unit includes: a correction parameter calculator for calculating a correction parameter for correcting the displacement of the probe based on a measurement condition in measuring an object; a corrector for correcting the displacement of the probe based on the correction parameter; and a displacement synthesizing unit that synthesizes the displacement of the movement mechanism and the displacement of the probe corrected by the corrector to calculate the position of the contact point.

Abstract: The present invention provides a method of correcting coordinates so as to quickly and properly arrange a sample in a field of view in a review apparatus for moving a sample stage onto the specified coordinates to review the sample. A review apparatus according to the present invention, which is a review apparatus for moving a sample stage onto coordinates previously calculated by a checking apparatus to review the sample, has a function of retaining a plurality of coordinate correction tables to correct a deviation between a coordinate value previously calculated by a checking apparatus and an actual sample position detected by the review apparatus. The review apparatus evaluates correction accuracy of the plurality of coordinate correction tables and applies one of the coordinate correction tables with the maximum evaluation value.

Abstract: A first method locates a component positioned underneath a surface of a target object using a pointing instrument, wherein a position of the component in the target object coordinate system is known. The first method includes calculating an orientation of the aim point axis of the instrument in the instrument coordinate system for the aim point axis of the instrument to be aligned with the component using at least an inverse calibration matrix, the position of the component in the target object coordinate system, and inverse kinematics of the instrument. The first method also includes rotating the aim point axis of the instrument to the calculated orientation. Second and third methods also are described for locating an access panel for accessing the component and/or maintenance zones in which the component resides.

Abstract: A method and an apparatus for dimensionally measuring parts by means of a coordinate measuring instrument. In order enable measurement of parts that are made of different materials with great accuracy, a computerized tomography sensor is integrated into the coordinate measuring instrument.

Abstract: In a coordinate measuring machine or any other kind of machine having at least one translational movement axis, correction values are determined by moving the mobile head of the machine along a defined path of movement. First and second position data are recorded by means of first and second position measuring devices. The first position data originate from position measuring devices of the machine. The second position data result from a reference measurement. The correction values are determined as a function of the first and second position data. A defined number of correction values is determined for each section of the path of movement, with the defined number varying in the sections as a function of the error profile defined by the correction values.

Abstract: A surface texture measuring instrument includes: a movement-estimating unit for estimating a movement condition of a drive mechanism based on a scanning vector command issued by a scanning vector commander to calculate an estimated operation state quantity; and a correction-calculating unit for correcting a detection value of a drive sensor in accordance with the estimated operation state quantity calculated by the movement-estimating unit. The movement-estimating unit includes: a nominal-model setting unit in which a nominal model representing signal transfer function of the scanning vector command from the issuance of the scanning vector command to a reflection on a movement position of the scanning probe is stored.

Abstract: A vehicle seat, an adjusting system and a method for moving at least one vehicle seat arranged in a vehicle cabin, particularly an aircraft seat, comprising seat components that are coupled or guided together, such as a seat part, a backrest and a leg rest, the location and/or inclination of which can be adjusted by means of at least one or more adjusting units. The adjusting system allows a separation of the basic functions from driving devices, with an electronic device for collision-free movement and for adjusting custom-designed functions and facilitating the adaptation of the custom-designed functions. The movement sequences and movements of the respective individual seat components and the seat components in relation to one another and the movements of the components or seats within an environment or group of seats are accomplished by means of a movement model in a coordinate system.

Abstract: Validating the error map of a CMM using a calibrated probe including a stylus, the probe capable of rotation about at least one axis, includes placing a calibration artifact on a table of the CMM, the table having an upper surface in an XY plane; positioning a Z-ram of the CMM in a first calibration position and a second calibration position with respect to the artifact such that the stylus contacts the artifact; calculating a measured value representing the measured length between the first and second calibration positions; calculating a nominal value based on the length of the stylus of the probe; comparing the nominal value to the measured value; and updating the error map of the CMM if the measured value differs from the nominal value by more than a predetermined value. The probe and/or the stylus moves relative to the Z-ram such that the calibration artifact remains stationary while the Z-ram is positioned in the first calibration position and the second calibration position.

Abstract: A method of calibrating a measurement scale in a motorised scanning head using a reference artefact is described. The method comprises the step of rotating a surface sensing device, such as a scanning probe, mounted on the scanning head about at least one axis of the scanning head to move the surface sensing device into a plurality of different angular orientations relative to the reference artefact. A step is then performed of measuring, with the surface sensing device, at least one property of the reference artefact at each of the different angular orientations. An error map or function is then created for at least one measurement scale of the scanning head using the properties of the reference artefact measured and optionally known or calibrated properties of that reference artefact. The method may comprise use of co-ordinate positioning apparatus, such as a co-ordinate measuring machine, to move the scanning head. The reference artefact may comprise a single feature or an array of features.

Abstract: A calibration method and also a calibration device are proposed to enable a spatial position and/or orientation of a surgical referencing unit of a surgical navigation system fitted with at least one inertial sensor to be specified in relation to a spatial coordinate system.