Patent ID: 7684759
Filing Date: 2010-03-23
Classification: G05B,G06F

Abstract:
1. A method for determining the damped natural frequencies of a dynamic system comprising the actions of: producing a frequency response function for the dynamic system; smoothing the frequency response function; identifying a set of possible candidate frequency values by determining when a derivative of the frequency response function traverses through zero; sorting the set of possible candidate frequency values based on amplitude; identify the next candidate in the sorted candidate frequency values starting from the beginning of the set that has not been eliminated; determining a range of influence by identifying a lower root frequency and higher root frequency; eliminating the candidate frequency value by comparing the candidate frequency value with a maximum or minimum amplitude in the range of influence and when the candidate frequency value is eliminated returning to the action of identify the next candidate; checking a direction of a change of phase in the range of influence occurs in an expected direction, and when direction is opposite the expected direction, eliminating the candidate frequency value and the returning to the action of identify the next candidate; determining if any frequency candidate values of lesser significance are in the range of influence by identifying frequency candidate values occurring later in the frequency candidate values set and when the frequency candidate value occurs later eliminating said later candidate frequency value and the returning to the action of verifying the current candidate; determining if any frequency candidate values of greater significance are in the range of influence by identifying frequency candidate values occurring earlier in the set frequency candidate values and when the earlier frequency candidate value has not been eliminated and appears in the range of influence of the currently considered candidate, eliminate the currently considered candidate frequency and the returning to the action of verifying the next candidate; eliminating the frequency candidate value by comparing a noise level in the frequency response function to the amplitude in the region of a pole and when the candidate frequency value is eliminated returning to the action of identify the next candidate; and returning to the action of identifying the next candidate until all frequency candidate values have been identified.