Real-Time 3D Profiling with RGB-D Mapping in Pipelines Using Stereo Camera Vision and Structured IR Laser Ring

This paper is focused on delivering a solution that can scan and reconstruct the 3D profile of a pipeline in realtime using a crawler robot. A structured infrared (IR) laser ring projector and a stereo camera system are used to generate the 3D profile of the pipe as the robot moves inside the pipe. The proposed stereo system does not require field calibrations and it is not affected by the lateral movement of the robot, hence capable of producing an accurate 3D map. The wavelength of the IR light source is chosen to be non overlapping with the visible spectrum of the color camera. Hence RGB color values of the depth can be obtained by projecting the 3D map into the color image frame. The proposed system is implemented in Robotic Operating System (ROS) producing real-time RGB-D maps with defects. The defect map exploit differences in ovality enabling real-time identification of structural defects such as surface corrosion in pipe infrastructure. The lab experiments showed the proposed laser profiling system can detect ovality changes of the pipe with millimeter level of accuracy and resolution.

I. Introduction

Underground infrastructure such as sewage pipes and water pipes undergo severe concrete [1] and metallic [2] corrosion, which considerably reduces their service life. Monitoring such degradation through predictive modeling requires reliable sensor data for high-quality predictions [3]–[6]. However, in hostile sewer pipelines, sensors can malfunction over time [7]. In addition to monitoring physical changes of pipes, there are requirements to monitor the sensor health conditions themselves [8]. Therefore, water utilities around the world are experiencing an uphill battle for maintaining underground assets in a good condition to avoid catastrophic failures such as pipe bursts and ground collapses [9]. Further, human entry to smaller sized pipelines for visual inspections is not possible due to occupational health and safety risks. Traditionally, CCTV cameras are mounted on remotely operated robotic platforms for inspecting such pipelines, however they only provide visual cues that has limited structural information for decision making.