Design of automatic tension control device for a vibrating wire sensor

The vibrating wire sensor is the structural health monitoring sensor which uses the vibration signal induced from the tension difference of a sensor attached to a structure. Vibrating wire sensors have produced by tuning the tension manually through measuring the frequency of the vibrating wire then fixed by pressing both ends of wire. Therefore, the accuracy of the product was determined by manual skill and this was the weak point to be enhanced. In particular, percentage defect was 75% mainly during the pressing process, which requires the expert. In this study, we developed the tuning device to adjust tension automatically with enhancing the precision and productivity of vibrating wire sensors. After tuning the tension, the fixing wire end is pressed pneumatically, the performance was monitored. Precision evaluation test confirmed that the nonlinearity of sensors is reduced from 0.398 to 0.056%.