Measuring instrument for dimensional measurement, use of the measuring instrument and method for dimensional measurement, as well as computer program

Abstract

Measuring device (10) for dimensionally measuring a measuring object (14) located in a measuring volume of the measuring device (10), comprising: - a measuring head (28) which is configured to acquire dimensional measurement data of the object being measured (14); - a guide structure (30) which is configured to guide the measuring head (28) and / or the object being measured (14) and to move it within the measuring volume, wherein at least one measuring device (22, 24, 26) is assigned to the guide structure (30) which is configured to record position data of the guide structure (30) from which a pose of the measuring head (28) can be calculated; - several temperature sensor units (40) configured to record temperature data for the measurement volume; and - an evaluation and control unit (34) designed to process the dimensional measurement data and the position data and to correct the dimensional measurement data and / or the position data based on the temperature data, wherein the temperature sensor units (40) each comprise a carrier device (44), a temperature sensor (42) connected to the carrier device (44) and a heating element (50) connected to the carrier device (44), wherein the evaluation and control unit (34) is configured to activate the heating elements (50) of the temperature sensor units (40) and to analyze a temperature profile over time based on the temperature data recorded by the temperature sensors (42) in order to use it (i) to detect a defect in at least one of the temperature sensor units (40); and / or (ii) to determine if at least one of the temperature sensor units (40) has not been installed correctly.

Description

[0001] The present invention relates to a measuring device for the dimensional measurement of a measurement object located within a measurement volume of the measuring device. The present invention further relates to a use of the measuring device and a method for the dimensional measurement of a measurement object located within a measurement volume. The present invention further relates to a computer program comprising software code configured to execute the inventive method when executed on a computer.

[0002] The measuring device according to the invention comprises a measuring head configured to acquire dimensional measurement data of the measurement object; a guide structure configured to guide the measuring head and / or the measurement object and to move it within the measurement volume, wherein at least one measuring device is assigned to the guide structure and is configured to acquire position data of the guide structure, based on which a pose of the measuring head can be calculated; a plurality of temperature sensor units configured to acquire temperature data relating to the measurement volume; and an evaluation and control unit configured to process the dimensional measurement data and the position data and to correct the dimensional measurement data and / or the position data based on the temperature data.

[0003] The measuring device according to the invention is preferably a coordinate measuring machine, whereby the term "coordinate measuring machine" is to be interpreted broadly in the present sense, so that any measuring device that serves to dimensionally measure and record the spatial coordinates of a measurement object is to be understood as a coordinate measuring machine in the sense of the invention. As an alternative to the conventional designs of such coordinate measuring machines (e.g., cantilever design, bridge design, gantry design, and column design), the measuring head of the measuring device according to the invention can thus also be attached, for example, to one end of a robot arm, e.g., an articulated-arm robot, in order to realize a measuring device or coordinate measuring machine in the present sense.

[0004] Coordinate measuring machines are used, for example, for quality assurance purposes, to inspect workpieces or to fully determine the geometry of a workpiece as part of a so-called "reverse engineering" process. A wide range of other applications are also conceivable, such as process control applications, in which dimensional measurement technology is directly applied for online monitoring and control of manufacturing and machining processes.

[0005] Coordinate measuring machines can use various types of sensors to detect the object being measured (the target). These sensors are typically mounted on a measuring head of the coordinate measuring machine. In addition to the actual sensors, the corresponding sensing elements are also attached to this measuring head. Depending on the type of sensor, these sensing elements can be, for example, one or more tactile styli or optical elements of an optical measuring sensor.

[0006] With tactile measurement sensors, the object being measured is contacted at several defined points. Optical sensors, on the other hand, enable contactless detection of the coordinates of a measuring object. There are also so-called multi-sensor systems in which several tactile and / or optical sensors are used together.

[0007] The high precision requirements placed on coordinate measuring machines in practice have led to a steady increase in their measuring accuracy over the years through various developments. For example, the measuring accuracy of some state-of-the-art coordinate measuring machines is now a few tenths of a micrometer or even less.

[0008] It's easy to understand that, within this accuracy range, external environmental influences can create interference that negatively impact measurement accuracy. Under laboratory conditions, environmental influences, such as external forces or temperature changes, can be minimized to a large extent. However, this is much more difficult to achieve when using the coordinate measuring machine in a production-like environment.

[0009] Temperature fluctuations, e.g., caused by switching internal heat sources such as electronic components, lamps, motors, etc. on or off, lead to rotational and longitudinal changes in the coordinate measuring machine's structure. Furthermore, fluctuations in the ambient temperature can be coupled into the overall system of the coordinate measuring machine, thus causing further thermal distortions. The consequence of these rotational and longitudinal changes and the thermal distortions is a "wandering" or "drifting" of the measuring object. This has a direct impact on the accuracy of the coordinate measuring machine.

[0010] Various approaches to correcting these thermal influences in coordinate measuring machines are already known from the state of the art. Examples of methods for correcting a temperature error during a measurement with a coordinate measuring machine are known from the following publications: Schalz, KJ: "Thermo-Vollfehler-Korrektur für Koordinaten-Meßgeräte" (Thermal Full Error Correction for Coordinate Measuring Machines), in Feinwerktechnik & Meßtechnik, Volume 98, No. 10, October 1, 1990; US 2021 / 0 191 359 A1 and DE 101 38 138 A1.

[0011] In the aforementioned methods, an attempt is always made to collect temperature data using several temperature sensors and to mathematically correct the thermally induced deformations of the measuring device using the temperature data provided by the temperature sensors.

[0012] One way to correct thermal deformation resulting from internal and external heat sources is to use a so-called temperature-strain correction. Temperature sensors are installed at significant locations on the measuring device. The temperature sensors serve to approximate the overall temperature field acting on the structure of the measuring device. If the relationship between temperature and strain fields is stored in a model, the thermal deformation at different structural points or structural elements of the measuring device can be mathematically predicted and corrected.

[0013] According to the current state-of-the-art solutions, the temperature sensors used for this purpose are usually glued to various positions on the measuring device. The temperature signals generated by the temperature sensors are sent to the measuring device's evaluation and control unit, where the temperature data is evaluated and processed.

