Bryan Bridge

Development of a climbing robot for inspection of long weld lines

Purpose – The project Climbing Robot Cell for Fast and Flexible Manufacture of Large Scale Structures seeks to modernise and take into the future the technology of the manufacture of large fixed welded structures. It creates a transportable manufacturing cell consisting of a team of cooperating climbing robot work tools whose activities are coordinated and integrated through a central intelligence. The purpose of this paper is to present a wheeled robot, called NDT robot, designed for the real time inspection of long weld lines simultaneously with the welding process.Design/methodology/approach – Neodymium permanent magnets are used for adhesion, which are capable of producing a maximum adhesion pressure of 4 × 104 Nm−2 at a 20 mm air gap. The strong neodymium magnets give the robot a high payload carrying capability. The arrangement of the magnet array increases its performance at large air gaps so that the robot has excellent capability to overcome obstacles, such as weld caps. The design of the wheeled...

Design of a climbing robot for inspecting aircraft wings and fuselage

Purpose – The paper aims to develop a robot that climbs on non‐ferrous surfaces, e.g. aircraft wings and fuselages, carrying a heavy payload up to 18 kg including scanning arm and various equipments, for non‐destructive testing (NDT).Design/methodology/approach – This robot in the study uses vacuum suction cups for adhesion, and two pairs of pneumatic cylinders to drive itself, moving in two directions in stepping gait. A rotation mechanism in the centre is used to correct the off‐course deviations by ± 5 degrees. Multiple universal joints are used to make every single suction cup, every robot foot and the whole structure flexible to negotiate with varying surface curvatures presented in different parts of aircraft. This flexible structure is also rigid once the robot is stuck on the surface to enable the NDT inspection being carried out reliably.Findings – The paper finds that the walking speed is limited by the cylinder stroke, time for generating vacuum and changing legs. Although most NDT inspection i...

A new method for assessing the mean grain size of polycrystalline materials using ultrasonic NDE

We re-analyze published data on ultrasonic inspection of a number of pure metals and alloys involving a range of mean grain sizes (from 0.0125 mm to 0.3 mm). We show that they may be described by one master curve graph consisting mainly of two distinct but parallel linear segments. This means that our presentation clusters the data under study into two distinct groups, each chracterized by its own generalized material constant. The slope of the segments suggests the predominance of scattering other than Rayleighs, since it is consistent with the second power law rather than the fourth. We argue that the attenuation is likely to be due to multiple scattering, particularly since our generalized material constants seem to be similar to the published stochastic scattering factors. The master curve graph suggests a new fast and simple method for assessing the mean grain size which may be carried out without recourse to standard specimens or measurements other than those routinely carried out during ultrasonic inspection. As the range of materials and grain sizes are in extensive use in industry the simple schedule proposed should prove of substantial use in practical material evaluation and production process control.

Novel Solutions to Design Problems of Industrial Climbing Robots

This paper aims to identify some design problems that affect system performance of climbing robots and to present novel solutions to the problems. The first problem is the interference of the umbilical cord for the robot with its mobility and dynamics; the second problem is the slow traveling speed of climbing robots, affecting the overall working efficiency of the system; the third one is unforeseen variations of surface curvature of objects on which a vacuum suction type of robot climbs, which reduces suction pressures and adhesion forces pulling the robot onto the surface; and the fourth is the intrinsic safety requirements of electrical components in flammable environments. The technical solutions have been developed and tested in laboratory and industrial field trials and have been proven to be well founded and unique. It has been verified that new techniques from other engineering areas, e.g. materials and information engineering, can be used to formulate novel solutions to overcome the obstacles. The technical approaches used in these solutions will strengthen the state of the art and contribute to the advance of climbing robot applicable technology.

Climbing robots—off the shelf

Outlines the development of a prototype climbing robot for remote testing using standard off‐the‐shelf components. The system construction is modularized so that it can be easily reconfigured for a different task. Describes the desired characteristics of a climbing inspection robot and how the prototype robot has been designed and constructed. Gives the system specifications and performance and concludes that laboratory operation of the CART prototype robot on a steel plate that simulates an oil storage tank has demonstrated that a cost‐effective system can be built entirely from standard, commercially available components.

