Position measurement in a positioning device

Abstract

Positioning device (10) with position measuring function, in particular for positioning a coordinate measuring sensor (206), wherein the positioning device (10) has a first kinematic element (K1) and at least a second kinematic element (K2) to which a first measuring element (M1) is attached, wherein the first and second kinematic elements (K1, K2) are connected to each other via a joint (G1); wherein at least one measuring device (18) and at least one sensor (16) for detecting the measuring device (18) and / or signals emitted therefrom are arranged on the first measuring element (M1) and are movable together with the second kinematic element (K2) relative to the first kinematic element (K1), and wherein at least indirectly the corresponding other measuring device (18) and sensor (16) are arranged on the first kinematic element (K1) and are movable together with the first kinematic element (K1) relative to the second kinematic element (K2) and its measuring element (M1), where, based on sensory perception, in addition to a relative position value corresponding to the degree of freedom of the joint (G1), at least one further relative position value for another degree of freedom can be determined; and wherein a mounting point (B1) of the first measuring element (M1) on the second kinematic element (K2) is located closer to an end of the second kinematic element (K2) that is farther from the joint (G1) than to the joint (G1).

Description

[0001] The invention relates to a positioning device with a position measurement function. The positioning device can be used in particular for coordinate measurements, for example, to position a coordinate measuring sensor relative to an object to be measured. Additionally or alternatively, it can position a tool, particularly for product manufacturing, relative to an object, but preferably also perform coordinate measurements.

[0002] It is known to measure objects, and in particular industrially manufactured workpieces, using coordinate measuring machines. This allows the surface coordinates of the workpiece to be determined in a reference coordinate system, for example, to check its geometric properties. Typically, a measuring sensor, which may be based on tactile or optical measuring principles, for example, is positioned and aligned by the coordinate measuring machine relative to the workpiece. For this purpose, the coordinate measuring machine has motion kinematics, usually with several individually driven motion axes. In particular, linear motion axes can be provided, which run orthogonally to one another, for example. By reading out position values ​​of the motion axes of the coordinate measuring machine and / or any measured values ​​determined by the measuring sensor (e.g. distance measured values), spatial coordinate values ​​of the object can be determined.

[0003] Typical coordinate measuring machines are generally unsuitable for workpiece machining due to their limited workspace and the spatial arrangement of their motion axes. Instead, coordinate measuring machines, and especially their kinematics, are usually optimized for pure workpiece measurement.

[0004] On the other hand, manufacturing equipment and, in particular, frequently used industrial robots (especially 6-axis articulated-arm robots) are not suitable for coordinate measurements. For example, industrial robots exhibit increased thermal expansion and / or deform comparatively significantly under load. However, a robot's position measurement system, which usually consists of encoders in these systems, can only partially capture these influences. A robot position calculated solely based on encoder values ​​can therefore only partially correspond to reality.

[0005] In practice, this usually means that object manufacturing and object measurement are carried out separately, using different equipment (e.g., a production robot for production and a separate coordinate measuring machine for object measurement). This is disadvantageous due to cost, transport, space, and time constraints.

[0006] Therefore, there are approaches in the state of the art to integrate coordinate measuring functions into the kinematics of manufacturing devices and / or to develop kinematics suitable for both manufacturing and coordinate determination. One objective can be to determine the coordinates of a machined workpiece and / or the coordinates of a predetermined reference point of a device, and in particular of a robot, such as its TCP (tool center point). From the latter coordinates, the coordinates of the workpiece can be indirectly deduced (for example, by knowing the dimensions of a measuring sensor or tool mounted on the robot) if contact with the workpiece is detected.

[0007] For example, it is known to equip industrial robots with optically detectable markers or targets and to detect these markers using a camera system. Optical detection can be understood as detecting electromagnetic radiation that corresponds in particular to the state of motion of the detection structure, e.g., because it is reflected differently from the perspective of a measuring camera depending on this state of motion. The detection of markers / targets is based on the idea that conventional position measuring systems for industrial robots, which typically consist of rotary encoders in the individual robot joints, do not have sufficient measurement accuracy, as described above. With optically detectable markers, on the other hand, an actual 3D pose (i.e., its spatial position) of the robot can be determined independently of the rotary encoder measurements.

[0008] The disadvantage in this case, however, is that camera systems cannot be operated reliably in all production environments, for example, due to contamination or heat. Setup effort is also increased, and permissible robot movements may be limited, as it must always be ensured that the optical markers are not obscured by individual robot links from the perspective of the camera systems.

[0009] There are also solutions in which coordinate measuring arms, which have multiple links connected via rotary joints, are attached to an industrial robot as a parallel kinematic system and move together with it. Compared to the industrial robot, these coordinate measuring arms can have more precise rotary encoders and, for example, measure the robot's 3D pose more precisely. Consequently, there is a mechanical connection and thus a mechanical constraint between the robot and the coordinate measuring arm, as well as between the individual links of the coordinate measuring arm.

[0010] In this case, however, it is disadvantageous that the robot's freedom of movement is restricted. More precisely, robot movements must always be restricted to prevent a coordinate measuring arm coupled to it from breaking off or being otherwise damaged. This can cause significant problems, especially when passing through singularities.

[0011] Furthermore, this solution is not suitable for all manufacturing environments, as the coordinate measuring arm and in particular its high-precision encoders have only limited resistance to contamination and other environmental influences.

[0012] DE 43 14 597 A1 also discloses a measuring arrangement for position determination in manipulators, the structure of which corresponds to that of the manipulator itself. A separate drive system is provided for a measuring component of this measuring arrangement, allowing it to be moved independently of a joint of the manipulator.

[0013] EP 2 092 269 B1 discloses a coordinate measuring machine with a ball joint. A ball body of the joint has an optically detectable coding. This is detected by a camera sensor to obtain position values.

[0014] US 4,606,696 A discloses a position determining mechanism with a plurality of structural members which are hinged together and decoupled from deformations of a surrounding structure.

[0015] An object of the invention is therefore to improve the accuracy of position measurements with and / or in kinematics that interact with an object.

[0016] This problem is solved by the subject matter of the appended independent claims. Advantageous further developments are specified in the dependent claims.

[0017] The solution according to the invention is also particularly directed at industrial or manufacturing robots, but is not limited thereto. Other devices and / or kinematics may also be provided, the position of which is to be determined, particularly with respect to a workpiece. However, these devices and / or kinematics preferably differ from the design of conventional coordinate measuring machines and are also preferably designed for manufacturing tasks.

[0018] In general, the following refers to a positioning device that can have a plurality of kinematic elements that are movable relative to one another. For example, a tool for machining a workpiece or a measuring sensor (in particular a coordinate measuring sensor) can be attached or attachable to the positioning device. The spatial position and / or position relative to a workpiece of such an attached unit can be determined using the solution according to the invention. In general, a complete spatial position can be determined with regard to all six spatial degrees of freedom, but only individual spatial degrees of freedom can also be determined.

[0019] As a first idea of ​​the invention, it was recognized that one reason for the insufficient measurement accuracy of existing kinematics and their possible rotary encoders is that the influence of deformations or thermal expansions cannot be adequately detected by sensors. In particular, one cause was identified as being that the aforementioned distorting influences can affect degrees of freedom that cannot be measured with sufficient accuracy using the rotary encoders. Consequently, the rotary encoder measurements suggest a spatial position that deviates from reality due to the unrecorded degrees of freedom, for example, because lateral offsets between coupled robot links are not incorporated into a measured angular position.

[0020] In general, the invention therefore provides for the provision of a novel measuring system in addition to or as an alternative to any rotary encoders. This system is preferably configured not only to measure individual rotational positions (or angular positions) between adjacent kinematic elements, but also to determine measured values ​​(referred to herein as position measured values) with respect to other degrees of freedom. These are preferably relative position values ​​of the connected kinematic elements and / or the measuring elements or components of measuring arrangements explained below relative to one another. Furthermore, the proposed measuring system is also characterized by increased mechanical freedom from constraints.

[0021] Using this measuring system, the influence of, for example, deformations and / or temperature expansions can be recorded sensor-based, at least with regard to these additional degrees of freedom, and incorporated into the ultimately determined position value. More precisely, this allows for a realistic position determination of a reference point (referred to herein as the reference location) of the positioning device (e.g., the TCP), and generally improves measurement accuracy.

[0022] For this purpose, the invention proposes providing at least one measuring element in addition to the kinematic elements, which can be connected to one another via rotary joints in a conventional manner, but also via linear joints, and whose relative position can optionally also be detected using conventional rotary encoders or linear sensors (e.g., glass scales). This measuring element is attached to one of the kinematic elements and can be moved together with it, for example, by a drive of the rotary joint.

[0023] However, position measurements are not recorded exclusively based on the kinematic elements and / or the rotary encoders coupled thereto, as has been the case so far. Instead, the measuring element and / or a measuring device connected thereto can be recorded or measured by sensors to obtain position values. Alternatively, a sensor for recording a measuring device can be arranged on a measuring element, which is, for example, at least indirectly coupled to an adjacent kinematic element. This enables the provision of a measuring arrangement that is preferably designed independently of a joint and any sensors or rotary encoders (for example, standard encoders) located there. By means of this measuring arrangement, position values ​​can preferably also be determined that are independent of the intended degree of freedom of the joint. These position values ​​can, for example, be incorporated into the calculation of a final target position value by addition, i.e.cannot simply be eliminated mathematically by compensation or the like, but can be directly incorporated into the final measurement result, for example as a fully added value or coordinate component.

