Sensors: Systematics

A key distinguishing criterion for sensors is the physical principle of transmission of the primary signal. The majority of sensors commonly used today can be categorised as tactile or non-contact. Tactile sensors obtain information about the position of a measurement point by contacting the measuring object with a probe tip, usually a stylus tip. The resulting deflection of the probe tip can be determined electrically or optically. Optical sensors capture the position of a measurement point by reflecting light off the workpiece surface. With X-ray tomography sensors, an object area is penetrated by X-rays and the three-dimensional geometry of the measuring object is reconstructed from the radiographic images. From this, the position of the measurement points is deduced.

The sensors can have their own measuring range (measuring sensors) or only recognise when a threshold value is exceeded (switching sensors). The direction of action of the sensors can be reduced to one or two coordinate axes (1D, 2D sensors) or include all three axes (3D sensors). The measured values of the respective non-measuring axes are given by the sensor position (e.g. position of the measuring axis of the sphere centre for 1D probes or position of the object plane for image processing). Sensors can measure individual points (point sensors), contours (line sensors) or surface areas (area sensors).