The advantages of capacitive vs. optical encoders

6th October 2015

Same Sky

Nat Bowers

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Whitepaper

In partnership with Ingvar Andermo, CUI Devices has developed a proprietary method of measuring rotational movement by implementing an ASIC to detect changes in the frequency of a signal modulated by capacitive reactance. Used for years as the key technology in digital callipers, it has been applied to position encoding in the form of the AMT series modular encoder.

Compared to the technology most commonly used in rotary encoders today, capacitive encoding holds many advantages over optical encoding.

An important aspect of motion control is system optimisation and loop time modification. When a system's response needs to be modified due to irregular or undesired behaviour, the correct change can be difficult to find. Either the system PID times need to be adjusted with timely code review and modification, or the line count (resolution) can be adjusted. With the AMT, the ability to dynamically modify the resolution greatly simplifies the system response modification process. The PID control engineer simply adjusts the line counts of the encoder, evaluating the overall response time until the desired result is obtained. Using an optical encoder, this process would require several different versions to be purchased, increasing overall cost and lengthening the design cycle.

Encoders are typically applied in environments that aren’t considered ideal. Temperature, vibration and contaminants are real threats to incumbent encoder technologies. The AMT series was specifically designed to operate reliably and accurately in challenging designs where precise motion feedback is required. This, paired with the flexibility and programmability of the AMT, makes it a compelling solution in a range of industrial, robotics, automation and renewable energy applications.

Download and read the full whitepaper below.