[0024] A measuring arrangement is understood here to mean the measuring devices and sensors described below, which can interact with one another to determine position values. Optionally, the measuring elements connected to these units can also be understood as a component of the measuring arrangement. For a multi-element positioning device with several joints, several measuring arrangements can also be provided (preferably one for each joint). The entire measuring arrangements can form a measuring system of the positioning device. Conventional rotary encoders of a rotary joint or general sensors for recording measured values ​​relating to the intended joint degree of freedom can be excluded from this measuring system. The measuring system can be provided parallel to, but preferably mechanically at least partially decoupled from, the kinematics of the positioning device, which brings with it the advantages explained below.

[0025] Preferably, the measuring system also determines position values ​​for the joint degree of freedom and, for example, for the rotational degree of freedom of each rotary joint. This allows the joints themselves to be designed with less precision, thus reducing the requirements for their guidance accuracy. Instead, possible guidance inaccuracies (particularly of a radial nature) can be accepted, as they can be detected by sensors and thus taken into account when determining the position. For example, such inaccuracies can be detected by sensors as a radial offset, which is added as a coordinate component when determining a final position value, for example, to a subsequently explained absolute (reference) position value.

[0026] It is further proposed to couple the measuring element to the associated kinematic element, and more precisely, to attach it to it, but in an area remote from the joint. In this way, deformations and, in particular, bending of the kinematic element can be comprehensively recorded along a large length thereof, for example, compared to attaching the measuring element close to the joint. In the latter case, bending of the kinematic element in areas remote from the joint would be insufficiently transmitted to the measuring element and thus could not be reliably detected by sensors.

[0027] In particular, a chain of kinematic links can be formed, for example, in the manner of a chain consisting of the individual links (or arm links) of an industrial robot. Adjacent links can each be connected via a joint. Analogously, a chain of measuring links can be formed, which are preferably not mechanically connected to one another, but are each assigned to and / or attached to a kinematic link. The position of the measuring links relative to one another can also be determined for degrees of freedom independent of the (kinematically / mechanically enabled or intended) degree of freedom of individual joints, in order to determine values ​​for selected additional degrees of freedom of the positioning device and / or components attached to it.

[0028] In this way, the measuring elements are mechanically decoupled from each other. Furthermore, a measuring element is preferably always attached to only a single kinematic element and can be moved together with it. Thus, fewer components have a direct mechanical effect on a single measuring element, and the measuring elements are each subject to fewer mechanical constraints than if an entire coordinate measuring arm were moved together with the device. This reduces movement restrictions for the positioning device and mitigates the risk of damage within the measuring system.

[0029] In summary, the proposed solution enables a certain degree of freedom from constraints, or in other words, limited mechanical force transmission between the kinematics of the positioning device and components of the measuring system, as well as between components of the measuring system. Particularly at the measurement location, there is preferably no mechanical coupling between the measuring system components. The measuring system or its components can therefore be described as completely free from constraints.

[0030] The measuring system proposed herein, which can be comparatively compact and / or does not require a mechanically interconnected multi-element kinematic system consisting of measuring elements, also makes it possible to arrange the measuring system at least partially within the positioning device. This increases robustness, as the measuring system can thus be reliably shielded from environmental influences.

[0031] In particular, embodiments of the invention provide for shielding the measuring arrangements used for position determination (particularly with sensors and / or measuring devices explained below) from the environment. In other words, these arrangements can be arranged internally within the positioning device, for example, by accommodating them in cavities therein. This increases reliability and also enables the solution presented here to be used in, for example, heavily contaminated manufacturing environments.

[0032] In particular, a positioning device with a position measuring function is proposed, wherein the position measuring function enables the measurement of at least selected spatial coordinates of the positioning device and, for example, a reference point thereof (for example, the TCP or a mechanical interface to the position measuring function enables the measurement of at least selected spatial coordinate values ​​of an object to be measured (for example, a workpiece) relative to which the positioning device moves.

[0033] The positioning device comprises a first (preferably rigid) kinematic member with an optional measuring member and at least one second kinematic member to which a first measuring member is assigned and, more precisely, to which the first measuring member is fastened (and thus preferably coupled for joint movement with the second kinematic member), wherein the first and second kinematic members are connected to one another via a joint; wherein at least one of at least one measuring device (or, in other words, a measuring embodiment) and at least one sensor (measuring sensor) for detecting the measuring device and / or signals emitted therefrom (for example optical signals and / or electromagnetic radiation) is arranged on the first measuring element, and the corresponding other of the measuring device and sensor is arranged at least indirectly on the first kinematic element, wherein, on the basis of the sensory detection (i.e., the detection of the measuring device by or with the sensor and, more precisely, on the basis of sensory measurement signals or measured values ​​generated thereby), in addition to a relative position value corresponding to the degree of freedom of the joint (i.e., for example, an angular position about a substantially parallel axis of rotation), at least one further relative position value (in particular of the positioning device or within its kinematics and particularly preferably of the kinematic elements to each other) can be determined for another degree of freedom (in particular for a translational degree of freedom if the joint is a rotational joint, or a rotational degree of freedom in a linear joint); and wherein a location of attachment of the first measuring member to the second kinematic member is closer to an end of the second kinematic member remote from (and / or facing away from) the joint than to the joint.

[0034] The indirect arrangement on the first kinematic element can comprise a purely optional (e.g., zeroth) measuring element being attached to the first kinematic element as an additional measuring element, on which the corresponding other of the measuring device and the sensor is arranged. Alternatively, a direct arrangement and, in particular, attachment to the first kinematic element can take place, in particular without an additional measuring element there.

[0035] In particular, the attachment location of the first measuring element (e.g., viewed along a longitudinal axis) is spaced from the joint by more than half the length of the kinematic element. This length may correspond to the largest spatial dimension of the kinematic element.

[0036] The positioning device can further comprise drive units, in particular electric motors. Each joint can be assigned a corresponding drive unit to move the kinematic elements relative to one another. More precisely, the kinematic elements can be pivoted or displaced relative to one another by the drive unit within the scope of the joint's degree of freedom and can also be held in the assumed positions.

[0037] Each rotary joint and / or drive unit can comprise a rotary encoder to determine the relative angular position of the kinematic links and / or the angular position of the rotary joint. Each linear joint and / or drive unit can comprise a linear sensor (e.g., with a scale) to determine the relative translational position of the kinematic links and / or the translational position or degree of displacement of the joint. In general, each joint or associated drive unit can therefore have a sensor for detecting movements related to the joint's degree of freedom.

[0038] Any kinematic elements and measuring elements described herein can be single-part or multi-part. The term "element" refers in particular to an arrangement within a group, chain, and / or sequence of corresponding kinematic elements and also a possible plurality of measuring elements. In particular, these can be arranged spatially consecutively, thus forming individual elements in this sequence.

[0039] As mentioned above, the first kinematic element can also include a measuring element. This is referred to below as the zeroth measuring element merely by way of example. However, the first kinematic element can generally be spatially fixed and / or form a base relative to which the first measuring element can be rotated. This opens up particular design flexibility for sensors or measuring devices positioned there, which do not necessarily have to be held by a measuring element and / or generally have to be spatially or structurally grouped together. Consequently, a separate zeroth measuring element or, in general, a measuring element on the first kinematic element is purely optional.

[0040] If more than two kinematic links are provided, which preferably form a kinematic chain, and in particular an open kinematic chain, the same applies to a measuring link assigned to the foremost kinematic link (i.e., the link located farthest from the base, the last link, and / or the link forming the open end), as explained above for the zeroth measuring link. This can therefore also be omitted, since no separate measuring link is required there, e.g., for holding a measuring device or a sensor.

[0041] Preferably, at least those kinematic elements have measuring elements that are connected at both ends to joints or to further kinematic elements. For explanatory purposes, reference may be made below to a plurality of measuring elements, as this corresponds to a preferred embodiment, wherein the corresponding features and explanations may also apply to variants with only one measuring element (the first measuring element). Statements made herein regarding a plurality of measuring elements can always apply to all measuring elements of a positioning device, but at least to those of kinematic elements that are connected at both ends (i.e., both ends) to joints and / or adjacent kinematic elements. Exceptions may therefore be made to a possible zeroth or foremost measuring element.

[0042] At least the second kinematic element and preferably also at least one further kinematic element, for example, if at least three kinematic elements are provided, can be elongated. This can be understood as meaning that a corresponding kinematic element has a pronounced longitudinal extension along a longitudinal axis. The longitudinal extension (i.e., length) can be the largest spatial dimension, for example, compared to cross-sectional dimensions along the longitudinal axis.

[0043] The kinematic members can, as explained below, be hollow at least in sections. They can be designed as conventional arm sections of an industrial robot. They can include data lines and / or energy or working fluid supply lines, particularly within their interior. Alternatively, such lines can also be attached to the kinematic members from the outside.

[0044] A kinematic link may have a first and a second end. These may be opposite each other (i.e., opposite) and / or spaced apart from each other. They may be connected by the longitudinal axis of a kinematic link and thus form opposite end regions of this kinematic link. A joint may be provided at each end of a kinematic link and / or a connection may generally be made to an adjacent joint and / or kinematic link.

[0045] The joint can have at least one translational and / or at least one rotational degree of freedom. It can be a linear joint or a rotational joint, or a combination thereof. The joint (in particular one that is deformation-free and / or temperature-unaffected) can have no other degrees of freedom or allow relative movements beyond at least one, preferably mechanically and / or structurally defined degree of freedom. However, such relative movements can still occur as a result of deformations, which can preferably be detected by the measuring system. For structural reasons, however, only a defined number (preferably only one or at least not more than two) of (macroscopic) relative movement degrees of freedom can be provided or intended for the joint.

