24-09-2014, 03:19 PM
WALL CLIMBER
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ABSTRACT:
The potential is enormous for wall-climbing robots which can
work in extremely hazardous environments, however, with the
limits of many factors, the application is rather limited. Our
work is to broaden the practical application by making
specialized robots. In this paper, we introduce wall-climbing
robots of two different absorption schemes we exploited: one
with single suction cup and the other with permanent magnetic
crawlers. The former adopts an omni directional vehicle and
can perform remote-control inspection of nuclear storage tanks, moreover, it is further developed for cleaning of high-rise buildings of both ceramic tile and glass surfaces. The latter consists of two types of robot, one is for maintenance
automation of storage tanks in petrochemical enterprises which
can do operations of sand-blasting, spray-painting and inspection; and the other is expected for monitoring boiler
water wall tubing
INTRODUCTION:
With the development of science and technology, there are increasing demands for better working conditions and higher living quality. The cleaning of high-rise buildings, the inspection and maintenance of storage tanks in nuclear power plants and petrochemical enterprises etc.- all these practical problems have an immediate need of automation. Unique of its special characteristics, wall-climbing robot has provoked high
attention world widely ever since it was born in 1960’s.
By now, a number of wall climbing robots have been exploited and some are in present use. However, we have to notice that the application of wall-climbing robots is still limited; apart from a few successful industrialized products, most are only prototypes for their speed, cost and reliability. For this, in the last decade, we mainly focus our attention on the application of the robots by simplifying their structure, making them specialized for each simple task and improving auxiliary equipment to convenient operation.
In the following, we’ll discuss in detail about the robots
we developed together with the applications
APPLICATIONS OF WALL-CLIMBER
Inspection of nuclear storage tanks
Storage tanks in nuclear engineering need to be inspected at intervals for fear of leakage. As the working conditions are most dangerous wall-climbing robot is recommended. Besides the robot, the whole remote control-inspect system includes carrier loader, manipulator, safety system, remote control board and flaw detector. First, the carrier loader transports the robot
to destination and then the manipulator is responsible for fetching the robot on and off the tanks. To simplify the structure, the manipulator is designed of folding and articulating type, with four necessary degrees of freedom and its final performer takes a bifurcation form
Cleaning walls
Up to now, the cleaning of most high buildings is manual
work with the aid of crane both dangerous and time consuming.
Considering a certain percentage of walls are smooth, without apparent rough and uneven in surface, which are most feasible to be cleaned by the wall climbing robot, we have developed a whole cleaning system including a hoist mounted on top of buildings, brush, carrier loader, cleaning machine of high pressure, control box and so on. To simplify the structure of the robot, two wheels mechanism is adopted in place of the omni-directional vehicle, which improves the flexibility of the robot and its maximum velocity also increases to 12m/min. As of suction absorption, the payload is limited, the hoist can on one hand, protect the robot in danger and on the other hand, share the weight of water hoses and control cables to enable the robot work high above the ground. Cleaning brushes are designed according to the work surface. For ceramic tile
Wall-climbing robot for maintenance of boiler water wall tubing
The fireside of boiler tubing in a fossil-fueled boiler is,
at best, an extremely harsh environment. Fireside corrosion accompanied with ash, slag-bonding and so on, has been always forming a hidden danger for the safe operation of calandric boilers, so it must be cleaned and monitored regularly. The typical approach is to vacuum-blast the fireside surface to remove ash, for hard slag-bonding, however, can only be removed using special tools such as scraper or steel brush. Considering most water wall tubing are of 60-100 meters high,
much operation has to be taken with the aid of cranes and scaffolds. In 1997 a wall-climbing 'robot with magnetic crawlers for cleaning and inspection of water wall tubing was developed. Its characteristic follows:
The entrance of boilers is limited ( with diameter
about 400mm ), which requests the robot to be compact; and performing operations of cleaning and removing slag-bonding also requests the robot to bear a payload no less than 30kg, so the robot is designed of crawler type. To raise absorption force, the magnetic sticking units are designed of circle, approximately tallying with the contours of tubes. The payload of the robot exceeds 40kg.
THREE LINK MANIPULATOR
In a three link manipulator the links are joined by generally two type of joints - Revolute and prismatic. While deriving the kinematic and dynamic formulation of three bar mechanism the assumptions are same as that of two bar mechanism
SELECTION OF MATERIALS FOR THE LEGS AND THE BODY:
For the legs carbon fibre is used. Same material will be used for the body of the crawler robot also. One of the key advantages of carbon fibre body is that carbon fibre is light in weight and it has sufficiently high strength. Also it is highly resistant to corrosion and wear; so high can used for a long period in hazardous environment where human being can’t work at all.
The only disadvantage of carbon fibre rod, body in this application is its high cost as compared to aluminium or any other metallic, non-metallic, polymer or composite material.
CONCLUSION:
Considering the severity of so many environmental conditions that have a critical need for automation, the exploitation of wall-climbing robots has broad prospect undoubtedly. During the past, we have been working on it and have made some progress, especially, the robot for cleaning walls is now being used for testing by several cleaning corporations, and the results are satisfactory. However, to make wall-climbing robots a popular replacement of manual work, an indispensable prerequisite is the high reliability and then high efficiency and affordable prices of the robot, which destined it to be a long run of improvement and development