Method and system for determining rotational speed by means of video camera

A system for determining a rotational speed of a rotatably mounted component of a machine, comprising

• a video camera for obtaining image data of a marked region of the machine component in the form of a plurality of frames,
• a data processing unit for evaluating the image data in order to determine the periodicity of the rotation of the machine component from the change over time of the image data of the marked region in the frames of the machine component, so as to determine the rotational speed of the machine component, as well as an output unit for output of the rotational speed of the machine component,
• wherein the video camera is configured by selecting an active region for obtaining the image data from the total number of pixels of the video camera, in which an observation area is imaged, which is then passed through by the marked region during the rotation of the machine component, wherein the active region comprises only a portion of the total number of pixels of the video camera, in order to increase the frame rate correspondingly, and
• wherein the observation area that is imaged by the video camera is shorter than the marked region in at least one dimension.