JPS6157807A - Inclinometer - Google Patents

Abstract

PURPOSE:To take measurements from a fine angle to a large inclination simultaneously while reducing the influence of terrestrial magnetism by arranging the 1st and the 2nd magnetic sensors at specific intervals, outputting relative deviations from a magnet piece provided in the middle, and amplifying and processing differentially both outputs. CONSTITUTION:The magnetic sensors 11 and 12 are arranged coaxially at the specific distance and the magnet piece 10 is provided in the middle between the sensors 11 and 12. Outputs of the sensors 11 and 12 are amplified by amplification systems 13 and 14. The magnet piece 10 is suspended from a gimbals mechanism 16 through a pendulum 16 and displaced to or from the sensors 11 and 12 when a fine inclination is caused. The sensors 11 and 12 are driven by an oscillator 17, whose signal is converted by a double frequency generator 18 into a signal of double freuquency and inputted to the amplification systems 13 and 14 as a signal from synchronous rectification. The amplificatin system 13 operates as a high-sensitivity inclinometer and the amplification sytem 14 has low sensitivity and functions to prevent saturation even if a large magnetic field is inputted. Thus, the influence of terrestrical magnetism, etc., is reduced and measurements from a fine angle to a large inclination are taken simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to an inclinometer, and particularly to an inclinometer used for measuring minute angular changes on the seabed or the like.

(b) Prior art Conventionally, in order to detect small angular fluctuations in the seabed, etc., a magnetic sensor uses one magnet piece, one magnetic sensor, and an amplifier to detect changes in the mutual distance between the magnet piece and the magnetic sensor due to inclination. It was designed to detect changes in the magnetic field received. However, with this type of inclinometer, increasing the gain of the amplification system to increase sensitivity increases noise, and even changes in the earth's magnetic field are affected. Furthermore, there is a limit to increasing the magnetic moment of the magnet piece, and when the magnetic sensor and the magnet piece are brought close to each other, an attraction phenomenon occurs, making it impossible to accurately detect minute inclinations.

Therefore, in order to eliminate the influence of geomagnetism, etc., a pair of magnetic sensors (flux gates) 1 and 2 are installed as shown in Fig. 2, and a thin plate 4 is attached to the gimbal mechanism 3 between these magnetic sensors 1 and 2. A suspended magnet piece 5 is arranged, and an oscillator 6
It is conceivable that the magnetic sensor sensor 2 is driven by the magnetic sensor 2, and the outputs of the magnetic sensors 1 and 2 are differentially led out and amplified by the amplification system 7. However, this technique has drawbacks in that it cannot correct the difference in sensitivity between the two magnetic sensors, and it cannot simultaneously measure high sensitivity and low sensitivity.

(c) Purpose An object of the present invention is to provide a highly accurate inclinometer that is as little influenced by geomagnetism as possible and can simultaneously measure small angles and large angles.

(D) Structure In order to achieve the above object, the inclinometer of the present invention is provided with two amplification systems corresponding to the pair of differentially operated magnetic sensors. That is, in the inclinometer of the present invention, a first magnetic sensor and a second magnetic sensor are arranged at a predetermined distance, a magnet piece is provided between these magnetic sensors, and the relative relationship between the magnet piece and the magnetic sensor is providing first and second amplification systems that output the displacement from the magnetic sensor and amplify the outputs of the first and second magnetic sensors, respectively;
The first amplification system provides negative feedback for a part of the output and also receives a part of the output of the second amplification system to provide a differential signal between the input to the first amplification system and the input to the second amplification system. The second
The amplification system is configured so that its output is negatively fed back and also fed to the input of the first amplification system, so as to obtain a low sensitivity output.

(E) Examples The present invention will be explained in further detail in (2) below with reference to Examples.

FIG. 1 is a block diagram of an inclinometer showing one embodiment of the present invention. In the figure, magnetic sensors 11 and 12 are arranged on the same axis with a predetermined distance apart, and a magnet piece 10 is provided between these magnetic sensors 11 and 12. Further, each output of the magnetic sensors 11 and 12 is amplified by an amplification system 13 and I4 and output.

The magnet piece 10 is suspended from the gimbal mechanism 15 by a pendulum 16, and when a slight inclination occurs, the magnetic sensor 1
It is designed to be displaced relative to 1.12.

The magnetic sensors 11 and 12 are driven by an oscillator 17. Further, the signal of the oscillator 17 is converted into a signal of twice the frequency by the frequency doubler 18, and is inputted to the amplification systems 13 and 14 as a signal for synchronous rectification.

The amplification system 13 includes an adder 19 that receives a signal from the magnetic sensor 11, a filter 20, and an adder 21 that receives the output of the filter 20 and the output of a filter 26 of the amplification system 14, which will be described later, and outputs the difference value. , an AC amplifier 22 that amplifies the output of the adder 21, a synchronous rectifier 23, a DC amplifier 24 that amplifies the synchronously rectified DC voltage and derives the output voltage Vol, and a negative output voltage Vol of the adder 21. It is composed of a resistor Rfl for feedback. Note that an external offset signal is input to the adder 21, so that the offset can be adjusted from the outside.