[0046] If the joint degree of freedom is also measured by the measuring system, a coarse measurement with a larger detection range, particularly one that covers the entire joint movement, is preferably performed additionally. The coarse and fine or high-resolution measurements obtained can then be combined to form a total measurement value.

[0047] Away from the attachment point, the measuring elements preferably cannot be supported on the kinematic elements. In other words, the attachment point can be the only attachment point or support point on and / or within the kinematic element(s), or at least the closest one from the perspective of the joint. Consequently, the measuring elements can extend freely and / or suspended into or through the associated kinematic elements, at least over a large part of their length.

[0048] Preferably, in a kinematic element that is connected at both ends to joints for connection to a respective adjacent kinematic element, the preferably single fastening location of the measuring element is selected such that it is spaced apart from one of the joints in the manner defined above. However, this can also result in the fastening location being positioned close to a joint at the correspondingly other (second) end. Nevertheless, this means that within the kinematic element there is only one fastening location that is also clearly spaced apart from at least one of the joints. Thus, in particular, bends along a large part of the length of a kinematic element can be detected and, so to speak, transferred to a joint that is significantly spaced apart from the fastening location and in particular to a sensor and / or a measuring device located there.

[0049] Preferably, however, the mounting locations of measuring elements of two adjacent kinematic elements are not selected such that they are each located close to a joint connecting these elements. In other words, a joint is preferably not directly surrounded or enclosed by corresponding mounting locations. Instead, at least one of the mounting locations is preferably located at a distance of more than half the distance of the kinematic element having this location. This prevents relative displacements of the kinematic elements from no longer being sufficiently transmitted to the measuring elements and / or from no longer being detected with sufficient accuracy by the sensor and measuring devices typically arranged in the region of the joint.

[0050] The following may also apply to the second kinematic member if it is connected to a further (third) kinematic member via a yet further joint: The second kinematic member may have a measuring device or sensor in the region of its end facing away from the (first) joint and / or first kinematic member, which is held, for example, on the measuring element of this kinematic member. The sensor or measuring device may be positioned near or in the region of the further joint and, for example, protrude into it. The third kinematic member, on the other hand, may have a (second) measuring element which has the correspondingly other measuring device or sensor in order to interact with the measuring device or sensor of the second kinematic member. This second measuring element is preferably connected to the third kinematic member at a fastening location correspondingly distant from the second joint.

[0051] Any relative position value described herein can be a relative position value of the measuring device and (or to) the sensor and / or of those components comprising the measuring device and the sensor (typically any adjacent measuring elements or a measuring element and an adjacent kinematic element). In particular, the relative position value can describe the relative position (in particular with respect to a defined spatial degree of freedom) between opposing sensors and / or measuring devices, between adjacent measuring elements, and / or between adjacent kinematic elements.

[0052] The relative position value can be defined in a predetermined reference coordinate system. This can be, for example, a machine coordinate system and / or a base coordinate system. In principle, however, a coordinate system linked to a kinematic element and / or measuring element is also possible.

[0053] In particular, the relative position value can be one of six spatial relative position values ​​or refer to corresponding 6 spatial degrees of freedom (three translational and three rotational), as they can be known to be defined in a spatial coordinate system.

[0054] It can also be provided that (in particular per joint) a plurality of sensors and / or measuring devices are present, in particular to determine a plurality of relative position values. These can, for example, interact in pairs. Additionally or alternatively, a measuring device can be detected by several sensors, which, however, are positioned differently from one another to determine different relative position values ​​(i.e., also differently positioned relative to the measuring device). For example, the sensors can surround the measuring device on different sides or be located opposite different sides of the measuring device.

[0055] As explained further herein, it is also possible to determine a relative position value, and in particular a rotational relative position value, by comparing the measured values ​​of different sensors. For example, a difference between the measured values ​​recorded in each case can be calculated, and a rotational relative position can be determined based on this difference.

[0056] The sensors can be light-sensitive and / or based on optical measuring principles. The measuring device can generate optically detectable signals (for example, electromagnetic radiation and in particular light in the visible wavelength range), for example, using at least one light source, preferably a laser source. Such signals can be detected by the sensor, for example, as an intensity value and in particular as a pixel value. In this way, intensity distributions (in particular pixel value distributions) in a sensor plane can be determined. Based on this, relative offsets in the sensor plane (i.e., lateral offsets) between the sensor and the measuring device can be determined.

[0057] The radiation sources can be integrated directly into the measuring device. Alternatively, they can be positioned outside of it and guide the radiation to the measuring devices, for example, via fiber optics.

[0058] In particular, the measuring device can be configured to emit structured light. The light can be structured with regard to its spatial and / or temporal properties. It can be a light pattern, in particular a location- and / or direction-dependent structured light pattern, and / or a temporal sequence of light patterns. Structured light can be understood to mean that by detecting a specific solid angle into which the light is radiated and / or detecting at least one light beam (or a set of light beams), the relative position between the detecting unit (i.e., the sensor) and the emitting unit (i.e., the measuring device) can be unambiguously determined. This can require knowledge of a relative arrangement of the sensor and measuring device and / or of an angle of incidence of the light.However, such properties can be easily identified and / or adjusted based on the spatial arrangement of sensors and measuring devices.

[0059] Alternatively or additionally, the measuring device can comprise optically detectable markers (also called targets). In this case, a sensor can preferably operate by imaging and / or capturing images of these markers. Using conventional image analysis algorithms, the desired relative position values ​​can be determined, for example, based on the orientation and / or distortion of the markers detected in the captured image files.

[0060] In principle, it is also possible to measure distances using the sensors and, based on these measurements, determine at least a relative position value. Inductive, capacitive, or optical measurement principles can be used for this purpose.

[0061] According to a further variant, the measuring device has optically detectable structures (detection structure), for example, a preferably three-dimensional topography. The sensor can be configured to detect these structures or at least selected properties and / or dimensions thereof (e.g., a height value distribution). For this purpose, the sensor can be, for example, a laser line sensor or generally configured for measuring using optical patterns (in particular, striped light patterns, "optical fringe patterns") and preferably also project these patterns onto the topography itself.

[0062] Alternative detection of such topographies can be achieved using triangulation sensors or white light sensors.

[0063] In a further development, the measuring device can emit electromagnetic radiation, particularly in the form of light, wherein this radiation preferably strikes optically scattering, reflecting, and / or diffractive or beam-splitting elements. It can then be detected by at least one sensor (for example, in the correspondingly optically scattered state). Generally speaking, irradiating objects and / or structures with the measuring device can generate a light distribution that can be detected by at least one sensor. Depending on the detected portion (or section) of the light distribution, a conclusion can then be drawn about the relative position of the sensor and the measuring device.

[0064] All of the measuring principles described herein for determining relative position values ​​can be based on the determination, for example in a calibration operation and / or during a design phase, of relationships between measured values ​​from the sensors (for example, recorded light distributions and / or pixel value distributions in a sensor plane) and relative positions between the sensor and the measuring device. These relationships can be stored in a controller and / or form a calibration table. During subsequent operation (in particular measuring operation) of the positioning device, the desired relative position values ​​can be determined on the basis of this previously stored information. For example, depending on a received sensor measured value, the stored information (in particular the aforementioned calibration table) can be searched for the corresponding entry (i.e., matching measured value) and the relative position value assigned to this entry can be read out.This can be done individually for each degree of freedom considered.

[0065] It is therefore not absolutely necessary to be able to mathematically and unambiguously calculate the desired relative position values ​​based on the sensors or their measured values. Instead, it may be sufficient to be able to make unambiguous assignments to the desired relative position values ​​based on the measured values. This can be achieved by appropriately spatially resolved optically detectable properties of the measuring device, and in particular by the signals or light patterns emitted / generated by it.

[0066] The described assignment should be unambiguous at least within a predetermined value range (of the sensor measured values). As explained in more detail below, a potentially relevant measured value range of the sensors can be determined, for example, by means of a rough measurement using a preferably different measuring arrangement (e.g., using any rotary encoders of rotary joints). Within this measured value range, the sensor measured values ​​can then advantageously be unambiguously assigned to the desired relative position values. Such a purely range-specific, unambiguous assignment reduces the requirements for the resolution and / or measurement accuracy of the sensors and measuring devices used.

[0067] Interacting measuring devices and sensors can also be referred to herein as a measuring arrangement or can be comprised of a measuring arrangement. Accordingly, a measuring arrangement can comprise at least one measuring device and a sensor interacting with it. However, if relative position values ​​are to be determined for multiple degrees of freedom, the measuring arrangement can also comprise a plurality of sensors and / or a plurality of measuring devices.

[0068] The positioning device, and in particular its measuring system, can also include a temperature sensor to compensate for temperature influences on the measurement of the relative position values ​​(for example, on the spatial position of the sensors and / or measuring devices, which is correspondingly influenced by this). Compensation can be performed, for example, using a temperature-dependent calibration and / or compensation table for determined relative position values. Similarly, at least one vibration sensor and / or deformation sensor can also be provided, and the sensor measurements generated by these can be used to compensate for error influences.

[0069] The aforementioned sensors (for deformation, vibration, and / or temperature) can, in particular, measure the at least one measuring element and / or interact with it. With multiple measuring elements, a corresponding sensor can be provided for each measuring element. In this way, influences on the measuring element can be compensated for that may not have the same effect on a kinematic element and / or do not originate from it, and thus do not affect the target position values ​​to be determined.

