Study of the impact of the incremental optical encoder sensor on the dynamic performance of velocity servosystems

• Main Authors: Yeny Vazquez-Gutierrez, Dara L. O'Sullivan, Richard C. Kavanagh
• Format: Article
• Language: English
• Published: Wiley 2019-05-01
• Series: The Journal of Engineering
• Subjects: servomechanisms; encoding; angular measurement; optical sensors; analogue-digital conversion; frequency measurement; voltage-controlled oscillators; encoder simulation model; small-signal dynamics models; closed-loop motor system; incremental optical encoder sensor; velocity servosystems; frequency response measurement; voltage-controlled oscillator; elapsed time methods; pulse count methods
• Online Access: https://digital-library.theiet.org/content/journals/10.1049/joe.2018.8255

This study focuses on the impact of the dynamics of the incremental optical encoder, particularly, at low speed, when the phase margin of the closed-loop system is reduced. This study presents an encoder simulation model, as well as a novel technique to measure experimentally the frequency response of the incremental optical encoder. Both the simulation model and the experimental technique rely on the similarities of an optical incremental encoder and a voltage-controlled oscillator. The experimental and simulation results are compared with the small-signal dynamics models of the encoder presented in the literature for the pulse count and elapsed time methods. The impact of the delay at low speed, on a realistic closed-loop motor system, is experimentally demonstrated.