DE102016115979B4 - Method and arrangement for ensuring reliable information on measurement uncertainties of measuring systems in changing environmental conditions - Google Patents

Abstract

Method for securing reliable information on measuring uncertainties of measuring systems in changing environmental conditions with the following steps:
- Qualifying the environmental conditions, based on type, type and configuration of measuring means and components of the measuring system and thus to be detected desired measured variables, by influencing factors relevant to the respective desired variable,
Assignment of the qualified relevant variable influencing variables of the environmental conditions to measurement uncertainty parameters of the measured variables,
continuous detection, storage and evaluation of at least one relevant variable influencing variable of the ambient conditions by suitable sensors, wherein at least one component temperature of a measuring means is measured within the measuring system,
- Designing calibration means such that the configuration of measuring means and components of the measuring system is sufficiently adaptable to a determined variation range of each relevant variable influencing variable,
Determination of the current measurement uncertainty and documentation of the history of each desired measured variable corresponding to the range of variation of each relevant influencing variable of the environmental conditions, and rejecting a calibration in the case of inadmissibly recognized environmental conditions representing a non-permitted state of emergency for at least one relevant influencing variable,
- Output of the currently achievable metrological uncertainty for each desired measurement on the basis of environmental conditions during calibration or output of a currently detected state of the measurement uncertainty of the system in real time based on the measured parameters of the environmental conditions.

Description

The invention relates to a method and an arrangement for securing reliable information on measurement uncertainties of measuring systems under varying environmental conditions, in particular in the accuracy specification of length measuring systems, preferably optically noncontact measuring, but also multi-sensor image measuring systems, preferably for use under production conditions.

Information on measurement uncertainties of measuring systems is made according to different procedures / standards. This information generally refers to well-defined and described conditions for the use of the systems and their calibration and / or adjustment.

The temperature and its time course have a very high influence on measuring uncertainty, especially in dimensional measuring technology.

The large variability of temperature and temperature usually prevailing under production conditions has a decisive influence on the measurement uncertainty of the measuring system in operational use. However, only the measurement uncertainty among the frequently ideal conditions of use described by the manufacturer in technical data sheets for the measuring systems, which can often not be adhered to during operational use, is known and guaranteed by contract. At best, manufacturers indicate deviating measurement uncertainties in relation to different environmental conditions. On the one hand, in many cases the ambient conditions present under real production conditions are not sufficiently known (ascertained) or have hitherto not been taken into account for the operative determination of measurement uncertainties of measuring systems. The concrete measurement uncertainty of measuring systems at the time of use under production conditions is therefore largely unknown. Thus, in case of doubt, it is also not certain whether or not a measuring system was "capable of measuring" at the time of determining measurement results (measured variables) for the specific measuring task.

Measurement accuracies are defined and contractually guaranteed as measurement uncertainties under certain conditions for calibration and adjustment. These are generally part of datasheets.

The environment-dependent parameters such as temperature, temperature profile (temperature gradient) can be determined by space classes, e.g. according to standard (VDI / VDE 2627).

Normally, the measurement uncertainty is described only under good conditions of use (high-quality measuring room). In part, manufacturers of very high-quality measuring systems state measurement uncertainties in relation to different environmental conditions. However, the disadvantage here is that these measuring systems do not provide any information for certain conditions specified by the optimum space class or by the manufacturer, and certainly not automatically adapt the displayed measurement uncertainty of the measurement results to changed environmental conditions.

Solutions are already known from the state of the art with which measuring errors can be reduced or measurement uncertainties can be indicated.

In the DE 697 37 336 T2 a method is disclosed for compensating for deviations of a transfer function of a transducer. Based on the measurement with the transducer, a desired transfer function is identified and an actual transfer function is determined. The measurement is first compensated with a transfer function derived from the actual transfer function and then with the desired transfer function and provided as a measured value. Statements about a real certain measurement uncertainty are not made.

