JPS6117910A - Angular velocity sensor - Google Patents

Abstract

PURPOSE:To improve the precision by providing a driving means, which rotates a piezoelectric ceramic substrate around an axis which passes symmetrical points and is vertical to the surface of the substrate, and a means which processes the electric output generated by the piezoelectric effect of two cut parts of the substrate. CONSTITUTION:A piezoelectric ceramic substrate 1 having cantilever-shaped cut parts 2a and 2b is rotated around the Z axis in an angular velocity omega by a driving part 4 to generate a Coriolis force fc. This force fc is obtained by converting the physical intersection at right angles between X and Y directions of an absolute angular velocity to the time intersection at right angles with a phase difference pi/2 in response to variations of X-direction and Y-direction components of the velocity of cut parts 2a and 2b and subjecting this intersection to sine wave modulation and is converted to an electric charge on cut parts 2a and 2b. This electric charge is converted to a voltage signal by a charge amplifier consisting of an operational amplifier 3a, a resistance 3b, and a capacitor 3c, and an output corresponding to the absolute angular velocity is generated by a signal processing part 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an angular velocity sensor that can be used for auto-navigation of autopilot vehicles such as aircraft and ships, or auto-stabilizers for various machines and devices. .

Configuration of conventional example and its problems A device for detecting angular velocity relative to an inertial frame (stiffness is referred to as absolute angular velocity in the text) - A so-called angular velocity sensor uses a rotating gyro to detect absolute angular velocity around an axis perpendicular to its rotation axis. A method of detecting the force acting on the gyro in proportion to has been used for a long time.

This type of gyro device generally rotates the rotor at high speed and detects the force applied to it as torque acting on the support, but in order to realize this dual structure of drive and detection, In addition, the device is mechanically complex, requires high precision, is large, heavy, and expensive, and is difficult to maintain. Its applications include aircraft autopilots, etc.
The system itself is limited to relatively large-scale and expensive ones.

On the other hand, with the progress of mechatronics in recent years,
Various consumer and industrial machines. There is a strong desire to realize a small, lightweight, and inexpensive external angular velocity sensor for automatic guidance and attitude control of equipment.

In order to meet this demand, a method has recently been proposed in which two masses of the same size arranged axially symmetrically are given a rotational motion about the axis of symmetry, and the Coriolis force acting on them is detected. If this is done, the difficulties associated with torque detection can be eliminated, the drive system and the detection system can be separated, and the burden on hardware can be significantly reduced.

In this type of method, the Coriolis force is applied in opposite directions by applying symmetrical motion to two equal masses,
The detection outputs are connected differentially to prevent errors caused by linear acceleration, gravitational acceleration, etc. Therefore, in order to ensure accuracy, the key point is consistency in the drive of the two masses and the detection sensitivity of the force acting on them, but currently there is a lack of concrete measures to achieve this. It is.

purpose of invention The purpose of the present invention is to achieve ideal consistency in driving and sensing. The objective is to provide a sophisticated angular velocity sensor that has been realized.

Structure of the Invention The angular velocity sensor of the present invention includes a piezoelectric ceramic substrate having two point-symmetrical cantilever-shaped cutout portions that are polarized, and a piezoelectric ceramic substrate having an axis passing through the symmetry point and perpendicular to the substrate surface. and a signal processing means for processing the electric output generated by the piezoelectric effect of the two cutouts to generate a corresponding output signal at an angular velocity relative to the inertial frame of the device. Since the detection part that receives the Coriolis force and generates an output in response to it is constructed by processing the same parts, their characteristics are completely consistent17, and when installing the individual parts, Such mounting is free from errors and achieves symmetrical drive with matching sensitivity directions, making it possible to detect angular velocity with high precision.

In addition, by using the piezoelectric ceramic substrate as a circuit configuration substrate and configuring all or part of a signal processing circuit, further miniaturization can be achieved, and external It also has the effect of eliminating noise.

51\Description of one embodiment Hereinafter, one embodiment of the angular velocity sensor of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of an embodiment of the angular velocity sensor of the present invention. In Fig. 1, 1 is a circular piezoelectric ceramic substrate,
Two cantilever-shaped cutouts 2 with the center as the point of symmetry
It has a and 2b.

Electrodes 2a and 2b are both formed in advance on the front and back surfaces and subjected to 5-polarization treatment, and when a force is applied in a direction perpendicular to the substrate surface (Z-axis direction), an electric charge is generated.

3a to 3C are operational amplifier ICs and resistors, respectively.

It is a capacitor, and the electrodes formed on the substrate allow 2
A and 2b are connected to form a charge amplifier.

