Litef Gmbh

Northrop Grumman Litef Gmbh

Eberhard Handrich

Bruno F Ryrko

Martin Hafen

Uwe Breng

Maik Wiemer

Thomas Gessner

Peter Leinfelder

Egbert Vetter

Wolfram Geiger

Manfred Kemmler

Wolfgang Ecke

Werner Schroder

Karla Hiller

Detlef Billep

Michael Newkirch

Bruno Rvrko

Klaus Hilpert

Hermann Hog

Wolfram Ebert

A method for quadrature-bias compensation in a Coriolis gyro whose resonator is in the form of a coupled system comprising a first and a second linear oscillator. The quadrature bias of the Coriolis gyro is determined. An electrostatic field is produced by variation of the mutual alignment of the two oscillators with respect to one another. The alignment/strength of the electrostatic field is regulated so that the determined quadrature bias is made as small as possible.

Method for quadrature-bias compensation in a Coriolis gyro, as well as a Coriolis gyro which is suitable for this purpose

A Coriolis gyro includes a first and a second resonator, each in the form of a coupled system comprising first and second linear oscillators. The first resonator can be caused to oscillate in antiphase with respect to the second resonator along a common oscillation axis. A system coupled in this way has the advantage that it is possible to measure rotation rate and acceleration simultaneously, with insensitivity to disturbances (e.g., externally or internally acting vibrations).

Method for measurement of rotation rates/accelerations using a rotation rate coriolis gyro, as well as a coriolis gyro which is suitable for this purpose

A method for producing a silicon torsion spring capable, for example, of reading the rotation rate in a microstructured torsion spring/mass system. The system that is produced achieves a low torsional stiffness compared to a relatively high transverse stiffness in the lateral and vertical directions. The method proceeds from a wafer or wafer composite and, upon suitable mask coverage, a spring with a V-shaped cross section is formed by anisotropic wet-chemical etching which preferably extends over the entire wafer thickness and is laterally delimited only by [111] planes. Two of the wafers or wafer composites prepared in this way are rotated through 180&#xb0; and joined to one another oriented mirrorsymmetrically with respect to one another, so that overall the desired X-shaped cross section is formed.

Method for producing a torsion spring

An accelerometer having a micromechanical pendulum, a capacitive pick off and a control loop reset by electrostatic forces and, in a time sequence, applies a resetting voltage between the pendulum and two electrodes spaced apart on opposite sides of the pendulum. The control loop is designed such that, firstly, no charge difference flows via the pendulum and a force of identical magnitude thus acts on both sides of the pendulum. Secondly, when a pendulum deflection occurs in response to a voltage difference, the time durations of the respectively applied voltage pulses are impeded in accordance with the acceleration. The simultaneous control of two components results in the control bias tending essentially to zero. The capability of temporarily switching to detection of the total charge as the control variable also allows control of the scale factor of the accelerometer.

Acceleration measuring device with pulse width modulation resetting

A spin rate measurement device for rotating missiles. Preferably, three micromechanical spin rate sensors whose three spatial axes are aligned at right angles to one another, each of which is designed to be excited, read and reset capacitively, are arranged on a single platform that can be rotated by means of a servo loop for rotation decoupling. The spin rate measurement device is distinguished by high bias and scale factor stability that can be checked at any time.

Rotational speed measurement device for rotating missiles

A single laser is stabilized sequentially in time with respect to different wavelengths in conjunction with a continuous, preferably linear, wavelength transition for absolute optical interferometric measurement. During the wavelength transition, the number of the traversing interferences is counted in a measuring channel. The length of a measuring section may be measured in absolute terms to give known and stable wavelengths and phase measurements of the two wavelengths. Active integrated optics and residual phase measurement by compensation in the integrated optics make it possible to detect wavelength differences of 10 &lgr;.

Method and device for measuring absolute interferometric length

A micromechanical rotation rate sensor based on the Coriolis principle includes two plate-like oscillators arranged one above the other in two planes for excitation to oscillate by means of an electrostatic drive. Three elements in each case form an oscillator structure. The oscillators are in each case suspended on opposite side edges by at least one web between an associated plate-like support and an associated drive plate element. The two supports and the two drive plate elements are, in each case, arranged one above the other in layers. A fixed plate element is located between the two drive plate elements so that, in each case, an identical narrow drive gap is defined between the drive plate elements. The drive gap is considerably smaller than the distance between the plate-like oscillators. An intermediate support that fills the intermediate space is inserted between the two plate-like supports and is completely electrically isolated from the surrounding frame to further reduce the respective capacitances to be recharged. The invention reduces the electrodynamic coupling between the drive and the read-out by a factor of about 100 in comparison with known micromechanical rotation rate sensors of like design.

