Encoders detect a rotary movement and use this to derive a measurement signal. The devices are used for speed control and for position determination. FAULHABER offers encoders with optical or magnetic measurement principle. In addition to precision and robustness, both variants are characterized by their compact design.
With the optical measurement, a code disc, which is divided into optically different fields, rotates with the motor shaft. A light beam directed at the disc is interrupted by the fields or reflected with interruptions. The analysis of the pulse sequence supplies the information about speed and relative position of the shaft. Optical encoders are insensitive to magnetic interference. They can achieve a very high position accuracy and repeatability.
With the magnetic measurement, a sensor magnet rotates with the motor shaft. Here, Hall sensors or special ICs detect the changes in the magnetic field that result from the rotary movement. Magnetic encoders are insensitive to dust, humidity, and thermal and mechanical influences.
An incremental encoder does not measure absolute positions, but rather relative positions. Incremental encoders determine a position relative to another reference position and transmit a specific number of uniformly distributed lines per revolution.
An absolute encoder, on the other hand, outputs an absolute position value, like a clock, which displays an absolute time. It does not need a reference variable and can determine the angular position of its shaft at any time. With single-turn absolute encoders, this applies for one shaft revolution. Multi-turn absolute encoders also detect the number of revolutions. Their signals can be used, e.g., to precisely determine the position in applications with lead screws.
The sensor pulses of the FAULHABER encoders are processed by special electronic components and converted into standardized output signals. Through interpolation, the physically recorded pulses can be mathematically divided into multiple signal periods. This allows the resolution to be increased many times over.
The encoders from FAULHABER are equipped with at least two channels: A and B. Both channels return a square wave signal that is offset by 90°. This signal can be used to determine the motor’s direction of rotation. With three channels, one channel is used for the index pulse, which indicates a completed full revolution.
FAULHABER offers a wide selection of encoders, which are designed for optimum combination with FAULHABER motors. The range of devices includes magnetic and optical two- and three-channel incremental encoders with a standard resolution of 16 to 1024 lines per revolution as well as single- and multiturn absolute encoders. Single-turn absolute encoders are available with a resolution of up to 10,000 steps.