Temperature Correction for Dimensional Measurement
20240142213 ยท 2024-05-02
Inventors
- Johannes Geiger (Nattheim, DE)
- Tobias Perkhuhn (Heidenheim, DE)
- Alwine Schroll (Schechingen, DE)
- Matthias Wahl (Korb, DE)
- Sabrina Rau (Koenigsbronn, DE)
- Malte Langmack (Aalen, DE)
Cpc classification
G01K1/026
PHYSICS
International classification
Abstract
A measurement device includes a measurement head configured to capture dimensional measurement data of a measurement object. A guide structure is configured to move and guide at least one of the measurement head and the measurement object in a measurement volume of the measurement device. A measurement unit is configured to capture positional data of the guide structure based on which a pose of the measurement head can be calculated. Multiple temperature sensor units are configured to capture temperature data about the measurement volume. Each temperature sensor unit includes a carrier element, a temperature sensor connected to the carrier element, and a heating element connected to the carrier element. A control system is configured to process the dimensional measurement data and the positional data and, based on the temperature data, correct at least one of the dimensional measurement data and the positional data.
Claims
1. A measurement device for dimensionally measuring a measurement object located in a measurement volume of the measurement device, the measurement device comprising: a measurement head configured to capture dimensional measurement data of the measurement object; a guide structure configured to move and guide at least one of the measurement head and the measurement object in the measurement volume, a measurement unit configured to capture positional data of the guide structure based on which a pose of the measurement head can be calculated; a plurality of temperature sensor units configured to capture temperature data about the measurement volume, wherein each of the plurality of temperature sensor units includes: a carrier element, a temperature sensor connected to the carrier element, and a heating element connected to the carrier element; and a control system configured to: process the dimensional measurement data and the positional data, and based on the temperature data, correct at least one of the dimensional measurement data and the positional data.
2. The measurement device as claimed in claim 1, wherein the control system is configured to: activate the heating elements of the plurality of temperature sensor units; and determine, based on the temperature data, a defect in at least one of the plurality of temperature sensor units.
3. The measurement device as claimed in claim 1, wherein the control system is configured to: activate the heating elements of the plurality of temperature sensor units, and determine, based on the temperature data, an incorrect mounting of at least one of the plurality of temperature sensor units.
4. The measurement device as claimed in claim 1, wherein the control system is configured to: activate the heating elements of the plurality of temperature sensor units, compare the temperature data with a predefined, absolute temperature target value, and determine, based on the comparison, at least one of (i) a defect in at least one of the plurality of temperature sensor units and (ii) an incorrect mounting of at least one of the plurality of temperature sensor units.
5. The measurement device as claimed in claim 1, wherein the control system is configured to: activate the heating elements of the plurality of temperature sensor units, compare the temperature data with a predefined, absolute temperature target value, and determine, based on the comparison, a defect in at least one of the plurality of temperature sensor units.
6. The measurement device as claimed in claim 1, wherein the control system is configured to: activate the heating elements of the plurality of temperature sensor units, compare the temperature data with a predefined, absolute temperature target value, and determine, based on the comparison, an incorrect mounting of at least one of the plurality of temperature sensor units.
7. The measurement device as claimed in claim 1, wherein the control system is configured to: activate the heating elements of the plurality of temperature sensor units, determine a temperature profile over time based on the temperature data, and determine, based on the temperature profile over time, at least one of (i) a defect in at least one of the plurality of temperature sensor units and (ii) an incorrect mounting of at least one of the plurality of temperature sensor units.
8. The measurement device as claimed in claim 1, wherein the control system is configured to: activate the heating elements of the plurality of temperature sensor units, determine a temperature profile over time based on the temperature data, and determine, based on the temperature profile over time, a defect in at least one of the plurality of temperature sensor units.
9. The measurement device as claimed in claim 1, wherein the control system is configured to: activate the heating elements of the plurality of temperature sensor units, determine a temperature profile over time based on the temperature data, and determine, based on the temperature profile over time, an incorrect mounting of at least one of the plurality of temperature sensor units.
10. The measurement device as claimed in claim 1, wherein each of the plurality of temperature sensor units includes a light-emitting element.
11. The measurement device as claimed in claim 10, wherein, for each unit of the plurality of temperature sensor units, the light-emitting element of the unit forms at least a part of the heating element of the unit.
12. The measurement device as claimed in claim 10, wherein the control system is configured to activate the light-emitting elements of the plurality of temperature sensor units with a mutual time offset.
13. The measurement device as claimed in claim 1, wherein: the control system includes a plurality of signal channels, each of the signal channels is assigned one of the temperature sensors, and each of the signal channels is assigned a second light-emitting element that is configured to light up when the respective signal channel is activated.