The amplification system 14 includes an adder 25 that receives the signal from the magnetic sensor 12, a filter 26, an AC amplifier 27, a synchronous rectifier 28, a DC amplifier 29, and an adder 25 that receives the signal from the magnetic sensor 12.
A resistor Rf2 provides negative feedback to the output voltage Vo2, and amplification system 1
3 and a resistor Rf2° for supplying the input to the adder 21.

Now, in this embodiment of the inclinometer, if the inclination angle is δ, the length of the magnet piece 10 swinging in the SN direction is 1. For (m),
Move by x=6・δ. With respect to this amount of movement X, the magnetic field in the Z direction that the magnetic sensors 11 and 12 receive is:
2--3M-x -z/ (x2+z2 Dan-(2 digits, M: magnetic moment of the magnet piece 10, 2: distance from the rib center of the magnetic sensor to the magnetic piece.

Taking the difference between the magnetic fields H1 and I2, ΔH=H1-H2=2Ht=2H2 (3).

Since the distance 2 is taken to be from several fins to several + fins, if it is derived differentially, it will be hardly affected by the magnetic gradient.

In addition, magnetic fields Hl and H are applied to the magnetic sensors 11 and 12, respectively.
2 is detected, and each detection output is sent to the amplification system 13.
14, the output Vol of the amplification systems 13 and 14
・Vo2 is the following formula Vol = Rfl /β1 ・l
:I+1- (Rf2-β1/11f2' ・β
2)・+12) ...(4) Vo2
=I12 ・Rf2 /β2− (5 square, β1
-β2: Represented by the coil constant of the magnetic sensors 11 and 12.

In the above equation (4), for example, when HI=H2, Vo
In order to set l=O, Rf2 ・β1−Rf2′−
β1, Zunawachi I? It suffices to deviate from f2 /Rf7-β2/β1, and even if there is some difference in distance 2 and it does not become H+ -)f, the resistances Rf2, l? By adjusting f2′, it is possible to set the offset I· to O.

It can be seen from equation (3) that in this example inclinometer, twice the sensitivity can be obtained compared to the case where only one magnetic sensor is used.

Also, from equation (4), the output Vol of the amplification system 13 is determined by the resistance 1?
By increasing f1, it becomes non-densely large, resulting in extremely high sensitivity. That is, the amplification system 13 operates differentially as a highly sensitive inclinometer.

On the other hand, the output Vo2 of the amplification system 14 is connected to the resistors Rf2 and Rf2.
By selecting a small value, it is possible to reduce the sensitivity, that is, to prevent the amplifier from being saturated even when a large magnetic field is input.

From the above, the infinitesimal angle δ (e.g. δ≦10' raclia
The output Vol of the amplification system 13 is used to measure n), and the output Vo2 of the amplification system 14 is used to measure a large inclination angle δ (δ>10′ radian).

In the above embodiment, the magnet piece 10 is suspended by the pendulum 16, but the magnetic sensors 11 and 12 may be suspended by the pendulum.

Further, in the second embodiment, the NS direction of the magnet piece 10 is horizontal, but the axis of the magnet piece may be set as the Z axis, and the axis of the magnetic sensor may be kept horizontal.

(f) Effects According to the inclinometer of the present invention, a pair of magnetic sensors are used differentially, so high sensitivity measurement is possible.Also, two amplification systems connected to the magnetic sensors are provided, one For high sensitivity,
Since the other one can be used for low sensitivity, it is possible to simultaneously detect a wide range of inclinations from minute angles to large inclinations.

Furthermore, even if there are variations in the coil constant between the magnetic sensors, or if there is an initial inclination or cis alignment between the magnetic sensor and the magnet piece, these can be corrected as desired.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an inclinometer showing one embodiment of the present invention, and FIG. 2 is a block diagram of the inclinometer which is the background of this invention. 10: Magnet piece, 11・12: Magnetic sensor, 13・
14: Amplification system,

Claims (1)

[Claims] (1) A first magnetic sensor and a second magnetic sensor are arranged at a predetermined distance, a magnet piece is provided between these magnetic sensors, and the relative displacement between the magnet piece and the magnetic sensor is output from the magnetic sensor. and the first and second
A first amplification system and a second amplification system each amplifying the output of the magnetic sensor are provided, and the first amplification system negatively feeds back a part of the output and receives a part of the output of the second amplification system. , 1st
The input to the amplification system and the input to the second amplification system are configured to be output differentially to obtain a highly sensitive slope output, and the second amplification system negative feedbacks the output. and is configured to also be applied to the input of the first amplification system,
An inclinometer characterized by obtaining low sensitivity output.