[0070] According to a further development, the sensor is configured for contactless detection, in particular for optical detection of the measuring device and / or signals generated / emitted thereby. Examples of this have been mentioned above. This limits and preferably completely eliminates mechanical force transmissions within the measuring system, thus enabling the above-described freedom from constraints in the measuring system.

[0071] Similar advantages can be achieved with an embodiment in which the first measuring element and the first kinematic element (and / or a zeroth measuring element assigned to it) do not contact each other. In general, measuring elements of a kinematic element cannot contact an adjacent kinematic element (i.e., one connected to the specifically assigned kinematic element via a joint) or a measuring element assigned to that element. This promotes the mechanical decoupling of the measuring elements from one another and thus the freedom from constraints of the measuring system.

[0072] Instead, the measuring elements can each have end regions facing the joint or extending into the described connection areas, which end at a distance from an adjacent kinematic element and / or measuring element and / or sensors or measuring devices located there. The corresponding sensor and measuring device can then be positioned at this end region.

[0073] Alternatively or additionally, it can be provided that the first measuring element is at least not directly connected to the joint. For example, there can be only an indirect connection via the kinematic element. However, due to the choice of mounting location, this indirect connection preferably occurs over a distance corresponding to more than half the length of the kinematic element. Thus, deformations of the kinematic element, in particular, can be detected by the measuring element and advantageously incorporated into the determined position values. This would be possible only to a very limited extent if the measuring element were directly supported on or directly connected to the joint.

[0074] According to a further development, the first measuring element is accommodated at least partially in a hollow body section of the associated second kinematic element and / or preferably each measuring element is accommodated at least partially in a hollow body section of a respective associated kinematic element. This enables the accommodated section to be at least partially shielded from environmental influences (in particular moisture and dust). The hollow body section is preferably hollow-cylindrical and / or has a closed surface. It can be a hollow arm section, as is common in conventional industrial robots.

[0075] Additionally or alternatively, it may be provided to position the measuring arrangements described herein, and in particular, interacting sensors and measuring devices, in a corresponding hollow body section. In particular, it may be provided to form a coherent hollow body section from interconnected kinematic elements, including a joint positioned therebetween, and more precisely, from their respective hollow body sections. This hollow body section then preferably contains the entire measuring arrangement (i.e., all sensors and / or measuring devices interacting to determine relative position values ​​with respect to these kinematic elements and the joint).

[0076] According to the above variants, an internal measuring sensor or an internal measuring system can be provided within the positioning device, which increases the range of applications even with regard to production environments with difficult measuring conditions.

[0077] In particular, the sensor and the measuring device can be arranged opposite each other in the area of ​​the joint. This increases compactness and enables reliable measurement of position values.

[0078] Furthermore, it can be provided that an absolute position value of at least one reference location of the positioning device is determined based on at least one of the relative position values. This can be the aforementioned TCP or, more generally, an interface of the positioning device for a unit that can be positioned thereby (for example, a tool or a measuring sensor). The relative position value can be determined and stored for this purpose. It can, for example, be added as a summand to a known absolute position (for example, from a device base).

[0079] In principle, it is advantageous if at least one absolute reference position value is known in the desired coordinate system. The determined relative position values ​​can refer to this reference position value and / or define the relative position based on it. For example, an absolute position value of the sensor or measuring device included in the first kinematic element can be defined as the reference position value. A determined relative position value, which defines, for example, the position of the first measuring element relative to the corresponding unit of sensor and measuring device, can be used, with knowledge of this absolute position value, to determine an absolute position value of the first measuring element (or corresponding to a predetermined reference location there) (for example, by adding it to known absolute positions and / or reference position values).

[0080] If, as is generally preferred, a kinematic chain with a plurality of joints and kinematic links connected thereto is provided, an absolute position value of a reference location, for example of a respective kinematic link, can be determined starting from the base and knowing previously measured relative position values. In other words, starting from the known absolute position value of the base and the measured relative position values, an absolute position value (in particular knowing the spatial extent of the measuring link) can be determined for the subsequent joint and / or a respective end of the measuring link. This can then be offset against the relative position value measured there to determine the absolute position value for yet another subsequent joint.Figuratively speaking, relative position values ​​measured from joint to joint can be used to determine local absolute values, and these local absolute values ​​can then be calculated with subsequent relative position values ​​measured (along the kinematic chain). This principle is explained further below using the figures.

[0081] In summary, one embodiment provides that the positioning device comprises at least one further (third) kinematic element with a second measuring element assigned to this kinematic element, wherein the third kinematic element is connected to the second kinematic element via a second joint, so that the kinematic elements (i.e. the first to third) preferably form a kinematic chain. In this case, a relative position value can also be determined between the first and second measuring elements, and the absolute position value of the reference location can also be determined on the basis of this determined relative position value. In particular, this position value can be determined on the basis of all measured relative position values ​​between adjacent measuring elements and / or kinematic elements. The reference location can lie outside the first to third kinematic elements, for example, on a further kinematic element that preferably does not immediately follow the third kinematic element.

[0082] If reference is made here to a relative position value between two measuring elements, this can refer to a relative position value between a sensor and a measuring device, which are connected to adjacent measuring elements.

[0083] According to a further aspect, the joint comprises a sensor (position sensor) for detecting movements and / or a position relative to the joint's degree of freedom. For example, a rotary joint can comprise a rotary encoder (e.g., a conventional encoder). A final position value, which can be, for example, the absolute position value of a desired reference location of the positioning device and / or an end result of the position measurement, can be determined based on both these sensor measured values ​​and the relative position values. In particular, a type of coarse measurement can be performed using the sensor measured values, and a fine measurement using the relative position values. This particularly applies to measurements of relative position values ​​corresponding to the joint's degree of freedom.

[0084] However, it may be provided to perform rough measurements for a plurality of, and in particular for all six, spatial degrees of freedom (especially for degrees of freedom that deviate from the joint degree of freedom). For this purpose, sensors or a rough measurement system can be provided, preferably with a sufficiently large unambiguous range to enable rough but unambiguous measurements even over sufficiently dimensioned value ranges of the relative positions. However, due to the limited range of motion of the degrees of freedom that deviate from the joint degree of freedom, the value ranges to be provided for the non-joint degrees of freedom are comparatively small, and the measurement system is simplified accordingly.

[0085] In principle, it can be provided that a measuring element, whose associated kinematic element is connected at both ends to further kinematic elements, projects into both connection areas to the adjacent kinematic elements and / or extends through the entire kinematic element. With regard to one of the joints with which a connection to one of the adjacent kinematic elements is made, the distance from the attachment point described above can then be present. Furthermore, the measuring element can have a sensor or measuring device at both of its ends in order to interact with the measuring elements of adjacent kinematic elements and / or the sensors or measuring devices there. In this case, the measuring element can extend on both sides from the attachment point into the corresponding connection areas, i.e. also beyond the attachment point to another (nearer) joint.

[0086] According to a further general aspect, it can be provided that, to determine relative position values ​​for a plurality of degrees of freedom, at least one sensor and one measuring device interact in pairs for each degree of freedom. It can also be provided that these pairs are distributed differently among adjacent measuring elements and / or kinematic elements. For example, a first measuring element can have the sensor of a first pair or the measuring device of a second pair, and the adjacent further measuring element can have the measuring device of the first pair and the sensor of the second pair.

[0087] In this context, adjacent kinematic elements and measuring elements can generally be understood as meaning those which follow one another directly along a kinematic or measuring element chain (i.e. without any further kinematic or measuring element in between).

[0088] As mentioned above, the measuring device can comprise at least one radiation source (for example, a laser source, in particular a laser diode) for generating electromagnetic radiation as a signal from the measuring device. The sensor can be configured to detect the radiation (or, more precisely, the radiation components impinging on it). Alternatively, the measuring device can be connected to a radiation source, for example, via an optical fiber, and receive and emit externally generated radiation via an optical fiber. The measuring device can thus comprise an exit region of the optical fiber or, more generally, an exit region for the radiation to irradiate at least one sensor.

[0089] Preferably, the sensor is spatially resolving and / or light-sensitive. For example, the sensor can comprise a matrix (i.e., an array) of light-sensitive pixels or detector elements (e.g., individual diodes), each of which can measure radiation intensity values. For example, the sensor can comprise a photodiode array. According to one variant, the sensor comprises a SPAD array (single photon avalanche diode). Alternatively, it can be a CCD or CMOS sensor.

[0090] As also mentioned, a relative arrangement of the sensor and the measuring device can be determined based on the sensor detection, in particular in a sensor plane and / or in at least one direction parallel to the sensor plane. Lateral measurements can therefore be performed, for example, by determining the position of detected optical markers, structured light components, or measured light distributions in the sensor plane.

[0091] To determine position values ​​for the joint degree of freedom and / or for at least one translational degree of freedom, interacting sensors and measuring devices are preferably positioned near the joint and / or in the connection area. However, to determine position values ​​for a bending degree of freedom, in particular about an axis running transversely to the longitudinal axis of the kinematic element and / or measuring element, the sensor or measuring device can be arranged at a distance from the joint. In particular, this unit can be arranged closer to the attachment location than to the joint in which the corresponding other unit of sensor and measuring device is located.

[0092] In this way, bending-related relative offsets can be recorded over the greatest possible length or longitudinal extent and thus the actual relative position, for example between two adjacent kinematic elements, can be determined more precisely.

[0093] Additionally or alternatively, at least two sensors can be provided, which, however, can, for example, only measure one measuring device or interact with it. The relative position value can be determined based on a comparison and, in particular, a difference between the respective detection results (e.g., intensity values ​​or distributions) of the sensors. This has proven particularly advantageous for a torsional degree of freedom, i.e., a bending deformation around a longitudinal axis of, for example, the measuring element.

