Probing process on a coordinate measuring machine with distance determination

Abstract

The invention relates to a method for performing a detection process using a coordinate measuring machine, the coordinate measuring machine comprising a measuring sensor for detecting an object and a plurality of distance sensors, in particular at least three distance sensors, wherein the method comprises: - moving the measuring sensor having a sensor longitudinal axis together with the distance sensors in a working space of the coordinate measuring machine; - acquiring distance measurement values ​​to the surroundings along corresponding sensor axes, the sensor axes extending along the sensor longitudinal axis, using the distance sensors; - determining surrounding coordinates taking into account the distance measurement values ​​of all distance sensors, wherein at least one of the surrounding coordinates is determined with respect to a coordinate axis extending at an angle to the sensor axes and / or to the sensor longitudinal axis. Further, the invention relates to an arrangement and a module for forming an arrangement, by means of which a corresponding detection process can be realized by means of a coordinate measuring machine.

Description

Technical Field

[0001] The invention relates to a method for carrying out a probing process in a coordinate measuring machine, an arrangement comprising a coordinate measuring machine and a module forming the arrangement. Background Art

[0002] The use of coordinate measuring machines is prior art, in particular when measuring industrial products. Coordinate measuring machines can be used to determine and check the dimensions, surface properties or, in general, quality characteristics of workpieces. Here, coordinate measuring machines that detect workpieces in a tactile manner are known. The measuring sensors used for this purpose and moved in the workspace by the coordinate measuring machine via a mobile motion system are generally referred to as tactile measuring sensors. Typically, the measuring sensor comprises a tactile measuring probe arranged at a signal generating probe (also called measuring head or sensor head). Usually, the measuring probe is embodied as a rigid measured value recorder and is movably mounted in the probe. Optical detection of objects or, in general, optical acquisition of objects is also known. For this purpose, for example, laser-based measuring sensors, such as white light sensors or triangulation sensors, can be used.

[0003] Typically, coordinate measuring machines acquire a plurality of object locations, in particular surface locations, in order to determine their coordinates. For this purpose, the measuring sensor must be moved between the individual measuring positions by means of a mobile kinematic system of the coordinate measuring machine and, if applicable, must also be appropriately arranged according to the object locations to be measured. In order to change between these positions in the working space, a so-called rapid traverse is typically activated, during which the movement speed of the mobile kinematic system of the coordinate measuring machine can be increased, in particular the axial acceleration can be increased. The intention is to reduce the required overall measurement time. In contrast, in the vicinity of the object location to be measured, a change to a reduced probing speed is usually made. This is based on the idea that, in general, in order to acquire measurement values ​​(in particular in the case of non-scanning surface measurements), the coordinate measuring machine should be stopped as soon as the measuring probe touches the surface and / or as soon as the optical sensor is located at the desired working distance relative to the object (e.g. a specified focal length).

[0004] The timely stopping of the movement is simplified by a correspondingly reduced probing speed and should prevent large probing forces or collisions with the object. Reducing the speed too late when approaching an object can mean that significant contact forces are generated between the tactile measuring probe and the object to be measured.

[0005] Hitherto, the probing speed has usually been selected by the operator as an empirical value or specified as a general setting. This relates in particular to the choice of a location, or more generally to the choice of an axis position, from which it is intended to change to a corresponding probing speed. However, it is recognized that this does not always contribute to a suitable measuring operation. For example, under practical conditions, too early or too late speed changes or braking may occur, which may unnecessarily increase the measuring duration or may involve damage, for example due to a collision between the measuring probe and the object.

[0006] DE 35 27 063 C1 describes a solution for adjusting the speed of a coordinate measuring machine based on the ambient conditions collected by sensors. Therein, a plurality of ultrasonic sensors are grouped in a circular manner around the quill axis of the coordinate measuring machine. The ultrasonic sensors have sensor axes along which measurements can be performed. These sensor axes extend parallel to the quill axis and therefore also parallel to the longitudinal axis of the measuring probe. In other words, the sound lobes generated respectively extend along the above-mentioned axes or components. The sensors are arranged to determine distance measurements (here again referred to as distance values ​​in a simplified manner) along their appropriately arranged sensor axes. If these drop below a specified threshold value, a risk of collision between the measuring probe and the surroundings can be inferred, and the coordinate measuring machine will slow down.

[0007] This solution offers advantages primarily in terms of avoiding collisions during the displacement of the coordinate measuring machine in the above-mentioned rapid traverse, i.e. when changing between different measuring positions to be approached. This document also includes teaching on the effect that the acquired obstacle may be a workpiece, so that an incremental deceleration can also be provided based on the acquired sensor measurements. However, no description is given of how an object should be successfully distinguished from an obstacle. Therefore, such a deceleration can only be achieved very inaccurately and may therefore only be achieved too early or too late.

[0008] For example, this document discloses the determination of the presence of an obstacle based only on a single sensor or the fact that its measurement signal is below a threshold value. If this is the case, the coordinates of the obstacle in the horizontal plane (i.e. perpendicular to the axis of the quill) can be determined based on the position of the quill in the workspace and, obviously, knowing the sensor that has been determined to be correspondingly below the threshold value or its position. However, it has been found that this generally does not allow a sufficient acquisition accuracy of the surroundings to be obtained, so that there may still be a possibility of premature or late speed adjustments.

[0009] The resulting disadvantage is that sufficient elasticity must be maintained at a mechanical level (for example in the form of an elastic mount for the tactile measuring probe in the probe) in order to compensate for any late braking that may occur. However, this in turn leads to a disadvantageous inherent weight shift when the measuring probe is mounted in the probe. If the measuring probe is tilted in space, for example by a conventional rotary joint, the inherent weight of the measuring probe causes a displacement relative to the probe due to the mechanical elasticity. For example, the measuring probe sags relative to the probe under its inherent weight, corresponding to the above-mentioned inherent weight shift. The measuring probe thus leaves its zero position, which is not caused by contact with the workpiece. In order to maintain sufficient measuring accuracy, this inherent weight shift usually needs to be compensated by complex balancing measures.

[0010] In the case of scanning object detection or simple point detection, elastic bearings or bearings with very low rigidity are also disadvantageous, for example because the decay time of the vibrations that occur is increased. Summary of the invention

[0011] It is therefore an object of the present invention to improve the operation of a coordinate measuring machine during probing of an object to be measured and in particular to facilitate need-based speed adjustment.

[0012] This object is achieved by what is described below. Advantageous developments are described in detail below.

[0013] The embodiments and descriptions relating to the above-mentioned prior art may also relate to the present solution or may be provided therein, provided that nothing else is specified or this is obviously not the case.

[0014] A basic finding of the present invention is that there is a need for improved sensor-based acquisition for determining the coordinates of the surroundings, in particular the coordinates of possible obstacles or objects, in view of which a speed adjustment, in particular a reduction in speed, should be performed. In particular, the present invention proposes increasing the number of sensors, whose measurement signals or measured values ​​are taken into account for determining the corresponding coordinates.

[0015] Thus, with regard to DE 35 27 063 C1 discussed above, it should be recognized that the coordinates of the obstacle determined in the horizontal plane always coincide with the location of the sensor at which the indicated above-threshold value has been measured. However, since the sensors therein are operated in a multiplex operation, the possibility cannot be excluded that only subsequently activated sensors may measure an even more relevant above-threshold value. Furthermore, at the moment of being identified as above-threshold, the surrounding sensors and their measurements are not taken to determine more accurate information about the range of the obstacle. This may be sufficient for the teaching disclosed therein, since the latter only relates to collision avoidance. However, if, as in the present case, the detection process should be monitored (i.e. intentional measurement and possible contact with the surroundings), more comprehensive information about the object is advantageous, since, for example, the detection direction does not need to coincide directly with the sensor axis, i.e. movements in other spatial directions and coordinates of the surroundings are generally also relevant.

[0016] In general, the solution improves the detection or early contact recognition in relation to the surroundings. In other words, a precise option is provided for identifying in time and with improved accuracy whether the measuring sensor is in the vicinity of the surroundings. Due to this improved accuracy, the option of relaxing the above-mentioned safety precautions at a structural level is also provided, in which case soft spring elements are intentionally provided or the measuring probe is intentionally mounted so that it is extremely stiff in order to increase the elasticity. In other words, this provides the option of designing the measuring system to be more rigid, since the expected impulse and / or compensating deflection movement of the measuring probe during workpiece detection is reduced.

