Limits...
Experimental estimating deflection of a simple beam bridge model using grating eddy current sensors.

Lü C, Liu W, Zhang Y, Zhao H - Sensors (Basel) (2012)

Bottom Line: Every three adjacent measuring points are defined as a measuring unit and a straight connecting bar with a GECS fixed on the center section of it links the two endpoints.In each measuring unit, the displacement of the mid-measuring point relative to the connecting bar measured by the GECS is defined as the relative deflection.Absolute deflections of each measuring point can be calculated from the relative deflections of all the measuring units directly without any correcting approaches.

View Article: PubMed Central - PubMed

Affiliation: Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China. chunfenglv@sjtu.edu.cn

ABSTRACT
A novel three-point method using a grating eddy current absolute position sensor (GECS) for bridge deflection estimation is proposed in this paper. Real spatial positions of the measuring points along the span axis are directly used as relative reference points of each other rather than using any other auxiliary static reference points for measuring devices in a conventional method. Every three adjacent measuring points are defined as a measuring unit and a straight connecting bar with a GECS fixed on the center section of it links the two endpoints. In each measuring unit, the displacement of the mid-measuring point relative to the connecting bar measured by the GECS is defined as the relative deflection. Absolute deflections of each measuring point can be calculated from the relative deflections of all the measuring units directly without any correcting approaches. Principles of the three-point method and displacement measurement of the GECS are introduced in detail. Both static and dynamic experiments have been carried out on a simple beam bridge model, which demonstrate that the three-point deflection estimation method using the GECS is effective and offers a reliable way for bridge deflection estimation, especially for long-term monitoring.

No MeSH data available.


Related in: MedlinePlus

Schematic diagram of the GECS.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3472811&req=5

f3-sensors-12-09987: Schematic diagram of the GECS.

Mentions: As shown in Figure 3, four coils marked 1, 2, 3 and 4 are divided into two parallel sets. The width of each coil is equal to that of the conductor, and the two sets of coils are λ/4 apart along the displacement direction. In each set, the two coils are half of the measuring wavelength apart, which forms the differential output signal to enhance the sensitivity and reduce the non-linear error. When displacement occurs, the eddy current effect between the coils and conductors will change periodically, which makes the inductance variation of each coil also periodic. Inductance of the coil can be converted into voltage, current or frequency by signal conversion circuit. In this paper, the adopted conversion circuit is frequency modulated circuit. This type of conversion circuit not only simplifies the circuit organization but also reduces mutual interference of the coils since the time sharing connection method by using the analog multiplexer.


Experimental estimating deflection of a simple beam bridge model using grating eddy current sensors.

Lü C, Liu W, Zhang Y, Zhao H - Sensors (Basel) (2012)

Schematic diagram of the GECS.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472811&req=5

f3-sensors-12-09987: Schematic diagram of the GECS.
Mentions: As shown in Figure 3, four coils marked 1, 2, 3 and 4 are divided into two parallel sets. The width of each coil is equal to that of the conductor, and the two sets of coils are λ/4 apart along the displacement direction. In each set, the two coils are half of the measuring wavelength apart, which forms the differential output signal to enhance the sensitivity and reduce the non-linear error. When displacement occurs, the eddy current effect between the coils and conductors will change periodically, which makes the inductance variation of each coil also periodic. Inductance of the coil can be converted into voltage, current or frequency by signal conversion circuit. In this paper, the adopted conversion circuit is frequency modulated circuit. This type of conversion circuit not only simplifies the circuit organization but also reduces mutual interference of the coils since the time sharing connection method by using the analog multiplexer.

Bottom Line: Every three adjacent measuring points are defined as a measuring unit and a straight connecting bar with a GECS fixed on the center section of it links the two endpoints.In each measuring unit, the displacement of the mid-measuring point relative to the connecting bar measured by the GECS is defined as the relative deflection.Absolute deflections of each measuring point can be calculated from the relative deflections of all the measuring units directly without any correcting approaches.

View Article: PubMed Central - PubMed

Affiliation: Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China. chunfenglv@sjtu.edu.cn

ABSTRACT
A novel three-point method using a grating eddy current absolute position sensor (GECS) for bridge deflection estimation is proposed in this paper. Real spatial positions of the measuring points along the span axis are directly used as relative reference points of each other rather than using any other auxiliary static reference points for measuring devices in a conventional method. Every three adjacent measuring points are defined as a measuring unit and a straight connecting bar with a GECS fixed on the center section of it links the two endpoints. In each measuring unit, the displacement of the mid-measuring point relative to the connecting bar measured by the GECS is defined as the relative deflection. Absolute deflections of each measuring point can be calculated from the relative deflections of all the measuring units directly without any correcting approaches. Principles of the three-point method and displacement measurement of the GECS are introduced in detail. Both static and dynamic experiments have been carried out on a simple beam bridge model, which demonstrate that the three-point deflection estimation method using the GECS is effective and offers a reliable way for bridge deflection estimation, especially for long-term monitoring.

No MeSH data available.


Related in: MedlinePlus