JP2582405B2 - Measurement device using pressure-sensitive conductive rubber and linear sensor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring device using a pressure-sensitive conductive rubber and a linear sensor, and particularly to a measuring device using a pressure-sensitive conductive rubber sensor and a linear sensor suitable for simple automatic measurement of the ground at a civil engineering site. About.

Conventional technology In order to promote so-called computerized construction, which advances construction while predicting ground behavior by measuring ground subsidence and ground surface displacement,
The present inventors have developed a pressure-sensitive conductive rubber sensor suitable for measuring soil pressure in soil at a construction site and a linear sensor using a variable voltage divider suitable for measuring ground displacement and the like. The pressure-sensitive conductive rubber sensor is disclosed in Japanese Utility Model Laid-Open Publication No. 1-131132, and the linear sensor using the variable voltage divider is disclosed in Japanese Patent Application Laid-Open No. 1-245102.

As a conventional measuring device that detects the state of the ground with a sensor, a high-precision, multifunctional general-purpose device that can input a strain gauge, a strain gauge transducer, and a thermocouple using a DC voltage or DC current as a power supply has been developed. It is used.

Problems to be Solved by the Invention However, these conventional measuring devices have high accuracy that is unnecessary for actual construction site measurement, and cannot cope with the diversity of actual site measurement while calling for multiple functions. There is a drawback that it is unsuitable as an on-site measurement device because special parts are often required. In addition, high precision,
In reality, there is no simple and inexpensive measuring device suitable for installation at all construction sites where computerized construction is desirable because of the high price due to multifunctionality.

An object of the present invention is to provide a simple and inexpensive measuring device for simultaneously measuring a change in the ground pressure and a displacement of the ground.

Means for Solving the Problems A measurement device using a pressure-sensitive conductive rubber and a linear sensor according to the present invention will be described with reference to the embodiment shown in FIGS. 1, 2A to 2D and FIGS. 3A and 3B. I do. In this embodiment, a plurality of pressure-sensitive electro-rubber sensors 1 are sequentially connected to a constant current power supply 3 via a first multiplexer 5, and a plurality of linear sensors 2 are sequentially connected to a constant voltage power supply 4 via a second multiplexer 6. I do.

The pressure-sensitive conductive rubber sensor 1 has a pressure-sensitive conductive rubber film in which conductive particles are mixed in an elastomer between two electrodes, and responds to pressure such as earth pressure acting between the two electrodes. The earth pressure and the like are detected by a change in the resistance value of the conductive rubber film. As shown in FIG. 2A, pressure-sensitive conductive rubber sensor 1
In passing a constant current of, for example, 1mA, the resistance value change or changes in the output voltages V ₁ in this case of R with respect to pressure change is exponential as in Figure 2B. Such a pressure-sensitive conductive rubber sensor 1 can be mass-produced at low cost and is easy to handle, and is suitable for simple measurement of soil pressure and pore water pressure at a construction site.

Linear sensor 2 is for generating an output such as a voltage V ₂ which changes linearly with respect to variations in the input of the displacement D or the like as shown in Figure 3B. One example of the linear sensor 2 is that when a wire stretched between two points on the ground with a constant tension is fed or taken in according to a relative displacement between the two points, the wire rotates in proportion to the amount of the feeding or taking in. Is a ground displacement meter consisting of a rotating potentiometer type variable resistor.
It looks like the figure.

The pressure-sensitive conductive rubber and the linear sensor-based measuring device for monitoring the distribution of the pressure and displacement of the ground according to the present invention are each configured with a film of the pressure-sensitive conductive rubber sandwiched between two electrodes and distributed and arranged in the ground to be measured. A plurality of pressure-sensitive conductive rubber sensors 1 for detecting earth pressure, a constant current power supply 3 for supplying a constant current to the plurality of rubber sensors 1, and a logarithmic converter such that the overall accuracy of the rubber sensor 1 is within 1% of the full scale of the rubber sensor 1. 7, a first multiplexer 5 for sequentially connecting a plurality of rubber sensors 1, a plurality of linear sensors 2 for displacement detection distributed in the ground to be measured, a constant voltage power supply 4 for applying a constant voltage to the plurality of linear sensors 2, a plurality of linear sensors. A second multiplexer 6 for sequentially selecting the output of the sensor 2, a third multiplexer for sequentially and selectively connecting the output of the logarithmic converter 7 and the output of the second multiplexer 6 to the analog / digital converter 10. A central processing unit 11 for controlling the multiplexer 8 and the first, second and third multiplexers 5 and 6 and for processing the output of the analog / digital converter 10; This prevents interference between the linear sensor 2 and the circuit of the linear sensor 2.