[0014] In practice, the following disadvantages arise in particular: (1) Ensuring consistent positioning of temperature sensors is usually either very costly or impossible in practice. However, precise sensor positioning at a defined location is essential for the robust and efficient functioning of a computational temperature correction. It is easy to understand that fluctuations in sensor positioning and orientation result in fluctuations in the correction quality. (2) With a larger number and / or longer supply lines, the temperature sensors currently used for the above-mentioned purposes are extremely difficult to handle and to distinguish from one another. (3) The assignment of the individual temperature sensors to the respective location or position on the measuring device also represents a significant problem. (4) Particularly in the case of adhesive joints, a temperature sensor may become detached from the measuring device. In this case, the temperature sensor measures the ambient temperature of the measuring device instead of the temperature of the respective structural element of the measuring device. This also leads to a correction error and thus to inaccuracies in the correction result. (5) When using multiple temperature sensors, it is often extremely difficult to check the functionality and to directly assign the error (e.g. a defective cable or a defective interface) to the respective temperature sensor.

[0015] DE 10 2019 134 019 A1 relates to a device for in situ calibration and / or validation of a thermometer with at least one temperature sensor and at least one reference element, which reference element consists at least partially of a material for which material at least one phase transition takes place at at least one predetermined phase transition temperature within the temperature range relevant for the operation of the thermometer, at which phase transition the material remains in the solid phase, and a corresponding method.According to the invention, the device has a communication module designed to communicate with a higher-level unit, in particular a process controller, which unit serves to control a process in which the device can be used, and to transmit at least one statement about an operating state, in particular a calibration and / or validation of the temperature sensor to the higher-level unit, and / or to receive at least one statement about a process state, in particular about a maintenance and / or calibration interval, from the higher-level unit. DE 10 2005 039 439 A1 relates to a device for temperature measurement. EP 2 142 878 B1 relates to an analog sensor with temperature control. DE 10 2017 006 454 B4 relates to a sensor and method for calibrating a sensor. DE 103 56 367 A1 relates to a component and a method for its production.

[0016] Against this background, it is an object of the present invention to provide a measuring device, a corresponding method, and a computer program that can overcome the aforementioned problems. In particular, the object is to improve the method of mounting the temperature sensors, simplify their assignment, and make it easier to verify their proper mounting, ultimately enabling even better computational compensation for temperature-related deformations of the measuring device.

[0017] According to a first aspect of the present invention, this object is achieved by a measuring device for dimensionally measuring a measurement object located in a measuring volume of the measuring device, wherein the measuring device comprises: - a measuring head designed to acquire dimensional measurement data of the measuring object; - a guide structure which is designed to guide the measuring head and / or the measuring object and to move it in the measuring volume, wherein the guide structure is assigned at least one measuring device which is designed to record position data of the guide structure, on the basis of which a pose of the measuring head can be calculated; - a plurality of temperature sensor units configured to acquire temperature data relating to the measurement volume; and - an evaluation and control unit designed to process the dimensional measurement data and the position data and to correct the dimensional measurement data and / or the position data based on the temperature data, wherein the temperature sensor units each comprise a carrier device, a temperature sensor connected to the carrier device and a heating element connected to the carrier device, wherein the evaluation and control unit is designed to activate the heating elements of the temperature sensor units and to analyse a temporal temperature profile based on the temperature data recorded by the temperature sensors in order to (i) to detect a defect in at least one of the temperature sensor units (40); and / or (ii) detect improper attachment of at least one of the temperature sensor units (40).

[0018] According to a second aspect of the present invention, the above-mentioned object is achieved by a measuring device for dimensionally measuring a measurement object located in a measuring volume of the measuring device, the measuring device comprising: - a measuring head designed to acquire dimensional measurement data of the measuring object; - a guide structure which is designed to guide the measuring head and / or the measuring object and to move it in the measuring volume, wherein the guide structure is assigned at least one measuring device which is designed to record position data of the guide structure, on the basis of which a pose of the measuring head can be calculated; - a plurality of temperature sensor units configured to acquire temperature data relating to the measurement volume; and - an evaluation and control unit designed to process the dimensional measurement data and the position data and to correct the dimensional measurement data and / or the position data based on the temperature data, wherein the temperature sensor units each comprise a carrier device, a temperature sensor connected to the carrier device and a heating element connected to the carrier device, wherein the temperature sensor units each have a light source, and wherein the illuminant is the heating element of the respective temperature sensor unit.

[0019] According to a third aspect of the present invention, the above-mentioned object is achieved by a measuring device for dimensionally measuring a measurement object located in a measuring volume of the measuring device, the measuring device comprising: - a measuring head designed to acquire dimensional measurement data of the measuring object; - a guide structure which is designed to guide the measuring head and / or the measuring object and to move it in the measuring volume, wherein the guide structure is assigned at least one measuring device which is designed to record position data of the guide structure, on the basis of which a pose of the measuring head can be calculated; - a plurality of temperature sensor units configured to acquire temperature data relating to the measurement volume; and - an evaluation and control unit designed to process the dimensional measurement data and the position data and to correct the dimensional measurement data and / or the position data based on the temperature data, wherein the temperature sensor units each comprise a carrier device, a temperature sensor connected to the carrier device and a heating element connected to the carrier device, wherein the temperature sensor units each have a light source, and wherein the evaluation and control unit is configured to activate the lighting means of the temperature sensor units with a time delay from one another.

[0020] According to a fourth aspect of the present invention, the above-mentioned object is achieved by a measuring device for dimensionally measuring a measurement object located in a measuring volume of the measuring device, the measuring device comprising: - a measuring head designed to acquire dimensional measurement data of the measuring object; - a guide structure which is designed to guide the measuring head and / or the measuring object and to move it in the measuring volume, wherein the guide structure is assigned at least one measuring device which is designed to record position data of the guide structure, on the basis of which a pose of the measuring head can be calculated; - a plurality of temperature sensor units configured to acquire temperature data relating to the measurement volume; and - an evaluation and control unit designed to process the dimensional measurement data and the position data and to correct the dimensional measurement data and / or the position data based on the temperature data, wherein the temperature sensor units each comprise a carrier device, a temperature sensor connected to the carrier device and a heating element connected to the carrier device, wherein the temperature sensor units each have a light source, and wherein the evaluation and control unit has a plurality of signal channels, wherein each of the signal channels is assigned one of the temperature sensors, and wherein each of the signal channels is assigned a second illuminating means which is configured to light up upon activation of the respective signal channel.

[0021] According to a fifth aspect of the present invention, the above-mentioned object is achieved by using the measuring device according to the invention to: (i) to use the temperature data to determine a defect in at least one of the temperature sensor units; and / or (ii) to use the temperature data to determine whether at least one of the temperature sensor units has been improperly mounted.