14. The measurement device as claimed in claim 1, wherein, for each unit of the plurality of temperature sensor units: the carrier element of the unit includes a circuit board, and the temperature sensor and the heating element of the unit are surface-mounted devices on the circuit board of the unit.
15. The measurement device as claimed in claim 1, wherein each of the plurality of temperature sensor units includes an attachment element that is configured to attach the carrier element to the measurement device.
16. The measurement device as claimed in claim 15, wherein: the attachment element includes a screw and a nut corresponding with the screw, and the carrier element is connected to the screw.
17. The measurement device as claimed in claim 1, wherein each of the plurality of temperature sensor units includes a housing in which the carrier element, the temperature sensor, and the heating element of the respective temperature sensor unit are arranged.
18. The measurement device as claimed in claim 1, wherein the plurality of temperature sensor units is attached to at least one of the measurement head and the guide structure.
19. A method for dimensionally measuring a measurement object located in a measurement volume, the method comprising: capturing dimensional measurement data of the measurement object with a measurement head of a measurement device, capturing positional data based upon which a pose of the measurement head can be calculated; capturing temperature data about the measurement volume using a plurality of temperature sensor units, each of which includes a carrier element, a temperature sensor connected to the carrier element, and a heating element connected to the carrier element; and based on the temperature data, correcting at least one of the dimensional measurement data and the positional data.
20. A non-transitory computer-readable medium comprising instructions including: capturing dimensional measurement data of a measurement object with a measurement head of a measurement device, capturing positional data based upon which a pose of the measurement head can be calculated; capturing temperature data about a measurement volume of the measurement device using a plurality of temperature sensor unit that each includes a carrier element, a temperature sensor connected to the carrier element, and a heating element connected to the carrier element; and based on the temperature data, correcting at least one of the dimensional measurement data and the positional data.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0066] The present disclosure will become more fully understood from the detailed description and the accompanying drawings.
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[0075] In the drawings, reference numbers may be reused to identify similar and/or identical elements.
DETAILED DESCRIPTION
[0076]
[0077] The measurement device 10 shown in
[0078] The measurement device 10 has a base 12, which includes, for example, a solid granite slab. The base 12 can serve as a holder for a measurement object 14. It is also possible for a movably mounted measurement stage to be arranged on the base 12, on which the measurement object 14 is placed.
[0079] Furthermore, a gantry 16 is arranged on the base 12 such that it is movable in the longitudinal direction. The gantry 16 has two columns projecting upward from the base 12, which are connected to one another by a crossbeam and have an inverted U-shape overall.
[0080] The direction of movement of the gantry 16 in relation to the base 12 is usually referred to as the Y-direction. A slide 18, which is movable in the transverse direction, is arranged on the upper crossbeam of the gantry 16. This transverse direction is usually referred to as the X-direction. The carriage 18 carries a quill 20, which is movable in the Z-direction, that is to say perpendicularly to the base 12.
[0081] Measurement units on the basis of which the X-, Y- and Z-positions of the gantry 16, the carriage 18, and the quill 20 can be determined are denoted by the reference signs 22, 24, 26. In other words, the measurement units 22, 24, 26 serve to capture positional data of the guide structure 30 of the measurement device 10. In the present example embodiment, this guide structure 30 includes the base 12, the gantry 16, the carriage 18, and the quill 20.
[0082] Typically, the measurement units 22, 24, 26 have measurement standards, which can be designed, for example, as glass scales that serve as measurement scales. These measurement scales, in conjunction with corresponding reading heads (not shown here), are configured 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 quill 20 relative to the carriage 18. Based on the positional data of the guide structure 30 captured by the measurement units 22, 24, 26, the pose of a measurement head 28, which is arranged at the lower, free end of the quill 20, can be determined.
[0083] The measurement head 28 is configured to capture dimensional measurement data of the measurement object 14. In the example embodiment shown in
[0084] The measurement data captured by the measurement head 28 during a measurement are evaluated together with the positional data recorded by the measurement units 22, 24, 26 in an evaluation and control unit 34. The evaluation and control unit 34 determines the spatial coordinates of the probe points on the measurement object 14 from the captured measurement data and positional data. The evaluation and control unit 34 can, for example, be configured to create a model of the measurement object 14 from these spatial coordinates and/or to compare the captured measurement data and positional data with corresponding test data in order to determine whether the shape of the measurement object corresponds to a desired shape. Typically, the evaluation and control unit 34 also serves to control the guide structure 30 for moving the measurement head 28.
[0085] The evaluation and control unit 34 has a computing unit 36, which is preferably designed as a computer on which corresponding measurement software is stored, with the aid of which a measurement can be carried out automatically or controlled manually by an operator. In addition to the computing unit 36, the evaluation and control unit 34 includes a display device 38, which is preferably designed as a screen or other display.
