A shaft encoder vs. an absolute shaft encoder

The main difference between the shaft encoder and the absolute shaft encoder is the metering technology. When the “absolute” is replaced with an “incremental” one, it makes a world of difference. This article gives an in-depth review of the implications.

What are the rotary/shaft encoders?

Encoder is a metering device that monitors the angular positioning of an object moving in a circular motion. The linear variant is used for estimating motion is a rectilinear direction. The rotary encoder often has a hollow shaft commonly referred to as “the hub,” which is attached to the spinning object. The internal mechanism depends on the sensing technology and the type of output signal.

The linear transducer is made up of a scale that converts movements into coded signals, and it also has a sensor that reads the signal and converts it to electrical data.

The scale can be designed to use either reflective or transmissive system, with phase grating or Ronchi ruling. The configuration options include self-supporting, thermally induced, or rack-mount.

Both the linear and rotary models of transducers operate by the same principle, which is sending measurements to a master system.

The master system processes the transmission by decoding the displacement signal to derive speed and other essential factors related to motion. Professional consultation about the technical aspects of shaft encoders is something what you always can request at rozum.com  

Why are Absolute Encoders so Special?

The function of the subtype rotary encoder is to implement a specific type of signal sensing method, to return the desired response, and to be used in the specific application.

Some of the available features that make this type of mechanism special include:

·         The measures value determines the distance of the rotating movement from a zero coordinate. And the coordinate remains unchanged irrespective of the system state.

·         Each reading has a unique binary code and delivers an objects angle with a high level of precision.

·         It does not require a homing procedure for measurement reference when powered up because the sensors return non-relative values.

·         The detectors can read parameters over a single revolution (single-turn) or multiple 360 degrees revolution (multi-turn).

·         It enhances high precision targeting in application because it is immune to noise interference.

·         It supports a wide range of data exchange protocols which enhances easy integration with application electronics.

Application to the servo actuators

The Rozum corporation choses to equip the RDrive servo motors with absolute shaft encoders for the following reasons:

The RDrive servo motors are designed to enable angular positioning.  It is efficient in providing accurate feedback on rotational movements.

  • Because it supports the BiSS protocol, it can freely communicate with the controlling electronics.

It allows the highest level of motion precision. The controllers can get the exact point of the motor, compare the values with commands, and make adjustments to movement trajectories when required.

  • The user can access the motion parameters at any instant without external aid or cost for additional mechanism.

The measurements are made at two spots simultaneously (on the output shaft and rotor) with 19-bit resolution. If you need the conversion for bit-resolution – check this page.

The job of the two encoders is to close the motion control and loop correctly.  Rozum Robotics use the best-in-class technology in RDrive actuators. It’s high accuracy, and repeatability make it perfect as a servomechanism.

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