Encoders provide velocity, acceleration, direction, and position feedback to motion systems. Two basic types of feedback are absolute and incremental. Absolute encoders report unique position information at all locations and are unaffected by power loss. Incremental encoders also deliver position information, but count from a reference, which may require that a system be reset to a known start position after a loss of power.
There are several variables to consider when choosing an encoder. The most common are:
There are also encoders available that address other environmental conditions, including exposure to corrosive and caustic chemicals and ambient temperatures that reach up to 120° C. For more information, refer to the white paper, Encoders in Inhospitable Environments.
Designers must identify an encoder resolution that reflects the system’s true needs. Resolution that is too high can increase costs and raise frequencies above the encoder or receiver’s capabilities. Also, higher resolution doesn’t necessarily translate into higher system accuracy. On the other hand, resolution that’s too low may limit the system’s ability to control speed or position accurately. Additionally, incremental encoders with quadrature phasing not only provide directional information but can increase resolution up to four times when combined with a compatible receiving device.
A system’s receiving device (controller) generally dictates encoder output. Thus, designers should first determine the controller’s input requirements, and then select a compatible encoder output driver. For more information, refer to our white paper Selecting Digital Encoder Outputs.
Three basic types of controllers exist:
Many controllers accept differential line-driver signals, cancelling common-mode noise while accommodating long encoder cable runs.
Mounting and installation depend on the style of the encoder. Thru-bore and blind hollow-bore encoders slide over and clamp onto a precision shaft, attaching directly to the motor frame through a flexible mount. A proper fit between the bore and shaft, as well as a good flex mount design, helps retain accuracy and encoder bearing life.
Shaft encoders, on the other hand, are usually mounted to a fixed surface and coupled to a driven shaft. Alignment between the shafts and the coupling’s design and quality also impacts accuracy and encoder bearing life.
To reduce the potential for electrical noise degrading an encoder’s signal, follow these key steps:
When considering how to apply an encoder for motion feedback in an industrial application, there are several basic factors to consider. There are a variety of resources available to aide in research for a solution. However, there are motion control experts well-versed in encoders and their options who can guide you to the right motion feedback solution for your application.
If you have a question about which encoder is right for your application, contact BEPC. You’ll talk to real engineers and encoder experts who can answer your questions about encoders and motion feedback, and you’ll get answers that make sense for your application.
BEPC’s corporate headquarters is in the United States. We offer expedited options on most models, even same-day options. With our industry-best three-year warranty, if something does go wrong, we’ve got you covered.
Contact BEPC today to find the right motion feedback device for your application.
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