[0017] In particular, a method for performing a probing process in (or using) a coordinate measuring machine is proposed, wherein the coordinate measuring machine comprises a measuring sensor for probing an object (measuring object) and a plurality of (preferably non-contact) distance sensors, in particular at least three distance sensors. The method comprises:

[0018] - moving a measuring sensor having a sensor longitudinal axis, and preferably a distance sensor together, in a working space of the coordinate measuring machine;

[0019] - using distance sensors to acquire distance measurements to the surroundings along respective sensor axes, wherein each sensor axis extends along (e.g. in a non-orthogonal manner, but also not necessarily parallel to) a sensor longitudinal axis;

[0020] - determining (or, in other words, calculating) surroundings coordinates (eg for at least one surroundings location) based on, or in other words, taking into account the distance measurements of all distance sensors.

[0021] Preferably, surroundings coordinates are determined based on the distance measurement values, which surroundings coordinates are associated with coordinate axes which extend at an angle to the sensor longitudinal axis and / or the sensor axis.

[0022] The extent of the sensor axis along the sensor longitudinal axis may be understood to mean that the arrangement of the sensor axis comprises a vector component not equal to zero, which extends parallel to the sensor longitudinal axis. However, there may also be a non-zero vector component extending orthogonally to the sensor longitudinal axis, such that the sensor axis extends obliquely or at an angle to the sensor longitudinal axis, but preferably not completely orthogonal thereto.

[0023] As mentioned above, the measurement sensor can operate optically or tactilely. However, without limiting its meaning, the following generally adopts a tactile measurement probe on a probe. To the extent that the argument of this article is based on the arrangement, axis or other spatial characteristics of the tactile measurement sensor, this may involve the corresponding arrangement, axis or spatial characteristics of the tactile measurement probe, but not necessarily also the arrangement, axis or spatial characteristics of the probe. In other words, the tactile measurement probe can define the spatial arrangement of the tactile measurement sensor considered in this article.

[0024] Typically, the measuring sensor can acquire coordinate values ​​of an object, for example in a specified instrument coordinate system. The measurement accuracy can be greater than the measurement accuracy of the distance sensor, for example at least 1.5 times higher. The measuring sensor can be based on a measurement principle that is different from the measurement principle of the distance sensor. In particular, the measuring sensor may not be an ultrasonic sensor or may not operate in a contactless manner. The longitudinal axis of the sensor may correspond to the optical axis of the optical sensor, for example along which electromagnetic radiation is radiated by the measuring sensor into the measurement scene. In the case of a tactile measurement probe, the longitudinal axis of the sensor may coincide with the axis of the stylus. In particular, the measuring probe may include an elongated axis, which correspondingly defines the longitudinal axis of the sensor or coincides with the longitudinal axis of the sensor.

[0025] The workspace can be a virtual space that includes all positions that the coordinate measuring machine can reach. As an alternative or in addition, this space can contain those possible object locations where the coordinate measuring machine can perform measurements. In principle, in a manner known per se, the coordinate measuring machine can acquire the spatial coordinates of the object to be measured, in particular its surface coordinates.

[0026] The distance sensor can preferably operate in a non-contact and / or non-tactile manner, i.e. without contact with the object in order to determine the measurement value. In particular, the distance sensor can be configured to radiate radiation (e.g. electromagnetic radiation or ultrasonic radiation) onto the object or generally into the surrounding environment along the sensor axis. The reflected radiation component can then be reflected back from the surrounding environment to the distance sensor again along the sensor axis. The distance sensor can generate a distance measurement value on this basis. Examples of suitable sensors include ultrasonic sensors or optical distance sensors, such as lidar sensors or triangulation sensors, which preferably all radiate laser radiation into the surrounding environment. Further alternatively, radar sensors can also be used. In particular, so-called ultra-short range radar systems (e.g., for distances exceeding 10 cm) can be used.

[0027] Preferably, the distance sensors are distributed around the measuring sensor or comprise a measuring sensor therebetween. As will be explained further below, the distance sensor may for example span a triangular, quadrilateral or generally polygonal shape. The measuring sensor may be arranged within this shape or within a footprint comprised therein, preferably centered. As an alternative or in addition thereto, the sensor longitudinal axis may intersect this shape or the footprint, preferably also centered. The distance sensor may be arranged in a plane extending at an angle to the sensor axis and / or the sensor longitudinal axis, in particular orthogonally to the sensor longitudinal axis.

[0028] The determined surroundings coordinates may define at least a two-dimensional coordinate vector, but preferably a spatial (i.e. 3-dimensional) coordinate vector, by which the relative position of the surroundings location is defined in a corresponding two-dimensional or three-dimensional coordinate system. For example, the relative position in the machine coordinate system may be defined in this way. The surroundings coordinates may each form a coordinate part or a coordinate component of this coordinate vector.

[0029] At least one surroundings location may be a virtual location or a physical location in the real surroundings. The first case relates to a situation where only coordinates of the real surroundings are approximated, i.e. coordinates of a location that is not directly measured by a distance sensor, for example, determined based on a distance value. In some cases, this location may not be a physical feature of the surroundings or may not correspond to the surroundings. Instead, it may be virtual, for example, located in an empty space above the surface of an actual object. However, for the purpose of detection advance recognition, it may contribute to a sufficiently accurate approximation of the real conditions in the surroundings.

[0030] A single surroundings coordinate may define a relative position in relation to one of the coordinate axes of the considered coordinate system. In contrast to the prior art, it may be provided that all (but at least two) surroundings coordinates (i.e., for example, the X, Y and Z coordinates in the corresponding X, Y, Z coordinate system) are determined taking into account the distance measurement values. In contrast, the possible coordinates of the distance sensor, i.e., for example, its position, may preferably be included at most partially in the determination of the surroundings coordinates. Preferably, the individual surroundings coordinates may be equated with the position of the distance sensor only if there are inadmissible deviations of the distance measurements from one another as discussed below. In general (i.e., there are no inadmissible deviations of the distance measurements from one another), the position of the distance sensor is preferably not determined at least independently and / or not without taking into account the distance measurement values. This differs from the solutions in the prior art, in which at least the individual coordinates (in particular in a plane orthogonal to the longitudinal axis of the sensor) are equated with the position of the distance sensor.

[0031] Thus, at least individual ones of the determined surroundings coordinates may lie in a horizontal spatial plane and / or in a plane extending at an angle to the sensor longitudinal axis and / or the sensor axis. Thus, the relative position or coordinates of the acquired surroundings at a lateral distance from the sensor axis and / or the sensor longitudinal axis and / or along a coordinate axis extending at an angle to the sensor axis and / or the sensor longitudinal axis may also be determined. Again, this is advantageously done based on actual distance measurements, which increases the accuracy associated with the overall equalization of the distance sensor position.

[0032] In particular, a preferred embodiment provides that at least one of the surroundings coordinates determined based on all distance measurements is located at a distance from the sensor axis and / or the sensor longitudinal axis, for example at a lateral distance therefrom and / or in a non-parallel plane relative thereto. In other words, surroundings coordinates may be determined based on the distance measurements, which are associated with a coordinate axis, which extends at an angle to the sensor longitudinal axis and / or the sensor axis. At least one of the surroundings coordinates determined based on the distance measurements may respectively preferably not be along one of the sensor axis and / or the sensor longitudinal axis.

[0033] This also represents a deviation from the prior art discussed at the outset, in which the determined surroundings coordinates are usually located directly on the sensor axis. The coordinates in a plane transverse to the sensor axis are fixedly defined by the position of the distance sensor and, in contrast to the preferred exemplary embodiment of the present disclosure, are not determined or calculated based on distance measurements. In particular, since a plurality of distance measurements of a plurality of distance sensors are taken into account, the present situation instead also facilitates the determination of surroundings coordinates of a location which is, so to speak, located between these sensors and / or between the locations of objects actually acquired by these sensors. Furthermore, all coordinates can preferably be determined, in particular calculated based on actually acquired measurements and are not assumed to be structurally fixed or equivalent to the position coordinates of the distance sensors. As a result, the actual conditions in the surroundings can be approximated more accurately.