The DE 198 46 597 A1 describes a method in which the measurement uncertainty coordinate measuring machines by statistical analysis of deviations between a measured reference value and with the Monte Carlo method simulated values, which were obtained under a variation of influence parameters, is determined. The measurement uncertainty is thus statistically verified only with a model function. In one in the DE 10 2014 214 771 A1 disclosed methods for the electronic creation of a measurement protocol are documented predefined environmental conditions in the measurement acquisition and measurement evaluation. On the basis of the measurement protocol, however, only those measurement uncertainties of the measurements that result from compliance with predefined environmental conditions can actually be identified.

The invention has for its object to find a new way to secure reliable information on measurement uncertainties of measuring systems under varying environmental conditions, especially under production conditions, which allows the user / user of the measuring system at each time of use, a qualified information on the real measurement uncertainty under the given environmental conditions to maintain or change by improving the environmental conditions / Operating conditions of the measuring system. Furthermore, especially service technicians should be enabled to no longer be able to install and / or calibrate the measuring system only under the very restrictive predetermined class conditions of the highest quality, but also under those environmental conditions that are subject to an existing extended measurement uncertainty specification.

In an extended task, the determination of the best possible measurement uncertainty, i. lowest measurement uncertainty, the measuring system under the influence of real environmental conditions in the given time window in the context of calibration fully automatic.

• - Qualifizieren der Umgebungsbedingungen, bezogen auf Art, Typ und Konfiguration von Messmitteln und Komponenten des Messsystems sowie damit zu erfassende gewünschte Messgrößen, durch für die jeweils gewünschte Messgröße relevante Einflussgrößen,
• - Zuordnen der qualifizierten relevanten veränderlichen Einflussgrößen der Umgebungsbedingungen zu Messunsicherheitsparametern der Messgrößen,
• - kontinuierliches Erfassen, Speichern und Bewertung wenigstens einer relevanten veränderlichen Einflussgröße der Umgebungsbedingungen durch geeignete Sensoren, wobei mindestens eine Komponenten-Temperatur eines Messmittels innerhalb des Messsystems gemessen wird,
• - Auslegen der Kalibriermittel derart, dass damit die Konfiguration von Messmitteln und Komponenten des Messsystems ausreichend an einen ermittelten Variationsbereich jeder relevanten veränderlichen Einflussgröße anpassbar ist,
• - Ermitteln der aktuellen Messunsicherheit und Dokumentation der Historie jeder gewünschten Messgröße entsprechend dem Variationsbereich jeder relevanten Einflussgröße der Umgebungsbedingungen, und Ablehnen einer Kalibrierung bei als unzulässig erkannten Umgebungsbedingungen, die einen nicht zulässigen Ausnahmezustand für mindestens eine relevante Einflussgröße darstellen,
• - Ausgabe der aktuell erreichbaren messtechnischen Messunsicherheit für jede gewünschte Messgröße auf Basis der Umgebungsbedingungen bei Kalibrierung oder Ausgabe eines aktuell erkannten Zustandes der Messunsicherheit des Systems in Echtzeit auf Basis der gemessenen Einflussgrößen der Umgebungsbedingungen.

According to the invention, the object is achieved with a method for securing reliable information about measurement uncertainties of measuring systems under varying environmental conditions with the following steps:

• - Qualifying the environmental conditions, based on type, type and configuration of measuring means and components of the measuring system and thus to be detected desired measured variables, by influencing factors relevant to the respective desired variable,
• Assignment of the qualified relevant variable influencing variables of the environmental conditions to measurement uncertainty parameters of the measured variables,
• continuous detection, storage and evaluation of at least one relevant variable influencing variable of the ambient conditions by suitable sensors, wherein at least one component temperature of a measuring means is measured within the measuring system,
• - Designing the calibration means such that the configuration of measuring means and components of the measuring system is sufficiently adaptable to a determined variation range of each relevant variable influencing variable,
• Determination of the current measurement uncertainty and documentation of the history of each desired measured variable corresponding to the range of variation of each relevant influencing variable of the environmental conditions, and rejecting a calibration in the case of inadmissibly recognized environmental conditions representing a non-permitted state of emergency for at least one relevant influencing variable,
• - Output of the currently achievable metrological uncertainty for each desired measurement on the basis of environmental conditions during calibration or output of a currently detected state of the measurement uncertainty of the system in real time based on the measured parameters of the environmental conditions.

