JPH0337115Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a material testing device, and is particularly suitable for use in material testing equipment that simultaneously measures strain, displacement, etc. of each part of a large structure by arranging a large number of sensors in each part of the structure. It is something that

Traditionally, in this type of large-scale testing, the output signals of numerous sensors were impedance-converted using amplifiers with low output impedance, and then transmitted over long distances via cables to a central control unit. The problem of noise entering from the cables cannot be avoided, and furthermore, there are disadvantages such as the complexity of routing a large number of cables, and the fact that the transmission signal is attenuated during transmission, resulting in a decrease in measurement accuracy.

An object of the present invention is to solve the above-mentioned drawbacks all at once and to provide a material testing device with a simple configuration.

The present invention consists of a sensor that receives the output of a carrier wave oscillator and converts physical quantities such as load and displacement of the test material into electrical signals, and a transmitter that modulates the output signal of this sensor and the output of the carrier wave oscillator at a high frequency and transmits it by radio waves. A receiving device is installed at a location far from the sensor installation location and receives and demodulates the radio waves from the transmitting device, and the magnitude of the output of the carrier wave oscillator demodulated by this receiving device is compared with a reference voltage. It has means for obtaining a deviation and a multiplier that multiplies the output signal of the carrier sensor demodulated by the receiving device by the deviation, and is configured so that the signal regarding the sensor output wirelessly transmitted from the transmitting device to the receiving device is calibrated for sensitivity. characterized by what has been done.

Hereinafter, embodiments of the present invention will be explained based on the drawings.

FIG. 1 shows a circuit block diagram of a sensor-side device, and normally a plurality of this device is used in parallel. Figure 2 shows the circuit block diagram of the central control unit.
Only the stand is used. Note that the device for issuing command signals and the like from the central control unit to each sensor side is not related to the gist of the present invention and will therefore be omitted.

The load cell 1 converts the stress of the material into an electric signal, and the differential transformer 2 converts the displacement of the material into an electric signal. The carrier wave oscillator 3 outputs a carrier wave of, for example, several hundred Hz to several thousand Hz, and this carrier signal is amplified by the excitation amplifiers 4 and 5 to directly drive the load cell 1 and the differential transformer 2, and is also amplified by the amplifier 6. and becomes the reference signal, signal C. The output of load cell 1 and the output of differential transformer 2 are:
A signal A and a signal B are obtained by being amplified by detection amplifiers 7 and 8, respectively. The modulator 9 receives signals A, B,
C is converted into a serial signal by time division control and subjected to harmonic modulation. The transmitter 10 transmits this from an antenna.

In the central control unit, the receiver 11 first receives the radio waves from the transmitter 10, and the demodulator 12 demodulates the radio waves.
Separate into signals A′, B′, and C′. The signal C' is amplified by an amplifier 13, converted to DC by an AC/DC converter 14 such as an absolute value rectifier circuit, compared with a reference voltage 15, and its deviation component is input to multipliers 22 and 23 as a multiplier. Signal A' is amplified by amplifier 16, demodulated by demodulator 18 using signal C' as a reference signal, and filter 20 extracts a DC signal proportional to the load, which is input to multiplier 22 as a multiplicand. Similarly, a DC signal proportional to the displacement is extracted from the signal B' by the amplifier 17, the demodulator 19, and the filter 21, and the multiplier 23
is input as the multiplicand.

Signal C is provided to calibrate sensitivity fluctuations due to ambient temperature and other factors in the location where the sensor is installed, and sensitivity fluctuations due to unstable radio wave conditions. By multiplying the received signals of the signals A and B by the deviation between the reference voltage 15 and the magnitude of the received signals of the signal C, the attenuation during transmission of the signals A and B is compensated for and sensitivity calibration is performed.

As explained above, according to the present invention, since radio waves are used to transmit and receive data between the sensors of the test equipment and the central control unit, there is no need for a connection cord between the sensors and the central control unit, and the sensor installation There are no restrictions on location, making it easy to install, and it also eliminates the problem of a reduction in SN ratio due to noise induced in the code, which was a problem when using a transmission code. Moreover, the magnitude of the demodulated output of the carrier wave oscillator output input to the sensor is compared with the reference signal, and based on the deviation,
Since the sensitivity of the signal related to the sensor output wirelessly transmitted to the receiving side is calibrated, it is possible to correct the distance of the sensor and other sensitivity fluctuation factors, and it is possible to obtain highly accurate test data. Another advantage is that sensitivity fluctuations due to amplitude fluctuations of the carrier wave oscillator itself can be calibrated.

[Brief explanation of drawings]

1 and 2 are circuit block diagrams showing an embodiment of the present invention, with FIG. 1 showing the sensor side and FIG. 2 showing the central control section side. 1, 2...sensor, 3...carrier wave oscillator, 9...
...Modulator, 10...Transmitter, 11...Receiver, 1
2...Demodulator, 14...AC/DC converter, 15
...Reference voltage, 22, 23... Multiplier.

Claims (1)

[Scope of utility model registration request] a sensor that receives the output of the carrier wave oscillator and converts physical quantities such as load and displacement of the test material into electrical signals; a transmitter that modulates the output signal of this sensor and the output of the carrier wave oscillator at a high frequency and transmits it by radio waves; A receiving device installed at a location away from the sensor installation location receives and demodulates the radio waves from the transmitting device, and the magnitude of the output of the carrier wave oscillator demodulated by this receiving device is compared with a reference voltage. and a multiplier for multiplying the output signal of the sensor demodulated by the receiving device by the deviation, and the signal regarding the sensor output wirelessly transmitted from the transmitting device to the receiving device is calibrated for sensitivity. Material testing equipment configured as follows.