Automatic generation of PID parameters for a scanning probe microscope
First Claim
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1. A method for controlling a scanning probe microscope, the method comprising:
- generating a scanning probe microscope model according to associated dynamics of the scanning probe microscope;
selecting filter parameters that shape selected dynamics of the scanning probe microscope model;
generating a notch filter using the filter parameters;
encoding the notch filter as PID parameters; and
implementing the PID parameters in a PID controller to control the scanning probe microscope.
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Abstract
Linear PID controllers have a transfer function that resembles the frequency response of a notch filter. The PID parameters, KP, KI, and KD (proportional, integral, and derivative gains, respectively) can be extracted from the parameters of a linear notch filter. The linearized modes of scanning probe microscope (SPM) actuators have frequency responses that resemble those of simple second order resonance. Reasonable feedback control can be achieved by an inverse dynamics model of the resonance. A properly parameterized notch filter can cancel the dynamics of a resonance to give good closed-loop response.
14 Citations
18 Claims
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1. A method for controlling a scanning probe microscope, the method comprising:
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generating a scanning probe microscope model according to associated dynamics of the scanning probe microscope; selecting filter parameters that shape selected dynamics of the scanning probe microscope model; generating a notch filter using the filter parameters; encoding the notch filter as PID parameters; and implementing the PID parameters in a PID controller to control the scanning probe microscope. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method as for controlling a scanning probe microscope including a cantilever and an actuator, the method comprising:
- automatically generating PID parameters that include a proportional gain, an integral gain, and a derivative gain, wherein automatically generating the PID parameters includes,
measuring a closed loop system response during operation with a nominal controller; deriving an open loop system response from the measured closed loop system response; removing an effect of the nominal controller from the derived open loop system response to yield a response of the actuator of the scanning probe microscope; performing a curve fit on a selected portion of the response of the actuator to obtain a transfer function; and generating resonance parameters from the transfer function, and using the generated resonance parameters to design a PID controller; and
applying the PID parameters to operate the actuator beyond a resonant frequency of the actuator.
- automatically generating PID parameters that include a proportional gain, an integral gain, and a derivative gain, wherein automatically generating the PID parameters includes,
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14. An instrument comprising:
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a scanning probe microscope including a cantilever and an actuator; a proportional-integral-derivative (PID) parameter generator that; generates a scanning probe microscope model according to associated dynamics of the scanning probe microscope;
selects filter parameters that shape selected dynamics of the scanning probe microscope model; generates a notch filter using the filter parameters; and encodes the notch filter as PID parameters; and a PID controller that receives the PID parameters and controls the scanning probe microscope. - View Dependent Claims (15, 16, 17, 18)
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Specification