3 research outputs found
TWINBOT: Autonomous Underwater Cooperative Transportation
Underwater Inspection, Maintenance, and Repair operations are nowadays performed using
Remotely Operated Vehicles (ROV) deployed from dynamic-positioning vessels, having high daily operational costs. During the last twenty years, the research community has been making an effort to design new
Intervention Autonomous Underwater Vehicles (I-AUV), which could, in the near future, replace the ROVs,
significantly decreasing these costs. Until now, the experimental work using I-AUVs has been limited to a
few single-vehicle interventions, including object search and recovery, valve turning, and hot stab operations.
More complex scenarios usually require the cooperation of multiple agents, i.e., the transportation of large
and heavy objects. Moreover, using small, autonomous vehicles requires consideration of their limited load
capacity and limited manipulation force/torque capabilities. Following the idea of multi-agent systems,
in this paper we propose a possible solution: using a group of cooperating I-AUVs, thus sharing the load
and optimizing the stress exerted on the manipulators. Specifically, we tackle the problem of transporting
a long pipe. The presented ideas are based on a decentralized Task-Priority kinematic control algorithm
adapted for the highly limited communication bandwidth available underwater. The aforementioned pipe
is transported following a sequence of poses. A path-following algorithm computes the desired velocities
for the robots’ end-effectors, and the on-board controllers ensure tracking of these setpoints, taking into
account the geometry of the pipe and the vehicles’ limitations. The utilized algorithms and their practical
implementation are discussed in detail and validated through extensive simulations and experimental trials
performed in a test tank using two 8 DOF I-AUV
Underwater robotic system for reservoir maintenance
In this paper a description and practical implementation of the developed prototype of an underwater hybrid robot is presented. The solution is based on the guidelines of Cracow waterworks (Municipal Waterworks and Sewer Enterprise, MPWiK S.A.). The prototype of the hybrid robot consists of a crawler robot and a ROV. Robots’ design, mathematical models of kinematics and dynamics of the crawler robot, ROV’s vision system architecture with image processing methods for surface crack detection and robot position and attitude estimation are investigated and examined. Results obtained from experimental validation of the developed prototype are presented and discussed. Finally, the paper establishes future research directions
Compliant Manipulation With Quasi-Rigid Docking for Underwater Structure Inspection
Offshore wind farms are a crucial source of renewable energy, but maintenance and repair can be challenging due to their remote locations and harsh environmental conditions. Professional divers or Remotely Operated Vehicles (ROVs) are commonly used to conduct maintenance operations, but they come with high daily operational costs. Autonomous Underwater Vehicles (AUVs) have the potential to improve the efficiency, safety, and costs of maintenance operations. This project evaluates the feasibility of using an AUV to conduct a cathodic protection (CP) survey, which involves measuring the corrosion potential of underwater structures to prevent deterioration. The AUV is equipped with a manipulator that has a CP probe with a sharp tip to puncture through the structure’s coating and make contact with the steel underneath. To ensure high accuracy and reduce environmental perturbances, the AUV attaches to the structure while conducting the survey. The technology and methods used in this project are demonstrated in a water tank using a Girona1000 AUV. Task Priority kinematic control is combined with a custom force control strategy based on admittance control to enable tracking of the end-effector configuration and contact force during the probing operation. The mission flow control is implemented using behavior trees. The results show that the use of AUVs for CP surveys is feasible and has the potential to significantly improve the efficiency, safety, and costs of maintenance operations in offshore wind farms