[0094] The sensors or sensor planes whose results are to be compared can be aligned parallel to one another. They can be located opposite a common or the same side of the measuring device, or they can enclose the measuring device between them (i.e., they can be located opposite different and, in particular, opposite sides of the measuring device). In principle, it can be provided that, depending on the relative alignment of the measuring device and the sensors whose results are to be compared, the sensors (for example, with the exception of an optional predetermined neutral position) detect different signals (for example, different light pattern components or structured light components) from the measuring device.

[0095] The positioning device is preferably a robot, preferably an industrial robot. The robot can be configured, in particular, for object measurement, for example, by incorporating a corresponding coordinate measuring sensor. The robot can be a multi-jointed robot, which can, for example, have at least four or up to six joints, and in particular rotational joints. A base of the robot can be stationary and form the first kinematic element.

[0096] A frontmost kinematic link of the robot (i.e., the link furthest from the base) can comprise an interface for attaching tools and / or measuring sensors (for example, a coordinate measuring sensor, such as a stylus, and / or an optical sensor, in particular an optical distance sensor). Between the first kinematic link and the frontmost kinematic link, the further kinematic links can be arranged in a kinematic chain.

[0097] However, object measurement can also be performed without a separate coordinate measuring sensor on the robot, for example, if the dimensions of a tool that is brought into contact with an object are known. In this way, for example, the spatial position of the object and / or the tool relative to it can be recorded and, if necessary, continuously checked in parallel with an object processing process. Using the solution according to the invention, this is achieved with significantly increased accuracy, in contrast to position determinations based solely on conventional robot encoders.

[0098] Furthermore, a plurality of sensors (and optionally also measuring devices) are preferably provided, by means of which relative position values ​​can be determined with respect to all six spatial degrees of freedom (preferably for each individual joint). In other words, the measuring arrangement assigned to a respective joint or pair of connected kinematic elements can be configured to determine corresponding relative position values ​​for all six spatial degrees of freedom, in particular of the adjacent measuring elements and / or kinematic elements. If such a comprehensive determination of degrees of freedom is carried out for all measuring arrangements and / or joints, the position can be determined particularly precisely, particularly with respect to all six dimensions of a desired reference location of the positioning device.

[0099] However, for reasons of effort or cost, it may be necessary to dispense with determining corresponding position values ​​for at least individual spatial degrees of freedom. This may be the case, for example, if relative movements of the measuring elements and / or the kinematic elements in or around certain degrees of freedom are negligible due to design or application reasons.

[0100] The invention also relates to a method for operating a positioning device, wherein the positioning device has a first kinematic member and at least one second kinematic member to which a first measuring member is fastened, wherein the first and second kinematic members are connected to one another via a joint; wherein at least one of at least one measuring device (or, in other words, a measuring embodiment) and at least one sensor (measuring sensor) for detecting the measuring device and / or signals emitted therefrom (for example optical signals and / or electromagnetic radiation) is arranged on the first measuring element, and the corresponding other of the measuring device and sensor is arranged at least indirectly on the first kinematic element, wherein the first measuring member is attached to the second kinematic member and a mounting location is closer to an end of the second kinematic member remote from the joint than to the joint, the method comprising: - Determining at least one relative position value (in particular of the first and second kinematic element) on the basis of the sensory detection.

[0101] The procedure may also include the following measures: - Determining, by means of the positioning device, a relative arrangement of the positioning device and / or a tool or measuring sensor attached thereto to an object to be measured; and / or - Determining a measured value relating to the object, in particular an object coordinate value, taking into account the relative position value. The relative position value can be fully incorporated into the object coordinate value as a coordinate value or coordinate component, for example, by addition.

[0102] The method may include all further measures, steps, and features to provide all effects, operating states, and interactions described herein. In particular, the method may be implemented with a positioning device according to any aspect described herein. Furthermore, all explanations and refinements of features of the positioning device may also apply to the identical method features or be provided for them. Exemplary embodiments of the invention are explained below with reference to the attached schematic figures. The same reference numerals may be used for similar or equivalent features across the figures. Fig. 1 shows a schematic representation of the kinematics of a positioning device according to an embodiment; Fig. 2 shows a schematic representation of a measuring system with several measuring elements, which is integrated into the positioning device of Fig. 1 is integrated; Fig. 3 shows a schematic representation of an exemplary measuring arrangement as used in the measuring system of Fig. 2 can be used. Fig. Figure 4 shows a schematic representation of an alternative measuring arrangement as used in the measuring system of Fig. 2 can be used. Fig. Figure 5 shows a schematic representation of another alternative measuring arrangement as used in the measuring system of Fig. 2 can be used.

[0103] In Fig. 1 shows the kinematics of an exemplary positioning device 10 as a schematic kinematic model. The positioning device 10 is designed as a conventional six-jointed articulated-arm robot. Consequently, the kinematics shown correspond to an open kinematic chain, which is rigidly connected to the ground at one end 200 and has a mechanical interface 204 for attaching a tool and / or measuring sensor at a second end 202 facing away from the ground (which forms a reference location or point described above).

[0104] The first kinematic link K1 forms a base of the chain. The kinematic link K7, which has the interface 204, forms a frontmost kinematic link of the chain. The intermediate kinematic links K2-K6 are each connected at their two opposite ends to a rotary joint G1-G6 and, via this, to another kinematic link K1-K7 located there. In other words, these links are each positioned between two other kinematic links K1-K7 and / or connected at both ends to adjacent kinematic links K1-K7.

[0105] At least some of the kinematic links K1 - K7 are elongated, in particular at least some of the kinematic links K2 - K6 positioned between two further links. The longitudinal extension corresponds to the shown straight shape of the kinematic links K1 - K7. In particular, the longitudinal axes of the kinematic links K1 - K7 not separately shown can coincide with the respective straight lines of these links shown. However, the kinematic links K1 - K7 are shown schematically in a highly simplified manner. As can be seen from Fig. As can be seen in Figure 2, the kinematic elements K1 - K6 are actually designed as hollow cylinders.

[0106] Shown is a sequence of kinematic elements K1 - K7, connected to each other via rotational joints G1 - G6. The rotational joints G1 - G6 each allow rotation around a defined axis of rotation, thus exhibiting a defined degree of freedom for rotation or rotational movement. The position of the rotational axes is indicated by the symbols chosen near the joints G1 - G6 and the double arrows indicated there.

[0107] More precisely, the joints G1, G4, and G6, represented by two triangles with their bases opposite each other, have a rotation axis running in the plane of the drawing and parallel to the connected kinematic elements K1 - K7. The joints G2, G3, and G5, represented as a combination of a sphere in a hemispherical mount, have a rotation axis perpendicular to the plane of the drawing.

[0108] What is not shown separately is that each of the joints G1 - G6 has its own drive unit for performing the rotational movements around the corresponding rotation axis.

[0109] Fig. 2 primarily aims at illustrating the positioning and extension of components of a measuring system 12 of the positioning device 10 in relation to the Fig. 1 depicted basic kinematics. The measuring system 12 comprises measuring arrangements 14, explained below, for each of the rotary joints G1 - G6, together with a plurality of measuring elements M1 - M6. Not shown separately are the structural details of the rotary joints G1 - G6, which, however, can correspond to conventional joints for industrial robots. As will be seen from Fig. As shown in Figure 5, they comprise at least one rolling bearing and preferably also a rotary encoder. The area between two adjacent kinematic elements K1-K7, in which the joints G1-G6 are arranged, corresponds to a connection area into which the measuring arrangements 14 explained below also extend at least partially.

[0110] The measuring system 12 comprises for each rotary joint G1 - G6 a measuring arrangement 14 consisting of at least one measuring sensor 16 (herein also referred to simply as sensor) and at least one measuring device (or measuring embodiment) 18. The fork-shaped representation of the measuring sensors 16 is merely exemplary and in view of the following configurations of the Fig. 3-5. The measuring sensors 16 are preferably flat or planar. They can be positioned in various ways relative to a measuring device 18, for example, using a correspondingly fork-shaped holder, and in particular, grouped around it. A fork-shaped holder or a measuring arrangement 14 can therefore also have a plurality of measuring sensors 16.

[0111] The measuring device 18 is also depicted only schematically as a point or sphere. This indicates a center of at least one beam source of the measuring device 18. From this beam source, electromagnetic radiation and, in particular, light patterns can be radiated onto the measuring sensor(s) 16 of each measuring arrangement 14. This applies to the variants of the following Fig. 3 to 4, whereas Fig. 5 shows a measuring device 18 in the form of an optically detectable 3D topography. Instead of being arranged directly within the measuring device 18, the beam source could also be arranged outside of it (and in particular outside of the positioning device 10), and the radiation could be transmitted to the measuring device 18 via a light guide.

[0112] Not shown separately, but based on the Fig. 3 and Fig. 4 is that the measuring arrangements 14 can also each have at least one measuring sensor 16 which is positioned clearly outside of a rotary joint G1 - G6 assigned to a measuring arrangement 14.

[0113] The measuring system 12 also includes a sequence of measuring elements M0 - M6. Each measuring element M0 - M6 is assigned to one of the kinematic elements K1 - K7 and, in particular, is attached thereto. The attachment locations B0 - B6 are marked with a cross. As explained in the general description section, the measuring element M0 of the first kinematic element K1 is merely optional, since the unit of the measuring arrangement 14 located there (and, in the example shown, the measuring device 18) does not necessarily have to be positioned or held by a separate element. The reason for this is the increased stability of the first kinematic element K1, which forms a base with a limited longitudinal extension. The same applies to the measuring element M6 in the frontmost kinematic element K7.

