基于数字合成与检波技术的电容位移传感器

调幅式电容传感器在实际应用中存在稳定性差、漂移大、线性度差等问题. 为解决这一综合技术障碍,采用直接数字合成和数字检波的方法,将传统电路中模拟的环节数字化,研制出了具有极高幅值和频率稳定性的载波信号,保证了检波过程中测量通道和参考通道良好的相位一致性. 运用HP5529 双频激光干涉仪对改进后的调幅式电容位移传感器进行长期稳定性实验及标定,实验结果表明:在30μm 量程范围内,分辨力为2 nm、稳定性为6 nm/ 30min、线性度为0. 16 % ,传感器性能良好. 可见,基于数字技术的调幅式电容位移传感器有效地改善了上述各项性能指标,实现了传感器的高精度、高稳定性.
关键词: 直接数字合成; 数字检波; 电容位移传感器
Abstract : In order to solve the problems of capacitance type sensor with amplitude modulation , bad stability and drift existing and big nolinearity direct digital synthesis technology was used to improve the amplitude and f requency stability of source waveform and digital demodulation technology was used to improve the characteristic of linearity . The long term stability experiment and calibration have been carried out to im2 prove sensor with HP5529. The experimental result s show that characteristic of the sensor is excellent . In
the range of 30μm , precision of the sensor is 2 nm、the stability is 6nm/ 30min、the linearity is 0. 16 %. Obviously , the use of digital technology greatly improved the characteristic of capacitance displacement type sensor with amplitude modulation , and realized high2precision measurement of stability.
Key words : DDS ; digital demodulation ; capacitance displacement sensor