4.4 Sensors and impacts

Working with the sensor database

The sensor database can be accessed by clicking +SENSOR in the toolbar or pressing D. The sensor database contains information about all accelerometers, microphones, impact hammers, and custom sensors to be used in the project. Some commonly used sensors are included in the initial installation and can be used by selecting the sensor, clicking use selected sensor, and placing the sensor in the project; see the figure below.

The bold-faced entries in the database are sensor models. Sensors added from these entries become generic sensors with no serial number and assume the default calibration values (these can, of course, be changed later). From the sensor models, so-called sensor instances are derived, which are the light-faced rows. These sensors have a serial number and specific calibration values for the sensor axes. New instances can be added by clicking on the three-dots icon on a sensor model. Options are available to add, remove and change models and instances as well.

Additional sensors can be added to the database by clicking the plus sign in the top right corner. Different properties are available for the four sensor types. Custom sensors can be defined to support, for instance, strain sensors and force response sensors.

The database can export all definitions to a DB file. This can be used to share definitions with colleagues. You will find the Import Database and Export Database options under the three-dots icon in the top right corner.

The following video explains how to work with the sensor database.

Adding master sensors

If you cannot find your sensor in the database, you can add it as a new master sensor. This master sensor will be added to the sensor database, with its general characteristics.

To create a master custom sensor, complete the next steps:

1. Open the sensor database.
2. Click on the + button.
3. Fill in the information of your sensor.
4. Click Add.

Adding sensor instances

If you reuse the same sensors every time, you can create sensor instances for them in the database. In these instances, you can specify the exact calibration value for each channel.

To create an instance, complete the next steps:

1. Open the sensor database.
2. Click on the 3 dots next to the master sensor.
3. Select Create New Instance. A window will open.
4. Fill in the correct information.
5. Click Add.

Adding sensors and impacts

The first time an accelerometer is added to the project, it must be selected through the sensor database. Subsequently, the same accelerometer can be added by pressing S. Impacts are added by pressing I. If geometries are defined, the sensors and impacts will snap to the surface of the geometry. Otherwise, they will be placed at the origin.

Excitation vs excitation sources

Excitations represent the physical locations where impacts are to be made. Accurately capturing the location and position of impacts is essential for an accurate Virtual Point Transformation.

Excitation sources represent the impact hammer(s) that will be used to execute the impacts (excitations). An excitation source must be defined to do a measurement, as this is where the hammer sensitivity is defined and can be added to the project using the sensor database.

Editing sensors and impacts

Editing information, mounting, visualization

Sensors and impacts can be edited by right-clicking on the object in the 3D viewer and selecting Edit object or right-clicking on the item in the Item Overview and selecting Edit Item. Multiple objects can be selected using CTRL+click and then edited simultaneously. Here, the object’s name, description, and corresponding Virtual Point can be edited, and the mounting properties can be updated using actual coordinates. Note that the coordinates are given in millimeters.

Sensors can be given an offset from their mounting point: the Out Offset moves the sensors out-of-plane, which comes in useful to compensate for base plates, whereas the X and Y Offset nudge sensor in its local mounting plane. Remind that all values can also be set for multiple objects in List Mode, especially suited for such bulk operations. Sensors furthermore have an Angle and Face property: this is used most often to rotate the sensor correctly.

The normal (sensors) and direction (impacts) are defined using an azimuth and elevation property. The azimuth defines the “yaw” angle in the XY plane and is bound between -180 and 180 degrees. The elevation defines the pitch and is bound between -90 and 90 degrees.

Finally, the color of the objects can be changed and visibility toggled on/off.

Manually moving sensors and impacts

Sensors and impacts can be moved and rotated manually by right-clicking on the object in the 3D viewer and selecting Move on Geometry or Move. Move on Geometry keeps the object mated to the surface of the geometry as with the initial definition. Move allows the object to be moved anywhere in space by clicking and dragging on an arrow, arc, or the origin of the local coordinate system axes.

Mirroring sensors/impacts

If you have a symmetric geometry, you might want to mirror sensors and impacts with respect to an axis.

To mirror sensors/impacts, complete the following steps:

1. In the 3D Viewer, select all the sensors/impacts you want to mirror.
2. Right-click and select Duplicate objects.
3. Right-click again (without removing the selection) and select Mirror.
4. Select the correct axis.

Channel and excitation names and templates

You can manually change the name of the channels or excitations with text, tokens, or a combination of both. You can either edit single channels manually or create a template to apply to all of them.

To create a template and assign it to multiple channels and excitations, complete the next steps:

1. Go to the List Mode.
2. 1.  Go to the Sensors tab and toggle the Channels mode.
   2. Go to the Excitations tab.
3. In the Name column, double-click one entry.
4. Type { and select the desired token(s). Add additional text (if wanted).
5. Press Enter.
6. Drag the just created template over other channel/excitation names using the control in the bottom right corner of the selection.

Replacing sensors

A sensor can be replaced by a different sensor model by right-clicking on the sensor and choosing Replace. Sensors can also be replaced within the Properties tab, accessed by either right-clicking on the sensor in the 3D viewer and selecting Edit object or by right-clicking on the sensor name in the Item Overview and selecting Edit Item.