調幅式電容傳感器在實際應用中存在穩定性差、漂移大、線性度差等問題. 為解決這一綜合技術障礙,采用直接數字合成和數字檢波的方法,將傳統電路中模擬的環節數字化,研制出了具有極高幅值和頻率穩定性的載波信號,保證了檢波過程中測量通道和參考通道良好的相位一致性. 運用HP5529 雙頻激光干涉儀對改進后的調幅式電容位移傳感器進行長期穩定性實驗及標定,實驗結果表明:在30μm 量程范圍內,分辨力為2 nm、穩定性為6 nm/ 30min、線性度為0. 16 % ,傳感器性能良好. 可見,基于數字技術的調幅式電容位移傳感器有效地改善了上述各項性能指標,實現了傳感器的高精度、高穩定性.
關鍵詞: 直接數字合成; 數字檢波; 電容位移傳感器
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