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The Role of Encoders in Miniature Motors

May 19, 2022

Encoders are a type of miniature motor accessory that provide feedback regarding motor speed and rotor direction and positioning. Though these aren’t required for every type of application, they are vital components for tracking motion in a closed loop system, especially when precise motion depends on accurate motor monitoring and control.

Encoders make motion control possible by sensing the motor’s speed and position and sending feedback signals to control components. Two square waves (or channels) shifted 90 electrical degrees from each other, along with an optional index pulse that occurs once per revolution, encode the angular position data. If your application requires a high level of accuracy for positioning and feedback, there’s a good chance that you’ll need to pair an encoder with your miniature motor to ensure your application functions as it should.

Types of Encoders

Encoders can be broken down based on both technology type and operating principle:

Technology Type. Encoders can typically be classified as incremental encoders or absolute encoders. Incremental encoders track precise motion relative to position and direction changes and provide feedback in real-time; they do not reference a specific point. Absolute encoders, on the other hand, provide exact positioning, which is more complex. This increased complexity leads to an increased cost.

Operating Principle. Encoders will operate on a magnetic or optical principle. Magnetic encoders utilize a magnetized disc that rotates; during the rotation, changes to the magnetic field are detected by sensors (such as Hall effect sensors), providing speed and positioning information. These types of encoders are well-suited for demanding applications where impact or ingress are possible. Optical encoders provide extremely accurate and precise positioning via the use of LED. Infrared light from an LED is passed through a metal code wheeling comprised of clear and opaque segments; this creates distinct light signals received by optoelectronic sensors. These types of encoders are not impacted by potential magnetic interference.

Coming Soon – the M-Sense22 Magnetic Encoder

Portescap is preparing to introduce our newest magnetic encoder, the M-Sense22, which will be capable of providing both incremental and absolute feedback for our brushless slotless motors ranging from 20mm to 40mm in diameter. This encoder features high accuracy up to 1.5 degrees, as well as a wide resolution range up to 1024 lines. Specific applications benefitting from the use of this encoder include missile fin actuation, drones, portable ultrasound probes, grippers, and nut runners/electric screwdrivers, among a wide variety of others in the Aerospace & Defense, Industrial Power Tools, Life Sciences, Surgical Power Tools, and Robotics markets. Reach out to us for more details here!