When detecting and storing (documenting) the influencing variable temperature other than the measurement of at least one component temperature, an ambient temperature is advantageously additionally measured by means of sensors arranged within the measuring system by sensors mounted outside the measuring system.

When capturing and storing influencing variables of the ambient conditions, it is expedient to carry out, in addition to the component temperature measurement, measurements of the specimen / workpiece temperature or of the vibration / vibration, air quality within the measuring system.

The assignment of the qualified influencing variables of the environmental conditions to the measurement uncertainty parameters of the measured variables advantageously takes place statically.

In a preferred embodiment, the assignment of the qualified influencing variables of the environmental conditions to the measurement uncertainty parameters of the measured variables can take place dynamically.

It proves to be expedient if, prior to the output of the currently achievable metrological measurement uncertainties or capability characteristics, an evaluation for feasibility under the given ambient conditions takes place for each desired measured variable.

The object is further achieved in an arrangement for securing the Uncertainty information of measuring systems under varying environmental conditions with measuring means for detecting desired parameters, which are affected by relevant for the measured variable variables of environmental conditions in their uncertainty, inventively solved in that sensor means for continuous detection and Storage means for storing at least one relevant variable influencing variable of the environmental conditions are present, wherein at least one sensor for measuring the temperature or for taking thermal images outside the measuring system is present, that a calculation unit for determining the current measurement uncertainty and storage means for storing the history of the measurement uncertainty Range of variation of each variable influencing variable of the environmental conditions, and comparison unit for checking whether given environmental condition are recorded in a range of influencing variables of the environmental conditions defined as inadmissible represent an undocumented exceptional state of at least one relevant influencing variable which excludes a calibration, and that an output unit for displaying the currently achievable metrological measurement uncertainty for each desired measured variable on the basis of the ambient conditions during calibration and the currently present influencing variables of the environmental conditions.

At least one further sensor for temperature measurement is advantageously arranged outside the measuring system. Furthermore, it is expedient if at least one further sensor for measuring the specimen / workpiece temperature is arranged within the measuring system.

It also proves to be advantageous for a rating unit to be present for testing the feasibility of the measurements under the given ambient conditions, so that the output unit can be controlled to indicate deviations of the ambient conditions of the present calibration state. The evaluation unit is expediently also provided for assessing measurement tasks for feasibility under the given or for expected possible ambient conditions.

The invention is based on the basic idea that the temperature behavior of the measuring system is basically known to the manufacturer, whereby the ambient temperature and its course and possibly the temperature (s) of the test object / workpiece or standard must be taken into account to compensate for the measured dimensions. A residual uncertainty remaining after the compensation, which is largely known, is then included in the uncertainty budget of the measuring system. Possibly. For example, other environmental conditions important for the corresponding measuring technology, such as Find vibration information in connection with tactile sensor input. This makes it possible to make statements about the accuracy under the intended conditions, which can be both an addition to the measurement result in the form of the indication of the minimum measurable tolerance and an estimate of the feasibility of further measurements under the given environmental conditions.

The measuring system according to the invention can, at any time after the evaluation of data from past and real-time environmental conditions and current part temperatures or other measurement conditions (such as "workpiece clean, dry, burr-free and possibly certain surface finish, eg ground") information on measurement uncertainty and " Provide measuring capability ", ie indicate a deterioration or improvement in the measurement uncertainty or the confidence interval of the measurement and possibly discard the measured value of a physical quantity.

When calibrating measuring systems, service technicians can carry out the acceptance tests with specific consideration of the existing environmental conditions. The currently achievable measurement uncertainty is documented.