[0022] According to a sixth aspect of the present invention, the above-mentioned object is achieved by a method for dimensional measurement of a measurement object located in a measurement volume, which method comprises the following steps: - Acquiring dimensional measurement data of the measuring object using a measuring head of a measuring device and acquiring position data on the basis of which a pose of the measuring head can be calculated; - collecting temperature data on the measurement volume using a plurality of temperature sensor units, each comprising a carrier device, a temperature sensor connected to the carrier device and a heating element connected to the carrier device; - activating the heating elements (50) of the temperature sensor units (40) and analyzing, based on the temperature data detected by the temperature sensors (42), a temporal temperature profile in order to (i) to detect a defect in at least one of the temperature sensor units (40), and / or (ii) detect improper attachment of at least one of the temperature sensor units (40); and - Correcting the dimensional measurement data and / or the position data based on the temperature data.

[0023] According to a seventh aspect of the present invention, the above object is achieved by a method according to claim 16.

[0024] According to an eighth aspect of the present invention, the above object is achieved by a method according to claim 17.

[0025] According to an eighth aspect of the present invention, the above object is achieved by a method according to claim 18.

[0026] Furthermore, according to a further aspect, the above-mentioned object is achieved by a computer program which has a software code which is designed to carry out the method according to the invention when executed on a computer.

[0027] It is understood that the features defined in the dependent claims and the design options mentioned in the following description relate not only to the measuring device according to the invention, but also, in a corresponding manner, to the use according to the invention, the method according to the invention, and the computer program according to the invention. For the sake of simplicity, the design options are explained below essentially with reference to the measuring device according to the invention, without explicitly listing the corresponding features again as equivalent method features.

[0028] The temperature sensor units used in the measuring device according to the invention each comprise a support device, a temperature sensor connected to the support device, and a heating element connected to the support device. This type of sensor design offers various advantages. The support device acts as a common support structure for the temperature sensor and the heating element. This enables a stable and space-saving arrangement of the temperature sensor. Furthermore, with the aid of the support device, the temperature sensor can be arranged at a desired position on the measuring device or its guide structure in a clearly defined and time-invariable manner.

[0029] The provision of a heating element, which is connected together with the temperature sensor to the support device of the respective temperature sensor unit, has the additional advantage of making it possible to detect a defect in at least the temperature sensor and / or to check whether the temperature sensor unit is properly attached to the measuring device. By selectively activating and deactivating the heating elements of the individual temperature sensor units and subsequently evaluating the temperature data provided by the temperature sensors, it is easy to determine whether a temperature sensor unit or parts thereof are defective or whether the temperature sensor unit is improperly attached.

[0030] For example, the heating elements of the temperature sensor units are switched on (activated) and then switched off again (deactivated) after a predefined period of time. During this time, the temperature data supplied by the temperature sensors, which preferably comprise time-dependent temperature signals, are evaluated in the evaluation and control unit. If an expected temperature increase is recorded by a temperature sensor during a time interval in which a specific heating element was activated, this can be used to determine relatively clearly whether the respective temperature sensor unit is correctly attached to the measuring device and / or whether the temperature sensor is generally defective. If the temperature sensor unit has become detached from the measuring device, a different course of the time-dependent temperature signal can generally be expected than if the temperature sensor unit is correctly attached to the measuring device.

[0031] The provision of at least one light source per temperature sensor unit further simplifies the assignment of the individual temperature sensors to one another.

[0032] The provision of an evaluation and control unit with multiple signal channels, wherein each of the signal channels is assigned one of the temperature sensors, and wherein each of the signal channels is assigned a second light source configured to illuminate upon activation of the respective signal channel, further simplifies the optical assignment of the temperature sensors to the individual signal channels of the evaluation and control unit. During the visual inspection, for example, it is immediately apparent whether the correspondingly selected temperature sensor is assigned to the correct signal channel of the evaluation and control unit. In such a case, the second light source assigned to the respective signal channel should illuminate simultaneously with the light source of the selected temperature sensor unit.If the two lamps do not light up synchronously, an incorrect assignment was obviously selected or the corresponding temperature sensor unit is not correctly connected to the evaluation and control unit.

[0033] According to one embodiment, the evaluation and control unit is configured to compare the temperature data with a predefined, absolute temperature setpoint and / or to analyze a temporal temperature profile in order to determine a defect in at least one of the temperature sensor units; and / or to determine an improper attachment of at least one of the temperature sensor units.

[0034] For example, the heating elements of the temperature sensor units are switched on (activated) and then switched off again (deactivated) after a predefined period of time. During this time, the temperature data supplied by the temperature sensors, which preferably comprise time-dependent temperature signals, are evaluated in the evaluation and control unit. If an expected temperature increase is recorded by a temperature sensor during a time interval in which a specific heating element was activated, this can be used to determine relatively clearly whether the respective temperature sensor unit is correctly attached to the measuring device and / or whether the temperature sensor is generally defective. If the temperature sensor unit has become detached from the measuring device, a different course of the time-dependent temperature signal can generally be expected than if the temperature sensor unit is correctly attached to the measuring device.

[0035] The heating elements are preferably electrical heating elements. However, it should be noted at this point that any type of electrical device is considered a heating element in the present sense, provided that the respective device actively generates heat when activated or switched on. For example, a light source or lamp is therefore also considered a "heating element" in the present sense.

[0036] According to a preferred embodiment, the temperature sensor units each have a light source, which is preferably connected to the support device of the respective temperature sensor unit. The light source comprises, for example, an LED light source.

[0037] The provision of at least one light source per temperature sensor unit further simplifies the assignment of the individual temperature sensors to one another.

[0038] Although such a light source can be provided per temperature sensor separately from the heating element of the respective temperature sensor, according to a particularly preferred embodiment, the light source is the heating element of the respective temperature sensor unit. In other words, according to this preferred embodiment, the temperature sensor units each have a light source which, in addition to its pure lighting function, which can serve for the optical detection of the respective temperature sensor, also assumes the function of a heating element. Compared to the previously mentioned embodiment of a separate light source and heating element per temperature sensor unit, this embodiment has the advantage of significantly lower costs and, at the same time, ensures a space-saving design of the temperature sensor unit, since the lighting and heating functions are each realized by one and the same element.

[0039] According to a further embodiment, the evaluation and control unit is configured to activate the lighting means of the temperature sensor units with a time delay relative to one another.

[0040] This embodiment is particularly preferred if the temperature sensors each have a light source in addition to the heating elements or if the heating elements are each designed as a light source.