[0034] It can generally be provided that the distance measurements for determining at least one surroundings coordinate are combined with one another by calculation or compared with one another and are therefore taken into account in determining the coordinate.

[0035] For example, the distance measurements of at least two distance sensors can be averaged. At positions between the distance sensors or between the positions of their sensor axes, the average value can be used to calculate the surrounding coordinates there (for example in the Z direction). Further, for example, for a first object recognition for orientation purposes, the minimum distance value from the distance values ​​determined by the distance sensors as a whole can be used. However, the variant described below is preferred; according to this, a system of linear equations is formed (or solved as a function of values / variables that have not yet been inserted) and the system of equations is solved taking into account the respectively determined distance measurements. Setting up such a system of equations can be equivalent to calculating a virtual intersection of three virtual planes, the surrounding coordinates defining the relative position of this intersection.

[0036] At least during normal operation without inadmissible deviations of the distance measurement values ​​as explained below, the surroundings coordinates can be determined including the distance measurement values ​​in preferably all considered spatial directions.

[0037] The distance measured values ​​that are taken into account for determining the coordinates can also be selected if the distance measured values ​​deviate from one another, in particular exceed a permissible deviation threshold or a permissible difference.

[0038] For example, if one of the distance measurement values ​​is significantly greater than the other distance measurement values ​​(e.g. in each case by more than a specified multiple, for example by at least 1.5 times), only one distance measurement value can be taken into account. This is preferably the smallest distance measurement value. The latter can be equal to a first surroundings coordinate (e.g. a vertical coordinate). The other surroundings coordinates, in particular in a direction orthogonal to the first surroundings coordinate (e.g. a horizontal coordinate), can be determined based on the position of the distance sensor that has provided this distance measurement value (in particular, can be equal to this position). However, since in this case all distance measurement values ​​are first considered and a selection is made therefrom in order to determine the surroundings coordinates, in this case the surroundings coordinates are also determined based on or in other words taking into account the distance measurement values ​​of all distance sensors.

[0039] In the case of the above-mentioned deviations of one distance measurement value from the other distance measurement values, the calculation described below can be performed instead, but the correspondingly deviated distance measurement values ​​are ignored. Instead of then determining the intersection point of the three planes, the intersection line of two planes is obtained. The surrounding coordinates of a predetermined point (or as a corresponding point) along this intersection line are then preferably determined. For this purpose, in particular the point closest to the measuring sensor, in particular the point located at the detection element of a possible measuring probe, can be considered. This is usually a point with a coordinate of 0 along two coordinate axes, in particular along the X-axis and the Y-axis of the preferred coordinate system described below, which can form the basis for the calculation of the surrounding coordinates.

[0040] The influence of one of the distance measurement values ​​being significantly smaller than the other two distance measurement values ​​may also be a deviation. For example, two distance measurement values ​​may be larger than the third distance measurement value by a predetermined factor, for example at least 1.5 times larger. In this case, the surrounding coordinates may also be determined again based on the smallest distance measurement value and the position of the distance sensor that has acquired this distance measurement value.

[0041] As a general aspect of the invention, at least some of the surrounding coordinates can be determined taking into account the coordinates of the distance sensor in addition (i.e. in addition to taking into account the distance measurement values). All coordinates mentioned herein can relate to a common coordinate system, in particular a machine coordinate system. In this respect, it is known that the measuring table surface forms a horizontal plane and a third axis extending orthogonally thereto can correspond to a vertical spatial axis along which gravity acts.

[0042] For example, from the perspective of the distance sensor, the surrounding environment coordinates can be coordinates that accurately represent the surrounding environment or approximate the surrounding environment. As described above, the surrounding environment coordinates may not necessarily be assigned to real or physical points of the surrounding environment. For example, the surrounding environment coordinates can be assigned to virtual points that approximate the real surrounding environment (see plane intersection below).

[0043] Typically, a minimum distance to be maintained can be specified; the measuring sensor should observe this relative to the surroundings. This can be a minimum distance that defines the maximum distance to which the measuring sensor can be displaced in a rapid movement. If the minimum distance is fallen below, a change to a reduced detection speed is possible. The surroundings can be maintained or further reduced depending on the determined distance values ​​and / or the specification of the surrounding coordinates until the desired working distance between the measuring sensor and the object exists. As will be explained further below, this may require determining whether the measuring sensor is actually moving to the object to be measured or is located in the vicinity of an (unknown) obstacle representing a risk of collision.

[0044] The surroundings coordinates can be used as a reference point for determining the current distance between the measuring sensor and the surroundings. In other words, the surroundings coordinates can be used as a reference point for the surroundings. The current coordinates of the measuring sensor can be derived in a manner known per se from the position of the axis of movement of the coordinate measuring machine and known dimensions of the measuring sensor (e.g. the shaft length in the case of a tactile measuring probe).

[0045] Embodiments of the solution proposed herein (i.e., of the method and arrangement and of the module) provide for determining, based on the surroundings coordinates, whether a predetermined minimum distance between the measuring sensor and the surroundings is below. As described above, for this purpose the current measuring sensor position (in particular its possible probe tip) can be compared with the surroundings coordinates, or the distance between the measuring sensor and these surroundings coordinates can be calculated.

[0046] If the minimum distance has been fallen below, the movement speed of the coordinate measuring machine can then be reduced, precisely, preferably, to a value above 0 mm / s. Therefore, there is no need for an immediate complete deceleration; instead, the detection procedure can only be started at the reduced speed. In particular, the reduction in speed can include at least 10% or at least 20% compared to the speed before falling below the minimum distance. The movement speed can then be further reduced based on the continuously determined distance to the surroundings, in particular based on the coordinates of the surroundings as a reference point, i.e. it can be continuously reduced based on the distance. When the object detection is determined, for example in a manner known per se by a measuring sensor probe that registers a corresponding deflection of a tactile measuring probe or by an optical sensor that registers the working distance it has reached, the movement speed can be reduced to 0 mm / s for the purpose of recording the measured values. Active braking is also possible.

[0047] Accordingly, one development provides that the measuring sensor is a tactile measuring sensor, the object to be detected is captured as the surroundings, and the reduced movement speed (or generally a movement speed above 0 mm / s) is maintained until contact between the measuring sensor (in particular its measuring probe) and the object is detected. The reduced movement speed can be a reduced movement speed that is set when the minimum distance is below; however, the reduced movement speed can also be a speed that is then still further changed, in particular further reduced based on the distance.

[0048] The above described variations facilitate activation of detection observations based on need, thus preventing speed reductions from being made too early or too late.

[0049] It can generally be provided that the distance sensors continuously capture the surroundings and / or continuously output distance measurement values ​​according to the output frequency of these sensors. Here, it can generally be provided that the distance sensors operate in parallel and measure in parallel. Depending on the sensor measurement principle used, this may require that the signals of the distance sensors radiated into the surroundings are different from each other (for example ultrasonic signals or waves with a sensor-specific frequency). However, the distance sensors can also work in series, wherein the series of measurements performed by the individual distance sensors can be carried out as quickly as possible next to each other in order to increase the significance of the determined coordinate values. Instead of measuring in series, this can also be referred to as sequential and / or successively activated measurements. Here, the corresponding series measurement cycle is preferably repeated continuously so that the surrounding coordinates can be determined continuously.

[0050] In general, the acquisition range of a distance sensor can be cylindrical and / or conical and extend along the respective sensor axis. In particular, the acquisition range can extend along the sensor axis and increase in cross-sectional size, wherein the increase can be at least temporarily achieved and can subsequently also be tapered again. In the case of ultrasonic sensors, the acquisition region can be a so-called sound lobe and can accordingly extend along the sensor axis, first in a widening manner and then again in a tapered manner.

[0051] As will be explained in more detail below, the acquisition regions can overlap one another. This can be achieved in such a way that the acquisition regions also overlap in the region of the measuring sensor, in particular in the region of a possible probe tip (e.g. a detection element such as a detection ball or a detection disk). Furthermore, the overlap can be achieved in such a way that the acquisition regions define at least in the region a spherical or at least hemispherical region around the corresponding tip or detection element, in which region a distance value determination can always be achieved with at least one or preferably at least two distance sensors. This contributes to the reliable acquisition of the surrounding contour in the immediate vicinity of the measuring sensor, which facilitates the needs-based control of the detection process.