[0114] The additional measuring elements M1 - M5, which are assigned to the kinematic elements K2 - K6 connected at both ends to adjacent elements, are elongated. The linear shape, shown only schematically, runs along the longitudinal axis of the respective measuring elements M1 - M5. It can be seen that these thus extend through essentially the entire length of an assigned kinematic element K1 - K6, but at least along more than half or more than three-quarters of this length.

[0115] It is further shown that all measuring elements M0 - M6 are housed within a cylindrical cavity of a respective kinematic element K1 - K7, i.e., they are positioned internally. The measuring arrangements 14 are also positioned internally, particularly since they are shielded from the environment by the joints G1 - G6 (not shown) and / or by the opposite end regions of the adjacent kinematic elements K1 - K7.

[0116] In summary, the positioning device 10 has an internal measuring sensor or an internal measuring system 12, which is protected from environmental influences that impair the measuring accuracy by the external kinematic elements K1 - K7 and / or joint components.

[0117] Furthermore, it is shown that the measuring elements M0 - M6 are not coupled to each other, let alone contacting each other. Direct force transmission between the measuring elements M0 - M6, and especially between consecutive or adjacent measuring elements M0 - M6, is therefore not possible.

[0118] The measuring elements M1 - M5, which are located opposite other measuring elements M0 - M7 on both sides or which are arranged between two other measuring elements M0 - M7, each have two end regions 20, 22 facing away from one another in the example shown. These are connected to one another by an elongated rod-shaped section. A respective fastening location B0 - B6 lies between the end regions 20, 22. In the exemplary embodiment shown, at least the measuring elements M1 - M5 therefore extend beyond their respective fastening locations B1 - B5 on both sides. The fastening can be achieved, for example, by means of a screwed clamp or bracket that holds and fixes the rod-shaped measuring element M0 - M6 at the respective fastening location B0 - B6.

[0119] In the following, reference is made to the first measuring element M1, the end regions 20, 22 of which are Fig. 2 are marked separately. The above statements also apply to the other measuring elements M2 - M5, which are positioned at both ends between other measuring elements M0 - M6.

[0120] At its first end region 20, the first measuring element M1 has at least one measuring sensor 16. This sensor is part of the measuring arrangement 14 for detecting relative position values ​​between the first two kinematic elements K1, K2. At its second end region 22, the first measuring element M1 has a measuring device 18, which is part of the measuring arrangement 14 between the second and third kinematic elements K2, K3.

[0121] It is not mandatory that different units of the respective measuring arrangements 14 are arranged at the end regions 20, 22 of a measuring element M0 - M6 (i.e., a measuring sensor 16 is provided at one end and a measuring device 18 at the other). Similar units can also be arranged there (see in Fig. 2, the measuring element M2 with two measuring sensors 16 and M3 with two measuring devices 18). This applies at least as long as different units (at least one measuring sensor 16 and at least one measuring device 18) opposite one another can interact in the area of ​​the joints G1 - G6.

[0122] Furthermore, it is also only optional for the measuring elements M0-M7 to extend beyond their respective mounting locations B0-B6 to the next (i.e., closer) joint G1-G6, where they hold one of the measuring device 18 and the measuring sensor 16. For example, the measuring elements M0-M7 could also each end at their respective mounting locations B0-B6 or at least not extend further to the next joint G1-G6. A measuring device 18 or the measuring sensor 16 located there can then be held by a separate mount.

[0123] However, it is advantageous for the solution shown if for each joint G1 - G6 there is a measuring element M0 - M7 extending to the joint, the fastening location B0 - B6 of which is spaced apart from this joint G1 - G6, in particular by more than half the length of the measuring element M0 - M7 and / or a kinematic element K1 - K7 assigned to it.

[0124] In summary, as a particularly preferred feature, the attachment locations B0-B6 are positioned such that each joint G1-G6 has only one attachment location B0-B6 in its vicinity (e.g., only one attachment location B0-B6 that is located at a distance of less than half the length of a respective kinematic element K1-K7 coupled by means of the joints G1-G6 from the corresponding joint G1-G6). However, from the correspondingly remotely mounted measuring element M0-M6, which extends to a joint G1-G6, changes in the position of the associated kinematic element K1-K7 can be mechanically detected over a wide range in the manner described and incorporated into a sensor measurement in the area of ​​this joint G1-G6.

[0125] In the case of the open kinematic chain shown, two consecutive fastening locations B0 - B6 are each spaced apart from each other by at least half, but preferably by at least two thirds or at least three quarters of the length of one of the kinematic links K1 - K7 which has one of these fastening locations B0 - B6.

[0126] Referring to the Fig. 2 lower measuring arrangement 14 or the rotation joint G1 there, the fastening point B1 is located near the end region 22 of the measuring element M1 remote from the rotation joint G1. This is equivalent to a positioning close to a (in Fig. 2 upper) end of the second kinematic link K2, which faces away from the first kinematic link K1. In particular, the attachment location B1 is significantly spaced from the rotational joint G1 and positioned closer to the end region 22 or the upper end of the kinematic link K2.

[0127] With reference to the relative position of the kinematic elements K1 and K2 to be determined, this means that at least one of the measuring elements M0, M1 (in this case the first measuring element M1) is positioned clearly spaced from the rotation joint G1 by means of which the kinematic elements K1 and K2 are attached to each other.

[0128] As described, deformations of the second kinematic element K2 can thus be transmitted to the measuring element M1 over a large part of its length, so that the unit of measuring sensor 16 and measuring device 18 coupled thereto can be displaced analogously to the kinematic element K2 and thus assumes a position representing the actual state of the second kinematic element K2. This can consequently result in a relative position of the measuring device 18 and the measuring sensor 16 that can be detected by the measuring arrangement 14.

[0129] Knowing the dimensions of the measuring elements M0 - M7 that are acceptable as constant and their relative positions to or within the respectively assigned kinematic elements K1 - K7, the relative position of the corresponding adjacent measuring elements M0 - M6 and / or kinematic elements K1 - K7 can also be determined based on this measured relative position of the measuring device 18 and the measuring sensor 16. As explained in the general description section, deviations from such dimensions, for example due to thermal expansion, can also be detected by sensors and taken into account mathematically when determining the aforementioned relative positions.

[0130] The measuring arrangements 14 are each configured to determine a position value (in this case, the angular position) of the measuring sensor 16 and the measuring device 18 about an axis parallel to the rotation axis of an associated joint G1 - G6 or about an axis coinciding with this rotation axis as a relative position value. However, since it cannot be ruled out that the measuring elements M0 - M6 are slightly displaced compared to an ideal, load-free position due to acting forces, these axes may extend at a slight angle (e.g., less than 5° or even less than 2°) to one another. Therefore, the relative position value may, under certain circumstances, refer to a rotational degree of freedom that does not exactly match that of the joint G1 - G6, but corresponds to it to a certain extent. This is referred to herein as determining a position value for a degree of freedom corresponding to the rotational axis.

[0131] However, such a deviation of the considered rotation axis has no decisive influence on the measurement accuracy with regard to the final coordinate determination of, for example, interface 204. For this purpose, it is more relevant to precisely determine the actual relative positions of the kinematic elements K1-K7, which is achieved according to the invention, in particular, by the arrangement of the mounting locations B0-B6. To determine these relative positions, the exact axes of rotation of the rotary joints G1-G6 do not necessarily have to be measured and / or observed.

[0132] The measuring arrangements 14 are further each configured to determine a corresponding position value for at least one further degree of freedom of the relative movement of the opposing measuring sensors 16 and measuring devices 18 and / or measuring elements M0 - M6 and / or kinematic elements K1 - K6. Preferably, and as shown in the examples of Fig. 3 - 5, corresponding relative position values ​​are determined for all six spatial degrees of freedom.

[0133] Not separately shown is that the measuring arrangements 14 transmit their measurement results, for example, via a data line, to a control device and / or a control computer of the positioning device 10. There, the measurement results can be evaluated in the manner described herein.

[0134] In particular, it can be provided that, as a higher-level objective of the position measurement with the measuring system 12, the absolute spatial coordinates of the interface 204 are determined. The interface 204 thus forms a predetermined reference point of the positioning device 10, whose spatial position is to be determined.

[0135] As an example, a fixed coordinate system is chosen as a reference coordinate system in which the spatial position of the base (i.e., the kinematic element K1) is known. Accordingly, the spatial position of the measuring device 18 located there is also known (or can be determined by knowing the relevant dimensions). The measuring device 18 or its absolute position forms a reference or reference point, based on which the spatial position of the interface 204 can be determined, taking into account the measured relative positions.

[0136] More precisely, the Fig. 2 first or lowermost measuring arrangement 14 determines the relative position of the measuring sensor 16 (and consequently of the measuring element M1 and / or kinematic element K2) to the measuring device 18 (or the measuring element M0 and / or kinematic element K1). In the case shown, this is done for each spatial degree of freedom.

[0137] If the relative position value measured for each degree of freedom is added to the known absolute position value for this degree of freedom, if necessary by adding relevant relative distances or other known geometric dimensions, an absolute position value can be determined for a further reference point (in particular along the measuring element 18). In other words, the absolute position of this further reference point is calculated taking into account the relative position detected by the sensor, i.e. the explicitly measured and preferably temporarily stored relative position value is incorporated into this position value as a calculated variable, in particular by addition. In the present case, in this way and with knowledge of the length of the first measuring element 18, for example, the absolute position of the measuring device 18, which is attached to the second end region 22 of the measuring element M1, is determined.