Furthermore, users / users of the measuring system can positively or negatively influence their performance with regard to the measurement uncertainty, if necessary, by correspondingly changing the environmental conditions, e.g. by changing the location of the measuring system or controlling the temperature by air conditioning or shielding from solar radiation or heat radiation.

The ambient conditions at the place of use of measuring systems with regard to temperature (for example in absolute length measurement) or with regard to vibrations (in roughness measuring systems) have the greatest influence on the metrological properties and thus the suitability of the measuring system for the respective measuring task. The environmental dependence (e.g., temperature dependence) of the metrological properties is determined and described according to the invention.

In principle, the method according to the invention can be used for all dimensional precision measuring systems and furthermore for contour, shape and / or roughness measuring systems in use under varying production or environmental conditions and resulting variable measurement uncertainty specifications. Depending on the type of sensors used in the measuring systems, varying parameters as influential factors with regard to environmental conditions (for example, temperature, vibration, air purity, etc.) are relevant as variable manufacturing or environmental conditions.

The measurement uncertainty specifications can either be predefined in certain classes for selection by the system or, in theory, can also be calculated dynamically by using an extended calculation model.

The invention thus opens up a new possibility for securing reliable information on measurement uncertainties of measuring systems under varying environmental conditions and the real and determined measurement uncertainty of measuring systems under varying environmental conditions, in particular under demanding production conditions (non-constant temperature, vibrations, poor air purity). The reliable ones Information on the measurement uncertainty allows the user of the measuring system to obtain qualified information about the real measurement uncertainty under the given environmental conditions at each time of use or to make a comprehensible impact on the actual measurement uncertainty by improving or worsening the operating conditions of the measuring system. Furthermore, it is above all possible for service technicians to be able to carry out installation and / or calibration of a measuring system no longer exclusively under a very limited predetermined room class condition, but also under those environmental conditions which are covered by an extended measurement uncertainty specification. In an extended solution variant, not only a fully automatic determination of the best possible measurement uncertainty of the measuring system under the influence of real environmental conditions in the context of calibration is possible, but there is the information about the measurement uncertainty of the measuring system in real time at each time of use. This can be suitably documented in a suitable form and used for any requirements as proof of quality (measuring equipment capability).

• 1: ein Blockschema des erfindungsgemäßen Verfahrensablaufs;
• 2: eine Darstellung der Temperatur über der Zeit für eine optische Komponente (beispielhaft TOLARIS OPTIC) aufgenommen;
• 3: eine Zuordnungstabelle der Messunsicherheit der Messgröße Durchmesser gegenüber physikalischen Einflussgrößen der Umgebungsbedingungen, wie Temperatur und Temperaturgradient, eingeteilt in Klassen/Intervalle;
• 4: ein Beispiel als Prinzipdarstellung für die Ausgabe/Anzeige der messmittelfähig ermittelten Abweichung des Istmaßes vom Nennmaß;
• 5: ein Beispiel für ein Kopfdaten-Protokoll zur Annahmeprüfung mit Angaben zur vorliegenden real ermittelten Messunsicherheit unter den gegebenen relevanten Einflussgrößen der Umgebungsbedingungen Temperatur und Temperaturgradient.

The invention will be explained in more detail with reference to embodiments and figures. Showing:

• 1 : a block diagram of the process sequence according to the invention;
• 2 a plot of the temperature over time for an optical component (exemplified by TOLARIS OPTIC) taken;
• 3 : an allocation table of the measurement uncertainty of the measured variable diameter compared to physical parameters of the environmental conditions, such as temperature and temperature gradient, divided into classes / intervals;
• 4 : an example as a schematic diagram for the output / display of the measured-medium-determined deviation of the actual dimension from the nominal size;
• 5 : an example of a head data protocol for acceptance testing with information on the actual measurement uncertainty determined under the given relevant parameters of the ambient conditions temperature and temperature gradient.