[0052] In contrast to the prior art discussed at the outset, in which the acquisition areas do not overlap, in particular not in the vicinity of the measuring sensor, let alone including the measuring sensor itself, it is actually possible to reduce the movement speed as soon as the contour of the object is determined in the immediate vicinity of the measuring sensor, or to monitor the distance to the surroundings even in the immediate vicinity of the measuring sensor (e.g. with regard to maintaining the above-mentioned minimum distance). This is deliberately not provided for in the prior art discussed at the outset, since said prior art is primarily concerned with braking the machine movement in rapid motion in order to avoid collisions, and not with detection processes.

[0053] In one development, it is provided to determine whether the distance sensor is capturing a known object (in particular an object to be measured) or an unknown object. Depending on the result of the determination, the movement of the measuring sensor and the distance sensor in the workspace can then be appropriately adjusted. In general, the capture of an unknown object can indicate the presence of a risk of collision, and in that case an emergency stop can be activated or an evasive movement can be performed. In contrast, if a known (or in other words expected) object is captured, in particular an object to be measured, the detection program can be activated or the operation can be continued as originally envisaged, taking into account the apparent absence of anomalies in the workspace. For example, the stroke of the coordinate measuring machine can also be programmed to bypass defined obstacles. Thus, if it is identified that the distance sensor is currently capturing an expected obstacle, the operation of the coordinate measuring machine can continue unaffected on the basis of the initially specified stroke. However, as already mentioned, in principle a distance-related speed reduction can also be provided, the extent of which can however vary depending on the type or notoriety of the object captured by the sensor.

[0054] For example, in this case it can be provided that a higher reduced movement speed is permitted in the case of known detected objects than in the case of unknown detected surroundings. This is based on the idea that the specified travel, in particular the programmed detection process, is in principle suitable for known or expected objects with a certain probability, so that no separate safety measures need to be taken. In contrast, if the movement is intended to approach unknown surroundings, it cannot be excluded that other collision-related interference contours that are not detected by the distance sensor are also present there. In this respect, in this case, the movement speed can be reduced again in addition in order to be able to stop as suddenly as possible when in doubt and / or in order to reduce the magnitude of possible contact forces.

[0055] As an alternative or in addition thereto, it can be provided that the minimum distance to be observed is selected to be smaller in the case of known or expected objects than in the case of unknown surroundings. In other words, a higher speed and a greater degree of approach (i.e. to a smaller distance) can be permitted in the case of known objects than in the case of unknown surroundings. This is based on the same motivation as explained above in connection with the movement speed.

[0056] Further additionally or alternatively, it can be provided that the distance-dependent reduction in movement speed is less noticeable in the case of known objects than in the case of unknown surroundings, in particular once a minimum distance has been fallen below. In other words, the distance-dependent speed reduction can be more noticeable (e.g., the increase is more noticeable) in the case of unknown surroundings than in the case of known objects.

[0057] In order to determine whether the object captured by the sensor system is a known feature or an unknown feature, for example a (virtual) workspace model or generally stored information about the operating situation, the measuring task, the object and / or the design of the coordinate measuring machine can be used. For example, the positions of existing or expected obstacles and the positions of the objects to be measured can be defined within the scope of such information stored in advance (in particular using a workspace model).

[0058] It is known that such information can be specified, at least approximately, by means of CAD models of the relevant objects and units. The setting of safety limits around the corresponding object models is also known, the representation of which can likewise be described by means of coordinate values ​​in the workspace. Thus, based on the always known measuring sensor position, it is possible to check whether the measuring sensor position is currently located in the vicinity of a known or expected object in the workspace (in particular in the workspace model), and on this basis the above-mentioned measures can be taken individually or in any combination.

[0059] According to a further variant, at least three distance sensors are provided. The (preferably spatial) coordinates of these distance sensors can be assumed to be known or can be determined based on the axis positions of the coordinate measuring machine. Depending on these coordinates and / or the correspondingly determined distance measurement values, a system of linear equations can be set and / or solved. This can be done under the assumption that the distance sensors capture the same point-like locations in the surroundings or determine distance values ​​associated therewith. This may be sufficiently accurate for the present purpose of switching to the detection mode. The coordinates of this location (preferably the complete spatial coordinates) can be determined as the surrounding coordinates by solving a system of linear equations.

[0060] This may be equivalent to determining the intersection of three (virtual) planes, whose positions are defined based on the determined distance values. More precisely, these planes may each have one of the sensor axes as normal vector and be spaced apart from the distance sensor along the sensor axis by the corresponding measured distance value. In this case, the normal vectors are not parallel to each other. Such a plane may be defined for each distance sensor (virtually), and the intersection of the planes may represent a point or location, the acquisition of which by all distance sensors is assumed as a hypothesis.

[0061] Determining the surroundings coordinates as the corresponding intersection points can include setting up and solving appropriate equation systems in advance and, for example, usually depends on the positioning and / or arrangement of the distance sensors and their sensor axes. In particular, the coordinates of the intersection points that have not yet been quantified can be determined depending on distance measurement values ​​that have not yet been acquired by the sensor system, i.e. these coordinates can be determined and / or defined based on the distance values. By using the distance measurement values ​​that are available or acquired during actual operation, the surroundings coordinates currently sought in each case can then be determined based on them. In other words, generally defined relations or generally defined functions can be solved, in which the surroundings coordinates are only quantified, for example by dummy variables or variables.

[0062] The above-described setup and / or solution of the system of equations and / or determination of the general equations or calculation methods of the sought coordinates based on subsequently inserted distance measurements may form separate measures of the method disclosed herein and may be claimed accordingly.

[0063] The invention also relates to an arrangement having:

[0064] a coordinate measuring machine, which comprises, for example, a mobile kinematic system, which preferably has at least one linear axis, further preferably has a plurality of mobile axes extending orthogonally to one another, preferably in pairs;

[0065] a measuring sensor for (tactile or optical) detection of an object, the measuring sensor having a sensor longitudinal axis;

[0066] a plurality of, in particular at least three, distance sensors, each of which is arranged to acquire distance measurements to the surroundings along a respective sensor axis, each sensor axis extending along (but preferably at an angle to) the sensor longitudinal axis; and

[0067] - a determination device, which is arranged to determine the coordinates of the surroundings based on the distance measurements of all distance sensors,

[0068] Preferably, surroundings coordinates are determined based on the distance measurement values, which surroundings coordinates are related to coordinate axes which extend at an angle to the sensor longitudinal axis and / or the sensor axis.

[0069] The determining device may be digitally and / or electrically operable. This may be a computer device. The computer device may include at least one processor and / or a storage device. Program instructions may be stored in the storage device and, when executed by the processor device, contribute to or perform the functions of the determining device described herein. The determining device may be included in a coordinate measuring machine or integrated in the coordinate measuring machine. For example, this determining device may be a control device of the coordinate measuring machine. The distance sensors may accordingly transmit their distance measurement values ​​to the determining device via a communication link (in particular a data line), which then performs the desired evaluation of the distance measurement values ​​and more accurately performs the desired coordinate determination. The determining device (or generally, in particular, the control device of the coordinate measuring machine) may further be arranged to perform the operation of the coordinate measuring machine, in particular its movement control, and further in particular to perform a movement speed adjustment according to any of the variants described herein.

[0070] As described, the (three-dimensional and / or spatial) acquisition area of ​​a distance sensor can overlap in each case with the acquisition areas of other distance sensors. According to one variant, it is provided that the corresponding acquisition areas overlap in at least one spatial area. This can be a spatial area that includes the measuring sensor, in particular its possible detection element (e.g. probe tip).

[0071] Preferably, the acquisition region of each distance sensor overlaps at least a portion of the acquisition region of at least one other distance sensor, preferably at least two other distance sensors. The corresponding overlapping region can be arranged in the vicinity of the measuring sensor. In particular, the acquisition regions and / or their overlap can be selected in such a way that the measuring sensor and at least its detection element are surrounded on all sides by the corresponding acquisition region, i.e. are not obscured by the measuring sensor when viewed from the distance sensor (i.e. there are no spatial regions in the vicinity of the measuring sensor, in particular in the vicinity of its possible detection elements, where acquisition is not possible). This is advantageous for controlling the detection process, since the region in the vicinity of the measuring sensor can then be monitored particularly reliably.