[0138] Since the measuring arrangement 14 in the associated joint G2 can then be used to determine the relative position of the measuring sensor 16 there to this measuring device 18, the absolute position of the measuring sensor 16 in the subsequent joint G3 can be determined analogously to the above method. This can be continued until the kinematic element K7 is reached. There, knowing the (fixed or structurally determined) relative position of the interface 204 to the measuring sensor 16 there, the absolute position of the interface 204 can be determined. This is done analogously to the above-described determination of the absolute position of the measuring device 18 of the second kinematic element K2.

[0139] Also indicated only very schematically is a measuring sensor in the form of a stylus 206, which is arranged at the interface 204 and has a probe sphere 208 at its tip. Given known dimensions of this stylus 206, the coordinates of the probe sphere 208 can be determined. If this comes into contact with a schematically indicated object 210 (in particular, an industrially manufactured workpiece), the coordinates of the probed surface location of the object 210 can be determined analogously to conventional coordinate measuring machines.

[0140] In the following, referring first to Fig. 3 is a part of a measuring system 12 which is used in the positioning device 10 from Fig. 2, is shown in a schematic plan view. The measuring arrangement 14 between the first and second kinematic elements K1, K2, as well as the first measuring element M1, are shown as an example. The axis of rotation R of the joint G1 is shown, along which the kinematic elements K1, K2 are connected to one another via a rolling bearing (not shown separately) and the associated connecting elements.

[0141] The first kinematic link K1 is stationary. The second kinematic link K2 rotates relative to it about the rotation axis R, with the motive force again being generated by a drive unit (not shown) of this joint G1. The internal measuring element M1, attached to the kinematic link K2 at location B2, rotates accordingly together with the kinematic link K2.

[0142] In the illustrated case, the measuring device 18 is configured to generate (light) signals in the form of electromagnetic radiation. For this purpose, three individual beam sources 30 are shown merely as an example, which radiate radiation at partially overlapping solid angles. Preferably, the beam sources 30 each comprise at least one laser diode.

[0143] However, it can also be provided that the measuring device 18 comprises only a beam source 30 in the form of a projector. This can, for example, radiate radiation into a three-dimensional and, for example, conical solid angle range in the manner of a planetarium projector. The radiated radiation can comprise light patterns and, in particular, structured light according to any of the types explained herein.

[0144] In particular, the beam source 30 can be a light source that can preferably be viewed from a plurality of, and preferably any, spatial direction(s) and / or emits radiation in a plurality of, and preferably any, spatial direction. In this case, a spatially and / or directionally structured radiation is preferably emitted by the beam source 30. The radiation is preferably designed in such a way that even by merely observing or detecting a section of this radiation, an unambiguous identification of the detected section can be achieved, at least in some areas. This can include relating this section to the entire emission segment or volume. The radiation is therefore preferably unambiguously coded and / or resolved over its entire solid angle range (e.g., 4Pi in steradients). The beam source 30 can comprise a diffractively or refractively emitting element and / or can be designed micro-optically.Alternatively, holographic approaches can be used to structure the radiation of the beam source 30.

[0145] The measuring sensors 16 are each light-sensitive and spatially resolving. More precisely, they are sensitive to wavelength ranges of electromagnetic radiation and can measure incident radiation intensity. For this purpose, they are each flat and have a matrix or grid composed of a plurality of individual detector pixels. The grid is preferably a SPAD array of the type explained in the general description section. The sensor planes (i.e., the plane in which the grid or matrix extends) are perpendicular to the plane of the page in all of the cases shown. This corresponds to an alignment of the sensor planes perpendicular to a plane containing a longitudinal axis L of at least the kinematic element K2 and the rotation axis R.

[0146] The measuring sensors 16 are each configured to detect distributions of the incident radiation in the respective sensor plane. This can be evaluated by the control device (not shown) to determine a lateral offset between the measuring device 18 (and / or its at least one radiation source 30) and the measuring sensors 16, for example, relative to a predefined relative neutral position of these units 16, 18. From this, relative position values ​​for all six spatial degrees of freedom can be determined in the manner described below.

[0147] The degrees of freedom result from the coordinate system of the Fig. 3. The Z-axis corresponds to a vertical spatial axis, which runs along a longitudinal axis of the first kinematic element K1 (not shown separately). The X and Y axes span a horizontal spatial plane. The rotational degrees of freedom A, B, and C shown represent rotations around the associated X, Y, and Z axes, respectively.

[0148] Shown are two measuring sensors 16, whose sensor planes run parallel to the longitudinal axis L and which are opposite each other along the X-axis. More precisely, these sensors accommodate the measuring device 18 between them or are located opposite each other on opposite sides of the measuring device 18. Furthermore, they are preferably intersected by the rotation axis R, advantageously intersected orthogonally (i.e., the rotation axis R runs perpendicular to the corresponding sensor planes).

[0149] Based on the measured values ​​determined with these measuring sensors 16, and more precisely, the respective recorded intensity distributions, relative offsets of the measuring element M1 to the measuring device 18 in the Y and Z directions can be measured, for example, using a calibration table. In particular, if the respective opposing radiation sources 30 radiate similar and / or suitably coded light patterns onto the opposing measuring sensors 16, the rotational position about the Y axis according to the rotational degree of freedom B can also be determined by comparing the measured values ​​respectively recorded with these measuring sensors 16.

[0150] Also shown are two measuring sensors 16 positioned in a common plane and on either side of the longitudinal axis L, whose sensor planes extend orthogonally to the longitudinal axis L and parallel to the X-axis and rotational axis R. Using these measuring sensors 16, a relative offset along the X-axis can be determined. Furthermore, a comparison of the measured values ​​of the respective sensors 16 can be used to determine a relative inclination and a torsional deformation about the Z-axis causing this inclination (i.e., a position corresponding to the rotational degree of freedom C).

[0151] For the remaining rotational degree of freedom A, which is the essential degree of deflection of the measuring element M1, a measuring sensor 16 of the measuring arrangement 14 is shown as an advantageous variant, which is positioned closer to the mounting location B2 of the measuring element M1 than to the observed or measured rotational joint G1. A sensor plane of this measuring sensor 16 is perpendicular to the longitudinal axis L and preferably parallel to the rotational axis R.

[0152] In a bend-free neutral position, this measuring sensor 16 detects the radiation radiated by the central radiation source 30, in the case shown, as a defined intensity distribution. If, due to deflection, the measuring element M1 is raised or lowered in its end region 22, which is correspondingly distant from the joint G1, the relative position of the measuring sensor 16 positioned there also changes relative to the radiation source 30. Accordingly, this measuring sensor 16 will also detect a different intensity distribution in its sensor plane.

[0153] Again, depending on the recorded intensity distribution, the current relative position of the measuring sensor 16 and the radiation source 30 with respect to the rotational degree of freedom A can be determined, preferably using a previously stored calibration table.

[0154] Based on the position values ​​determined for the individual degrees of freedom and knowing the spatial extent of the measuring element M1 as well as the absolute position of the measuring device 18 in the joint G1, the absolute spatial position can then be determined automatically by the control device for the end region 22 and any reference location defined there.

[0155] It is indicated, for example, that in the end region 22 a measuring device 18 is also arranged, which projects into the following joint G2 or interacts with opposite measuring sensors 16 of the following measuring element M2 (see Fig. 2). The absolute position of this measuring device 18 can be determined based on the determined absolute position of the reference location. In particular, this measuring device 18 itself can form or contain the reference location.

[0156] In this way, the complete spatial relative position of the coupled kinematic elements K1, K2 can be determined with respect to all spatial degrees of freedom using only rotary encoders (corresponding to the rotation axis R of the rotary joint G1), in contrast to the conventional measurement of only a single rotational degree of freedom. Since the relative position values ​​determined for each degree of freedom are added together to determine absolute reference position values, the accuracy of determining this reference position is significantly increased.

[0157] In Fig. 4 is one opposite Fig. 3 shows an alternative measuring arrangement 14, shown in a highly simplified manner. This can also be used to measure the relative position of the kinematic elements K1, K2 in particular from Fig. 2. The measuring device 18, whose extension is outlined in dashed lines, is arranged on a measuring element M0, which extends along the again vertical spatial axis Z. The further kinematic element K2 and the measuring element M1, whose longitudinal axis L is indicated, extend at an angle to the Z-axis. A rotation axis R of the first rotary joint G1, also not shown separately, runs along the Z-axis, so that the kinematic element K2 can at least partially accommodate the measuring device 18, but can rotate about it. This essentially corresponds to the configuration of the first axis or a first joint of a SCARA robot.

[0158] Arrows indicate individual radiation sources 30 and their incident directions. The radiation emitted by these sources (preferably light radiation and / or radiation in the optically visible range) is directed toward optically scattering and / or reflecting elements 31. These distribute the radiation in a spatially defined manner and direct it toward the again planar measuring sensors 16.

[0159] The measuring sensors 16 are in turn grouped around the measuring device 18 in such a way that they can determine the relative position of the measuring elements M0, M1 with respect to all six spatial degrees of freedom. All of the measuring sensors 16 in turn determine lateral offsets relative to the measuring device 18 or the light patterns or light distributions generated thereby according to any of the approaches described herein.

[0160] As an example, this degree of freedom determination is carried out as follows: Two of the measuring sensors 16 are aligned parallel to each other, face each other along an axis designated Q, and enclose the measuring device 18 between them. Based on the respective recorded intensity distributions, lateral offsets in the Y and Z directions can be determined. A rotation around the Z axis can be determined by comparing the recorded results.