[0086] The measurement device 10 also has a plurality of temperature sensor units 40, which are configured to capture temperature data about the measurement volume of the measurement device 10. The temperature sensor units 40 are attached to the guide structure 30 and the measurement head 28 distributed at different positions. Each of these temperature sensor units 40 includes a temperature sensor 42 (see
[0087] The evaluation and control unit 34 is configured to evaluate the measurement data captured by the measurement head 28 and the positional data captured by the measurement units 22, 24, 26 and to correct the measurement data and/or the positional data based on the temperature data captured by the temperature sensors 42. The evaluation and control unit 34 carries out a mathematical correction, by means of which temperature-induced deformations of the measurement head 28 and/or of the guide structure 30 are compensated for in order to increase the measurement accuracy. Typically, the temperature-induced deformation of the guide structure 30 is many times greater than the temperature-induced deformation of the measurement head 28 simply due to its size. Depending on the embodiment and configuration of the measurement device 10, it is still conceivable to mathematically compensate for both the temperature-induced deformation of the guide structure 30 and the temperature-induced deformation of the measurement head 28.
[0088] The method described in the European patent application with the application number 21 188 853.2, for example, can be used as a mathematical correction method that is implemented in the evaluation and control unit 34.
[0089]
[0090] The temperature sensor 42 is electrically connected to corresponding conductor tracks provided for this purpose on the circuit board 46. The temperature sensor 42 is preferably designed as an SMD component (surface-mounted device component). An SO (small outline), an SOP (small outline package) or a TO (transistor outline) design is particularly preferably chosen. For example, the temperature sensor can be installed in an SOP 8 or a TO92 semiconductor housing.
[0091] The circuit board 46 can be coated with a material with high thermal conductivity, for example copper, aluminum, silver or gold, to increase thermal conductivity and to reduce any time constants. In the example embodiment shown in
[0092] Furthermore, a heating element 50 is arranged on the circuit board 46 serving as a carrier element 44. The heating element 50 here includes a light-emitting element 52, which is preferably designed as an LED light-emitting element. The light-emitting element 52 is electrically connected via corresponding conductor tracks provided on the circuit board 46.
[0093] 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.
[0094] 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 of 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.
[0095] The evaluation and control unit 34 is also configured to control the heating elements 50 or light-emitting element 52 of the individual temperature sensor units 40 in order to selectively switch them on and off. In the example embodiment shown in
[0096] In order to use the effect of the heating up as efficiently as possible, it is preferred that the heating element 50 is arranged in spatial proximity to the temperature sensor 42. In the example embodiment shown in
[0097] The temperature sensor unit 40 further includes an attachment element 56 for attaching the carrier element 44 to the guide structure 30 or to the measurement head 28 of the measurement device 10. In the example embodiment shown in
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[0099] It is understood that other types of attachment element 56 can also be selected to attach the carrier element 44 to the measurement device 10. For example, it is possible to use a lining element in conjunction with a spring, a rivet connection or a clamping connection for this purpose. The only important thing is that a permanently identical positioning of the temperature sensor unit 40 on the machine structure of the measurement device 10 is ensured.
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[0101] In addition, in the example embodiment shown in
[0102] To improve the last-mentioned effect, the heating element 50 in the example embodiment shown in
[0103] In the example embodiments shown in
[0104] When the heating element 50 is switched off, the temperature sensor 42 measures relatively precisely the temperature of that part of the measurement 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 of the measurement head 28 to which the temperature sensor unit 40 is attached. Accordingly, when the heating element 50 is switched off, the temperature correction method, which is shown schematically in
[0105] For this purpose, the evaluation and control unit 34 captures the dimensional measurement data of the measurement object 14 with the aid of the measurement head 28 in a first method step S101. At the same time, the evaluation and control unit 34 meanwhile captures the positional data of the measurement head 28 from the measurement units 22, 24, 26. The evaluation and control unit 34 also captures the temperature data supplied by the temperature sensors 42 (step S102). The captured dimensional measurement data, positional data, and temperature data are evaluated in the evaluation and control unit 34. In method step S103, the evaluated measurement data and/or positional data are ultimately corrected based on the temperature data. In this method step S103, the temperature-induced deformation of the measurement head 28 and/or of the guide structure 30 is taken into account, with the result that the measurement data and/or positional data are corrected in accordance with the mathematical correction method depending on the temperature data.