[0072] As a further general aspect of the method and arrangement and also of the modules described below, it can be provided that the sensor axis extends at an angle to the sensor longitudinal axis. For example, the sensor axis can intersect the sensor longitudinal axis at an angle greater than 0° up to 70°, for example at an angle between 20° and 40°. The intersection angle can be the smallest possible angle that can be inscribed between the specified axes. This allows acquisition areas to overlap each other as described and / or to include measuring sensors and / or detection elements. Since the (vector) direction component parallel to the sensor longitudinal axis is still retained, the sensor axis still extends (at least partially) along the sensor longitudinal axis.

[0073] As a further general aspect of the solution proposed herein, at least three distance sensors can be provided that span a (virtual) triangle, in particular an isosceles triangle. The measuring sensor can be positioned within this triangle, or the sensor longitudinal axis can intersect a triangular plane within the triangular outline. In other words, when the position of the measuring sensor, in particular the position of its detection element, is projected into the plane of the triangle, the position can be located within the triangle.

[0074] This facilitates reliable determination of desired surrounding coordinates using a small number of distance sensors. In particular, this allows the above-mentioned plane intersection points to be determined reliably and with little effort.

[0075] The invention also relates to a module, wherein the module comprises a distance sensor and at least a part or in other words a component of a measuring sensor according to any of the above-mentioned variants (in particular a tactile measuring probe), and further comprises an interface via which the module can be connected to a coordinate measuring machine. In particular, the module can therefore be provided and / or arranged to form an arrangement according to any of the above-mentioned aspects. As is also known from replaceable measuring sensors, in particular measuring probes, the interface can be a mechanical interface for introduction into an interface of a coordinate measuring machine designed in a complementary manner (for example at its quill or at the probe / sensor head). In the present case, preferably a data link is also established in the process (i.e. a communication interface is preferably also provided and / or integrated in the above-mentioned interface) in order to transmit the distance measurement value to the control device, in particular the above-mentioned determination device.

[0076] As components, the tactile measurement sensor may include at least a measuring probe and a probe. For example, the module may include the measuring probe. However, the module preferably does not include the probe. Instead, the module may be coupled to a probe that is arranged on the coordinate measuring machine or included by the coordinate measuring machine via an interface. If the measurement sensor is an optical measurement sensor, the module preferably includes the measurement sensor as a whole but at least its measurement value recording optical components.

[0077] In other words, the module can thus be a structurally integral, individually manageable and / or generally entirely replaceable component or assembly. Its dimensions can be significantly smaller than those of the coordinate measuring machine. The module can be integrally connected to the coordinate measuring machine, or in other words, can be replaced. In a manner similar to known probe interchange processes, this can be achieved automatically, i.e. without requiring manual intervention to couple the aforementioned interfaces to one another.

[0078] Providing such a module offers the advantage that the distance sensor can be appropriately selected, positioned and / or arranged for a given measuring sensor. In particular, this relates to the extent of its acquisition area, a possible overlap and / or coverage of the acquisition areas, or in other words, the envelope of the measuring sensor, in particular the envelope of its detection elements. This is because, depending on the extent of, for example, a tactile measuring probe, it may be necessary to appropriately arrange the distance sensor, in particular its sensor axis, for the purpose of establishing the above-mentioned overlap and / or envelope. Integration into a common module thus ensures that the distance sensor is appropriately arranged relative to the measuring sensor and that the measuring operation can be started immediately after coupling to the coordinate measuring machine, thus saving time and effort.

[0079] As a general aspect, it can be provided that the distance value of the distance sensor is in any case transmitted to the determination device via a communication link provided in the coordinate measuring machine, for example via a communication bus. This ensures that the module or generally the distance sensor can be used or retrofitted in the case of existing coordinate measuring machines without requiring a comprehensive hardware adaptation.

[0080] In particular, the distance measurements can be used as position measurements for controlling the coordinate measuring machine, as long as a minimum distance has not yet been determined to be undershot. Typically, these position measurements are related to a reference point of a coupled measuring sensor, the spatial relative position of which is calculated, for example, based on the current axis positions of the mobile motion system and / or the known dimensions of these axes and the known dimensions of the measuring sensor. In contrast, according to one embodiment, it can be provided that such position information is determined based on distance measurements, i.e., for example, based on the dimensions and axis values ​​of the individual moving axes and the distance measurements, until a minimum distance has been undershot.

[0081] For example, in the case of positioning with high requirements in terms of accuracy, such as when inserting into a borehole or navigating in a borehole, the distance value of the distance sensor can be used as a directly controlled variable. The position can be controlled in such a way that the distance signals have equal magnitude or become equal.

[0082] When inserted into the drill hole, the lateral position (laterally relative to the drill hole axis) at which the sum of the distance signals reaches a local maximum can be selected. For this purpose, a lateral search movement or a sideways search movement can be implemented.

[0083] As an alternative or in addition thereto, the identification of a step or kink in at least one distance signal (or in the continuously output distance values ​​and / or in the time curve of the distance values) can localize the edge of the borehole when inserted into the borehole. In particular, a step can occur in the time curve of the distance signal. If the steps of the distance signals of different sensors deviate from each other (in particular the time of the distance signal and / or its distance value when the step occurs), this indicates a non-concentric arrangement with respect to the borehole and can indicate a lateral compensating movement.

[0084] It should be understood that the arrangement and module may include any further features to provide all functions, operating states and interactions described herein. In particular, the method according to any aspect of the present invention may be implemented by the arrangement and module, and the arrangement and module may have correspondingly required features and developments. All descriptions and developments related to method features may also be applicable to the same features of the arrangement and module, or may be arranged therein. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Exemplary embodiments of the present invention will be described below based on the attached schematic drawings. In this case, features that are identical or act in the same way may be provided with the same reference numerals throughout the drawings.

[0086] Figure 1 A schematic diagram of an arrangement according to an exemplary embodiment of the invention is shown, the arrangement comprising a coordinate measuring machine and a module according to the invention.

[0087] Figure 2 Shows Figure 1 Individual stereograms of the modules.

[0088] Figure 3 A side view of the module during operation is shown.

[0089] Figure 4 A schematic diagram of the module during operation is shown.

[0090] Figure 5 An illustrative sketch is shown to highlight the calculation of movement coordinates based on the obtained distance measurements.

[0091] Figure 6 A flow chart of a method according to the invention is shown.

[0092] 7A to 7C shows the use of Figures 1 to 4 The module measures the drilled holes. DETAILED DESCRIPTION

[0093] Figure 1 The arrangement 200 shown comprises a gantry coordinate measuring machine (CMM) 211. The gantry coordinate measuring machine comprises a measuring table 201 on which columns 202, 203 are arranged movable in the Y direction of a Cartesian coordinate system. The coordinate system is drawn separately and can be a machine coordinate system, the origin of which is located, for example, on the measuring table surface.

[0094] The object 100 to be measured is located on a measuring table 201. Further, indicated by a dotted line is the outline of a virtual workspace 102, in which coordinate measurements can be performed.

[0095] Columns 202, 203 together with beam 204 form the gantry of CMM 211. Beam 204 is connected to columns 202 and 203 at their opposite ends respectively. Electric motors, not depicted in more detail, move columns 202, 203 linearly in the Y direction along the Y movement axis. Here, for example, each of the two columns 202, 203 is assigned an electric motor. Beam 204 is combined with a transverse slide 207, which is movable in the X direction of a Cartesian coordinate system along the beam 204, for example, by air bearings. The current position of transverse slide 207 relative to beam 204 can be determined based on sub-scale 206. The movement of beam 204 in the X direction (i.e. along the X movement axis) is driven by a further electric motor.

[0096] A quill 208 movable in the vertical direction is mounted on the transverse slide 207 and is connected at the lower end to a probe 209 via an optional mounting device 210. The quill 208 can be moved by a further electric motor, preferably along a Z movement axis in the Z direction of a Cartesian coordinate system relative to the transverse slide 207. The probe 209 can be brought into almost any position in the area below the crossbeam 204 by the electric motor of the CMM. In a known manner, the probe (or sensor head) 209 contains measuring components or signal generating components in order to capture the deflections of the measuring probe 11.