Preferably, the output of the third multiplexer 8 is applied to an analog / digital converter 10 after passing through a filter 9.

Operation In FIG. 2B, the resistance value which is the output of the pressure-sensitive conductive rubber sensor 1 to which a constant current is applied, that is, the terminal voltage V ₁
Is known to change exponentially with pressure F. The than measured directly the output V _1, the output variation width when the pressure F is large or when less than a predetermined range can not too small or too large and accurate measurement. The present inventors use a commercially available logarithmic converter 7 to output the output V ₁ of the pressure-sensitive conductive rubber sensor ₁ to the
As shown in FIG. 2C, the output of the conductive rubber sensor 1 is converted into an easily measurable amount by performing logarithmic conversion and further inverting as described later as necessary, and furthermore, the total accuracy is reduced to 1 of full scale (FS).
%.

Sequentially logarithmically converts the output V ₁ scans a plurality of pressure-sensitive conductive rubber sensor 1 in the first multiplexer 5 in the pressure-sensitive conductive rubber and a linear sensor usage measuring device of the present invention. Further converted into a digital value in addition to the analog / digital converter 10 the output after the logarithmic conversion and the object to be selected linear sensor output V ₂ from the second multiplexer 6 via the third multiplexer 8. Full-scale (F
Can be suppressed to within 1% of the S), overall accuracy for the linear sensor output V ₂ without logarithmic transformation can be suppressed to within 1% of the full scale (FS).

The output V ₁ is accompanied to the increase in pressure in the output characteristic of the logarithmic converter 9 which is exemplified in 2C diagram is lowered, which like the curve of a 2D view the output V ₁ with increasing pressure increases It may be reversed.

The sensor outputs V ₁ and V ₂ once digitized can be subjected to known measurement value processing, that is, printing, external recording, transmission, data processing, and the like.

Thus, the measuring device using the pressure-sensitive conductive rubber and the linear sensor according to the present invention can eliminate unnecessary high precision and multiple functions, and can easily measure the ground pressure and the ground displacement required for the information processing with the required accuracy. Therefore, the above-described object of providing a ground measurement device having required functions at a low price is achieved.

Embodiment FIG. 1 is a block diagram showing a configuration of an embodiment of a measuring device using a pressure-sensitive conductive rubber and a linear sensor according to the present invention. First
The reason for using the three multiplexers of the multiplexer 5, the second multiplexer 6, and the third multiplexer 8 is as follows.
Since the pressure-sensitive conductive sensor 1 is driven from the constant current power supply 3 and the linear sensor 2 is driven from the constant voltage power supply 4, the influence between the two power supplies can be avoided. The power supply is basically 100 V AC, but the car battery 18 can be used in the event of a power failure.

FIG. 4 shows an example of a power supply circuit including a constant current power supply 3, a constant voltage power supply 4, and a battery 18 for an automobile, and FIG.
6 shows an example of a logarithmic converter 7 and a third multiplexer 8 connected to the first multiplexer 5, and FIG. 7 shows a multiplexer control circuit.
17 shows an example. The second multiplexer 6 may have the same configuration as the first multiplexer 5.

In the illustrated embodiment, the analog measured quantity at the output of the third multiplexer 10 is passed through a 10 Hz low-pass filter 9 for the purpose of noise elimination and then applied to a double-integrating analog / digital converter 10 for measurement as digital data. I'm taking out. The use of a 10 Hz low-pass filter 9 and a double-integrating analog-to-digital converter 10 assumes no high-speed data acquisition. Sixth
The figure shows an example of the low-pass filter 9, and FIG. 8 shows an example of the analog / digital converter 10.

As the CPU 11, a Z80A Z80A shown in FIG. 9 was used in this embodiment. A communication interface such as RS-232C system by the CPU 11 via the I / O interface 12
13, printer drive 14, external storage device drive 15 such as cassette, keyboard interface such as numeric keypad
16 and the multiplexer control circuit 17. FIG. 10 shows an example of the external storage device drive 15 and the keyboard interface 16, FIG. 11 shows an example of the printer drive 14, and FIG. 12 shows an example of the communication interface 13.

This embodiment is provided with an internal storage device for storing digitally converted data. As for the capacity, when 32 channels are provided for the pressure-sensitive conductive sensor 1 and 64 channels are provided for the linear sensor 2, data for 10 days can be stored at a measurement frequency of 2 times / day.

