Sundstrand Data Control, Inc.

Craig J Cornelius

Rex B Peters

Brian L Norling

Steven F Grlj

A drive system for providing different excitation voltages to the separate beams of a multiple beam vibrating transducer is disclosed. In one embodiment of the invention an amplified voltage at the resonant frequency of a master beam is amplified and applied to a secondary beam, to force the secondary beam to vibrate at the resonant frequency and amplitude of the master beam to force the transducer to resonate at the frequency of the master beam. Since the transducer vibrates at the resonant frequency of one of the beams, the transducer energy losses to the adjacent mounting structure are reduced. This results in a higher transducer quality factor so that frequency shifts in the resonant frequency can be readily measured as changes in the parameter that the transducer is intended to monitor.

Vibrating beam transducer drive system

A matched pair of vibrating beam force transducers for use in an instrument such as an accelerometer, to provide enhanced linearity and common mode tracking, while decreasing the possibility of lock in or cross-talk between the transducers. In a preferred embodiment, first and second transducers are provided, the transducers producing respective first and second output signals having respective first and second frequencies. The transducers are connected in an arrangement in which for a given acceleration, one frequency increases and the other frequency decreases. The first transducer comprises a pair of first beams, and the second transducer comprises a pair of second beams. The beam dimensions are selected such that the Euler buckling constants of the first and second transducers are substantially equal to one another, and such that the first and second frequencies are different from one another when the acceleration is zero and preferably are different from one another throughout the operating range of the accelerometer. In preferred arrangements, the transducer beams have a constant thickness, and the transducers have common axial stiffnesses.

Matched pairs of force transducers

An accelerometer comprising a support (52) and a proof mass (40) mounted to the support by a flexure (50) or the like, such that the proof mass can rotate about a hinge axis (HA) perpendicular to sensitive axis (SA). An isolator (42) is also mounted to the support by an isolator suspension system (60, 62) that is relatively compliant for isolator movement parallel to a transducer axis (TA) normal to the hinge axis, and relatively noncompliant for isolator rotation about the hinge axis. Force transducers (80, 82) are connected between the isolator and the proof mass. The force transducers are parallel to the transducer axis, and positioned on opposite sides of the hinge axis from one another, such that rotation of the proof mass about the hinge axis puts one force transducer in tension and the other force transducer in compression. The isolator suspension system reduces the magnitude of common mode inputs, such as those caused by differential thermal expansion of the crystals with respect to other accelerometer components.

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Redmond, WA, United States of America

Craig J Cornelius