Feedback Devices

What are Feedback Devices?

Feedback devices are devices required in closed loop systems that provide a signal to the drive or motion controller to monitor an operation and verify the correct operation occurs. Feedback devices used in motion control applications are either resolvers or encoders.

What are Resolvers?

Resolvers are electromagnetic feedback devices that convert angular shaft position into analog signals, which are then processed for digital position information. A transmitter-type resolver is used for rotor primary excitation and stator secondary outputs. Receiver-type resolvers are designed for stator primary excitations and rotor secondary output.

What are Encoders?

Encoders are the most popular type of feedback device and are electromechanical devices used to translate linear or rotary displacement into corresponding series of digital signals or analog output voltage. Encoders can be either incremental or absolute.

  • Incremental Encoders: devices that generate electrical signals with two output channels, channel A and channel B. These outputs are interpreted by a motion controller to determine position and velocity information. When an incremental encoder is powered on, the position is unknown.
  • Absolute Encoders: absolute encoders have a specific value for each mechanical position. Unlike incremental encoders, when an absolute encoder is powered on, the position is known. These encoders provide digital data in parallel or serial format to the motion controller. This data is then used to determine the position/velocity.

For more information, browse through our selection of feedback devices below!