White Paper: Sensors/Data Acquisition

Smaller, Faster, More Accurate: How Advances in Rotary Encoder Technologies are Revolutionizing the Sensing Industry


As motion control systems have grown in complexity, the need has expanded for sensors to measure the many shaft rotations needed for proper control of the system. Rotary sensors have been available for almost 100 years but with large, heavy analog devices whose accuracy was measured in degrees.

Netzer has developed a noncontact rotary sensor based on capacitive technology. This sensor (DS-16) is a thru hole mount 16 mm in diameter and 4 g in weight. It provides a digital output with a resolution of 5 millidegrees (16 bits) and an accuracy of less than 35 millidegrees. Larger diameter sensors are also available from Netzer with resolutions down to 170 microdegrees (21 bits) and accuracies of less than 5 millidegrees.

The paper contains more details on the performance of these sensors and their technology. A section is devoted to discussing other methods used to build rotary sensors. These include the technologies of induction, optics, and magnetics. The final section contains a story of the first noncontact position sensor in history (1835) built by Michael Faraday in a failed attempt to design an electric motor. It is still on display in the British Museum.


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