• - Qualifizieren der Umgebungsbedingungen, bezogen auf Art, Typ und Konfiguration von Messmitteln und Komponenten des Messsystems sowie damit zu erfassende gewünschte Messgrößen, durch für die jeweils gewünschte Messgröße relevante Einflussgrößen,
• - Zuordnen der qualifizierten relevanten veränderlichen Einflussgrößen der Umgebungsbedingungen zu Messunsicherheitsparametern der Messgrößen,
• - kontinuierliches Erfassen, Speichern und Bewertung wenigstens einer relevanten veränderlichen Einflussgröße der Umgebungsbedingungen durch geeignete Sensoren, wobei mindestens eine Komponenten-Temperatur eines Messmittels innerhalb des Messsystems gemessen wird,
• - Auslegen der Kalibriermittel derart, dass damit die Konfiguration von Messmitteln und Komponenten des Messsystems ausreichend an einen ermittelten Variationsbereich jeder relevanten veränderlichen Einflussgröße anpassbar ist,
• - Ermitteln der aktuellen Messunsicherheit und Dokumentation der Historie jeder gewünschten Messgröße entsprechend dem Variationsbereich jeder relevanten Einflussgröße der Umgebungsbedingungen, und Ablehnen einer Kalibrierung bei als unzulässig erkannten Umgebungsbedingungen, die einen nicht zulässigen Ausnahmezustand für mindestens eine relevante Einflussgröße darstellen,
• - Ausgabe der aktuell erreichbaren messtechnischen Messunsicherheit für jede gewünschte Messgröße auf Basis der Umgebungsbedingungen bei Kalibrierung oder Ausgabe eines aktuell erkannten Zustandes der Messunsicherheit des Systems in Echtzeit auf Basis der gemessenen Einflussgrößen der Umgebungsbedingungen.

The invention is in the in 1 refer to shown procedure. The main steps are summarized as follows:

• - Qualifying the environmental conditions, based on type, type and configuration of measuring means and components of the measuring system and thus to be detected desired measured variables, by influencing factors relevant to the respective desired variable,
• - assignment of the qualified relevant variable influencing variables of the environmental conditions to measurement uncertainty parameters of the measured variables,
• continuous detection, storage and evaluation of at least one relevant variable influencing variable of the ambient conditions by suitable sensors, wherein at least one component temperature of a measuring means is measured within the measuring system,
• - Designing the calibration means such that the configuration of measuring means and components of the measuring system is sufficiently adaptable to a determined variation range of each relevant variable influencing variable,
• Determination of the current measurement uncertainty and documentation of the history of each desired measured variable corresponding to the range of variation of each relevant influencing variable of the environmental conditions, and rejecting a calibration in the case of inadmissibly recognized environmental conditions representing a non-permitted state of emergency for at least one relevant influencing variable,
• - Output of the currently achievable metrological uncertainty for each desired measurement on the basis of environmental conditions during calibration or output of a currently detected state of the measurement uncertainty of the system in real time based on the measured parameters of the environmental conditions.

The user of the system always has a direct influence on the measuring uncertainty of the measuring system by influencing the environmental conditions, eg placing the measuring system in a high-quality climate cabin (best measurement uncertainty of the measuring system). If the measuring system is operated in variable environmental conditions, the measuring equipment capability of the system for measuring certain workpiece tolerances may change according to the assignment of environmental conditions to measurement uncertainty specifications as defined by the manufacturer. One of the main users of the invention is now or may be when activated / used as a function that the operator receives a corresponding indication during use, for example "Please note that at the time of the measurement due to the currently deteriorated compared to the acceptance state In a further additional function, the currently measured test plan can then be analyzed with regard to the existing tolerances and, as a result, another more detailed statement on the given effect of the changed measuring capability on individual characteristics such as diameter and lengths are taken. If necessary, the following statement can be made in the worst case: "Test plan can not be measured for measuring purposes! Please improve environmental conditions to enable capable measurement! "

Determination and indication of measurement uncertainties

The achievable measurement uncertainty is - fully automatically by the measuring system - depending on the actual environmental conditions during calibration, adjustment or system application specified. The relationship between measurement uncertainty and capability characteristics and tolerances is through MSA (Measurement System Analysis) according to ISO / IEC Guide 99 : 2007 defined. The measurement uncertainty as a term is defined as a deviation from a certified value. This uncertainty is given in the unit of the measured variable, eg for length measurements in mm. A Meseunsicherheit can be attributed to one or described causes. The overall measurement uncertainty of the measuring system is a combination of partial uncertainties, as described below and for the calculation of which there are binding regulations.

