Measuring and testing – Speed – velocity – or acceleration – Angular rate using gyroscopic or coriolis effect
Patent
1999-05-24
2000-08-01
Moller, Richard A.
Measuring and testing
Speed, velocity, or acceleration
Angular rate using gyroscopic or coriolis effect
G01P 904
Patent
active
060949856
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a rotation rate sensor as a micromechanical component in silicon.
Rotation rate sensors (gyroscopes) serve for the measurement of angular velocity. Mechanical gyroscopes correspond in their function to a gyro compass and measure occurrent rotations by a precessional motion of a rotating body. Given a rotation of such an arrangement about an axis which is situated perpendicular to the axis of rotation of the rotating body, a rotary motion emerges about a line which is situated perpendicular to these other two axes of rotation. The strength of the torque effecting this rotation is a measure of the rotary motion of the overall system. In systems wherein complete rotations are not possible or are not desirable, the free rotation of the gyroscope can be replaced by an oscillating rotation. U.S. Pat. No. 5,313,835 and U.S. Pat. No. 5,377,544 describe micromechanical gyroscopes in which a ring is fastened to springing braces on a substrate such that the ring can be made to rotate in an oscillating fashion by electrostatic forces, given the application of suitable voltages at electrodes that are provided for this purpose. Additional electrodes over and under the ring are provided for the detection of an excursion of the ring out of the plane of rotation. A described alternative measuring method is to totally compensate potential excursions of the rotor from its plane of rotation by means of a closed electrical circuit and to determine the size of the torque from the voltage necessary to do this.
SUMMARY OF THE INVENTION
It is an object of the present Invention to propose a micromechanical rotation rate sensor which can be produced with good operating characteristics in surface micromechanics in the framework of a VLSI-compatible production process. This object is achieved by the inventive micromechanical rotation rate sensor which has an annular structure with a relatively thick strut arranged along a diameter of this ring. In a plan view, this ring with the strut looks like a spoked wheel from which all the spokes have been removed except for two that lie on the same line. This linear double-spoke which supplements the ring, which is designated a strut overall here and in the claims, also serves for the securing of the ring on the substrate, which is preferably silicon. It must be possible to make the ring rotate in an oscillating manner about its center axis, i.e. the axis extending through the center point of the ring and lying perpendicular to the ring plane. An excursion of the ring from the neutral position must also be possible by a tilting from the ring plane. In the inventive rotation rate sensor, this tilting is provided about an axis which extends parallel to the position of the strut in the neutral position of the ring. This rotation rate sensor thus detects a rotation which occurs about an axis that lies perpendicular to the center axis of the ring and to the axis of the strut in the neutral position of the ring.
The springing suspension of the ring which is necessary for this is achieved by springing braces which are attached to the strut, on the one hand, and to anchoring arrangements that are secured on the substrate, on the other hand. These springing braces are preferably attached to the strut optimally close to the center point of the ring, and the anchoring arrangements on the substrate should also be arranged optimally close to the center point of the ring. The utilization of a rotor which is formed by a ring with an optimally rigid strut that extends along a diameter has the advantage that only negligibly small non-linear components, if any, arise in the restoring springing force. It is particularly important here that the strut is optimally rigid, particularly in relation to the elasticity of the springing braces at which it is suspended. This is best achieved by the provided width of the strut The relative change in the torsional rigidity, given small angles of excursion, is particularly small in the given embodiment The greater this relative change in th
REFERENCES:
patent: 5226321 (1993-07-01), Varnham et al.
patent: 5313835 (1994-05-01), Dunn
patent: 5377544 (1995-01-01), Dunn
patent: 5511419 (1996-04-01), Dunn
Hierold Christofer
Kapels Hergen
Naher Ulrich
Noe Reinhold
Scheiter Thomas
Moller Richard A.
Siemens Aktiengesellschaft
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