Anti-resonance mixing filter

Details Anti-resonance mixing filter Anti-resonance mixing filter

1999-10-25

2001-05-29

Masih, Karen (Department: 2837)

Electricity: motor control systems

Closed loop speed control system for dc motor with commutator

Armature control by digital or combined analog and digital...

C318S586000, C318S580000, C318S561000, C318S254100, C318S132000, C318S434000, C388S806000, C388S815000

Reexamination Certificate

active

06240246

ABSTRACT:

TECHNICAL FIELD
The present invention relates a system and method for filtering feedback signals available in an electromechanical actuation system to mitigate the adverse effects of load resonance on position control loop stability.
BACKGROUND OF THE INVENTION
There are many components of an aircraft that are positioned by electromechanical or pneumatic-mechanical actuation systems. In these systems, an electric or pneumatic motor drives an actuator in response to signals from an electronic control unit. To assure that these aircraft components are accurately and correctly positioned, the control unit needs to know position of the actuator moving the component. To achieve this, highly accurate position sensors are used on the actuators to sense the position of the actuator and provide to the control unit a corresponding signal. One such sensor commonly used is a linear variable displacement transducer, (LVDT).
Because of compliance or resilience in the actuator and in the mounting of the actuator, the actuator will amplify displacement oscillations when operating at its natural or resonant frequency. These amplified oscillations are picked up by high accuracy position sensors like the LVDT. The LVDT feeds the oscillation through the control system and as a result can drive the control system unstable.
Accordingly, a need exists for a filtering system that isolates these oscillations from the control unit and thus allow the use of high accuracy sensors.
SUMMARY OF THE INVENTION
An object of this invention is to provide a filter that isolates oscillations that are amplified when operating at resonant frequencies.
The present invention achieves this object by providing anti-resonant mixing filter and method therefor that is incorporated into a closed loop control system that controls the movement of a structure that amplifies displacement oscillations when operating at a resonant frequency. The method comprises the steps of sensing a first parameter of the structure and generating a first signal thereof, the first parameter being sensitive to the oscillations and sensing a second parameter that is isolated from the oscillations and generating a second signal thereof, there being a known relationship between the first and second parameters. Applying a lag to the first signal and then combining the first and second signals to form a third signal in which the oscillations in the first signal are attenuated This third signal is then used by the control system so that amplified oscillations, at the resonant frequency, cannot feed through the controller to drive the system unstable. In the preferred embodiment, this method is coded into the control system.
These and other objects, features and advantages of the present invention are specifically set forth in or will become apparent from the following detailed description of a preferred embodiment of the invention when read in conjunction with the accompanying drawings.


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