The ability to measure means sets this uncertainty of measurement in relation to the tolerance of the measurand, for which there are standardized key figures with standardized calculation rules, which are assumed to be known at this point. The capability characteristics describe whether a measuring system is sufficiently accurate or not for a defined measuring task. Thus, a limit value for a tolerance can be calculated from which the measuring system is capable of measuring.

In the measurement and processing process performed by the measurement system, an automatic assignment of measurement uncertainty information either from data in predefined classes, e.g. in the form of a matrix (look-up table) or calculated dynamically via a model, to the environmental conditions. The most important variable influence on dimensional measured values is the temperature, which is determined if necessary at different places in and around the measuring system. Other influencing factors may be air purity, vibration frequencies / amplitudes.

This forms the basis for statements on capability characteristics at measurement standards and on specimens and workpieces for the operating conditions expected and present by the user / user and is therefore the basis of contractually guaranteed and verifiable properties.

According to the invention, sensors are used for detecting environmental conditions (above all sensors for detecting influencing variables, such as ambient temperature, machine temperature, component temperature (s) and / or test piece / workpiece temperature or, if required, further influencing variables, such as vibration, sound / loudness , Air humidity, air pressure, air purity (eg due to oil mist in the air.

Thus, the important possibility, especially in dimensional metrology, to detect and evaluate temperatures and their courses / gradients over a longer period of time, and in a suitable compensation and use model, the above mainly linear or cubic expansion coefficients but also empirical found constants and measurement error diagrams each of which contains qualified influencing factors. For empirical constants and measurement error profiles, look-up tables are also preferably used for the measurement uncertainty determination or the compensation model.

The achievable measurement uncertainty is specified depending on the environmental conditions and forms the basis for statements on performance characteristics for the operating conditions expected by the user.

Example of temperature measurement

The most important variable influence on dimensional measured values is the temperature, which is determined if necessary at different places in and around the measuring system.

For this reason, sensors for measuring temperatures are used as qualified factors in non-contact optical measuring systems. The detection of influencing variables is not limited to a temperature, such as the ambient temperature, but usually requires much more significant factors such as the Prüflings- / workpiece temperature, the component temperature (s) and / or the machine temperature or, if necessary, other factors, such as Vibration, air purity (e.g., due to oil mist in the air), sound / loudness, humidity, air pressure, etc.

When measuring the ambient temperature (outside the measuring system), a measurement is selected near the workpiece, preferably at the same room height. The temperature of the device is preferably attached to the machine bed, while component temperatures are taken from individual essential measuring components, such as the measuring optics and the camera or even at the sensor block thereof.

Another important temperature for optically measuring systems is the workpiece temperature or the sample temperature of the calibration standard.

With regard to the effects of temperature, the measuring system performs a fully automatic assignment of real temperature conditions for use in calibration / adjustment and for displaying inaccurate measurements - the information on real measurement uncertainties is thus given, as in 3 in front. The example shown contains abstracted values, it serves only to illustrate the basic procedure.

The measurement uncertainty refers to the entire measuring system. The individual influencing variables (in this case different temperature measurements as well as a temperature gradient of one or more temperatures) are only included as subcomponents in the calculation of the measurement uncertainty, as explained below.

wobei U als häufig benannter maximal zulässigen Fehler U_MPE (maximum of premissible error) aufgefasst wird, k eine statistische Konstante (bevorzugt mit k = 2 gesetzt) ist und u(y) eine kombinierte Messunsicherheit bedeutet.When determining the measurement uncertainty, an expanded measurement uncertainty U is preferably used in accordance with the following relationship: $$\text{U = k}\cdot \text{u}\left(\text{y}\right).$$

where U is considered to be the frequently called maximum allowable error U _MPE (maximum of premissible error), k is a statistical constant (preferably set to k = 2) and u (y) is a combined measurement uncertainty.