Effect of the Invention As described in detail above, the pressure-sensitive conductive rubber and linear sensor-based measuring device of the present invention includes a multiplexer that sequentially connects a plurality of pressure-sensitive conductive rubber sensor outputs to a logarithmic converter, and an output of the logarithmic converter. Since a configuration including a multiplexer for sequentially and selectively connecting a plurality of linear sensor outputs to an analog / digital converter is used, the following effects are obtained.

(A) The distribution of earth pressure, ground displacement, and the like and its temporal change can be easily measured by a single measuring device using a simple pressure-sensitive conductive rubber sensor or linear sensor.

(B) Since it is composed only of low-cost sensors and commercially available parts, mass production at low cost can be expected.

(C) The computerized construction can be performed by automatically and continuously monitoring the ground condition without special skilled technicians.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a measuring device using a pressure-sensitive conductive rubber and a linear sensor according to the present invention. FIGS. 2A to 2D are explanatory views of the pressure-sensitive conductive rubber sensor, and FIGS. 3A and 3B are FIG. 4 is a circuit diagram of a power supply, FIG. 5 is a circuit diagram of a multiplexer, FIG. 6 is a circuit diagram of a logarithmic converter and the like, FIG. 7 is a circuit diagram of a multiplexer control circuit, FIG. Is a circuit diagram of an analog / digital converter, and FIG. 9 is a CPU.
FIG. 10 is a circuit diagram of an I / O interface, etc.
FIG. 1 is a circuit diagram of a printer drive, and FIG. 12 is a circuit diagram of a communication interface. DESCRIPTION OF SYMBOLS 1 ... Pressure sensitive conductive sensor, 2 ... Linear sensor, 3 ... Constant current power supply, 4 ... Constant voltage power supply, 5 ... 1st multiplexer, 6 ... 2nd multiplexer, 7 ... Logarithmic converter, 8
... Third multiplexer, 9 filter, 10 analog / digital converter, 11 central processing unit, 12
…… I / O interface, 13 …… Communication interface, 1
4 ... Printer drive, 15 ... External storage device drive, 16 ... Keyboard interface, 17 ... Mux control circuit, 18 ... Automotive battery.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Teruichi Suzuki 1-2-7 Moto-Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. (72) Inventor Seiji Morikawa 1-2-7 Moto-Akasaka, Minato-ku, Tokyo No. Kashima Construction Co., Ltd. (72) Inventor Toshihiko Takahashi 1-2-7 Moto-Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. (72) Inventor Makoto Sato 1-2-7 Moto-Akasaka, Minato-ku, Tokyo Kashima (56) References JP-A-62-175630 (JP, A) JP-A-60-158327 (JP, A) JP-A-59-88616 (JP, A) JP-A-58-147797 (JP) , A) Actually open 1979-61656 (JP, U)

Claims (3)

(57) [Claims] 1. A plurality of pressure-sensitive conductive rubber sensors for detecting earth pressure, each having a film of pressure-sensitive conductive rubber sandwiched between two electrodes and distributed in the ground to be measured, and a constant current applied to the plurality of rubber sensors. A constant current power supply to be supplied, a first multiplexer for sequentially connecting the outputs of the plurality of rubber sensors to a logarithmic converter such that the total accuracy of the rubber sensor is within 1% of the full scale of the rubber sensor, and distributed in the ground to be measured. A plurality of linear sensors for detecting displacement, a constant voltage power supply for applying a constant voltage to the plurality of linear sensors, a second multiplexer for sequentially selecting outputs of the plurality of linear sensors, an output of the logarithmic converter, and an output of the second multiplexer. A third multiplexer sequentially and selectively connected to the analog / digital converter, and controlling the first, second and third multiplexers and the analog multiplexer. A central processing unit for processing the output of the analog / digital converter, wherein the third multiplexer prevents interference between the circuit of the rubber sensor and the circuit of the linear sensor to monitor the distribution of pressure and displacement of the ground. Measurement device using pressure-sensitive conductive rubber and linear sensor. 2. A measuring device according to claim 1, wherein the output of said third multiplexer is sequentially and selectively applied to a filter, and the output of said filter is connected to said analog / digital converter. Sensor-based measuring device. 3. The measuring device according to claim 1, wherein a keyboard, an external storage device, a printer, and a signal transmission interface are provided under the control of the central processing unit.