Micromechanical rpm sensor

A method and a device for compensating Shupe effect drift errors in a fiber gyro that result from time-dependent temperature changes. A closed loop fiber optic gyro includes a VCO control loop and an evaluation unit that incorporates a model which is dependent on the optical path length of light through the fiber coil. The closed loop gyro is arranged to compensate for temperature-dependent drift changes that result from changes in optical path length.

Closed loop fiber optic gyro with shupe effect compensation

Micromechanical rotation speed sensor

A small modulation current is applied to the light source of a Sagnac-type fiber optic gyroscope to increase accuracy and/or stability of scale factor (open loop configuration) and to reduce bias errors and random walk (closed-loop configuration). The phase and amplitude of the modulation current are controlled through a control circuit whose reference is picked off at a first beamsplitter in series with the light source. In such a way, light emitted from the light source into the interferometer contains no modulation. The elimination of modulation removes a source that would otherwise cause deterioration of gyroscope stability resulting from light returning from the interferometer or due to electrical interference, thus limiting measurement accuracy.

Method and apparatus for increasing the stability of a fiber optic

A high precision micromechanical accelerometer comprises a layered structure of five (5) semiconductor wafers insulated from one another by thin oxide layers. The accelerometer is formed by first connecting a coverplate and a baseplate to associated insulating plates. Counter-electrodes, produced by anisotropic etching from the respective insulating plates, are fixed to the coverplate and the baseplate respectively. The counter-electrodes are contactable through the cover or baseplate via contact windows. A central wafer contains a unilaterally linked mass (pendulum) that is also produced by anisotropic etching and which serves as a movable central electrode of a differential capacitor. The layered structure is hermetically sealed by semiconductor fusion bonding. A stepped gradation from the top is formed at a wafer edge region for attaching contact pads to individual wafers to permit electrical contacting of individual wafers. The invention permits fabrication of a .mu.B device characterized by extremely small leakage capacitances and high temperature stability.

Micromechanical accelerometer with plate-like semiconductor wafers

A high precision micromechanical accelerometer comprises a layered structure of five (5) semiconductor wafers insulated from one another by thin semiconductor material oxide layers. The accelerometer is formed by first connecting a coverplate and a baseplate to associated insulating plates. Counter-electrodes, produced by anisotropic etching from the respective insulating plates, are fixed to the coverplate and the baseplate respectively. The counter-electrodes are contactable through the cover or baseplate via contact windows. A central wafer contains a unilaterally linked mass (pendulum) that is also produced by anisotropic etching and which serves as a movable central electrode of a differential capacitor. The layered structure is hermetically sealed by semiconductor fusion bonding. A stepped gradation from the top is formed at a wafer edge region for attaching contact pads to individual wafers to permit electrical contacting of individual wafers. The invention permits fabrication of a .mu.B device characterized by extremely small leakage capacitances and high temperature stability.

Micromechanical accelerometer and method of manufacture thereof

A micromechanical bending spring joint is formed of selectively etched wafer material. The joint includes a pair of leaf springs arranged alongside each other. Each spring is inclined at an oblique angle to the opposed surfaces of the wafer and such springs cross to define a point of intersection. The joint, selectively etched from a single wafer, is characterized by high precision of fulcrum position, bending spring constant and transverse axis rigidity.

Pendulum with bending spring joint

A method and apparatus for reading out angular rates by means of a passive optical resonator provides for the generation of three component light beams individually tuned to distinct resonator modes. One component light beam is radiated into the resonator in the opposite direction to the two other component light beams. By means of an evaluating logic, differences are formed between the counterrotating light beams and the differences weighted and subtracted from each other to provide angular rate. The optical length of the resonator, and, thus, temperature are available as a weighted sum of the differences. Temperature drift may be eliminated from angular rate measurements by compensation according to the invention.

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Kirchzarten, Germany

Eberhard Handrich