[0041] In addition to the previously mentioned functional tests, the individual temperature sensor units can then be visually assigned based on the light sources. This is particularly advantageous when using a large number of temperature sensors, as assigning the temperature sensors is often very difficult in such cases.

[0042] According to a further embodiment, the evaluation and control unit has a plurality of signal channels, wherein one of the temperature sensors is assigned to each of the signal channels, and wherein a second illuminating means is assigned to each of the signal channels, which is configured to light up upon activation of the respective signal channel.

[0043] This further simplifies the optical assignment of the temperature sensors to the individual signal channels of the evaluation and control unit. For example, the visual inspection immediately shows whether the selected temperature sensor is assigned to the correct signal channel of the evaluation and control unit. In this case, the second lamp assigned to the respective signal channel should light up simultaneously with the lamp of the selected temperature sensor unit. If the two lamps do not light up synchronously, an incorrect assignment was obviously selected or the corresponding temperature sensor unit is not correctly connected to the evaluation and control unit.

[0044] It goes without saying that this type of assignment can also be carried out automatically by the evaluation and control unit.

[0045] According to a further embodiment, the carrier device comprises a printed circuit board and the temperature sensor and the heating element are designed in SMD construction.

[0046] This has the advantage of allowing a compact design of the temperature sensor units, and the temperature sensor, heating element, and light source (if present) can be easily connected electrically directly to the circuit board. Furthermore, the circuit board, as a connecting structure, ensures good thermal conductivity, especially between the temperature sensor and the heating element.

[0047] To increase thermal conductivity and reduce any time constants, the circuit board can be coated on one or both sides with a material with high thermal conductivity, such as copper, aluminum, silver, or gold. It is also advantageous for space reasons to keep the circuit board as small as possible.

[0048] According to a further embodiment, the temperature sensor units each have a fastening means for attaching the carrier device to the measuring device. The fastening means can, for example, comprise an adhesive, a plug connector, a rivet, or a screw connector. Particularly preferably, the fastening means comprises a screw.

[0049] This enables a particularly stable and time-invariant / constant way of attaching the temperature sensors to the measuring device. In particular, it ensures that the temperature sensors are consistently positioned, which is essential for the robust and efficient functioning of the temperature-dependent computational correction.

[0050] According to a preferred embodiment, the fastening means comprises a screw connection with a thread and a nut corresponding to the thread.

[0051] The nut is designed to lock the thread. This type of connection is particularly advantageous when the support device of the respective temperature sensor is connected to the thread in a rotationally fixed manner, i.e., when rotation of the support device of the temperature sensor relative to the thread is impossible. To mount the temperature sensor, only the nut can be rotated, whereas the screw, together with the support device of the temperature sensor, which is connected to it in a rotationally fixed manner, does not need to be rotated. This reduces the risk of damage to the supply cable(s) of the temperature sensor. This design also has the advantage that the cable outlet of the sensor can be set to a fixed, defined angular position.

[0052] According to a further embodiment, the temperature sensor units each have a housing in which the carrier device, the temperature sensor and the heating element of the respective temperature sensor unit are arranged.

[0053] On the one hand, such a housing has the natural advantage of protecting the components of the temperature sensor unit. On the other hand, such a housing has the advantage that the temperature of the temperature sensor is not too dependent on external temperature influences. The housing thus provides a certain degree of thermal shielding. Furthermore, if the heating element is activated, the housing can ensure a comparatively faster temperature rise of the other components of the temperature sensor unit, which allows the aforementioned analyses (determining a defect in the temperature sensor unit and determining whether the temperature sensor unit is improperly mounted) to be carried out more efficiently.

[0054] According to a preferred embodiment, the temperature sensor units are attached to the measuring head and / or the guide structure.

[0055] This enables direct measurement of the temperature data necessary for calculating the thermal deformation of the measuring device. The guide structure of the measuring device refers to the entire structure of the measuring device, which allows the measuring head to be moved relative to the measuring object. Depending on the design of the measuring device, the guide structure can include, for example, a movable measuring table, one or more cantilever arms, a bridge, a gantry, a stand, or one or more robot arms.

[0056] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0057] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. They show: Fig. 1 is a schematic view of a measuring device according to an embodiment of the present invention; Fig. 2 shows a schematic representation of a temperature sensor and an illustration of the attachment of the temperature sensor according to a first embodiment; Fig. 3 is a schematic diagram of a temperature sensor and an illustration of the mounting of the temperature sensor according to a second embodiment; Fig. 4 is a schematic diagram of a temperature sensor and an illustration of the mounting of the temperature sensor according to a third embodiment; Fig. 5 is a schematic diagram of a temperature sensor and an illustration of the mounting of the temperature sensor according to a fourth embodiment; Fig. 6A and Fig. 6B is a schematic diagram illustrating a functional test of the temperature sensor; Fig. 7 is a schematic block diagram illustrating the method according to the invention according to an embodiment; and Fig. 8 a schematic block diagram to illustrate the method according to the invention or the use of the measuring device according to the invention according to the embodiment.

[0058] Fig. Figure 1 shows an embodiment of the measuring device according to the invention in a schematic, perspective view. The measuring device is designated in its entirety by reference numeral 10.

[0059] In the Fig. The measuring device 10 shown in Figure 1 is a coordinate measuring machine, depicted in a simplified form. However, the design of the measuring device 10 is by no means limiting.

[0060] The measuring device 10 has a base 12, which, for example, comprises a solid granite slab. The base 12 can serve as a mount for a measurement object 14. It is also possible for a movable measuring table to be arranged on the base 12, on which the measurement object 14 is placed.

[0061] Furthermore, a portal 16 is arranged on the base 12, which can be displaced in the longitudinal direction. The portal 16 has two columns projecting upwards from the base 12, which are connected to each other via a crossbeam and have an overall inverted U-shape.

[0062] The direction of movement of the gantry 16 relative to the base 12 is commonly referred to as the Y-direction. A carriage 18 is arranged on the upper crossbeam of the gantry 16 and is movable in the transverse direction. This transverse direction is commonly referred to as the X-direction. The carriage 18 carries a spindle 20 that is movable in the Z-direction, i.e., perpendicular to the base 12.

[0063] Reference numerals 22, 24, 26 denote measuring devices by means of which the X, Y, and Z positions of the gantry 16, the carriage 18, and the sleeve 20 can be determined. In other words, the measuring devices 22, 24, 26 serve to record position data of the guide structure 30 of the measuring device 10. In the present embodiment, this guide structure 30 includes the base 12, the gantry 16, the carriage 18, and the sleeve 20.