[0106] With the aid of the heating elements 50 provided in the temperature sensor units 40, it is also possible to carry out a functional check of the temperature sensor units 40. The process of the functional check is shown as an example and schematically in
[0107] To carry out the functional check, the evaluation and control unit 34 can, for example, be configured to activate the heating elements 50 of the temperature sensor units 40 and to leave them switched on for a predefined period of time so that they produce this heat Q (step S104). To detect this heat Q emitted by the heating elements 50, the evaluation and control unit 34 captures the temperature data from the temperature sensors 42 during this period (step S105). Based on the temperature data captured in step S105, the evaluation and control unit 34 can ascertain a defect in one of the temperature sensor units 40 through appropriate evaluation and/or determine that one of the temperature sensor units 40 has not been correctly mounted. For this purpose, the evaluation and control unit 34 evaluates the temperature data captured by the temperature sensors 42 in step S106 and compares them with predefined threshold values or expected temperature profiles.
[0108] For example, the evaluation and control unit 34 is configured to calculate a temperature profile over time per temperature sensor 42 from the temperature data and to compare this temperature profile over time with a predefined, absolute temperature threshold value and/or a predefined temperature profile over time. The predefined, absolute temperature threshold value can, for example, be set to a temperature value that is at least expected if the heating element 50 and the temperature sensor 42 are functioning correctly. If this temperature threshold value is not reached, this is an indication that the corresponding temperature sensor unit 40 is not functioning correctly, since, for example, the heating element 50 and/or the temperature sensor 42 of the respective temperature sensor unit is defective.
[0109] By comparing the temperature profile recorded over time by the temperature sensor 42 of the respective temperature sensor unit 40 with a predefined, expected temperature profile over time, the evaluation and control unit 34 can further determine whether the temperature sensor unit 40 is correctly mounted on the measurement head 28 or the guide structure 30 of the measurement device 10.
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[0111] If the temperature sensor unit 40 is correctly mounted on the measurement head 28 or the guide structure 30, a significantly lower and slower rise in the temperature detected by the temperature sensor 42 is to be expected. This is because, if the temperature sensor unit 40 is correctly mounted, a significant portion of the heat emitted by the heating element 50 flows into the measurement head 28 or the guide structure 30, with the result that the temperature detected by the temperature sensor 42 rises much more slowly over time and ultimately reaches a lower maximum temperature value (cf. bottom diagram in
[0112] If, on the other hand, the temperature sensor unit 40 has become detached from the measurement head 28 or the guide structure 30, the temperature captured by the temperature sensor 42 rises significantly faster with the same heating power of the heating element 50 and, due to the lower heat capacity of the temperature sensor unit 40 compared to the heat capacity of the measurement head 28 or the guide structure 30, reaches a higher maximum temperature value more quickly.
[0113] The evaluation and control unit 34 can accordingly ascertain whether the respective temperature sensor unit 40 is functioning correctly and is correctly arranged on the measurement device 10 by analyzing the temperature data supplied by the temperature sensors 42 and comparing them with an absolute temperature threshold value and/or by analyzing the profile of the temperature ascertained by the temperature sensors 42 over time.
[0114] This functional check of the temperature sensor units 40, carried out in steps S104-S106, can be integrated into the regular temperature capture process and temperature correction process, which was illustrated using steps S101-S103. For example, the evaluation and control unit 34 can be configured to carry out this functional check at regular intervals and to issue a fault message if one of the aforementioned defects is determined during the functional check.
[0115] If the heating elements 50 are designed as light-emitting element 52, or the temperature sensor units 40 each include a light-emitting element 52 in addition to the heating elements 50, an optical assignment of the temperature sensor units can take place in a simplified manner, as shown below.
[0116] For this purpose, the evaluation and control unit 34 is preferably configured to activate the light-emitting element 52 of the temperature sensor units 40 with a mutual time offset. 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 light-emitting element 60 (see
[0117] The stated 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 advantageous in particular if a large number of temperature sensor units 40 are used on the measurement device 10. This is because, in such a case, the assignment of the temperature sensor units 40 in a conventional manner can usually only be ensured with great effort. However, it is understood that the provision of a light-emitting element 52 per temperature sensor unit 40 is not necessarily required for the aforementioned functional check of the temperature sensor units 40. Accordingly, in the simplest case, the temperature sensor units 40 can also be equipped with only a heating element 50 (without light-emitting element 52).
[0118] It is to be understood that the foregoing is a description of one or more preferred example embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.
[0119] As used in this specification and claims, the terms for example, e.g., for instance, such as, and like, and the verbs comprising, having, including, and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.
[0120] The term non-transitory computer-readable medium does not encompass transitory electrical or electromagnetic signals propagating through a medium (such as on a carrier wave). Non-limiting examples of a non-transitory computer-readable medium are nonvolatile memory circuits (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only memory circuit), volatile memory circuits (such as a static random access memory circuit or a dynamic random access memory circuit), magnetic storage media (such as an analog or digital magnetic tape or a hard disk drive), and optical storage media (such as a CD, a DVD, or a Blu-ray Disc).
[0121] The phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean at least one of A, at least one of B, and at least one of C. The phrase at least one of A, B, or C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR.