Amphibious NDT Robots

Oil, petrochemical, and food processing industries worldwide store their raw materials and product in tens of thousands of storage tanks. The tanks are mostly constructed using welded steel plates and therefore subject to corrosion and weld cracking. Testing the structural integrity of these storage tanks with non-destructive testing (NDT) techniques is an expensive and time consuming activity. The walls of a large tank can usually be tested manually (for corrosion thinning and weld defects using ultrasonic techniques) from outside the tank. Access to most areas of a wall is obtained by constructing scaffolding or abseiling down from the top. However, erecting scaffolding is expensive and the inspection is tedious and slow. These costs can be reduced and the inspection speeded up by using climbing robots that deploy ultrasonic probes with scanning arms

Keynote: Robotic Non Destructive Testing

This keynote paper aims to highlight the application of mobile robots to perform inspection and non destructive testing (NDT) in industries such as aerospace, large scale fabrication, pipelines, petro-chemical storage and power generation. It describes industrial tasks where regular inspection is essential to ensure the integrity of infrastructure such as storage tanks, pressure vessels, pipelines, aircraft, ships, etc, and to provide managers of capital assets with data to plan outages and to make decisions on the life span of their infrastructure. The development of robot prototypes is described for these industrial tasks. These robots deploy NDT systems by first providing access to large vertical structures or to test sites that are inaccessible to humans. They are designed to reduce outage time, or where possible, carry out the NDT online thus preventing costly outages

Development of Climbing Robots with Different Types of Adhesion

There is enormous potential in industrial inspection tasks for climbing robots than can work in hazardous environments, climb on different types of surfaces and enter into very small spaces that have difficult access. For example when cleaning, painting, repairing and diagnostic inspection of walls of general buildings, or performing non destructive testing inspection and maintenance of oil storage tanks, nuclear power plants, petrochemical factories, medical applications etc. The paper describes several types of robot adhesion in different environments, some of which have been incorporated into wall climbing robot designs. The adhesion methods discussed generate forces with permanent magnets, vacuum suction cups, propellers, needles or grippers, glue or adhesive tape, and Van der waal’s effect

Design of a Climbing Robot for Inspecting Aircraft Wings and Fuselage

This paper focuses on the design of a wall climbing robot. The robot carries a Cartesian scanning arm and a payload of various non-destructive testing (NDT) sensors while walking on the topside and downside of wings and on varying surface curvatures presented by the fuselage of different types of aircraft. The robot uses pneumatic cylinders to actuate the robots motion in X and Y directions. It uses suction cups to adhere the robot to the surface. The main achievement of this robot is the capability to cope with varying surface curvature when climbing around the aircraft while carrying a payload of up to 18kg. The robot achieves this capability with sufficient flexibility in its structure, feet and suctions cups to cope with varying surface curvature while remaining rigid once the robot feet adhere to the surface. Robot rigidity ensures a stable climbing motion and the vibration free deployment of the NDT sensors

Climbing Robot Cell For Fast And Flexible Manufacture Of Large Scale Structures

This paper describes the specification stages of a project which seeks to modernise and take into the future the technology of the manufacture of large fixed welded structures such as box girder bridges, storage tanks, ships and other steel fabrications which arise on construction sites, in large chemical and foodstuff plants, on offshore oil platforms etc, bringing the world of fast and flexible manufacturing to areas were construction is presently carried out by traditional use of manual labour, scaffolding and cranes and the inconvenient delivery by road of large factory prefabricated components. The Project will achieve this by creating a transportable manufacturing cell (CROCELLS) consisting of a team of cooperating climbing robot work tools whose activities are coordinated and integrated through a central intelligence. Unlike factory based cells the robot work tools must be mobile and small so that they are able to climb over long distances, to great heights and over curved surfaces and surfaces with ridges or protusions such as nodal joints providing many technical robotics problems to be solved. Small robots have payload limitations but the essence of the cooperating robot concept is that large payloads of work tools can be achieved with small robots by distributing the payload over several robots. Each robot will be dedicated to a different task to optimise overall system performance, hence there could be be a surface profiler and navigator, welder, bolt and rivet placer, hot weld quality inspector, and cold weld inspector on separate platforms. The cell will be deployed through every stage of a product life cycle, during construction where the system will perform instant weld quality diagnostics and repairs, in service inspection and repair, and final lifetime assessment. The CROCELLS concept is described in detail and system specifications are given which arise from an analysis of the industrial problems to be solved in a first exploitation phase addressed to the business requirements of the end users in the project. Then the hardware and software Architecture optimized for these specifications is presented for a prototype system presently under construction. Presently large fabrications on construction sites suffer from long fabrication times prescribed by traditional methods. The proposed mobile manufacturing cell will greatly reduce these times with economic benefits estimated at 630 M€ per annum in save time and 1956M€ per annum equipment sales taking EU export markets into account, with data for the global market being typically a factor of 4 highe

PDA Depth Control of a FPSO Swimming Robot

This paper introduces a Proportional, Derivative and Adaptive (PDA) depth control method for a swimming and walking robot designed for Floating Production Storage and Offloading vessel (FPSO) inspections. The depth of the robot is controlled by adjusting the mass of the buoyancy tank on the top of the robot while keeping the overall robot volume constant, so that the robot weight is adjusted around its neutral buoyancy point. The robot can swim to a given depth in short time without too much overshoot, and maintain that depth even with the disturbance from the thrusters that drive the robot moving horizontally. The control algorithm is adaptive to varying depth to let the robot have similar dynamic performance in any depth in the tank

Amphibious Robot For Weld Inspection Inside Floating Production Oil Storage Tanks

An amphibious and mobile robotic inspection system is described that has been developed to test welds located inside a floating production storage oil tank (FPSO tank). The robot has been designed to operate both in air and while submerged in oil to test welds on structural strengthening plates and tank walls. It operates in air when the tank has been emptied with only a few inches of product remaining on the floor. In this case the robot moves on the floor of the tank and inspects welds on the bottom of the strengthening plates and the floor. The robot operates in a liquid by swimming down from a manhole in the roof of the tank and settling on the floor in the vicinity of a test area. In both air and liquid, ultrasonic sensors profile the surrounding strengthening plates and tank walls and guide the robot autonomously along the welds. A Cartesian scanning arm mounted on the robot scans the welds with an ACFM probe and performs non-destructive testing (NDT) after the robot has been positioned correctly

Wall Climbing And Pipe Crawler Robots For Nozzle Weld Inspection Inside Nuclear Pressure Vessels

This paper describes the design and development of a NDT robotic solution to test circumferential welds located inside pipe nozzles at a distance of 700mm from the inside walls of nuclear pressure vessels. These welds are currently inspected using very large robot arms that are taken into the containment area and assembled. This is a time consuming operation that exposes operators to radiation. A preferred solution is to develop a light weight and compact robot that can be carried into the containment area and inserted into a pressure vessel using an overhead crane. The crane is then removed and used for other tasks. The robot must then be operated to accomplish the weld inspection task in all the pipe nozzles located in the pressure vessel

Mobile wall climbing and swimming robots to inspect aircraft, storage tanks, pressure vessels and large infrastructure

Non-destructive testing (NDT) of very large critical infrastructure that may be located in hazardous environments, poses the problem of first gaining access to the test site before the testing can be performed. Providing access usually constitutes the major part of the cost and time spent on the testing. Hence, a great deal of effort has been directed recently at developing mobile robotics that transports a payload of NDT sensors to the test site, preferably without taking the structure out of service. The paper describes a number of mobile, wall climbing, swimming and pipe climbing robots that have been designed by the authors to perform the non-destructive internal inspection of petrochemical storage tanks and nuclear pressure vessels, the inspection of the wings/fuselage of aircraft and the blades on wind turbines by climbing on their external surfaces

Ripple oscillations in the left temporal neocortex are associated with impaired verbal episodic memory encoding

Background: We sought to determine if ripple oscillations (80-120Hz), detected in intracranial EEG (iEEG) recordings of epilepsy patients, correlate with an enhancement or disruption of verbal episodic memory encoding. Methods: We defined ripple and spike events in depth iEEG recordings during list learning in 107 patients with focal epilepsy. We used logistic regression models (LRMs) to investigate the relationship between the occurrence of ripple and spike events during word presentation and the odds of successful word recall following a distractor epoch, and included the seizure onset zone (SOZ) as a covariate in the LRMs. Results: We detected events during 58,312 word presentation trials from 7,630 unique electrode sites. The probability of ripple on spike (RonS) events was increased in the seizure onset zone (SOZ, p<0.04). In the left temporal neocortex RonS events during word presentation corresponded with a decrease in the odds ratio (OR) of successful recall, however this effect only met significance in the SOZ (OR of word recall 0.71, 95% CI: 0.59-0.85, n=158 events, adaptive Hochberg p<0.01). Ripple on oscillation events (RonO) that occurred in the left temporal neocortex non-SOZ also correlated with decreased odds of successful recall (OR 0.52, 95% CI: 0.34-0.80, n=140, adaptive Hochberg , p<0.01). Spikes and RonS that occurred during word presentation in the left middle temporal gyrus during word presentation correlated with the most significant decrease in the odds of successful recall, irrespective of the location of the SOZ (adaptive Hochberg, p<0.01). Conclusion: Ripples and spikes generated in left temporal neocortex are associated with impaired verbal episodic memory encoding