An Electronically Stabilized Multi-Color Multi-Ring Structured Light Sensor for Gas Pipelines Internal Surface Inspection

Natural gas pipeline network extends over 2.5 million miles in the united states of America. The aging of these infrastructures combined with damage from various external threats are creating safety concerns for both operators and residents in the vicinity of these pipelines. In this paper, we are presenting a miniaturized structured light based three-dimensional (3D) imaging sensor for the inspection of internal walls of plastic natural gas distribution pipelines. The sensor is an 18-mm diameter optical inspection device that can be inserted inside the pipe to provide the operator with a 3D map of the internal surface of the inspected pipe. The introduction of the 3D map simplifies the identification of damages like deformations and material loss and leads to a better evaluation of the damage severity when compared to LED assisted cameras. The sensor is also accompanied with an embedded electronic stabilization algorithm to reduce the effect of misalignment when the sensor is attached to a scanning platform, and to facilitate the registration of consecutive frames from the sensor. The algorithm exploits the geometry constraints provided by the cylindrical shape of the pipe to estimate the orientation and position of the sensor with each collected frame.