KR960010419B1 - Total direction piezo-electric sensor in gyroscope - Google Patents

Abstract

The piezo-electric sensor senses three dimensionally the rotary angle in any direction while eliminating noises except the rotary angle. The sensor comprises: drive piezo-electric elements(1,11,2,12,3,13), vertically attached to surface centers of a metallic cube(7) of a regular hexahedron, performing a linear movement according to vibration in a thickness direction if an electric power is transmitted; sensing piezo-electric elements(4,14,5,15,6,16), attached to the drive piezo-electric elements(1,11,2,12,3,13) via insulation adhesives, generating electric charges correspondent to Coriallis force by the linear movement of the drive piezo-electric elements(1,11,2,12,3,13) and external rotary speed; differential amplifiers(41,42,43) amplifying the difference of the electric charges between each element pairs(4-14,5-15,6-16).

Description

Omnidirectional Piezoelectric Angle Sensor

1 is a perspective view of the omni-directional piezoelectric rotation angle sensor of the present invention.

2 is a configuration diagram of a driving element and a sensing unit of the omnidirectional piezoelectric rotation angle sensor of the present invention.

Figure 3 is a detailed view of the drive element and the detector element of the omni-directional piezoelectric rotation angle sensor of the present invention.

4 is a configuration diagram of the measurement circuit of the omni-directional piezoelectric rotation angle sensor of the present invention.

* Explanation of symbols for main parts of the drawings

1,11,2,12,3,13: piezoelectric element for driver 4,14,5,15,6,16: piezoelectric element for detector

7: metal cube 21: thermosetting adhesive

31; Metal plate 32: conductive adhesive layer

33,34: piezoelectric element 36: silver electrode

41, 42, 43: operational amplifier 44: drive terminal

45: detection terminal

The present invention relates to a three-dimensional piezoelectric rotating angle sensor designed to remove a noise other than the rotation angle as being capable of measuring the rotation angle in three dimensions.

In general, the piezoelectric rotation angle sensor is collectively referred to as a piezoelectric vibratory gyroscope, and its principle is the same as that of the cope electron, and when a rotational angular velocity is given to a vibrating object, a Coriolis force is generated in a direction perpendicular to the vibration direction. It is a sensor using the phenomenon.

This principle has been applied to elastic vibrating bodies such as sound pieces since around 1953, and has been commercialized. Unlike conventional rotary angle sensors with rotary shafts, piezoelectric rotary angle sensors have no bearing friction and thus have a long service life and short start-up time. Low power and low price.

Therefore, it is used for azimuth measurement of robots and unmanned transportation vehicles, attitude control of aircraft and ships, and angular velocity measurement to prevent screen vibration of video camera. In particular, high-precision piezoelectric rotation angle sensors have been developed for driving a vehicle, which have high civil demands and can measure the effects of earth rotation.

Conventional piezoelectric circuit angle sensor has a problem that is affected by noise generated by changes in ambient sound pressure, heat, humidity in addition to the rotation angle.

An object of the present invention is to provide an omnidirectional piezoelectric rotation angle sensor that can remove noise other than the rotation angle in order to solve the above problems.

The present invention is a bimorph (piemorph) -type piezoelectric element is fixed to the center of each side of the cube to be fixed by an adhesive to form a right angle to the drive unit and the sensing unit of the piezoelectric element to achieve the same direction of the Coriolis force It is characterized by.

Hereinafter, the present invention will be described in detail with reference to the drawings.

Referring to FIG. 1, a bimorph piezoelectric element pair as shown in FIG. 2 is attached perpendicularly to the center point on each side of the cube metal body 7.

Here, the bimorph piezoelectric element pair has a form in which the sensing unit safety element 23 and the driving unit piezoelectric element 25 connected by the insulating adhesive 21 are perpendicular to each other.

Each of the piezoelectric elements described above takes the form of a thin element attached to each side of the rectangular parallelepiped formed as shown in FIG.

On the other hand, the drive piezoelectric elements 1, 11, 2, 12, 3, 13 and the detector piezoelectric elements 4, 14, 5, 15, and 6 16, two piezoelectric elements 33, 34 polarized in the same direction of the arrow direction as shown in Fig. 3 are placed on both sides of the metal plate 31 (e.g., copper plate). It consists of a bimorph type adhere | attached with the conductive adhesive 32, respectively.

In addition, silver (Ag) electrode layers 35 are coated on the other surfaces of the piezoelectric elements 33 and 34 that are not adhered to the metal plate 31.