[0097] The module 10 according to an exemplary embodiment of the present invention is attached to the probe 209 via the sensor interface of the coordinate measuring machine 211. Figure 2 For example, the probe comprises a tactile measurement probe 11, which together with the probe 209 is a component of a measurement sensor 12 of a coordinate measuring machine 211. In order to increase the mobility of the measurement probe 11 relative to the object 100, at least one rotary joint can optionally be additionally provided between the probe 209 and the module 10. Preferably, the module 10 comprises neither the probe 209 nor the optional rotary joint, but rather the measurement probe 11 as a part (or in other words a component) of the measurement sensor 12.

[0098] A control device 300 is further shown, which controls the movement of the movable part of the CMM 211 along the movement axis. The control device 300 is also arranged to perform one or more of the steps explained in the general part of the description. Further, the control device comprises (or forms) a determination device 302 and is connected to all measuring units (in particular of the module 10) via a communication link 304 in order to receive and evaluate measurement values ​​therefrom. More precisely, the control device is preferably connected in each case to at least one incremental measurement of each of the movement axes X, Y, Z and receives coordinate values ​​about the corresponding axis therefrom.

[0099] Figure 2 Shows Figure 1 1 is a separate stereoscopic illustration of a module 10 of FIG. Once again, the measuring probe 11 can be identified. The measuring probe is a stylus known per se, which comprises an elongated shaft 14 and a detection element 16. For example, the detection element is embodied as a detection ball. The measuring probe 11 also has a sensor longitudinal axis L, along which the shaft 14 extends. In other words, the relative position of the sensor longitudinal axis L is determined by the shaft 14, since the sensor longitudinal axis L extends centrally through the shaft and along the shaft.

[0100] As will be explained below, the measuring probe 11 is centrally positioned relative to the carrier 17. The carrier 17 is a plate-shaped component. At the back 18 facing away from the measuring probe 11, the carrier has an interface 20, which is not shown separately, and which is preferably both a mechanical interface and a data transmission interface (i.e., it facilitates both the mechanical connection and the data transmission link). Through this interface 20, the module 10 can be connected to the sensor head 209 in a mechanical and data transmission manner. As an alternative to setting a physical data link or a data link interface, a wireless data link can also be established, for example using Bluetooth. The distance measurement value from the module 10 can be transmitted to the determination device 302 via any of the described data links.

[0101] The module 10 further has a sensor arrangement comprising three distance sensors S1, S2, S3. In this case, the sensor S2 faces away from the Figure 2 The distance sensor (hereinafter also referred to as sensor only) S1-S3 has a signal source 20 and a signal receiver 22 in a purely exemplary manner, which are formed separately from each other or arranged spaced apart from each other. The signal source 20 can radiate the measurement signal (or sensor signal) into the surrounding environment and the signal receiver 22 can receive the signal component reflected by the surrounding environment. Then, a distance measurement value can be generated based on this received component. The sensors S1-S3 are implemented as ultrasonic sensors or sound transducers only by way of example. The signal source 20 radiates sound waves into the surrounding environment accordingly, which can be measured by the signal receiver 22 after reflection in the surrounding environment. The distance value can be generated in a manner known per se based on a determined flight time difference between the radiated signal and the received signal. Alternative measurement principles or sensor designs are specified in the general part of the description.

[0102] Further, a sensor axis A1-A3 of each of the sensors S1-S3 is shown. The sensors S1-S3 all emit signals (in the case shown, sound waves, but alternatively also electromagnetic radiation, in particular laser radiation) into the surroundings along these axes A1-A3. It can be seen that the sensor axes A1-A3 all intersect the longitudinal axis L, but at a small distance from the detection element 16 (for example, seen from the perspective of the carrier 17, in particular below this detection element 16).

[0103] As will be explained below, the acquisition areas of the sensors S1-S3 therefore extend along the sensor axes A1-A3 and at an angle to the longitudinal axis L (but along this longitudinal axis) and overlap one another. In particular, this is achieved in such a way that these overlap in the vicinity of the detection element 16 and all acquisition areas are preferably identical there. In this way, the measuring probe 11, in particular the detection element 16, can be surrounded by the acquisition areas in such a way, or in other words, enveloped by the acquisition areas, that a virtual spherical or hemispherical space can be defined, in particular around the detection element 16, within which a distance measurement can be performed at each position. This can be achieved by an arrangement and arrangement of the distance sensors A1-A3 relative to the measuring probe 11, which will be explained in more detail below, in which case the measuring probe 11, when viewed from the sensors S1-S3, does not cover or shield any spatial area in such a way that the sensors S1-S3 can perform distance measurements there.

[0104] Figure 3 Shows Figure 2 A schematic, greatly simplified side view of a module 10 (eg corresponding to Figure 1 ). Once again, the carrier 17 with the rear interface 20 and the measuring probe 11 on which the detection element 16 is arranged can be identified. Further, two of the distance sensors S1, S3 are shown, the second distance sensor S2 not being shown separately because it is covered by the measuring probe 11. The inclined arrangement of the sensors S1-S3 (which, however, also applies correspondingly to the invisible sensor S2) relative to the sensor longitudinal axis L can be identified. More precisely, the respective sensor axes A1, A3 intersect the sensor longitudinal axis L at an angle W of, for example, 30°. Also shown are the ranges indicated by the wavefronts of the acquisition areas E1, E3 of the sensors S1, S3, wherein the invisible sensor S2 has a similar acquisition area E2. The acquisition areas E1-E3 are three-dimensional and expand in a conical manner starting from the sensors S1-S3. In a manner known per se, these acquisition areas can also be tapered again at a certain distance from the sensors S1-S3, resulting in a lobed form, but this is not shown separately in the present case.

[0105] Due to the oblique positioning or inclination of the sensor axes A1 - A3 relative to the longitudinal axis L, it can be recognized that the detection areas E1 - E3 overlap one another in the area of ​​the detection element 16 . The advantages achievable thereby are specified above.

[0106] Attention should be paid to the fact that the acquisition regions E1-E3 are only schematically shown for illustration purposes. Preferably, these acquisition regions have smaller transverse dimensions, for example smaller cross-sectional dimensions, in particular diameters, relative to the respective sensor axes A1-A3. This takes into account the fact that the distance values ​​determined in the illustrated case are defined only with respect to the distance along the sensor axis A1-A3 and not with respect to the distance transverse thereto. In other words, in the illustrated example, the exact position of the location at which the ultrasound radiation is reflected within the cross-sectional plane of the acquisition regions E1-E3 is not determined spatially resolved. However, such sensor-related unsharpness in the determination of the surroundings coordinates can be at least partially compensated by the present consideration of distance measurements from a plurality of sensors S1-S3 (in particular within the scope of the calculation method described below).

[0107] In general, it should be mentioned that the acquisition areas E1-E3 of the sensors can be defined in a manner known per se, by virtue of the distance measurements being able to be acquired within these virtual spatial areas or volumes and with sufficient quality. Sufficient criteria for defining acquisition areas are known, in particular in the context of ultrasonic sensors. In other words, audio signals or sound waves also exist outside the acquisition areas shown here, which have been emitted by the sensors S1-S3 but cannot be acquired again with sufficient quality after reflection. These are therefore not assigned to the acquisition areas E1-E3.

[0108] Figure 4 A plan view of the carrier 17 is shown, more precisely, Figure 2 1-8. However, for illustrative purposes the carrier 17 is shown in a transparent manner and, in addition, other components that would cover the line of sight of the detection element 16 are omitted. As the remaining components of the module 10, apart from the outer shape of the carrier 17, the distance sensors S1-S3 can still be identified by their respective acquisition areas E1-E3. The illustration of the acquisition areas E1-E3 has been chosen to be very schematic and exaggerated. The respective rings represent dimensions, in particular sections of the acquisition areas E1-E3 along the respective sensor axes A1-A3, wherein, as a simplification, the inclination of these axes A1-A3 has not been taken into account separately when showing the cross-sectional outer shape. As with regard to Figure 3 As stated, there are no preferred dimensions for the cross-sections. Figure 3 , it is obvious that there is a cross-sectional dimension (ie, a corresponding small circle) starting from sensors S1 - S3 along the corresponding sensor axis A1 - A3, and then the circular dimension successively widens along the sensor axis A1 - A3.

[0109] Further, Figure 4 The sensors S1-S3 are shown to span a virtual isosceles triangle 30. The angular distance ZA between the sensors S1-S3 is accordingly 120° in each case. In this case, the (virtual) plane containing the spanning triangle 30 extends in an exemplary manner parallel to the interface 20 and / or orthogonal to the sensor longitudinal axis L. Accordingly, the sensor axes A1-A3 are also inclined relative to this plane.

[0110] Due to this arrangement of the sensors S1-S3, it can be recognized that their acquisition areas E1-E3 respectively overlap one another in the vicinity of the detection element 16 and, more precisely, all acquisition areas E1-E3 overlap one another there. Starting from the detection element 16, this is followed by a large area (when considered in the sheet plane or in the radial direction) in which at least two acquisition areas E1-E3 overlap and only then adjoins an area which is covered or enveloped by only one acquisition area E1-E3. Overall, however, it is once again clear that the arrangement of the acquisition areas E1-E3 is selected in such a way that at least one of the sensors S1-S3 can acquire distance measurement values ​​in a large spatial volume around the detection element 16 in order to be able to precisely control the detection process.

[0111] Figure 5 Shown based on Figure 4 A schematic diagram of the diagram of Figure 1 ; however, due to the observed orientation of the module 10, its axes are aligned with Figure 1 The module 10 is not shown in detail. However, the positions of the sensors S1, S3 and S2 are marked. These sensors can be arranged in such a way that the sensor S1 is located on the Y axis and the spanning triangle 30 is located in the XY plane. It should be understood that the choice of coordinate system is purely exemplary and it can also be provided that the coordinate system selected for the module 10 (which is the basis for the coordinate determination described below) is transformed into Figure 1 The parent machine coordinate system.

[0112] The sensors S1, S3, S2 are evenly distributed along the circumference of the schematically drawn circle K (see also Figure 4 The sensors are all at the same distance from the origin of the coordinate system. Once again, the inclination angle W of the sensor axes A1, A2, A3 relative to the sensor longitudinal axis L is plotted for illustration purposes. Figure 5 Only the sensor axis A3 is drawn in .

[0113] As a preferred assumption, it is considered that the three sensors S1, S3, S2 capture the same location in the surroundings. Further, taking into account the size of the limited capture area E1-E3 and the distances considered, it is preferably assumed that the locations at the same distance from the respective sensors S1, S2, S3 are located in a common plane (and not, for example, in a hollow spherical half shell around the respective sensor axis A1, A2, A3). This improves accuracy in view of setting the following plane equation.

[0114] The range of the sensor axis A3 of the sensor S3 is indicated in an exemplary manner. The explanations given below regarding the sensor S3 apply analogously to the sensors S1, S2. In the operating state shown, the module 10 has approached the surroundings and, for example, an object 100, whose surface segments are roughly marked. Due to the two-dimensional range of the acquisition area E3 perpendicular to the sensor axis A3, i.e. in the plane EA (distance plane) extending perpendicularly to this axis A3, the distance values ​​measured along the sensor measurement axis S3 can only be limited and of acceptable accuracy. In order to improve the acquisition accuracy of the surroundings, the present exemplary embodiment proposes to take into account the corresponding planes EA or distance planes of all sensors S1-S3, which extend perpendicularly to the corresponding sensor axes A1-A3 at the respectively measured distances (only for Figure 5 The corresponding normal vectors of these planes EA extend parallel to or coincide with the corresponding sensor axes A1-A3. The sensor axes A1-A3 can also be referred to as the lines of the viewing direction of the corresponding sensors S1-S3 into the surroundings.

[0115] It is proposed to determine the intersection points of the distance planes EA of the sensors S1-S3 and, more precisely, preferably their complete spatial coordinates as surroundings coordinates. In particular, this also concerns coordinates in the XY plane, i.e. in a plane perpendicular to the sensor longitudinal axis L or, in general, parallel neither to the sensor axes A1-A3 nor to the sensor longitudinal axis L. This also allows the position of the acquired measuring points to be more closely defined within this plane than if the distance values ​​were purely considered.

[0116] Due to the inclined arrangement of the sensor axes A1 - A3 , it is advantageously provided that the position is also calculated along the vertically presented Z-axis; ie the latter is not simply equivalent to a measured distance value as is sometimes achieved in the prior art when using a single sensor.

[0117] As mentioned above, it is assumed that the detected object location closest to the detector element 16 is located at the intersection of the three distance planes EA. This has the position vector are the position vectors of the three position points at distances from the plane EA, for which the following apply:

[0118] (I)

[0119] Find the plane equation of the distance plane EA in normal form:

[0120] (II)

[0121] Where e=1...3 is the number of the distance sensors S1-S3; is the viewing direction or sensor axis A1-A3 of the distance sensor S1-S3; d is the distance measurement of the distance sensor S1-S3; and is the normal vector of the distance plane EA in the direction of this distance sensor S1-S3.

[0122] therefore, Corresponds to the position vector of a point on the line from the coordinate origin to the viewing direction or sensor axis A1 - A3 of the distance sensor S1 - S3 , which point is at a distance d from the distance sensor S1 - S3 .

[0123] Inserting (I) into (II) yields the following result:

[0124] (III)

[0125] The following applies to the viewing directions of the distance sensors S1 - S3 or to the lines of the sensor axes A1 - A3 , where as the location of the distance sensors S1-S3 and λ as Distance parameters along the line:

[0126] (IV)

[0127] The corresponding normal vectors (i.e. the directions of the sensor axes S1-S3) can be calculated in the considered coordinate system according to Figure 5 The position determination of the distance sensors S1-S3 described, wherein the value of 30° can be traced back to these exemplary positions. The product of the two angle functions can be traced back to the fact that the normal vector, in particular the projection onto the XY plane, forms the basis for determining in particular its X and Y components:

[0128] (V)

[0129]

[0130] (VI)

[0131]

[0132] (VII)

[0133]

[0134] The following applies to the three distance sensor viewing directions or lines of sensor axes S1 - S3 :

[0135] (VIII)

[0136] (IX)

[0137] (X)

[0138] If (VIII), (IX), (X) are inserted into (III) and if the expression is simplified in each case, the following system of equations (XI), (XII), (XIII) is obtained, where the last row (XI), (XII), (XIII) respectively forms the most simplified expression:

[0139] (XI)

[0140] (XII)

[0141] (XIII)

[0142] This system of equations contains the intersection coordinates v x 、v y 、v z As the only unknown variable, the system of equations can be solved for v x 、v y 、v z and stored in advance (e.g. at the manufacturer or before the current measurement operation). By inserting the current distance measurement values ​​d1-d3, we can then obtain v x 、v y 、v z The value of is used as the surrounding environment coordinates to be sought.

[0143] It should be noted that the positions of the distance sensors S1-S3 are included in the above equations (XI-XIII) at least indirectly (see the angle function associated with 30°). x 、v y 、v z And thus also the coordinates of the surroundings are not determined solely on the basis of these positions, since the distance measurements d1 - d3 are always also included. Overall, the coordinates are thus determined on the basis of the distance measurements d1 - d3 of the different sensors S1 - S3 .

[0144] In the example shown, the calculations described above are performed by a determination device 302 which continuously receives the distance values ​​d1-d3. Subsequently, the distance between the measuring probe 11, in particular the detection element 16, and the calculated (virtual) plane intersection is preferably determined. In particular, the distance vector is preferably formed such that the direction in which the corresponding measured object 100 or, in general, the surrounding coordinates are positioned relative to the module 10 can also be determined.

[0145] Based on the absolute value of this distance vector, the determination device 302 can then check whether a minimum distance between the measuring probe 11, in particular the detection element 16, and the surroundings is currently observed. In addition thereto or as an alternative thereto, it can be checked whether the measuring probe 11 is currently moving towards the corresponding intersection point in view of the current movement direction of the module 10. If the minimum distance is below and optionally there is a corresponding movement in the aforementioned direction, the movement of the measuring probe 11 can be adjusted according to any of the variants described in the general part of the description. In particular, the movement speed can be reduced.

