Signal Conditioning Technology For Sensor Of Active Vibration Isolator

Active vibration isolation system (AVIS) has been widely applied in IC manufacture equipment and high precision measurement equipment, due to its merits of wider bandwidth and lower isolation vibration transmissibility comparing to its counterpart, i.e. passive vibration isolation system. Sensor unit is its essential part and impacts on its accuracy and bandwidth. So research on signal conditioning technology for the sensor of active vibration system has its specific importance and practical value.This thesis investigates the requirements of active vibration isolation system and its sensors. Performances of displacement and velocity sensors widely used in engineering field are also studied and the sensors for AVIS are selected form these two types of sensors.The vibration measurement model is established and it includes measurement part, amplification part, transmission part and serial correction part. Based on this model, factors which impact measurement bandwidth of the velocity sensor are analyzed. And low-frequency extension methods of the velocity sensor are discussed with compair of their advantages and disadvantages. According to the compair result, extended filtering is finally selected for low-frequency expansion of the absolute velocity sensor.Based on the vibration measurement model and theory of error, the effect of electrical noise on low-frequency extension range of velocity sensor is analyzed, and the function relations between electrical noise level and low-frequency extension range of velocity sensor are obtained. They can be used to select absolute velocity sensor and in low frequency vibration measurement.Based on the principle of the lag correction and its amplitude-frequency characteristics, the signal conditioning circuits of absolute velocity sensor and the displacement sensor are designed by theoretical analysis and simulation. Finally, the sensors signal conditioning board is manufactured.The testing platform is built to verify the low-frequency signal extension capability of the sensor signal conditioning board. And the experiment result shows that the sensor signal conditioning method can be used in AVIS.