Discrete time control

D

Thread Starter

Dapo

Hi dear experts,

If the feedback signal in a digital control system has less resolution than the output signal, the output will be made to switch between 2 quasi-stable states. In other words, for a constant set-point, the output looks like a superposition of the constant signal and a sinusoid.

Has anyone experienced this (especially with motor Resolvers/Encoders)? If you have kindly shed more light!

Regards
Dapo
 
For constant Set-point Output control signal (current/torque command for example) can switch between 3 (+LSB, 0 and -LSB) and even more states. And such finity resolution of Output leads to non-stability of Feedback (encoder) signal is named a Jitter. The Jitter can be more than +/-1 in units of feedback resolution - it depends from Output and Feedback resolutions as well.
 
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