In this case, according to the invention, the combined measurement uncertainty is determined according to the following equation: $$u\left(y\right)=\sqrt{\left(u_{CAL}^2+u_{eVR}^2+u_{BI}^2+\mathrm{...}+u_{T1}^2+u_{T2}^2+\mathrm{...}+u_{TGr}^2+\mathrm{...}\right)}$$

The combined uncertainty u is composed of any number of subunits u _i , whereby the individual subunits must be crystallized out of the measuring system itself. For that purpose, the influencing variables are determined via series of measurements under systematically changed environmental conditions, ie qualified as influencing variables which demonstrably or unambiguously determine the measurement uncertainty of the measured variables. most clearly influence.

u_CAL

- zertifizierte Messunsicherheit des verwendeten Messnormals (aus Zertifikat)

u_EVR

- Streuung der Messung am Messnormal (durch Messungen bestimmt)

u_BI

- Abweichung des Mittelwerts der Messung am Messnormal vom zertifizierten Wert (durch Messungen bestimmt)

u_T1

- Komponententemperatur (z.B. Optik) (durch Versuche / Messreihen)

u_T2

- Prüflings-/Werkstücktemperatur (durch Versuche / Messreihen)

u_TGr

- Temperaturgradient (ΔT/h) (durch Versuche / Messreihen)

In the above equation (2), the following partial measurement uncertainties have been used for optical linear encoders:

u _CAL

- certified measurement uncertainty of the measuring standard used (from certificate)

u _EVR

- Scattering of the measurement at the measurement standard (determined by measurements)

u _BI

- Deviation of the mean value of the measurement at the measurement standard from the certified value (determined by measurements)

u _T1

- Component temperature (eg optics) (by experiments / measurement series)

u _T2

- DUT / workpiece temperature (by tests / measurement series)

u _TGr

- temperature gradient (ΔT / h) (by tests / measurement series)

Thus, the measurement uncertainty and a measurement capability of the measuring system can be determined and displayed.

The user / user of the measuring system is thus free to initiate corresponding measures with potentially non-measurable results.

Evaluation of the significance of measurement results during the measurements

For measurements of workpieces, the measurement uncertainty achieved under the given environmental conditions, e.g. be calculated in the form of a minimum measurable measurable tolerance

4 illustrates the internal running test routine by comparing a workpiece feature (eg. Length measurement), which is to be included as a measure. For this purpose, the workpiece data, here symbolically only one workpiece feature with nominal size, upper tolerance OT and lower tolerance UT, have been entered into the measuring system and stored. These workpiece data are compared with the measured value of the measured variable and the nominal deviation of the measured value determined therefrom as well as the maximum possible measuring error (referred to as "permissible tolerance") associated with the measured influencing variables of the measured value of the measured variable. Since the upper tolerance of the workpiece characteristic is specified with OT = 0.0800 mm and the lower tolerance UT = 0.08 mm total tolerance from which the maximum measurement uncertainty of the measured variable (the permissible tolerance) is 0.0422 using the currently measured influencing variable ( Temperature) is calculated, the feature tolerance is greater than the minimum allowable tolerance, so that the measured variable (the feature of the workpiece to be measured) was thus measured trustworthy.

The example shown contains example values of a measurement for a length and is for illustrative purposes only. It shows the nominal deviation as an important control variable in workpiece production. For the determination of the permissible tolerance, a calculation is carried out that is statistically based on the MSA already mentioned above.