[0146] As further described in the general part of the specification, it can also be checked in the process whether the distance sensors S1-S3 have captured a known object or an unknown object (or an unknown surrounding environment). In the case of an unknown surrounding environment, a greater speed reduction can generally be introduced at an earlier time or a smaller distance. For example, in the case of an unknown surrounding environment, the moving speed can be reduced by 50% at a distance of 100mm, while in the case of a known object, this can only be achieved at a distance of 10mm. In addition to it or as an alternative, in the case of an unknown object, the speed can be reduced to 20% at a distance of 10mm and / or to 10% at a distance of 5mm. Once a distance of 1mm is reached, an emergency stop can be introduced and a collision warning can be optionally output. In contrast, in the case of a known object, a reduction in the moving speed to 50% can only be achieved at a distance of 10mm, a reduction to 10% can be achieved at a distance of 5mm, and a reduction to 5% can be achieved at a distance of 1mm. Then, it is also possible to switch to a detection mode (for example, by walking through a so-called detection search path using a measuring probe 11).

[0147] at last, Figure 6A flow chart of a method according to the invention is shown, which has been described above by way of overview. In step S1, a determination device 302 receives distance measurements from all distance sensors S1-S3. In step S2, the complete spatial coordinates of the reference point and, in the example shown, the complete spatial coordinates of the virtual intersection of three virtual planes are calculated as surrounding coordinates based on these distance measurements. In step S3, a distance vector between the detection element 16 and this intersection is determined. In step S4, the absolute value of this vector is determined as a distance value, and the distance value is compared with a minimum distance. If the distance value drops below the minimum distance, the movement speed is reduced in step S5. Subsequently, the distance can be continuously updated as described and the movement speed can be further reduced successively or incrementally as the distance decreases until contact between the measuring probe 11 and the object 100 has been determined. The option of additionally determining and taking into account the direction, for example in the context of step S3, is mentioned above.

[0148] Fig. 7A The measurement of a borehole 400 using a module 10 similar to the previous figures is shown. A side view of the module 10 is shown, so not all sensors S1-S3 are identifiable. For example, only two imaged sensors S1-S2 are mentioned below.

[0149] The borehole 400 extends along a borehole axis BA. The measuring sensor 12 should be aligned as precisely as possible along this borehole axis BA, i.e. placed centrally in the borehole 400. For this purpose, the distance values ​​of the sensors S1-S2 are used in the present case, which form the basis for an open-loop position control or preferably a closed-loop position control of the measuring sensor 12.

[0150] exist Fig. 7A In this case, the module 10 is still arranged at a relatively large distance Z1 from the borehole 400 . The sensors S1 - S2 provide the same distance measurement values. The sensor axes A1 , A2 intersect the surface 402 of an object in the surroundings of the borehole 400 .

[0151] exist Figure 7B In the case of the sensor axis A1, A2, the distance Z2 from the borehole 400 is reduced. It can be recognized that the sensor axes A1, A2 have extended into the borehole 400. When the sensor axes A1, A2 change from measuring the surface 402 of the object near the borehole 400 to measuring inside the borehole 400, the time measurement value curve of each sensor S1-S2 has a step. This is for Figure 7C One of the sensors S1 , S2 is shown by way of example and is denoted by SK.

[0152] In the case of a consistent arrangement of the measuring sensor 12 and the drilling axis BA, the sensors S1-S2 provide the same distance values. Figure 7CThe steps SK in occur at the same time and at the same distance value.

[0153] In the case of a non-concentric arrangement, the sensors S1-S2 have different times and distance values ​​for the step SK in their respective measured value curves. In the case of the profile of the sensor axes S1, S2 shown, the module 10 can then be displaced along the x-axis for the purpose of establishing concentricity. If the step of the sensor S2 occurs later in comparison, the displacement is achieved in the positive x-direction, if this is the case for the sensor S1, the displacement is achieved in the negative x-direction.

Claims

1. A method of performing a probing process using a coordinate measuring machine (211), wherein: The coordinate measuring machine (211) comprises a measuring sensor (12) for detecting an object (100) and a plurality of distance sensors (S1-S3), And wherein the method comprises: - moving a measuring sensor (12) having a sensor longitudinal axis (L) together with distance sensors (S1-S3) in a working space (102) of the coordinate measuring machine (211); - using the distance sensors (S1-S3) to acquire distance measurements (d1-d3) to the surroundings along respective sensor axes (A1-A3), which extend along the sensor longitudinal axis (L); - taking into account the distance measurements (d1-d3) of all distance sensors (S1-S3) to determine the coordinates of the surroundings, wherein at least one of the surroundings coordinates (X, Y, Z) is determined with respect to a coordinate axis (X, Y) extending at an angle to the sensor axes (A1-A3) and / or to the sensor longitudinal axis (L), wherein at least three distance sensors (S1-S3) are provided and the surrounding coordinates (X, Y, Z) of the intersection of three planes are determined, wherein the relative position of each plane is defined taking into account one of these distance measurements (d1-d3), And / or wherein the surrounding coordinates (X, Y, Z) are determined by solving a system of equations set based on the distance measurements (d1-d3).

2. The method according to claim 1, in, The plurality of distance sensors are at least three distance sensors (S1-S3).

3. The method according to claim 1, Further including: - using these surroundings coordinates (X, Y, Z) to determine whether a predetermined minimum distance between the measuring sensor (12) and the surroundings has been fallen below; If this is the case: - then the movement speed of the coordinate measuring machine (211) is reduced to a value higher than 0 mm / s.

4. The method according to claim 3, in, The measuring sensor (12) is a tactile measuring sensor (12), and the object (100) to be detected is collected as the surrounding environment and maintained at a moving speed greater than 0 mm / s until contact between the measuring sensor (12) and the object (100) is detected.

5. The method according to any one of the preceding claims, Further including: - determining whether the distance sensors (S1-S3) are capturing known objects (100) or unknown surroundings; as well as - Based on this determination, the move is altered.

6. The method according to claim 5, in, A higher reduced movement speed is permitted in the case of a known object (100) than in the case of an unknown surrounding environment.

7. The method according to claim 3, in, This minimum distance is smaller in the case of a known object (100) than in the case of an unknown surrounding environment.

8. A system for performing a probing process using a coordinate measuring machine, comprising: - coordinate measuring machine (211); a measuring sensor (12) for detecting an object (100) and having a sensor longitudinal axis (L); - a plurality of distance sensors (S1-S3), each distance sensor being arranged to acquire distance measurements (d1-d3) to the surroundings along a respective sensor axis (A1-A3), the sensor axis extending along a sensor longitudinal axis (L); as well as - a determination device (302) which is arranged to determine surroundings coordinates (X, Y, Z) taking into account the distance measurement values ​​(d1-d3) of all distance sensors (S1-S3), wherein at least one of the surroundings coordinates (X, Y, Z) is determined with respect to a coordinate axis (X, Y) which extends at an angle to the sensor axes (A1-A3) and / or to the sensor longitudinal axis (L), wherein at least three distance sensors (S1-S3) are provided and the surrounding coordinates (X, Y, Z) of the intersection of three planes are determined, wherein the relative position of each plane is defined taking into account one of these distance measurements (d1-d3), And / or wherein the surrounding coordinates (X, Y, Z) are determined by solving a system of equations set based on the distance measurements (d1-d3).

9. The system according to claim 8, in, The plurality of distance sensors are at least three distance sensors (S1-S3).

10. The system according to claim 8, in, The acquisition area (E1-E3) of each distance sensor (S1-S3) overlaps at least a portion of the acquisition area (E1-E3) of at least one other distance sensor (S1-S3).

11. A system according to any one of claims 8 to 10, in, The sensor axes (A1-A3) extend at an angle (W) to the sensor longitudinal axis (L), and / or Therein, at least three distance sensors (S1-S3) are provided, which span a triangle (30).

12. The system according to claim 11, in, The triangle is an isosceles triangle (30).

13. A module (10) for forming a system according to any one of claims 8 to 12, in, The module (10) comprises at least the distance sensors (S1-S3) and at least one component of the measurement sensor (12), and an interface (20) through which the module (10) can be coupled to the coordinate measuring machine (211).

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