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US 8,412,360 B2Granted
Method and system for robust attenuation of mechanical resonances using a multi-rate low pass filter
AssigneeHitachi Asia Ltd.
InventorsQing Wei Jia, Kensuke Amemiya
Life of this patent
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Abstract
A system for a providing a multi-rate digital low pass filter that attenuates high frequency resonances in a control signal. The filter described by a transfer function having a phase-advanced factor (or an approximation of phase-advanced factor) and a low pass filtering function; either cancels or avoids an unstable pole in the phase advanced factor at z=−1.
Claims13
A control system for providing a control signal for a plant, said control system comprising:
- a digital signal processor that generates a control signal based upon a sample of a previously output control signal;
- and
- a multi-rate digital low pass filter provided by said digital signal processor that attenuates high resonance frequencies from said control signal, wherein said multi-rate digital low pass filter has a transfer function having a low pass filtering function and a phase-advanced factor having an unstable pole at z=−1, wherein said transfer function includes one selected from the group consisting of said low pass filtering function that cancels said unstable pole and an approximation of said phase-advanced factor that avoids said unstable pole.
A method for removing high resonance frequencies from a control signal, said method comprising:
- generating a control signal in a digital signal processor;
- applying said control signal to a multi-rate digital low pass filter to attenuate high resonance frequencies from said control signal, wherein said multi-rate digital low pass filter has a transfer function having a low pass filtering function and a phase-advanced factor having an unstable pole at z=−1, and wherein said transfer function includes one selected from the group consisting of said low pass filtering function that cancels said unstable pole and an approximation of said phase-advanced factor that avoids said unstable pole.
Dependencies are inferred from the claim text.