FIELD TRIALS OF A CELL OF CLIMBING COOPERATING ROBOTS FOR FAST AND FLEXIBLE MANUFACTURING OF LARGE SCALE ENGINEERING STRUCTURES

This paper describes the first and successful trials of a novel transportable manufacturing cell composed of cooperating climbing robots for on line quality controlled welding of large scale engineering structures such as ship hulls, large storage tanks and wind turbine towers. The cell performed welds on a 7 metre long by 2 metre wide place configured at several inclinations including the vertical thus covering the typical range of hull angles that arise on a large ship. The cell also performed self evaluation of its work by measuring the quality of the weld melt in real time so that corrections to the weld process parameters could be performed immediately thus minimizing the time spent on welding repairs.

Automated NDT of Floating Production Storage Oil Tanks with a Swimming and Climbing Robot

This paper describes the design and development of a prototype swimming and wall-climbing robot that gains access to internal tank wall and floor surfaces on Floating Production Storage Oil (FPSO) tanks for the purposes of carrying out Non-Destructive Testing (NDT) of welds while the tank is in-service and full of oil. A brief description is given of the inspection environment and the three NDT techniques (ultrasonic phased arrays, eddy current arrays, and Alternating Current Field Measurement ACFM arrays) that will be used to detect weld cracks and floor corrosion and pitting.

ON THE DESIGN OF MULTI-TASK, COMPACT, CLIMBING ROBOTIC NDT SYSTEMS FOR REMOTE OPERATION ON LARGE SURFACES AND IN HAZARDOUS ENVIRONMENTS

An analysis is given of the problems associated with the design of multiple purpose Robotic NDT systems which are readily transportable between different geographical locations and are able to climb over large areas of vertical walls and ceilings of any material composition to provide access to remote and hazardous environments. The analysis is illustrated by the description of a prototype system, designed in a modular fashion with off-the-shelf components to minimise development and subsequent batch production costs. Essentially the system consists of a pneumatically powered vehicle carrying an anthropomorphic arm i.e. an arm with at least six degrees of freedom that replicates some relevant advantageous characteristics of the human arm. Its performance is illustrated by some indicative trial results using ultrasonic wet and dry contact techniques applied to a simulated wall of a large ferrous oil storage tank containing corrosion thinning defects.

Acquisition of Time of Flight Diffraction Data by Mobile Robots

It is shown that Time of Flight Diffraction (TOFD) data acquired with 6 and 7 axes robot scanning arms (that are carried by mobile wall climbing vehicles which can travel on curved surface) is of a much better quality than that acquired by manual deployment. The robotic devices are able to operate in remote and hazardous locations while maintaining more constant contact forces and obtaining repeatable data unaffected by fatigue which manual operators find very difficult to match.

A NEW ALGORITHM FOR THE USE OF AN ANTHROPOMORPHIC ROBOT MANIPULATOR ARM IN REMOTE AND LABORATORY NDT APPLICATION

Abstract Published studies of serial link arm usage for the manipulation of sensors in NDT are rare, perhaps because there is a perception that the cumulative errors in spatial location along such arms are too great for satisfactory imaging. These errors, with good programming. are not as serious as they might seem at first sight and the flexibility of serial arms is most attractive. This paper shows that a serial link robot manipulator ann can be used to perform raster scans (as used in ultrasonic c-scanning) with precision in spatial resolution as good as is required in the NDT industry and normally achieved by means of conventional x-y cartesian scanners. It also presents an iterative method to compute the inverse kinematics (ie the programme of sequence of joint angles) needed to constrain a serial link robot manipulator to perform an NDT scanning operation (eg to perform a plan or raster scan whilst maintaining a constant angle between the probe and the surface under inspection). The iterative method...