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OpenIndy User Documentation

Open source software solution for industrial measurement (metrology, laser tracker, quality control)

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Measurement

Measurement Overview


Overview  Preperation  Measurement  

Simulation (virtual Laser-Tracker)

This section shows a simple measurement task with the implemented virtual Laser-Tracker. The task is to measure a point and a plane and register the point into the plane.

error model of the virtual Laser-Tracker (16 errors)

Connect the virtual Laser-Tracker

The first step is to set and connect the virtual sensor. The instrument is set as the active station. As a default, STATION01 is the active station and is marked in dark grey. Other stations, if you have some, are marked light grey. Only one station can be active, but it is possible to switch them.
To set the instrument click Station > set sensor. The following dialog will appear:

set instrument dialog

In this dialog you first have to select your sensor type, which is laser tracker in the screenshot. After that you choose the VirtualTracker by selecting it in the list view and pressing set. The program now asks you if you want to connect the sensor automatically, confirm with yes.

Configure the measurement task

We will work in the station coordinate system (original coordinate system of the selected sensor). Therefor use the combobox on the left side, right above the table-view. Switch from PART to STATION01.

In the next step you need to create the features you want to measure. Therefor use the toolbar on the left. There is a button for each feature you can create. Clicking on one of them opens the creation dialog, where you can put in your settings and parameters for the features you want to create.

For the task you need to create a point and a plane. Click on create point create point and type in the name “p1”.It is not common and not nominal. Leave the default function as BestFitPoint. After clicking on create, the point will be created. Repeat the same procedure for creating a plane > create plane create point

Add register Function to the point-feature

For our task we need a function, which will register our point into the plane. To do this, select the point and click Function > set function or use the set function. Select the new function tab and double click on Register. In the list view you have to choose the Register-Function and set up all necessary parameters (here you choose the created plane).

configuration of measurement

Measurement

After the features are created, functions are applied and the sensor is set and connected, we can start measuring the features. For this, select the feature you want to measure and click on measure in the sensor control pad. You can find it by clicking View > sensor control or by clicking on the sensor control pad. Before you can measure you have to choose an actual position the virtual sensor is pointing at. Click on the move command in the sensor control pad and choose a 3D-Position.

Point
0/0/10

Plane
12/12/0
12/14/0
14/14/0
14/12/0

move command

Result

After all mesurements are finished, the table view shows the result set. For the “registered” point you get the 3D-position (x= 0, y=0 , z=10.0->0.0). For the plane you get a 3D-position (x/y/z) and a 3D-direction (i/j/k). For all measured geometries you get information about the accuracy (stdev).

result set

Common measurement example

This section shows one possible way to solve an example task. There are also other ways or orders of steps to solve it.

The measurement task

The task is to check some features of the object vs CAD nominal data. Ten focal points of drill-holes have to be checked against a nominal CAD data. The coordinates of the nominal data are in the object coordinate system, so you also have to transform between the instrument coordinatesystem and the object coordinatesystem. The four marked drill-holes are used as checkpoints for the transformation.

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the object that has to be checked

Set instrument

The first step is to set and connect an instrument. The instrument is set at the active station. On default, STATION01 is the active station and is marked in dark grey. Other stations, if you have some, are marked light grey. Only one station can be active, but it is possible to switch them.
To set the instrument click Station > set sensor. The following dialog will appear:

set instrument dialog

In this dialog you first have to select your sensor type, which is laser tracker in the screenshot. After that you choose the instrument by selecting it in the list view and pressing set. The programm now asks you if you want to connect the sensor automatically, or if you want to connect to it later by hand.

Import nominal data

One of the first steps to solve the task is to import the nominal data (are tagged as golden rows) for the drill-holes. To do this. click on File > import > nominals. In the import dialog choose the data format which is ASCII in our example and the geometry typ (point). As third parameter you need to choose the destination coordinatesystem for the nominal geometries. In our case use the default PART coordinate system, which is the coordinate system of the not yet transformed plain. You can also choose other coordinate systems, if you create them via the toolbar by clicking on create coordinate system before importing the nominal data.

