Positioning System for Pipe Inspection with Aerial Robots Using Time of Flight Sensors.

This paper describes a positioning system for aerial robots consisting of a linear array of time-of-flight (ToF) sensors whose orientation angle is controlled with micro servo, allowing the detection and accurate localization of the contour of a pipe to be inspected. The system, integrated in a hexarotor vehicle, has three operation modes: searching, aligning, and tracking. In the first phase, a scan motion is conducted rotating the servo in a wide range until one of the four ToF sensors of the array detects a close obstacle. Then, the rotation angle is adjusted to align the array with the normal vector of the surface, tracking actively its contour while providing an estimation of the relative position and orientation. The paper details the design and implementation of the system, the control scheme, the position estimator, and its integration in an aerial robot. Experimental results carried out in test-bench show the performance of the system.