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Entry  Sun Oct 7 23:39:10 2012, Den, Update, Modern Control, state estimation est_time.pngest_freq.pdf
    Reply  Mon Oct 8 09:51:30 2012, rana, Update, Modern Control, state estimation 
       Reply  Mon Oct 8 12:34:52 2012, Den, Update, Modern Control, state estimation 
Message ID: 7503     Entry time: Mon Oct 8 12:34:52 2012     In reply to: 7499
Author: Den 
Type: Update 
Category: Modern Control 
Subject: state estimation 



 I guess that the estimated state has the same low pass filter, effectively, that we use to low pass the feedback signal in SUSPOS. I wonder if there is an advantage to the state estimation or not. Doesn't the algorithm also need to know about the expected seismic noise transmission from the ground to the optic?

 I think state estimation and optimal control are two different techniques that are often used together. Sometimes (as for pendulum) we can use LQG without state estimation as we need only position and velocity. But for more complex systems (like quad suspension) the states of all 4 masses can be reconstructed in some optimal way using information from only one of them if the dynamics is sufficiently well known. When current system states are measured/estimated we can apply control where all our filters are hidden.

 The algorithm needs to know about expected seismic noise transmission from the ground to the optic, but it might be not very precise. I gave it some rough estimate, there are better ways to do it. I think that we'll understand whether we need state estimation or not when we'll move to more complex systems. Brett uses a similar approach for his modal control. Interesting if these methods + seismometer readings will be able to say if one of your sensors is noisier then others.










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