The nominal points file for the measurement task:
p1 -50.737 0.082 0.000
p2 -35.867 36.062 0.000
p3 0.096 50.816 0.000
p4 35.924 35.920 0.000
p5 50.796 0.012 0.000
p6 35.861 -35.981 0.000
p7 -0.086 -50.734 0.000
p8 -36.015 -35.797 0.000
p9 0.000 0.000 0.000
p10 104.199 0.000 0.000

import nominal dialog

Create features to be measured

In the next step you need to create the features you want to measure. For this use the toolbar on the left. There is a button for each feature you can create. Clicking on one of them opens the creation dialog, where you can put in your settings and parameters for the features you want to create.

For the task you need to create 10 points. The name of the actual measurement features has to be the same as the corresponding nominal one. Click on Create point create point, type in the name “p1” and set the count = 10. They are not common and not nominal. Leave the default function as BestFitPoint. After clicking on create, ten points will be created and automatically be named after the count number from p1 to p10.

create feature dialog


Add functions

To solve a feature it is neccessary to add functions to it. You already set the default function in the create feature dialog. Every function has input parameters, that you have to assign to it (e.g. obervations or a plane and a distance). For our task we added a “Best Fit function” to the features we measure in the creation dialog. To do this manually, select a feature and click Function > set function or use the set function icon. Then choose your function by clicking it. There are only functions displayed, that can be applied to the selected feature at this state. After double clicking the next view appears, where you can add or remove the input parameters that the function needs. Also you see all functions that are applied to this feature in the order they are performed. In our case we first add the best fit function and then measure the feature, so all observations of the feature are used for the best fit immediately. It is also possible to measure the feature first and then add the function. This way you have to assign the observations of the feature to the function via the treeviews in the function menu.

add input parameter.

You can remove functions by doing a right click on them in the function menu and choosing delete function.

Measuring features

After the features are created, functions are applied and the sensor is set and connected, we can start measuring the features. For this, select the feature you want to measure and click on measure in the sensor control pad. You can find it by clicking View > sensor control or by clicking on the sensor control pad icon.

measure the current selected feature (p1)

You will notice, that the measured points are displayed as not yet solved (columns are tagged yellow). Because we could not measure the focal point of the drillholes directly, we need to solve the problem by applying some functions.

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unknown offset problem

For this, we measure the ground plane, and move it on its own normal vector with the value of the reflector radius. To do this use the function “Shift”. After this we project our drill-hole points in the plane and have the offset corrected values we want.

Transformation parameter

After measuring all neccessary features, we need to transform our measurements, because the nominal data for the feature is in the PART system whereas the actual feature data is in the instrument coordinate system. In order to do this, we need to create a transformation parameter via the button Create transformation parameter create transformation parameter. In the dialog you have to give this transformation parameter a name and set a start and destination coordinate system. After creating the parameter set it is displayed in its own tableview tab “transformation parameter”. Here you can select it by clicking on it. You can also edit the parameters by hand if you choose “show properties” after right clicking the transformation parameter set.

Apply a function to the transformation parameter

After you created the transformation parameter you can set some values by hand (see paragraph above), or you can calculate parameters by applying a function to the transformation parameter feature. Click on Function > set function and click on the tab “new function”. The default plugin, that we used for this measurement task, contains a 7 parameter helmert transformation. Select the transformation function by double clicking it.

Apply checkpoints to the 7 parameter transformation

After selecting the function, the input parameter have to be applied to the function. In the available elements window, we need to apply the nominal (imported at the beginning) and actual (measured) checkpoints, specified at the beginning of the guide (p1,p3,p5,p7). Apply the dialog and now the transformation parameter will be calculated and applied on the feature.

applying checkpoints (nominal and actual) to the function

After this step it is important to change the “use” column of the transformation parameter feature from false to true by double clicking the matching field, so that the parameter can be applied as transformation on the coordinate systems.
Now it is possible to transform between STATION01 and PART. You can do this, by switching the active coordinate system in the combobox right above the feature tableview. This combobox includes all existing coordinate systems whether instrument systems or part systems.

Save and load project

After the actual values are transformed and compared with the nominal values of the features, you should save the project by clicking on File > save as and specify a path and folder. OpenIndy saves the project in an openindyXML.xml file where all features, their relations, observations, functions and other parameters are stored, so that it is possible to restore the complete project at a later time. To load and restore a project click File > open project.

extract of a project xml file