[0161] With another in Fig. 4 displacements along the X-axis can be detected by the measuring sensor 16 positioned furthest forward along the longitudinal axis L and directly opposite the observer.

[0162] The deflection around the X-axis can be measured with the measuring sensor 16, positioned along the longitudinal axis L and significantly away from the measuring device 18. The torsional degree of freedom (i.e., rotation around the Y-axis) can be determined by comparing the measured values ​​of both measuring sensors 16, positioned parallel to each other along the longitudinal axis L and accommodating the measuring device 18 between them.

[0163] In Fig. 5 shows yet another embodiment. Here, a first and second kinematic element K1, K2 are shown as examples, which are analogous to the variant from Fig. 2 are arranged within a positioning device 10, which is otherwise not shown in detail. The kinematic elements K1, K2 are not shown in full. In particular, a central portion of the second kinematic element K2 has been omitted, so that only its end regions 20, 22 are shown.

[0164] The kinematic elements K1, K2 are again hollow and accommodate measuring elements M0, M1. The measuring element M1 of the second kinematic element K2 is also shown as openwork (i.e., without a central section). The measuring element M1 is attached to a mounting location B1 on an inner end face of the kinematic element K2. Also indicated very schematically is a measuring device 18, which is attached to an inner side or end face of the kinematic element K2 facing away from the mounting location B1.

[0165] The kinematic elements K1, K2 are connected to each other via a rotary joint G1, resulting in the indicated rotation axis R. Roller bearings W1 are also shown as an example, which rotatably support a bearing journal of the first kinematic element K1. Also shown is the position of a known encoder 209 for measuring the angle of rotation of the kinematic elements K1, K2.

[0166] The measuring elements M0, M1 are not directly connected to or mounted within the rotary joint G1. As mentioned, the mounting location B1 of the first kinematic element K1 is instead positioned remotely from the joint G1 (in the far end region 22). The same applies to the zeroth measuring element M0, even though its mounting location is not listed separately.

[0167] In the variant shown, the measuring sensors 16 for measuring a multi-part measuring device 18 (or also a plurality of individual measuring devices 18) are positioned on the measuring element M1, for example, which are arranged in an opposite region of the zeroth measuring element M0.

[0168] The measuring sensors 16 are optical sensors designed to detect height variations of the measuring device 18. For example, they can be optical distance sensors and, in particular, triangulation sensors. Therefore, highly simplified beam paths S are also schematically indicated, which depict a path of the laser radiation emitted by the measuring sensors 16 and its reflections on an opposite measuring device 18. The measuring devices 18 preferably have three-dimensional (3D) optically detectable topographies.

[0169] By way of example only, two of the measuring sensors 16 are positioned externally along the X-axis (i.e., close to the respective inner walls of the surrounding kinematic elements K1, K2) and are located there opposite a measuring device 18. Intermediate along the X-axis are two measuring sensors 16, which irradiate different outer sides of a measuring device 18 positioned between them.

[0170] A relative rotation of the measuring elements M0, M1 about the X-axis (ie a movement which essentially corresponds to a rotation about the parallel rotation axis R) can in principle be detected by all of the measuring sensors 16.

[0171] A movement along the X-axis can be determined based on a deviation of the distance signals detected by the two middle or inner measuring sensors 16.

[0172] When rotating around the Z-axis, the external measuring sensors 16 provide opposing measuring signals (i.e. indicate different directions of rotation).

[0173] The detection of additional degrees of freedom (in particular, a rotation around Y and / or a translation along Y and / or Z) is not mandatory. However, the topographies, and in particular the central topography, can be designed in such a way that they reflect differently depending on the movement (rotation or translation). In particular, motion-dependent parallax effects can also occur in the view of the central sensors 16, which allow a differentiation between rotation and translation, and thus, for example, a Y translation can also be detected.

[0174] Finally, it should be noted that the division of measuring sensors 16 and measuring devices 18 within a measuring arrangement 14 into one of the measuring elements M0 - M6 as shown in the preceding figures is not mandatory. The measuring elements M0 - M6 can also have mixed forms, ie, they can carry both measuring sensors 16 and measuring devices 18. By way of example, referring to Fig. 5, for example, the external measuring sensors 16 could each be positioned at the zeroth measuring element M0 and the measuring devices 18 there could instead be positioned at the first measuring element M1 (i.e., an inverted arrangement could be provided there compared to the variant shown).

Claims

[1] Positioning device (10) with position measuring function, in particular for positioning a coordinate measuring sensor (206), wherein the positioning device (10) has a first kinematic member (K1) and at least one second kinematic member (K2) to which a first measuring member (M1) is fastened, wherein the first and second kinematic members (K1, K2) are connected to one another via a joint (G1); wherein one of at least one measuring device (18) and at least one sensor (16) for detecting the measuring device (18) and / or signals emitted therefrom is arranged on the first measuring element (M1) and is movable together with the second kinematic element (K2) relative to the first kinematic element (K1), and the corresponding other of the measuring device (18) and sensor (16) is arranged at least indirectly on the first kinematic element (K1) and is movable together with the first kinematic element (K1) relative to the second kinematic element (K2) and its measuring element (M1), wherein, on the basis of the sensory detection, in addition to a relative position value corresponding to the degree of freedom of the joint (G1), at least one further relative position value for another degree of freedom can be determined; and wherein a fastening location (B1) of the first measuring element (M1) on the second kinematic element (K2) is closer to an end of the second kinematic element (K2) remote from the joint (G1) than to the joint (G1). [2] Positioning device according to claim 1, wherein the sensor (16) is configured for contactless detection and in particular for optical detection of the measuring device (18) and / or signals emitted therefrom; and / or wherein an indirect arrangement on the first kinematic element (K1) comprises that a further measuring element (M0) is fastened to the first kinematic element (K1), on which the corresponding other of the measuring device (18) and the sensor (16) is arranged. [3] Positioning device according to claim 1 or 2, wherein the first measuring element (M1) and the first kinematic element (K1) do not contact each other; and / or wherein the first measuring element (M1) is at least not directly connected to the joint (G1). [4] Positioning device according to one of the preceding claims, wherein the first measuring element (M1) is at least partially accommodated in a hollow body section of the associated second kinematic element (K2). [5] Positioning device according to one of the preceding claims, wherein the sensor (16) and the measuring device (18) are arranged opposite one another in the region of the joint (G1). [6] Positioning device (10) according to one of the preceding claims, wherein an absolute position value of at least one reference location (202) of the positioning device (10) is determined on the basis of at least one of the relative position values. [7] Positioning device (10) according to claim 6, comprising at least one further kinematic element (K3) with an associated second measuring element (M2), wherein the further kinematic element (K3) is connected to the second kinematic element (K2) via a second joint (G2), wherein a relative position value between the first and second measuring element (M1, M2) can also be determined and the absolute position value of the reference location (202) is also determined on the basis of this relative position value. [8] Positioning device (10) according to one of the preceding claims, wherein the joint (G1) comprises a position sensor (209) and wherein a final position value can be determined on the basis of both the sensor measured values ​​of this position sensor (209) and the relative position values ​​detected by the sensor (16). [9] Positioning device (10) according to one of the preceding claims, wherein the measuring device (18) comprises at least one radiation source (30) for generating electromagnetic radiation as a signal of the measuring device or is connected to such a radiation source (30) and wherein the sensor (16) is arranged to detect the radiation. [10] Positioning device (10) according to one of the preceding claims, wherein the sensor (16) is spatially resolving and / or wherein a relative arrangement of sensor (16) and measuring device (18) can be determined on the basis of the sensor detection. [11] Positioning device (10) according to one of the preceding claims, wherein the relative position value relates to a bending degree of freedom and the sensor (16) is arranged closer to the attachment location (B1) than to the joint (G1). [12] Positioning device (10) according to claim 11 with the exception of claim 5, wherein at least two sensors (16) are provided and the relative position value is determined based on a difference between the respective detection results of the sensors (16). [13] Positioning device (10) according to one of the preceding claims, wherein the positioning device (10) is a robot, in particular for object measurement; and / or wherein a plurality of sensors (16) are provided, by means of which relative position values ​​with respect to all six spatial degrees of freedom can be determined. [14] Method for operating a positioning device (10), wherein the positioning device (10) has a first kinematic member (K1) and at least one second kinematic member (K2) to which a first measuring member (M1) is fastened, wherein the first and second kinematic members (K1, K2) are connected to one another via a joint (G1); wherein one of at least one measuring device (18) and at least one sensor (16) for detecting the measuring device (18) and / or signals emitted therefrom is arranged on the first measuring element (M1) and is movable together with the second kinematic element (K2) relative to the first kinematic element (K1), and the corresponding other of the measuring device (18) and sensor (16) is arranged at least indirectly on the first kinematic element (K1) and is movable together with the first kinematic element (K1) relative to the second kinematic element (K2) and its measuring element (M1), wherein a mounting location (B1) of the first measuring element (M1) on the second kinematic element (K2) is closer to an end of the second kinematic element (K2) remote from the joint (G1) than to the joint (G1), the method comprising: - Determining at least one relative position value based on the sensor detection. [15] The method of claim 14, further comprising: - Determining, by means of the positioning device (10), a relative arrangement of the positioning device (10) and / or a tool or measuring sensor (206) attached thereto to an object (210) to be measured; - Determining a measured value relating to the object (210), in particular an object coordinate value, taking into account the relative position value.

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