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Capacitive displacement sensors share many similarities to eddy current (or inductive) displacement sensors; however capacitive sensors use an electric field as opposed to the magnetic field used by eddy current sensors [10] [11] This leads to a variety of differences between the two sensing technologies, with the most notable differences being ...
Sensors can measure physical properties, such as the distance between objects, the presence of light and the frequency of sound. [3] They can measure: Object Proximity: The presence/absence of an object, bearing, color, distance between objects. Physical orientation. The co-ordinates of object in space.
There are two types of capacitive sensing systems: mutual capacitance, [5] where the object (finger, conductive stylus) alters the mutual coupling between row and column electrodes, which are scanned sequentially; [6] and; self-capacitance, where the object (such as a finger) loads the sensor or increases the parasitic capacitance to ground.
Ultrasonic sensors can detect the movement of targets and measure the distance to them in many automated factories and process plants. Sensors can have an on or off digital output for detecting the movement of objects, or an analog output proportional to distance. They can sense the edge of the material as part of a web guiding system.
A sensor's accuracy may be considerably worse than its resolution. For example, the distance resolution is the minimum distance that can be accurately measured by any distance-measuring devices. In a time-of-flight camera, the distance resolution is usually equal to the standard deviation (total noise) of the signal expressed in unit of length.
The most common method for comparing two images in content-based image retrieval (typically an example image and an image from the database) is using an image distance measure. An image distance measure compares the similarity of two images in various dimensions such as color, texture, shape, and others.
Four-point measurement of resistance between voltage sense connections 2 and 3. Current is supplied via force connections 1 and 4. In electrical engineering, four-terminal sensing (4T sensing), 4-wire sensing, or 4-point probes method is an electrical impedance measuring technique that uses separate pairs of current-carrying and voltage-sensing electrodes to make more accurate measurements ...
Proximity sensors are also used in machine vibration monitoring to measure the variation in distance between a shaft and its support bearing. This is common in large steam turbines, compressors, and motors that use sleeve-type bearings. A proximity sensor adjusted to a very short range is often used as a touch switch.