Inspection Robots in Oil and Gas Industry: a Review of Current Solutions and Future Trends <s> B. Unmanned Underwater Vehicles <s> Recent technological advances and the growing demands for underwater operations suggest that autonomous underwater vehicles will become increasingly present in commercial and research activities, performing tasks such as survey, inspection of sub-sea pipelines and object recovery. This fact calls for the development of guidance and control algorithms for the execution of this kind of mission. This paper proposes a reactive control approach for pipeline following by a torpedo-like autonomous underwater vehicle. The method presented here, called the Deformable Virtual Zones (DVZ) method was originally conceived at the LIRMM for obstacle avoidance by mobile robots and AUVs. It consists of the modelling of a virtual zone around the robot, whose configuration depends on the robots states. The intrusion of proximetric information in this zone inflicts a deformation, and the control signal is computed so that the robot will react in order to minimise this deformation. We extend this sensor-based control method by proposing a new DVZ configuration for pipeline following by an autonomous underwater vehicle. Simulation results allow verifying its robustness as the pipeline changes direction, taking into account AUV dynamics. The proposed method is currently being implemented using the TAIPAN II, a small sized torpedo-like AUV developed at the LIRMM, fitted with a profiling sonar system. Experimental results will soon be available. <s> BIB001 </s> Inspection Robots in Oil and Gas Industry: a Review of Current Solutions and Future Trends <s> B. Unmanned Underwater Vehicles <s> Underwater structures like oil and gas production systems, ship hulls or the foundations of buildings, piers and offshore wind facilities have to be regularly inspected to evaluate the state of the structure and to plan future interventions for repair and maintenance. These inspections are currently done by remotely operated vehicles (ROVs) or by divers but they are time-consuming, expensive and need to be planned a long time in advance. Therefore a current trend in the offshore industry is to look into sub-sea resident autonomous underwater vehicles (AUVs) as inspection systems. There is a big difference between the currently available survey AUVs and inspection AUVs with respect to their primary mission capabilities. Whereas a survey AUV needs to map a wide area and have a high precision relative position between the scans, an inspection class AUV needs to find the inspection targets repeatedly. Within this paper we introduce the navigation problem in detail and the methods used for the inspection. We also present the initial tests with the FlatFish AUV applying the new approach to address this problem. <s> BIB002
Oil and gas companies have thousands of kilometres of pipelines and other assets in the sea to produce and transport their products. These undersea structures can easily develop corrosion and cracks since these structures are often made from metal materials. In order to prevent financial and environmental disasters caused by leaking out of the product, these facilities need to be inspected frequently. ROVs and AUVs are effective and affordable platforms to perform underwater inspection tasks. The inspection ROVs are operated by the surface operator. They are alternative vehicles to human workers in conditions that are too deep and too dangerous for human beings. What is more, with the help of ROVs, inspection tasks can be performed 24 hours and 7 days. Due to these advantages, the oil and gas technologies have developed ROV technologies from the 1980s  . After that, a large amount of advanced ROVs with a group of sensors were used to carry out inspection tasks which vary in size and weight  [28]   [31]. These ROVs consist of a vehicle body, control cabin, umbilical, video cameras, handling system, launch system and power supplies. The main features of these ROVs are summarized in TABLE I.   TABLE I. DIFFERENT ROVS COMPARATION For the deep-sea inspection tasks, the major cost of using an ROV is caused by the human operator. If these tasks can be performed autonomously, this cost can be reduced. Based on the previous technologies and economic constraints, using the AUVs may be a replacement for the ROVs for inspection purpose and currently it has gained great research interest. Compared with ROVs, AUVs demand more accurate and efficient sensors, guidance systems and algorithms for the execution of this kind of mission. The LIRMM BIB001 presented a Deformable Virtual Zones (DVZ) method that is a sensor-based control approach. It builds the model of a virtual zone around the robot. Once the obstacles are detected by proximity sensors, there will be deformation and the control signal will be calculated by minimising the deformation in the DVZ. The FlatFish project BIB002 utilized the asset layoutbased navigation methods. Since almost all of the underwater assets are connected together, they can be inspected by following pipelines and tie-backs to reach the different part of facilities. The sonar and camera are used to target and inspect the facilities. In  , image-processing technologies are adopted to AUV's navigation. At first, it detects the pipeline corners in the captured image. After that, the obstacles are identified by Hough Transform (HT) and velocity and angle values can be calculated according to this information. Finally, the AUV can move along the pipeline by itself and inspect these structures autonomously.