Method and system for predicting limit cycle oscillations and control method and system utilizing same
First Claim
1. A method for predicting limit cycle oscillations in a natural system, the method comprising the steps of:
- measuring oscillatory behavior in the natural system to obtain a first signal based on the oscillatory behavior;
statistically processing the first signal to obtain a corresponding envelope signal;
monitoring instantaneous changes in a function which is based on the envelope signal; and
generating a classifier signal when the instantaneous changes are less than a predetermined threshold value for a predetermined time period whereby the classifier signal is a prediction of the limit cycle oscillations.
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Abstract
A data-driven method and system are provided for predicting limit cycle oscillations such as chatter to obtain a classifier signal which, in turn, may be utilized by a control method and system. The method and system utilize algorithms based on random field theory which are applied to "vibration" data to predict when chatter phenomenon may emerge during an ongoing machining process. Using real data from a turning operation on a lathe, the onset of chatter can be predicted so that sufficient time is available to deploy an automatic control strategy such as reduction or random variation of spindle speed to quench the "chatter". The method and system preferably use instantaneous scale of fluctuation.
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Citations
26 Claims
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1. A method for predicting limit cycle oscillations in a natural system, the method comprising the steps of:
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measuring oscillatory behavior in the natural system to obtain a first signal based on the oscillatory behavior; statistically processing the first signal to obtain a corresponding envelope signal; monitoring instantaneous changes in a function which is based on the envelope signal; and generating a classifier signal when the instantaneous changes are less than a predetermined threshold value for a predetermined time period whereby the classifier signal is a prediction of the limit cycle oscillations. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for controlling limit cycle oscillations of an object, the method comprising the steps of:
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generating an electrical signal based on oscillatory behavior of the object; statistically processing the electrical signal to obtain a corresponding envelope signal; monitoring instantaneous changes in a function which is based on the envelope signal; generating a classifier signal when the instantaneous changes are less than a predetermined threshold value for a predetermined time period whereby the classifier signal is a prediction of the limit cycle oscillations; and controlling the limit cycle oscillations of the object based on the classifier signal. - View Dependent Claims (11, 12, 13)
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14. A system for predicting limit cycle oscillations, the system comprising:
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a detector for generating a first signal based on oscillatory behavior; a signal processor for statistically processing the signal to obtain a corresponding envelope signal; a monitor for monitoring instantaneous changes in a function which is based on the envelope signal; and a signal generator for generating a classifier signal when the instantaneous changes are less than a predetermined threshold value for a predetermined time period whereby the classifier signal is a prediction of the limit cycle oscillations. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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23. A system for controlling limit cycle oscillations of an object, the system comprising:
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a detector for generating an electrical signal based on oscillatory behavior of the object; a signal processor for statistically processing the electrical signal to obtain a corresponding envelope signal; a monitor for monitoring instantaneous changes in a function which is based on the envelope signal; a first signal generator means for generating a classifier signal when the instantaneous changes are less than a predetermined threshold value for a predetermined time period whereby the classifier signal is a prediction of the limit cycle oscillations; and a second signal generator for generating an output control signal based on the classifier signal. - View Dependent Claims (24, 25, 26)
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Specification