Measuring and testing – Speed – velocity – or acceleration – Angular rate using gyroscopic or coriolis effect
Reexamination Certificate
1999-10-13
2001-09-04
Moller, Richard A. (Department: 2856)
Measuring and testing
Speed, velocity, or acceleration
Angular rate using gyroscopic or coriolis effect
Reexamination Certificate
active
06282956
ABSTRACT:
TECHNICAL FIELD
This invention relates to an angular velocity sensor, and more particularly to a multi-axial angular velocity sensor capable of independently detecting angular velocity components about respective axes in an XYZ three-dimensional coordinate system.
BACKGROUND ART
In the automobile industry, machinery industry, and the like, there has been an increased demand for sensors capable of precisely detecting acceleration or angular velocity of a moving object (body). In general, an object which carries out free movement in a three-dimensional space bears an acceleration in an arbitrary direction and an angular velocity in an arbitrary rotational direction. For this reason, in order to precisely grasp movement of this object, it is necessary to independently detect acceleration components in every respective coordinate axial direction and angular velocity components about every respective coordinate axis in the XYZ three-dimensional coordinate system, respectively.
Hitherto, multi-dimensional acceleration sensors of various types have been proposed. For example, in the International Laid Open No. WO88/08522 based on the Patent Cooperation Treaty (U.S. Pat. No. 4,967,605/U.S. Pat. No. 5,182,515), there is disclosed an acceleration sensor in which resistance elements formed on a semiconductor substrate are used to detect applied acceleration components in every respective coordinate axial direction. Further, in the International Laid Open No. WO91/10118 based on the Patent Cooperation Treaty (U.S. patent appln. Ser. No. 07/761771), a multi-axial acceleration sensor having self-diagnostic function is disclosed. Further, in the International Laid Open No. WO92/17759 based on the Patent Cooperation Treaty (U.S. patent appln. Ser. No. 07/952753), there is disclosed an acceleration sensor in which electrostatic capacitance elements or piezoelectric elements are used to detect applied acceleration components in every respective coordinate axial direction. Further, also in the Japanese Patent Application No. 274299/1990 (Tokuganhei 2-274299) specification and the Japanese Patent Application No. 416188/1990 (Tokuganhei 2-416188) specification (U.S. patent appln. Ser. No. 07/764159), a multi-axial acceleration sensor similar to the above is disclosed. In the Japanese Patent Application No. 306587/1991 (Tokuganhei 3-306587) specification (U.S. patent appln. Ser. No. 07/960545), a novel electrode arrangement in a similar multi-axial acceleration sensor is disclosed. In addition, in the International Application PCT/JP92/00882 specification based on the Patent Cooperation Treaty, a multi-axial acceleration sensor using piezoelectric element of another type is disclosed. The feature of these acceleration sensors is that a plurality of resistance elements, electrostatic capacitance elements or piezoelectric elements are arranged at predetermined positions of a substrate having flexibility to detect applied acceleration components on the basis of changes in resistance values of the resistance elements, changes in capacitance values of the electrostatic capacitance elements or changes in voltages produced in the piezoelectric elements. A weight body is attached on the substrate having flexibility. When an acceleration is applied, a force is applied to the weight body and bending occurs in the flexible substrate. By detecting this bending on the basis of the above-described changes in resistance values, capacitance values or charges produced, it is possible to determine acceleration components in respective axial directions.
On the contrary, the inventor of this application cannot find any literature relating to a multi-dimensional angular velocity sensor so far as he knows. Ordinarily, angular velocity sensors are utilized for detecting an angular velocity of a power shaft, etc. of a vehicle, and only have a function to detect an angular velocity about a specific single axis. In such cases of determining a rotational velocity of the power shaft, it is sufficient to use an one-dimensional angular velocity sensor. However, in order to detect angular velocity with respect to an object which carries out free movement in a three-dimensional space, it is necessary to independently detect angular velocity components about respective axes of the X-axis, the Y-axis and the Z-axis in the XYZ three-dimensional coordinate system. In order to detect angular velocity components about respective axes of the X-axis, the Y-axis and the Z-axis by using one-dimensional angular velocity sensors conventionally utilized, it is necessary that three sets of angular velocity sensors are prepared to attach them in specific directions permitting detection of angular velocity components about respective axes. For this reason, the structure as the entirety of the sensor becomes complicated, and the cost also becomes high.
DISCLOSURE OF THE INVENTION
An object of this invention is to provide a novel multi-axial angular velocity sensor having a relatively simple structure and capable of independently detecting angular velocity components about respective axes of X-axis, Y-axis and Z-axis in XYZ three-dimensional coordinate system, respectively.
The fundamental principle utilized in this invention resides in that in the case where an angular velocity &ohgr; about a first coordinate axis is exerted on an oscillator placed in an XYZ three-dimensional coordinate system, when this oscillator is oscillated in a second coordinate axis direction, a Coriolis force proportional to the magnitude of the angular velocity &ohgr; is produced in a third coordinate axis direction. In order to detect angular velocity &ohgr; by utilizing this principle, means for oscillating an oscillator in a predetermined coordinate axis direction, and means for detecting displacement in a predetermined coordinate axis direction produced in the oscillator by action of the Coriolis force are required. In addition, in order to detect all of angular velocity component &ohgr;x about the X-axis, angular velocity component &ohgr;y about the Y-axis, and angular velocity component &ohgr;z about the Z-axis, means for oscillating the oscillator in three axes directions and means for detecting displacements in the three axes directions produced in the oscillator are required. This invention provides a sensor having such means, and is characterized as follows.
(1) The first feature of this invention resides in a multi-axial angular velocity sensor for detecting angular velocity components about respective coordinate axes in a three-dimensional coordinate system, comprising:
an oscillator having mass;
a sensor casing for accommodating this oscillator therewithin;
connection means for connecting the oscillator to the sensor casing in the state having a degree of freedom such that it can move in respective coordinate axes directions;
excitation means for oscillating the oscillator in the respective coordinate axes directions; and
displacement detecting means for detecting displacements in the respective coordinate axes directions of the oscillator.
(2) The second feature of this invention resides in that, in the above-described multi-axial angular velocity sensor having the first feature, there is further provided control means for executing:
first detecting operation for giving an indication to the excitation means so as to oscillate the oscillator in a first coordinate axis direction, and for giving an indication to the displacement detecting means so as to detect a displacement in a second coordinate axis direction of the oscillator, thus to determine an angular velocity component about a third coordinate axis on the basis of the detected displacement;
a second detecting operation for giving an indication to the excitation means so as to oscillate the oscillator in the second coordinate axis direction, and for giving an indication to the displacement detecting means so as to detect a displacement in a third coordinate axis direction of the oscillator, thus to determine an angular velocity component about a first coordinate axis on the basis of the detected displ
Ladas and Parry
Moller Richard A.
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