Reference numeral 4 denotes a drive unit which applies rotational motion to the piezoelectric ceramic substrate 1 at a uniform angular velocity ω about an axis passing through its center and perpendicular to the plane.

Reference numeral 5 denotes a signal processing section, and its operation will be explained below in the above-described configuration of the charge amplifier.

In the driving state described above, when the device rotates with respect to the inertial system at an angular velocity having components in the X direction and Y direction in the figure, Coriolis waves of equal size are generated in opposite directions along the KZ axis of the cutout portions 2a and 2b. Force fc acts.

This Coriolis force fc is 2a due to rotational drive.

In response to changes in the X-direction and Y-direction components of the velocity of 2b, the Y-direction component of the absolute angular velocity and the X-direction component change by π/2 from each other.
In other words, X is the absolute angular velocity.

The Y direction, which is physically orthogonal, is converted into a temporally orthogonal one, which has a phase difference of π/2, and is sinusoidally modulated.

In this way, the Coriolis force generated as a result of physically modulating the absolute angular velocity by rotational motion is
2b, it is linearly converted into electric charge due to the piezoelectric effect.

At this time, 2a and 2b generate charges in the same way even if a force other than the Coriolis force acts on them, but by connecting them with a difference of 7...-2 dynamic, a disturbance that acts on both in the same direction The components cancel out, and the components corresponding to the Coriolis force acting in the opposite direction are added.

In order to have a complete offset effect, 2a.

It is necessary that the piezoelectric sensitivities of 2b be completely matched, which is achieved by forming 2b, 2a, and 2b from the same piezoelectric ceramic substrate by similar processing and polarizing them at the same time.

The charge signal generated as described above is extremely susceptible to disturbances such as electrostatic induction due to the high output impedance of the capacitors 2a and 2b, and there is a problem in transmitting it over such a long signal path. However, by forming a charge amplifier on the piezoelectric ceramics that form 2a and 2b and converting it into a voltage signal near the gate, it is converted into a low output impedance signal that is resistant to electrical disturbances, and is extracted by means such as a plan. be able to.

As shown in the above-mentioned Coriolis force generation mechanism, this electrical signal is generated by the two-directional components ΩX and Ωy of the absolute angular velocity.
Since they are synthesized by sinusoidally modulating them with a phase difference of π/2, they can be separated by a synchronous detection circuit to obtain outputs proportional to ΩX and Ωy.

Therefore, in this embodiment, only the charge amplifier is used as the signal processing circuit configured on the ceramic substrate 1-, but the amount can be increased within the limits of the substrate area, etc. It would be possible to mount all of the signal processing circuits, including synchronous detection, or conversely, if there is no need to consider electrical disturbances, all of the signal processing could be performed by external circuits. can.

In addition, the signal can be taken out using a non-contact means such as a rotary transformer after high-frequency modulation, instead of using a brush.

Effects of the Invention It is clear from the above description that the angular velocity sensor of the present invention has two mechanical-electrical converters that pick up the Coriolis force on the same piezoelectric ceramic substrate 9... Mechanical acceleration of translational acceleration, gravitational acceleration, etc. There is almost no error signal generated due to target disturbance, realizing highly accurate angular velocity detection.

Furthermore, by providing all or part of the signal processing means on the piezoelectric ceramic substrate, the problem unique to piezoelectric ceramics such as capacitive high output impedance can be overcome, and a structure that is resistant to electrical disturbances can be achieved. This also contributes to the miniaturization of the device.

In this way, by realizing highly accurate angular velocity detection using a means that requires a more complex and highly accurate mechanism than a torque pickup, applications of this type of device, which were previously limited, are now possible. It is expected that the range will expand.

[Brief explanation of drawings]

The figure is a perspective view showing the angular velocity sensor of the present invention. 1...Piezoelectric ceramic substrate, 2a, 2b...
...Polarized cantilever-shaped cutout, sa,
3b. 3C...each forms a charge amplifier with an operational amplifier, a resistor, and a capacitor; 4...driver section; 5...signal processing section. Figure 1

Claims (2)

[Claims] (1) A piezoelectric ceramic substrate having two point-symmetric cantilever-shaped cutout portions that are polarized, and a driving means for rotating the piezoelectric ceramic substrate through the point of symmetry and around an axis perpendicular to the substrate surface. , signal processing means for processing the electrical output generated by the piezoelectric effect of the two cutouts to generate an output signal corresponding to the angular velocity with respect to the inertial system of the device. (2) The angular velocity sensor according to claim 1, wherein all or part of the signal processing means is provided on the piezoelectric ceramic substrate.