[0064] Typically, the measuring devices 22, 24, 26 have measuring elements, which can be configured, for example, as glass scales, which serve as measuring scales. These measuring scales, in conjunction with corresponding reading heads (not shown here), are designed to determine the position of the gantry 16 relative to the base 12, the position of the carriage 18 relative to the gantry 16, and the position of the sleeve 20 relative to the carriage 18. Based on the position data of the guide structure 30 acquired by the measuring devices 22, 24, 26, the pose of a measuring head 28, which is arranged at the lower, free end of the sleeve 20, can thus be determined.

[0065] The measuring head 28 is designed to acquire dimensional measurement data of the measuring object 14. In the Fig. In the embodiment shown in Figure 1, the measuring head 28 is a tactile measuring head having a tactile stylus 32 extending in the Z direction, toward the base. This tactile stylus 32 is configured to scan the surface of the measurement object 14 at a plurality of measurement points. While scanning the surface of the measurement object 14, the measuring head 28 acquires the dimensional measurement data.

[0066] The measurement data acquired by the measuring head 28 during a measurement are evaluated together with the position data acquired by the measuring devices 22, 24, 26 in an evaluation and control unit 34. The evaluation and control unit 34 determines the spatial coordinates of the contact points on the measuring object 14 from the acquired measurement data and position data. The evaluation and control unit 34 can, for example, be configured to create a model of the measuring object 14 from these spatial coordinates and / or to compare the acquired measurement data and position data with corresponding test data in order to determine whether the shape of the measuring object corresponds to a desired shape. Typically, the evaluation and control unit 34 also serves to control the guide structure 30 for moving the measuring head 28.

[0067] The evaluation and control unit 34 has a computing unit 36, which is preferably designed as a computer on which appropriate measurement software is stored, with the aid of which a measurement can be carried out automatically or manually controlled by an operator. In addition to the computing unit 36, the evaluation and control unit 34 comprises a display device 38, which is preferably designed as a screen or other display.

[0068] The measuring device 10 according to the invention further comprises a plurality of temperature sensor units 40, which are configured to record temperature data relating to the measuring volume of the measuring device 10. The temperature sensor units 40 are mounted at various positions on the guide structure 30 and the measuring head 28. Each of these temperature sensor units 40 comprises a temperature sensor 42 (see Fig. 2-5), which can be configured, for example, as an NTC thermistor or a PTC thermistor. Alternatively, other types of resistive temperature sensors or optical temperature measuring sensors can also be used as temperature sensors 42 in the temperature sensor units 40.

[0069] The evaluation and control unit 34 is configured to evaluate the measurement data acquired by the measuring head 28 and the position data acquired by the measuring devices 22, 24, 26, and to correct the measurement data and / or the position data based on the temperature data acquired by the temperature sensors 42. The evaluation and control unit 34 performs a computational correction by means of which temperature-related deformations of the measuring head 28 and / or the guide structure 30 are compensated in order to increase measurement accuracy. Typically, the temperature-related deformation of the guide structure 30 is many times greater than the temperature-related deformation of the measuring head 28 due to its size alone. Depending on the embodiment and design of the measuring device 10, it is nevertheless conceivable to computationally compensate both the temperature-related deformation of the guide structure 30 and the temperature-related deformation of the measuring head 28.

[0070] As a computational correction method implemented in the evaluation and control unit 34, the method described in the European patent application with the application number 21 188 853.2 can be used, for example.

[0071] Fig. Figure 2 shows a schematic view of one of the temperature sensor units 40 according to a first embodiment. The temperature sensor 42 is mounted on a support device 44. The support device 44 includes a circuit board 46, which functions both as a mechanical support for the temperature sensor 42 and serves as the electrical connection for the temperature sensor 42.

[0072] The temperature sensor 42 is electrically connected to corresponding conductor tracks provided on the circuit board 46. The temperature sensor 42 is preferably designed as an SMD (surface-mounted device) component. Particularly preferred is an SO (small outline), SOP (small outline package), or TO (transistor outline) design. For example, the temperature sensor can be installed in an SOP8 or TO92 semiconductor package.

[0073] The circuit board 46 can be coated with a material of high thermal conductivity, such as copper, aluminum, silver, or gold, to increase thermal conductivity and reduce any time constants. Fig. In the embodiment shown in Figure 2, the circuit board 46 is coated on both sides with such a coating 48. The coating should be applied in such a way that it does not negatively affect the conductor tracks of the circuit board 46, for example, causing a short circuit.

[0074] Furthermore, a heating element 50 is arranged on the circuit board 46, which serves as the support device 44. The heating element 50 here comprises a light source 52, which is preferably configured as an LED. The light source 52 is electrically connected via corresponding conductor tracks provided on the circuit board 46.

[0075] Preferably, at least one cable 54 connected to the circuit board 46 serves for the electrical connection of the temperature sensor unit 40. The respective temperature sensor unit 40 is connected to the evaluation and control unit 34 via this cable 54.

[0076] The evaluation and control unit 34 is configured to process and evaluate the temperature data supplied by the individual temperature sensors 42. The temperature data from the individual temperature sensors 42 are preferably digital signals that are temperature-dependent, so that the evaluation and control unit 34 can calculate a time-dependent temperature profile for each individual temperature sensor 42 from these digital signals.

[0077] The evaluation and control unit 34 is further configured to control the heating elements 50 or lighting means 52 of the individual temperature sensor units 40 in order to selectively switch them on and off. Fig. In the embodiment shown in Figure 2, the illuminant 52 forms the heating element 50 of the respective temperature sensor unit 40. Therefore, when switched on, the illuminant 52 should introduce enough heat Q into the carrier device 44 or the circuit board 46 that it can be measured by the temperature sensor 42 after a defined time. If this cannot be guaranteed, it is also possible not to use the illuminant 52 itself as the heating element 50, but to use an additional thermal resistor that emits sufficient heat Q when current is flowing through it. In this case, the aforementioned thermal resistor (not shown) would form the heating element 50.

[0078] In order to utilize the warming effect as efficiently as possible, it is preferred that the heating element 50 is arranged in spatial proximity to the temperature sensor 42. In the Fig. In the embodiment shown in Figure 2, the heating element 50 and the temperature sensor 42 are therefore arranged side by side on the same side of the circuit board 46. It may even be advantageous to apply the heating element 50 directly to a pin of the temperature sensor 42 to further enhance the effect.

