Dual function system having a piezoelectric element
First Claim
1. A dual function system for producing a mechanical effect on a body and sensing a response thereto which comprises a piezoelectrically responsive element which both produces and senses mechanical effects, means for applying a first signal to said element for actuating said element to produce the mechanical effect on the body and for obtaining from said body via element piezoelectrically a second signal, and means for processing by additively combining said first and second signals for providing an output signal, said output signal representing the response of said element to said effect while said first signal is being applied.
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Abstract
Self sensing actuator system using a piezoelectric actuator device allows the device to perform both as an actuator and sensor. The sensor functions can be either measurements of stress or measurements of strain. The actuator can be used as a force generator or positioning device, both in open and closed loop configurations, and is useful for purposes ranging from dynamic damping to shape control (i.e., shaping or controlling deformation of a body).
36 Citations
16 Claims
- 1. A dual function system for producing a mechanical effect on a body and sensing a response thereto which comprises a piezoelectrically responsive element which both produces and senses mechanical effects, means for applying a first signal to said element for actuating said element to produce the mechanical effect on the body and for obtaining from said body via element piezoelectrically a second signal, and means for processing by additively combining said first and second signals for providing an output signal, said output signal representing the response of said element to said effect while said first signal is being applied.
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6. A dual function system for producing a mechanical effect and sensing a response thereto, which comprises a piezoelectrically responsive element, means for applying the first signal to said element for actuating said element to produce said effect and for obtaining a second signal in response to said effect, means for processing said first and second signals for providing an output signal, said output signal representing the response of said element to said effect, and further comprising means responsive to said output signal for generating said first signal.
- 7. A dual function system for producing a mechanical effect and sensing a response thereto, which comprises a piezoelectrically responsive element, means for applying the first signal to said element for actuating said element to produce said effect and for obtaining a second signal in response to said effect, means for processing said first and second signals for providing an output signal, said output signal representing the response of said element to said effect, and wherein said processing means comprises a bridge circuit having primary and reference legs, said element being connected in said primary leg, means in said primary and reference legs for respectively obtaining third and fourth signals of magnitude corresponding to the voltage across said element when said mechanical effect is a certain constant magnitude, and means for providing said output signals in accordance with the difference in said third and fourth signals when said first signal is applied to each of said legs.
- 13. A self sensing piezoelectric actuator system which produces stress or strain, which comprises a piezoelectric device having first and second electrodes and a body of piezoelectric material, a source of voltage, a connection between said first electrode on said piezoelectric device and said source so that a portion of said voltage appears at said second electrode, first means presenting a certain impedance corresponding to the impedance of said device when under a predetermined stress or strain, second means including said device and connected to said second electrode thereof which also presents said impedance, and third means, including said first and second means, responsive to said portion of said voltage for sensing stress or strain in said body of piezoelectric material.
Specification