Here, length (l), width (W) and thickness (t) should be at least 14: 1.6: 0.35.

The piezoelectric elements configured as shown in FIG. 2 take the form of being attached as shown in FIG. 1 so as to face the X, Y, and Z axes.

That is, the piezoelectric elements 1, 11, 4, 14 are placed on the X axis, the piezoelectric elements 2, 12, 5, 15 are placed on the Y axis, The piezoelectric elements 3, 13, 6, and 16 lie on the Z axis.

Looking at the operation of the piezoelectric sensor configured as described above are as follows.

Piezoelectric elements when the piezoelectric elements (1) (11), (2) (12) and (3) (13) placed on the lines of the X, Y, and Z axes, respectively, bend and vibrate by an external signal corresponding to the resonance frequency. Elements 4, 14, 5, 15 and 6, 16 are subjected to linear motions V _Y , V _Z and V _X , respectively.

When the rotational speed (Ω _X ) on the YZ plane, the rotational speed (Ω _Y ) on the XZ plane, and the rotational speed (Ω _Z ) on the XY plane are applied by the linear motion, piezoelectric elements (4) (14), (5) ( The Coriolis force (Fc), which appears at 15) and (6) and 16, respectively, is expressed as follows. In other words,

Fcz = -2mV _Y Ω _X

Fcx = -2mV _Z Ω _Y

Fcy = -2mV _X Ω _Z

Therefore, by substituting the known constant (m) with V _X = V _Z = V _Y and the measured Coriolis force, the angle of rotation (Ω _X ) (Ω _Y ) (Ω _Z ) can be found. It is possible to measure the rotation angle on a three-dimensional image consisting of the XY and XZ planes and the YZ plane as the rotation angle sensor.

On the other hand, when the rotational speed given from the outside is not accurately divided into rotational angular velocity (Ω _X ), (Ω _Y ), (Ω _Z ), the piezoelectric elements 4, 14, 5, 15, and 6 16) components in the XY, XZ, and YZ plane directions will be detected respectively, and the total rotational speed and rotational angle will be represented as the vector sum of these components.

Referring to FIG. 4, one terminal of the power supply is connected to the cube metal body 7 (not shown), and the driving unit piezoelectric element is connected to the driving terminal 44 so that voltage is driven through the driving terminal 44. When applied to 1), (11), (2), (12), (3), and (13), the piezoelectric elements of the driving unit vibrate in the thickness direction, so that the piezoelectric elements (1), (11), (2), ( 12, (3), (13) is to perform the linear motion (V _Y ), (V _Z ), (V _X ) respectively.

Here, the piezoelectric elements 4, 14, 5, 15, and 6, which form the sensing unit, have linear motions V _Y , V _Z , V _X , Charges corresponding to the Coriolis force (Fc) are generated by the rotational speed given from the outside, respectively.

At this time, the difference between the charge amounts of the pairs (4), (14), (5), (15) and (16) of the piezoelectric elements is amplified by the differential amplifiers (41) (42) and (43), respectively. 45).

The sensing and driving piezoelectric elements of FIG. 4 are exactly the same, and the polarization directions of the respective piezoelectric elements are also directed as shown in FIG. Therefore, when a rotational speed is given around the center point of the cube 17, for example, charges of opposite signs are generated in the piezoelectric element pairs 4 and 14 on the X-axis, respectively.

On the other hand, if d X ambient pressure, temperature, noise, indicated by the humidity change appears as both have the same sign electric charge due to the Coriolis seuhim in the piezoelectric elements 4, 14 Fcz + X = _Y -2mV Ω _X, - Fcz + X = + 2mV _Y Ω _{X. When} the difference is obtained by the operational amplifier (4), the effect of noise is eliminated and only the Coriolis force is shown as a double amplified value.

Therefore, the present invention has the effect of improving the accuracy of the piezoelectric rotation angle sensor by removing noise other than the rotation angle.

Claims (1)

In the piezoelectric rotating angle sensor, six drive part piezoelectric elements, each consisting of a cubic cube made of metal, a thin plate-shaped cube, and one end of which is attached perpendicularly to the center of the surface angle of the cube, and the other end of the drive piezoelectric element. And a sensing unit piezoelectric element which is formed of an insulating adhesive to be attached and a rectangular parallelepiped in the form of a thin plate, and is attached to the driving unit piezoelectric element by the insulating adhesive, and wherein the driving unit piezoelectric element and its corresponding surface are attached at right angles to each other. The omnidirectional piezoelectric angle sensor.