FBG load cell technology and WIM application

摘要

In a weigh-in-motion(WIM) scale, the load cells are the paramount parts, and the traditional strain gauges are used as main sensing elements. However, the performance of these electrical sensors is poor in durability and stability. Fibre Bragg grating (FGB) is of good sensing characters, this experiment therefore used them to replace the strain gauges in the load cells, and to apply in a real WIM system. Two FBGs were adhered on a cantilever load cell by means of a special fiber holder, one of them acted as a tensive sensor, the other acted as a compressive sensor. To subtract their measuring results, the response was doubled, furthermore, the environmental interference was eliminated. The repeatability was calibrated reaching 0.02% in full 0-20 ton scale. Four FBG load cells were set as supports of weighting plate in an axial WIM scale to weigh vehicles. The results showed that the FBG scale performed better than strain gauge scale under the same WIM dynamic processing program. Under the speed of llkm/h, the measuring accuracy can be kept within 1%, while the measuring accuracy of strain gauge scale was about 3%.