Experimental research on the precision of wheeled caliper arm for measuring pipeline deformation

Wheeled type caliper is a half way pig between utility and intelligent pig. It is designed to efficient detect, size and locate deformations of the pipeline. Mapping the pipeline can also be achieved with the integration of triaxial accelerometer and gyroscope. In this paper, the wheeled caliper arm was designed and experimental research on the precision of the wheeled caliper arm was conducted to evaluate its performance. The effects of the deformation size, the spring pre-tightening force and the pigging velocity on the precision of the wheeled caliper are investigated. Experimental results indicate that the precision of the caliper can be greatly affected by the pigging velocity and the pre-tightening force. High pigging velocity has large contribution on the increment of the measurement error. However, the error can be reduced or even eliminated by increasing the pre-tightening force. Experimental results can provide guidance for the reasonable selecting of the pigging velocity, and the pre-tightening force to provide enough contact force.