[0079] The temperature sensor unit 40 further comprises a fastening means 56 for fastening the carrier device 44 to the guide structure 30 or the measuring head 28 of the measuring device 10. In the Fig. 2, the fastening means 56 comprises an adhesive layer 58.

[0080] Fig. 3-5 show further embodiments of a temperature sensor unit 40 according to the invention. Fig. In the embodiment shown in Figure 3, a screw connection with a thread 62 is selected as the fastening means 56 instead of a purely adhesive connection. The support device 44 is connected to the thread 62 in a rotationally fixed manner. This is preferably achieved by fastening the support device 44 to the screw on which the thread 62 is arranged. To fasten the support device 44 to the screw, an adhesive layer 58' or another suitable fastening type can be selected. The screw or thread 62 is preferably countered by a nut 64. This has the particular advantage that the screw itself does not have to be turned, and damage to the connecting cable 54 is thereby effectively avoided.

[0081] It is understood that other types of fastening means 56 can also be selected to attach the support device 44 to the measuring device 10. For example, a covering element in conjunction with a spring, a rivet connection, or a clamp connection can be used. The only important thing is that a permanently consistent positioning of the temperature sensor unit 40 on the machine structure of the measuring device 10 is ensured.

[0082] Fig. 4 shows a further embodiment of a temperature sensor unit 40 according to the invention. Fig. The embodiment shown in Figure 4 differs from the one shown in Fig. 3 in that a housing 66 is additionally provided, which at least partially surrounds the support device 44, the temperature sensor 42, and the heating element 50. The housing 66 acts as a type of thermal shield to reduce external temperature influences and increase the accuracy of the temperature measurement of the temperature sensor 42.

[0083] In addition, the temperature sensor 42 in the Fig. 4, the heating element 50 is arranged on the underside of the support device 44, so that it is in direct contact with the fastening means 56. This can be advantageous for increasing the accuracy of the temperature measurement. In such a case, however, it is necessary that heat conduction between the heating element 50 and the temperature sensor 42 is still ensured.

[0084] To improve the latter effect, the Fig. In the embodiment shown in Figure 5, the heating element 50 is designed separately from the illuminant 52. For example, the heating element 50 in this case is a separate thermal resistor, which is arranged together with the temperature sensor 42 on the underside of the support device 44.

[0085] In the Fig. 4 and Fig. In the embodiments shown in Figure 5, the housing 66 is preferably transparent or at least partially transparent (in any case not opaque) so that the illuminant 52 is also visible from outside the housing 66. If no illuminant 52 is provided, the housing 66 can also be completely opaque.

[0086] When the heating element 50 is switched off, the temperature sensor 42 measures relatively accurately the temperature of that part of the measuring device 10 on which the temperature sensor unit 40 is arranged. Depending on the arrangement, the temperature sensor 42 thus measures the respective part of the guide structure 30 or the measuring head 28 to which the temperature sensor unit 40 is attached. Accordingly, when the heating element 50 is switched off, the temperature correction method described in Fig. 7 is shown schematically.

[0087] For this purpose, in a first method step S101, the evaluation and control unit 34 acquires the dimensional measurement data of the measurement object 14 using the measuring head 28. At the same time, the evaluation and control unit 34 acquires the position data of the measuring head 28 from the measuring devices 22, 24, 26. Likewise, the evaluation and control unit 34 acquires the temperature data supplied by the temperature sensors 42 (step S102). The acquired dimensional measurement data, position data, and temperature data are evaluated in the evaluation and control unit 34. In method step S103, the evaluated measurement data and / or position data are ultimately corrected based on the temperature data.In this method step S103, the temperature-related deformation of the measuring head 28 and / or the guide structure 30 is taken into account, so that the measurement data and / or position data are corrected according to the computational correction method depending on the temperature data.

[0088] With the help of the heating elements 50 provided in the temperature sensor units 40, it is also possible to perform a functional test of the temperature sensor units 40. The process of the functional test is shown schematically in Fig. 8 shown.

[0089] To perform the functional test, the evaluation and control unit 34 can, for example, be configured to activate the heating elements 50 of the temperature sensor units 40 and leave them switched on for a predefined period of time so that they produce heat Q (step S104). To detect the heat Q emitted by the heating elements 50, the evaluation and control unit 34 records the temperature data of the temperature sensors 42 during this period (step S105). Based on the temperature data recorded in step S105, the evaluation and control unit 34 can, through appropriate evaluation, determine a defect in one of the temperature sensor units 40 and / or detect an improper attachment of one of the temperature sensor units 40. To this end, the evaluation and control unit 34 evaluates the temperature data recorded by the temperature sensors 42 in step S106 and compares it with predefined threshold values ​​or expected temperature profiles.

[0090] For example, the evaluation and control unit 34 is configured to calculate a temperature profile over time for each temperature sensor 42 from the temperature data and to compare this temperature profile with a predefined, absolute temperature threshold and / or a predefined temperature profile over time. The predefined, absolute temperature threshold can, for example, be set to a temperature value that is to be expected at a minimum in the event of proper functioning of the heating element 50 and the temperature sensor 42. If this temperature threshold is not reached, this is an indication that the corresponding temperature sensor unit 40 is not functioning properly, for example because the heating element 50 and / or the temperature sensor 42 of the respective temperature sensor unit is defective.

[0091] By comparing the temporal temperature profile recorded by the temperature sensor 42 of the respective temperature sensor unit 40 with a predefined, expected temporal temperature profile, the evaluation and control unit 34 can further determine whether the temperature sensor unit 40 is properly attached to the measuring head 28 or the guide structure 30 of the measuring device 10.

[0092] Fig. 6A and Fig. 7B show, by way of example and schematically, an expected temperature profile which the temperature sensor 42 records when the heating element 50 is activated for a predefined period of time, wherein Fig. 6A shows the case of a proper attachment of the temperature sensor unit 40 to the measuring head 28 or the guide structure 30 and Fig. 6B shows the temperature profile detected by the temperature sensor 42 in the case of improper attachment of the temperature sensor unit 40.

[0093] If the temperature sensor unit 40 is properly attached to the measuring head 28 or the guide structure 30, a significantly smaller and slower increase in the temperature detected by the temperature sensor 42 is to be expected. This is because, if the temperature sensor unit 40 is properly attached, a significant portion of the heat emitted by the heating element 50 flows into the measuring head 28 or the guide structure 30, so that the temperature detected by the temperature sensor 42 increases significantly more slowly over time and ultimately reaches a lower maximum temperature value (see lower diagram in Fig. 6A with lower diagram in Fig. 6B).

