摘要:
A sensor for measuring angular rotation rates about three orthogonal axes is based upon sensing Coriolis acceleration forces with a pair of nearly-identical rotors coupled coaxialy by a torsion spring and counter-oscillating in rotation. The torsional oscillator is mounted within a case by means of radial vanes, each comprisig two piezoelectric ceramic plates bonded to a thin metal core responsive to drive signals and providing rotational vibration isolation. The arms of the rotors are designed as piezoelectric open loop accelerometers. Electrodes of selected configurations are mounted to the outer surfaces of the planar members to collect charge indicative of Coriolis accelerations proportional to the angular rotations about the orthogonal axes.
摘要:
A vibrating rotation rate sensor of the type that includes a generally-planar, H-shaped frame of piezoelectric material such as quartz. A first set of drive electrodes is fixed to a pair of upper tines and a second set of pickoff electrodes is fixed to a pair of lower tines. An array of control electrodes is fixed to the upper tine pair adjacent the cross-piece of the H-shaped frame. The control electrodes permit the application of control signals for nulling Coriolis-induced out-of-plane vibration of the upper tines allowing use of a resonant frame.
摘要:
A multisensor includes a ring-like piezoelectric drive. The ring, which may comprise a closed configuration formed of straight ring segments, surrounds a rotor assembly formed of a pair of rotors, each having a central hub. Vanes extend radially from the central hubs of the rotors to the inner surface of the ring and are fixed to the ring adjacent the intersections of the substantially-straight ring segments. The ring is formed of a laminate of layers of piezoelectric material. Adjacent layers are of opposite piezoelectric polarity whereby an a.c. signal drives the alternating expansions and contractions of pairs of laminated layers.
摘要:
A three axis inertial measurement unit is shown having a low inertia mechanical oscillator formed from two platforms counterbalanced against each other. Each platform is dithered at its natural frequency about a single torsional axis. A plurality of accelerators are mounted upon at least one of the counterbalanced platforms with each accelerometer having at least an input axis mounted at a predetermined angle to the torsional axis and to the platform. Each platform has a three legged, Y-shaped mounting member with a rotor member positioned between the legs of the mounting member. Web members which form the legs of the mounting member join the rotor member to the Y-shaped mounting member. Additionally, driving webs are mounted on each side of the web members for further joining the mounting member to the rotary member.
摘要:
An inertial measurement unit capable of providing information relating to all six degrees of freedom in an orthogonal three axis system is shown having a mechanical oscillator constructed from two counterbalanced platforms which form a single unit for low inertic rotation about a single torsional axis. Each platform has a Y-shaped rotor member whose legs are positioned between inwardly extending, mounting web members. Driving web members are provided on each side of the mounting web members for rotating the rotor member. A plurality of accelerometers are mounted upon at least one of the counterbalanced platforms. Each accelerometer has an input axis, an output axis, and pendulous axis. Each accelerometer is mounted such that the input axis is at a predetermined angle to the single axis of rotation and the counterbalanced platform. The accelerometers are used to measure angular rate along the pendulous axis and linear acceleration along the input axis. These signals may then be electronically separated to produce acceleration and angular rate outputs for a three axis orthogonal system.
摘要:
An inertial measurement unit capable of providing information relating to all six degrees of freedom in an orthogonal three axis system is shown having a mechanical oscillator constructed from two counterbalanced platforms which form a single unit for rotation about a single torsional axis. A plurality of accelerometers are mounted upon at least one of the counterbalanced platforms. Each accelerometer has an input axis, an output axis, and a pendulous axis. Each accelerometer is mounted such that the input axis is at a predetermined angle to the single axis of rotation and the counterbalanced platform. The accelerometers are used to measure angular rate along the pendulous axis and linear acceleration along the input axis. These signals may then be electronically separated to produce acceleration and angular rate outputs for a three axis orthogonal system.
摘要:
A system for measuring changes in an environmental parameter such as displacement, velocity, acceleration, or pressure, includes a laser for providing a pulsed, coherent light signal, and an interferometer having a first and second optical legs of unequal optical path lengths. The signal is split into first and second beams that are directed into the first and second optical legs. Either a fixed mirror disposed on a frame or a moving mirror on one side of the proof mass reflects the first beam received at the end of the first optical leg. The frame also suspends a proof mass at opposite ends. An optical pick-off embodied in a movable mirror formed on the proof mass reflects the second beam received from the end of the second optical leg. The proof mass with mirror moves in response to changes in the value of the parameter to be measured. An optical coupler combines the first and second beams after they have been reflected back into their respective optical legs, producing an interference signal, which is detected by an optical detector. The detector generates an electronic signal, which is analyzed in a microcomputer. To compensate for gravity, the proof mass has an asymmetrical profile. As a velocity sensor for seismic measurements, its construction is guided by the mass of the proof mass and spring stiffness of the hinges. Represented mathematically, those terms are selected to minimize the acceleration and displacement components, leaving only the velocity component as a function of the ratio of mass to damping coefficients.
摘要:
A fiber optic particle motion accelerometer has a housing with a mid-section mounted therein such that the mid-section flexes in response to acceleration along a sensing axis. A proof mass is mounted to an outer edge of the mid-section. A first spiral-wound optical fiber coil is mounted to a first side of the mid-section and a second spiral-wound optical fiber coil is mounted to a second side of the mid-section. A first hinge is formed in the mid-section adjacent the mounting of the mid-section in the housing, and a second hinge is formed in the mid-section between the proof mass and the first and second fiber optic coils. The optical fiber coils are included in an interferometer such that acceleration along the sensing axis produces a phase difference between optical signals propagating in the optical fiber coils.
摘要:
To minimize the uncompensated part of the Shupe error, a one or more continuous coils (28, 44, 46) thermally stable material is added to a composite coil assembly (20) to dominate the composite in terms of thermal expansion and elastic modulus. The thermally stable material includes a plurality of continuously coiled fibers (28, 44, 46) selected from a material group which possesses a high modulus and a low coefficient of thermal expansion. The preferred fiber is formed from a carbon-graphite material which is selectively wound within the optical fibers (22) in the coil assembly and/or is wound about the interior and exterior circumferences of the coil assembly.
摘要:
A system for measuring changes in an environmental parameter, such as velocity or pressure, includes an optical signal source for providing a coherent light signal, and an interferometer having a first and second optical legs of unequal optical path lengths. The signal is split into first and second beams that are respectively directed into the first and second optical legs of the interferometer. A fixed mirror reflects the first beam received at the end of the first optical leg. An optical pick-off includes a movable mirror, positioned to reflect the second beam received from the end of the second optical leg. The movable mirror is movable in response to changes in the-value of the parameter to be measured. An optical coupler combines the first and second beams after they have been reflected back into their respective optical legs, producing an interference signal, which is detected by an optical detector. The detector generates an electronic signal having a value indicative of the value of the interference signal. The electronic signal is analyzed to correlate its value to changes in the value of the environmental parameter to be measured.