Logging of achievable accuracy / measurement uncertainty and calibration

Acceptance tests document the relevant ambient conditions (here temperature and temperature gradient in the example) as well as the resulting measurement uncertainty. In 5 a measurement protocol is shown in which the exemplary calibration state is documented from a series of measurements (here, for example, 50).

Based on temperature and gradient during calibration / adjustment, the possible measurement uncertainty is determined. This forms the basis for the metrological evaluation of the assumption according to the methods used.

Claims (11)

Method for securing reliable information on measuring uncertainties of measuring systems in changing environmental conditions with the following steps: - Qualifying the environmental conditions, based on type, type and configuration of measuring means and components of the measuring system and thus to be detected desired measured variables, by influencing factors relevant to the respective desired variable, Assignment of the qualified relevant variable influencing variables of the environmental conditions to measurement uncertainty parameters of the measured variables, continuous detection, storage and evaluation of at least one relevant variable influencing variable of the ambient conditions by suitable sensors, wherein at least one component temperature of a measuring means is measured within the measuring system, - Designing calibration means such that the configuration of measuring means and components of the measuring system is sufficiently adaptable to a determined variation range of each relevant variable influencing variable, Determination of the current measurement uncertainty and documentation of the history of each desired measured variable corresponding to the range of variation of each relevant influencing variable of the environmental conditions, and rejecting a calibration in the case of inadmissibly recognized environmental conditions representing a non-permitted state of emergency for at least one relevant influencing variable, - Output of the currently achievable metrological uncertainty for each desired measurement on the basis of environmental conditions during calibration or output of a currently detected state of the measurement uncertainty of the system in real time based on the measured parameters of the environmental conditions. Method according to Claim 1 , wherein when detecting and storing the influencing variable temperature, in addition to the measurement of at least one component temperature by means of sensors arranged within the measuring system, an ambient temperature is additionally measured by sensors mounted outside the measuring system. Method according to Claim 1 , In addition to the component temperature measurement, measurements of the specimen / workpiece temperature, vibration / vibration, air quality within the measuring system are carried out when detecting and storing influencing variables of the environmental conditions. Method according to Claim 1 , wherein the assignment of the qualified influencing variables of the environmental conditions to the measurement uncertainty parameters of the measured variables takes place statically. Method according to Claim 1 , wherein the assignment of the qualified influencing variables of the environmental conditions to the measurement uncertainty parameters of the measured variables takes place dynamically. Method according to Claim 1 , wherein before the output of currently achievable metrological performance characteristics for each desired measurement, an assessment for feasibility under the given environmental conditions. Arrangement for securing the measurement uncertainty information of measuring systems under variable environmental conditions with - measuring means for detecting desired parameters, which are influenced by relevant for the measured variable variables of environmental conditions in their uncertainty, characterized in that - sensor means for continuous detection and storage means for storing at least one relevant there are at least one sensor for measuring the temperature or for taking thermal images outside the measuring system, a calculation unit for determining the current measurement uncertainty and storage means for storing the history of the measurement accuracy according to the range of variation of each variable influencing variable of the environmental conditions are present, and a comparison unit is available to check whether given environmental conditions in a un permissible defined range of influencing variables of the Ambient conditions are detected that represent an undocumented exceptional state of at least one relevant influencing variable that excludes a calibration, and - an output unit for displaying the currently achievable metrological uncertainty for each desired measurement on the basis of the ambient conditions during calibration and the currently present parameters of environmental conditions exists , Arrangement according to Claim 7 , characterized in that at least one further sensor for temperature measurement is arranged outside the measuring system. Arrangement according to Claim 7 , characterized in that at least one further sensor for measuring the Prüflings- / workpiece temperature is disposed within the measuring system. Arrangement according to Claim 7 , characterized in that a rating unit for testing for feasibility of measurements under the given environmental conditions is present, so that the output unit for indicating deviations of the ambient conditions of the present calibration state is controllable. Arrangement according to Claim 10 , characterized in that the evaluation unit is provided for evaluating measurement tasks for feasibility under the given or for expected possible environmental conditions.

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