[0094] If, however, the temperature sensor unit 40 has become detached from the measuring head 28 or the guide structure 30, the temperature detected by the temperature sensor 42 increases significantly faster with the same heating power of the heating element 50 and reaches a higher maximum temperature value more quickly due to the lower heat capacity of the temperature sensor unit 40 compared to the heat capacity of the measuring head 28 or the guide structure 30.

[0095] The evaluation and control unit 34 can accordingly determine whether the respective temperature sensor unit 40 is functioning properly and is correctly arranged on the measuring device 10 by analyzing the temperature data supplied by the temperature sensors 42 and comparing this with an absolute temperature threshold value and / or by analyzing the time course of the temperature determined by the temperature sensors 42.

[0096] This functional check of the temperature sensor units 40, performed in steps S104-S106, can be integrated into the "regular" temperature detection and temperature correction process described in steps S101-S103. For example, the evaluation and control unit 34 can be configured to perform this functional check at regular intervals and to issue a fault message if one of the aforementioned defects is detected during the functional check.

[0097] If the heating elements 50 are designed as illuminants 52, or if the temperature sensor units 40 each have a illuminant 52 in addition to the heating elements 50, an optical assignment of the temperature sensor units can be carried out in a simplified manner, as shown below.

[0098] For this purpose, the evaluation and control unit 34 is preferably configured to activate the lighting means 52 of the temperature sensor units 40 with a time offset from one another. The evaluation and control unit 34 has a plurality of signal channels, wherein each of the signal channels is assigned one of the temperature sensors 42, and wherein each of the signal channels is assigned a second lighting means 60 (see Fig.1) which is designed to light up when the respective signal channel is activated. If the lamps 52 are activated one after the other, it is possible to determine which temperature sensor unit 40 is assigned to which signal channel based on the second lamps 60 lighting up accordingly. The visual inspection also makes it immediately apparent whether the temperature sensor 42 selected by the evaluation and control unit 34 has been attached to the designated channel or not. If the lamp 52 of a temperature sensor unit 40 does not light up synchronously with the second lamp 60 of the respective signal channel, the temperature sensor 42 has not been assigned to the correct signal channel of the evaluation and control unit 34. With the help of a corresponding ID chip, this type of assignment of the temperature sensor units 40 in the evaluation and control unit 34 can also be automated.

[0099] The aforementioned type of optical or automated assignment of the individual temperature sensor units 40 to the signal channels of the evaluation and control unit 34 is particularly advantageous when a plurality of temperature sensor units 40 are used on the measuring device 10. In such a case, the assignment of the temperature sensor units 40 can generally only be ensured by conventional means with considerable effort. However, it is understood that the provision of a light source 52 per temperature sensor unit 40 is not absolutely necessary for the above-mentioned functional test of the temperature sensor units 40. Accordingly, in the simplest case, the temperature sensor units 40 can also be equipped "only" with a heating element 50 (without light source 52).

