CN111336908A

CN111336908A - Novel inductance micrometer

Info

Publication number: CN111336908A
Application number: CN202010360083.0A
Authority: CN
Inventors: 王普群; 李根生
Original assignee: Luoyang Ruiyan Electronic Technology Co ltd
Current assignee: Luoyang Ruiyan Electronic Technology Co ltd
Priority date: 2020-04-30
Filing date: 2020-04-30
Publication date: 2020-06-26

Abstract

The invention belongs to the technical field of electronics, and provides a novel inductance micrometer. The novel inductance micrometer provided synthesizes sine waves in a sine wave generator link by adopting a digital synthesis technology, provides sine wave signals with single frequency for a sensor, and directly samples and analyzes alternating current signals; the CPU calls sine wave data stored in a ROM in the chip and sends the sine wave data to a DAC port, the DAC outputs corresponding sine wave voltage, single-frequency sine waves are output to a sensor input end OSC after band-pass filtering and amplification, and signal excitation of a sensor is completed; the output signal of the sensor is amplified by an operational amplifier and then biased by a bias circuit to obtain a direct current signal containing an alternating current component, and the direct current signal is output to an ADC (analog to digital converter) for sampling; and analyzing the digital signals by adopting Fourier transform software, and calculating the amplitude and the phase of the alternating current signals according to the DAC output time sequence to obtain the displacement value of the sensor. The measurement precision and stability of the invention are greatly improved.

Description

Novel inductance micrometer

Technical Field

The invention belongs to the technical field of electronics, and particularly relates to a novel inductance micrometer.

Background

The inductance micrometer is an instrument for displaying and transmitting displacement by utilizing the displacement change of an inductance transducer (LVDT), can be widely applied to various industries of national economy such as aerospace, machinery, construction, textile, railway, coal, metallurgy, plastics, chemical industry, scientific research colleges and the like, and is a high-technology product for measuring elongation, vibration, object thickness, expansion and the like.

The inductance micrometer is a precise instrument which utilizes the electromagnetic induction principle of an inductance sensor to realize the change of the inductance of the sensor caused by the change of the displacement and then detects the change through a circuit to realize the display of a pointer or the digital display.

The inductive sensor structure consists of a magnetic core, a magnetic sleeve, a primary coil and a secondary coil, and can also adopt a self-inductance principle to take out a middle tap to be used as secondary output; the primary coil and the secondary coil are distributed on the coil framework, and the magnetic core can freely move in the coil. When AC voltage with certain frequency is applied to the primary coil, the magnetic core moves in the coil to change the magnetic field distribution in space, so that the mutual inductance between the primary coil and the secondary coil is changed, the secondary coil generates different induced voltages, and the displacement of the magnetic core is changed into AC voltage signal output.

The schematic block diagram of a conventional electrical micrometer is shown in fig. 1.

The sine wave of the excitation sensor in the traditional circuit is generated by an LC oscillator, and due to the limitation that the circuit is an inductance three-point structure, the generated sine wave has poor frequency stability and poor amplitude stability, so that the stability of the whole measuring system is influenced.

The phase-sensitive rectifying link in the traditional circuit consists of a bridge rectifying circuit consisting of four diodes, and due to the nonlinearity of the diodes and the sensitivity to temperature, the linearity and the temperature stability of the whole system are determined to be insufficient.

Disclosure of Invention

The invention aims to provide a novel inductance micrometer, which can improve the precision and stability of the inductance micrometer.

