調(diào)幅式電容傳感器在實際應(yīng)用中存在穩(wěn)定性差、漂移大、線性度差等問題. 為解決這一綜合技術(shù)障礙,采用直接數(shù)字合成和數(shù)字檢波的方法,將傳統(tǒng)電路中模擬的環(huán)節(jié)數(shù)字化,研制出了具有極高幅值和頻率穩(wěn)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(jìn)后的調(diào)幅式電容位移傳感器進(jìn)行長期穩(wěn)定性實驗及標(biāo)定,實驗結(jié)果表明:在30μm 量程范圍內(nèi),分辨力為2 nm、穩(wěn)定性為6 nm/ 30min、線性度為0. 16 % ,傳感器性能良好. 可見,基于數(shù)字技術(shù)的調(diào)幅式電容位移傳感器有效地改善了上述各項性能指標(biāo),實現(xiàn)了傳感器的高精度、高穩(wěn)定性.
關(guān)鍵詞: 直接數(shù)字合成; 數(shù)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