Reduction Of Periodic Disturbances
AssigneeControl Techniques Limited
InventorMichael Cade
Life of this patent
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Abstract
A method of reducing periodic disturbances in the feedback quantity of a controlled system is disclosed. The method includes receiving a feedback signal and repeatedly deriving respective magnitudes of harmonic components of the feedback signal to produce corresponding error signals. The error signals and harmonic components are used to generate harmonic control signals. The harmonic control signals are used to create a plurality of negative feedback loops acting to reduce the error signals. The present disclosure thus provides negative feedback control in the frequency domain. In one specific disclosed embodiment, the control is tied to the periodic domain resulting from the rotation of an actuator motor shaft.
Claims20
A system comprising a controlled system and a harmonic controller connected to the controlled system to provide a harmonic control signal to the controlled system for reducing periodic disturbances in a feedback quantity of the controlled system, the system having a plurality of control loops, the harmonic controller comprising for each control loop:
- a magnitude calculator coupled to the controlled system to receive a feedback signal representative of the feedback quantity and configured to repeatedly calculate a value of a magnitude of a respective harmonic component of the feedback signal;
- an integrator coupled to the magnitude calculator to receive the repeatedly calculated values, the integrator being configured to sum the received values to produce an accumulated value;
- a harmonic generator configured to generate a harmonic signal having the same frequency as the respective harmonic component and a phase relative to the respective harmonic component set to compensate for an estimated phase shift produced by the controlled system between the harmonic control signal and the feedback signal at the frequency of the respective harmonic component;
- a multiplier coupled to the integrator and harmonic generator to multiply the accumulated value and the harmonic signal to produce a generated harmonic component;
- wherein the harmonic controller is arranged to sum the generated harmonic components to produce the harmonic control signal and to apply the harmonic control signal to the controlled system to reduce the periodic disturbance in the feedback quantity.
A method of reducing periodic disturbances in a feedback quantity of a controlled system using a harmonic control signal, the method comprising:
- receiving a feedback signal representative of the feedback quantity;
- repeatedly deriving respective magnitudes of harmonic components of the feedback signal to produce error signals;
- estimating respective phase shifts produced by the controlled system between the harmonic control signal and the feedback signal for each harmonic component;
- using the error signals, phase shifts and harmonic components to generate a harmonic control signal;
- controlling the controlled system with the harmonic control signal to create a plurality of negative feedback loops acting to reduce the error signals.
Dependencies are inferred from the claim text.