The invention adopts the following technical scheme for achieving the purpose:

a new kind of inductance micrometer gauges, adopt the digital synthesis technology to formate the sine wave in the sine wave generator link, provide the sine wave signal of the single frequency for the sensor, make frequency and amplitude stability improved; in order to improve the linearity and stability of the sensor and eliminate nonlinear and unstable factors brought by a phase-sensitive rectifying circuit, the alternating current signal is directly sampled and analyzed, so that earlier complete data of the sensor is obtained; further, the CPU calls sine wave data stored in a ROM in the chip and sends the sine wave data to a DAC port, the DAC outputs corresponding sine wave voltage, single-frequency sine waves are output to a sensor input end OSC after band-pass filtering and amplification, and signal excitation of the sensor is completed; the AC signal output by the sensor is output to a DC blocking capacitor after operational amplification, and then is biased by a bias circuit to provide a DC level for the AC signal so as to obtain a DC signal containing an AC component, and the DC signal is output to an ADC (analog to digital converter) for sampling; analyzing the obtained digital signal by adopting Fourier transform software, and calculating the amplitude and the phase of the alternating current signal by the Fourier transform software according to the DAC output time sequence to obtain the displacement value of the sensor; furthermore, an STM32H750 chip of ST semiconductor company is adopted, and a 12-BIT DAC and a 16-BIT ADC are arranged in the STM32H750 chip.

The inductance micrometer obtained by the technical scheme of the invention has greatly improved measurement precision and stability.

Drawings

Fig. 1 is a schematic block diagram of a conventional inductance micrometer.

Fig. 2 is a schematic block diagram of the present invention.

FIG. 3 is an electrical schematic of the DAC sine wave synthesis of the present invention.

Fig. 4 is an electrical schematic of sensor output signal processing.

Detailed Description

The invention is described in connection with the drawings and the detailed description;

the novel inductance micrometer shown in fig. 2, 3 and 4 adopts an STM32H750 chip of ST intentionally-made semiconductor corporation, and a DAC (digital-to-analog converter) with 12 BITs and an ADC (analog-to-digital converter) with 16 BITs are built in the novel inductance micrometer; the CPU calls sine wave data stored in a ROM in the chip and sends the sine wave data to a DAC port, and the DAC outputs corresponding sine wave voltage; the sensor is loaded to the input end of the sensor after being amplified by an operational amplifier N1A through a band-pass filter circuit consisting of R1, C1, R2 and C2, and a sine wave signal with single frequency is provided for the sensor to serve as an excitation signal of the sensor; the signal is closely related to the frequency of the single chip microcomputer crystal oscillator, so the frequency is very accurate and stable; the output signal of the sensor is amplified by an operational amplifier N1B and then output to a CX1 blocking capacitor through a pin 7, a direct current signal containing an alternating current component is obtained through the bias of a bias circuit composed of RP1 and RP2 and is directly sent to an ADC for sampling; analyzing the obtained digital signal by adopting FFT (Fourier transform software), and accurately calculating the amplitude and the phase of the alternating current signal according to the output time sequence of the DAC to obtain the displacement value of the sensor; the data is sent to the LCD display, the displacement of the sensor can be seen more visually, and the data can be output to external equipment through the RS232 communication port.

Claims

1. The utility model provides a novel inductance micrometer, its characterized in that: synthesizing sine waves by adopting a digital synthesis technology in a sine wave generator link, and providing sine wave signals with single frequency for a sensor; sampling and analyzing the alternating current signal directly so as to obtain earlier complete data of the sensor; further, the CPU calls sine wave data stored in a ROM in the chip and sends the sine wave data to a DAC port, the DAC outputs corresponding sine wave voltage, single-frequency sine waves are output to a sensor input end OSC after band-pass filtering and amplification, and signal excitation of the sensor is completed; the AC signal output by the sensor is output to a DC blocking capacitor after operational amplification, and then is biased by a bias circuit to provide a DC level for the AC signal so as to obtain a DC signal containing an AC component, and the DC signal is output to an ADC (analog to digital converter) for sampling; analyzing the obtained digital signal by adopting Fourier transform software, and calculating the amplitude and the phase of the alternating current signal by the Fourier transform software according to the DAC output time sequence to obtain the displacement value of the sensor; furthermore, an STM32H750 chip of ST semiconductor company is adopted, and a 12-BIT DAC and a 16-BIT ADC are arranged in the STM32H750 chip.