Optimization Design of Excitation Strategy on Vibrating Wire Sensor

Abstract

There are two ways of excitation on steel-string sensor—high-voltage plucked excitation or low-voltage scanning frequency excitation. But both of them have disadvantages. The disadvantages of high-voltage plucked excitation are that it has a large damage to sensor, the signals got through this way attenuate fast, and measurement accuracy of the signals is poor. On the other hand, low-voltage sweeping excitation scans a long time and signals got though this way are hard to catch. This paper proposes a kind of feedback type low excitation method, which is pre-excite a sensor with a lower voltage on plucked vibration, and use vibration frequency got from this way as output of the excitation driver to vibrate the sensor for the second time. Because the feedback signal frequency is approximate to the real one, the string can reach a resonance state in a very short time. The optimal excitation strategy is verified by a new designed exciting and measuring circuit. It is confirmed that resonance amplitude can be larger in a shorter excitation time by this way, and result in an enhanced anti-interference ability, reduced the cost of signal processing circuit, increased available measuring time and improved the accuracy of frequency measurement.