Claims

[1] Measuring device (10) for dimensional measuring of a measuring object (14) located in a measuring volume of the measuring device (10), comprising: - a measuring head (28) which is designed to acquire dimensional measurement data of the measuring object (14); - a guide structure (30) which is designed to guide the measuring head (28) and / or the measuring object (14) and to move them in the measuring volume, wherein the guide structure (30) is assigned at least one measuring device (22, 24, 26) which is designed to record position data of the guide structure (30), on the basis of which a pose of the measuring head (28) can be calculated; - a plurality of temperature sensor units (40) configured to acquire temperature data relating to the measurement volume; and - an evaluation and control unit (34) which is designed to process the dimensional measurement data and the position data and to correct the dimensional measurement data and / or the position data on the basis of the temperature data, wherein the temperature sensor units (40) each comprise a carrier device (44), a temperature sensor (42) connected to the carrier device (44) and a heating element (50) connected to the carrier device (44), wherein the evaluation and control unit (34) is designed to activate the heating elements (50) of the temperature sensor units (40) and to analyse a temporal temperature profile on the basis of the temperature data detected by the temperature sensors (42) in order to (i) to detect a defect in at least one of the temperature sensor units (40); and / or (ii) detect improper attachment of at least one of the temperature sensor units (40). [2] Measuring device according to claim 1, wherein the temperature sensor units (40) each have a lighting means (52). [3] Measuring device according to claim 2, wherein the illuminating means (52) is the heating element (50) of the respective temperature sensor unit (40). [4] Measuring device according to claim 2 or 3, wherein the evaluation and control unit (34) is designed to activate the lighting means (52) of the temperature sensor units (40) with a time offset from one another. [5] Measuring device according to one of the preceding claims, wherein the evaluation and control unit (34) has a plurality of signal channels, wherein each of the signal channels is assigned one of the temperature sensors (42), and wherein each of the signal channels is assigned a second illuminating means (52) which is designed to light up upon activation of the respective signal channel. [6] Measuring device according to one of the preceding claims, wherein the carrier device (44) comprises a printed circuit board (46) and the temperature sensor (42) and the heating element (50) are designed in SMD construction. [7] Measuring device according to one of the preceding claims, wherein the temperature sensor units (40) each have a fastening means (56) for fastening the carrier device (44) to the measuring device (10). [8] Measuring device according to claim 7, wherein the fastening means (56) comprises a screw connection with a thread (62) and a nut (64) corresponding to the thread (62), wherein the carrier device (44) is preferably connected to the thread (62) in a rotationally fixed manner. [9] Measuring device according to one of the preceding claims, wherein the temperature sensor units (40) each have a housing (66) in which the carrier device (44), the temperature sensor (42) and the heating element (50) of the respective temperature sensor unit (40) are arranged. [10] Measuring device according to one of the preceding claims, wherein the temperature sensor units (40) are attached to the measuring device (10), in particular to the measuring head (28) and / or the guide structure (30). [11] Measuring device (10) for dimensional measuring of a measuring object (14) located in a measuring volume of the measuring device (10), comprising: - a measuring head (28) which is designed to acquire dimensional measurement data of the measuring object (14); - a guide structure (30) which is designed to guide the measuring head (28) and / or the measuring object (14) and to move them in the measuring volume, wherein the guide structure (30) is assigned at least one measuring device (22, 24, 26) which is designed to record position data of the guide structure (30), on the basis of which a pose of the measuring head (28) can be calculated; - a plurality of temperature sensor units (40) configured to acquire temperature data relating to the measurement volume; and - an evaluation and control unit (34) which is designed to process the dimensional measurement data and the position data and to correct the dimensional measurement data and / or the position data on the basis of the temperature data, wherein the temperature sensor units (40) each comprise a carrier device (44), a temperature sensor (42) connected to the carrier device (44) and a heating element (50) connected to the carrier device (44), wherein the temperature sensor units (40) each have a lighting means (52), and wherein the illuminant (52) is the heating element (50) of the respective temperature sensor unit (40). [12] Measuring device (10) for dimensional measuring of a measuring object (14) located in a measuring volume of the measuring device (10), comprising: - a measuring head (28) which is designed to acquire dimensional measurement data of the measuring object (14); - a guide structure (30) which is designed to guide the measuring head (28) and / or the measuring object (14) and to move them in the measuring volume, wherein the guide structure (30) is assigned at least one measuring device (22, 24, 26) which is designed to record position data of the guide structure (30), on the basis of which a pose of the measuring head (28) can be calculated; - a plurality of temperature sensor units (40) configured to acquire temperature data relating to the measurement volume; and - an evaluation and control unit (34) which is designed to process the dimensional measurement data and the position data and to correct the dimensional measurement data and / or the position data on the basis of the temperature data, wherein the temperature sensor units (40) each comprise a carrier device (44), a temperature sensor (42) connected to the carrier device (44) and a heating element (50) connected to the carrier device (44), wherein the temperature sensor units (40) each have a lighting means (52), and wherein the evaluation and control unit (34) is configured to activate the lighting means (52) of the temperature sensor units (40) with a time offset from one another. [13] Measuring device (10) for dimensional measuring of a measuring object (14) located in a measuring volume of the measuring device (10), comprising: - a measuring head (28) which is designed to acquire dimensional measurement data of the measuring object (14); - a guide structure (30) which is designed to guide the measuring head (28) and / or the measuring object (14) and to move them in the measuring volume, wherein the guide structure (30) is assigned at least one measuring device (22, 24, 26) which is designed to record position data of the guide structure (30), on the basis of which a pose of the measuring head (28) can be calculated; - a plurality of temperature sensor units (40) configured to acquire temperature data relating to the measurement volume; and - an evaluation and control unit (34) which is designed to process the dimensional measurement data and the position data and to correct the dimensional measurement data and / or the position data on the basis of the temperature data, wherein the temperature sensor units (40) each comprise a carrier device (44), a temperature sensor (42) connected to the carrier device (44) and a heating element (50) connected to the carrier device (44), wherein the temperature sensor units (40) each have a lighting means (52), and wherein the evaluation and control unit (34) has a plurality of signal channels, wherein one of the temperature sensors (42) is assigned to each of the signal channels, and wherein a second illuminating means (52) is assigned to each of the signal channels, which is configured to light up upon activation of the respective signal channel. [14] Use of the measuring device (10) according to any one of claims 11-13 to: (i) to determine a defect in at least one of the temperature sensor units (40) based on the temperature data; and / or (ii) to determine, based on the temperature data, an improper attachment of at least one of the temperature sensor units (40). [15] Method for the dimensional measurement of a measuring object (14) located in a measuring volume, comprising the following steps: - capturing dimensional measurement data of the measurement object (14) with a measuring head (28) of a measuring device (10) and capturing position data on the basis of which a pose of the measuring head (28) can be calculated; - detecting temperature data relating to the measurement volume using a plurality of temperature sensor units (40), each comprising a carrier device (44), a temperature sensor (40) connected to the carrier device (44), and a heating element (50) connected to the carrier device (44); - activating the heating elements (50) of the temperature sensor units (40) and analyzing, based on the temperature data detected by the temperature sensors (42), a temporal temperature profile in order to (i) to detect a defect in at least one of the temperature sensor units (40), and / or (ii) detect improper attachment of at least one of the temperature sensor units (40); and - Correcting the dimensional measurement data and / or the position data based on the temperature data. [16] Method for the dimensional measurement of a measurement object (14) located in a measurement volume, comprising the following steps: - capturing dimensional measurement data of the measurement object (14) with a measuring head (28) of a measuring device (10) and capturing position data on the basis of which a pose of the measuring head (28) can be calculated; - Acquiring temperature data relating to the measurement volume using a plurality of temperature sensor units (40), each comprising a carrier device (44), a temperature sensor (40) connected to the carrier device (44), and a heating element (50) connected to the carrier device (44), wherein the temperature sensor units (40) each comprise a light source (52), and wherein the light source (52) is the heating element (50) of the respective temperature sensor unit (40); and - Correcting the dimensional measurement data and / or the position data based on the temperature data. [17] Method for the dimensional measurement of a measuring object (14) located in a measuring volume, comprising the following steps: - capturing dimensional measurement data of the measurement object (14) with a measuring head (28) of a measuring device (10) and capturing position data on the basis of which a pose of the measuring head (28) can be calculated; - Acquiring temperature data relating to the measurement volume using a plurality of temperature sensor units (40), each comprising a carrier device (44), a temperature sensor (40) connected to the carrier device (44), and a heating element (50) connected to the carrier device (44), wherein the temperature sensor units (40) each comprise a light source (52), and wherein the light sources (52) of the temperature sensor units (40) are activated with a time offset from one another; and - Correcting the dimensional measurement data and / or the position data based on the temperature data. [18] Method for the dimensional measurement of a measurement object (14) located in a measurement volume, comprising the following steps: - capturing dimensional measurement data of the measurement object (14) with a measuring head (28) of a measuring device (10) and capturing position data on the basis of which a pose of the measuring head (28) can be calculated; - detecting temperature data relating to the measurement volume using a plurality of temperature sensor units (40), each comprising a carrier device (44), a temperature sensor (40) connected to the carrier device (44), and a heating element (50) connected to the carrier device (44), the temperature sensor units (40) each comprising a lighting means (52); - correcting, by means of an evaluation and control unit (34), the dimensional measurement data and / or the position data based on the temperature data; - wherein the evaluation and control unit (34) has a plurality of signal channels, wherein one of the temperature sensors (42) is assigned to each of the signal channels, and wherein a second illuminating means (52) is assigned to each of the signal channels, which is designed to light up upon activation of the respective signal channel. [19] A computer program comprising software code adapted to carry out the method according to any one of claims 15-18 when executed on a computer.

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