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 Figure 4‑5.

The bold-faced entries in the database are sensor models. Sensor 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.

Figure 4-5: Sensor database with sensor models (bold-faced) and instances (normal-faced)

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 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 important 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 in order 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 name, description, and corresponding virtual point of the object 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, which is especially suited for such bulk operations. Sensor furthermore have an Angle and Face property: this is used most often to correctly rotate the sensor.

Figure 4-6: Sensor properties

Figure 4-7: Excitation properties

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.

 

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 right clicking on the sensor name in the Item Overview and selecting “Edit Item”.

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