For higher positioning and speed control, FAULHABER provides a wide range of encoders to combine with the complete portfolio of FAULHABER DC-, brushless, and stepper motors. In the area of encoders, FAULHABER offers 2- and 3-channel incremental magnetic and optical encoders with standard quadrature resolution from 16 to up to 10,000 pulses per revolution or single-turn absolute encoders with a resolution of up to 4,096 steps.
FAULHABER encoders: Optical encoders
Optical encoders are characterised by a very high position and repeat accuracy as well as a very high signal quality due to the precise measuring element. Furthermore, they are insensitive to magnetic interference.
In optical encoders, a code disc with a measuring element is used that is attached to the shaft of the motor. A distinction is made here between reflective and transmissive optical encoders.
With reflective encoders, the light from an LED is reflected by the reflective surface of the code disc and collected by photodetectors. Reflective optical encoders are especially compact since the LED, the photodetectors and the electronics can be mounted on the same circuit board or even on the same chip. For these reasons, FAULHABER primarily uses reflective optical encoders.
Transmissive encoders make use of the transmitted light process. Here, the light from the LED passes through slits in the code disc and is collected by photodetectors on the other side of the code disc.
FAULHABER encoders: Magnetic encoders
Magnetic encoders are especially insensitive to dust, humidity and thermal or mechanical shock. In magnetic encoders from FAULHABER, sensors are used that determine the changes of the magnetic field. The magnetic field is changed by the movement of a magnetic object. This can be the magnet of the motor or an additional sensor magnet with a defined measuring element that is attached to the shaft of the motor.
Using magnetic encoders, an additional sensor magnet is usually necessary. In case of integrated digital or analogue Hall sensors, however, the movement of the rotor magnet in the motor can be measured directly. With integrated Hall sensors, such as nearly all FAULHABER Brushless DC-motors have, there is generally no additional sensor magnet is necessary.
Digital Hall sensors for magnetic encoders
The term sensor refers to digital or analogue Hall sensors which, in case of the FAULHABER Brushless DC-Motors, are usually mounted directly on the motor circuit board. Digital Hall sensors are used primarily for the commutation of the Brushless DC-Motors and for simple speed control. Nearly all FAULHABER brushless DC-Motors are equipped by default with three integrated digital Hall sensors and are thus ideally suited for use in combination with incremental encoders from FAULHABER.
A comparison of analogue Hall sensors and encoders
Analogue Hall sensors are an economical, simple and compact alternative to encoders. Due to the higher resolution, these can also be used for exact rotational speed or position control. For the analogue Hall sensors option from FAULHABER please refer to “Controller combinations” directly in the motors’ data sheets under this selection, no encoder is necessary. If you opt for an analogue Hall sensor, it is recommended that the sensor will be operated with FAULHABER Controllers, which are perfectly laid out for the analogue Hall signals.
Incremental encoders with high accuracy with modular design
The incremental encoders from FAULHABER are constructed according to optical or magnetic principles as well as in a single-chip version. The encoder supplies two 90° phase-shifted square wave signals with up to 10,000 pulses. In the 3-channel version, an additional index pulse is available per motor revolution.
Absolute angle information immediately after switching on
In combination with the FAULHABER DC-motors, the absolute encoder is ideal for commutation, rotational speed and position control. Absolute means each shaft position within a revolution is assigned a unique angular value through the encoder.