Title of Invention

A PNEUMATIC INCH-WORM ROBOT

Abstract

A pneumatic inch worm robot which comprises a front gripping unit (1) having at least three radially piston cylinders (2) at 120°apart, in such a manner so as to provide simultaneous gripping of the inside wall of a pipe/tube (13A) by pads (3), the said pads (3) fixed on curved plates (4) which are fitted at the piston rod ends (5), the said gripping unit having at its front end a conical head (6), the said conical head (6) consisting of at least three radially spring loaded wheels (7) for guiding the crawler robot through a pipe/tube (13A), the rear of the said front gripping unit being connected by a flexible joint (8) to the said piston rod end (9) of driving unit (10), the said driving unit being fitted with a spring (11) connected to the rear gripping unit (12) the three units (1,10,12) being connected to a pneumatic control source such as herein described .

Full Text

Field Of The Invention Prior Art This invention relates to a pneumatic inch-worm robot. The robot of the present invention has a direct relevance to the power plants, petroleum refineries, chemical and pharmaceutical units and other such process industries. This invention particullarly relates to a compact system comprising multiple piston-cylinder arrangements for generating inch-worm type locomotion as well as for gripping of the system against the inside wall of a pipe/tube with the application of pneumatic pressure. The purpose of this invention is to access tube walls from inside as well as the interior location of the pipe for cleaning, inspection or any other requirement. Periodic cleaning and inspection of pipelines/tubes in petroleum refineries, boilers power plants, chemical and pharmaceutical indus tries is extremely important to prevent catastrophic failure. Manual inspection of these areas are risky, painstaking and often impossible due to inaccessibility. The existing units used for such purposes in foreign countries like Canada, U.K., U.S.A., Japan are of different sizes. The actuation and the mechanisms employed are also different depending upon the purpose for which they are employed. Mostly, the miniature inch-worm crawler robots are driven by special type of actuators e.g. Hydrogen Storage Alloy (HSA), Giant Magnetostrictive Alloy (GMA), Shape Memory Alloy (SMA) etc. Interior-inspection is also done through fibre-optic techniques. The field of inspection of pipeline-integrity, specially, the inspection of internal surface is called pigging. The known methods of pigging are through the following techniques which have their specific limitations: Magnetic Flux Leakage (MFC) tool, one of the manufacturer in U.S.A. is 'Pipetronics'. The method of sensing of the surface-unevenness is through the change of magnetic flux-characteristics. The locomotion of instrumented pig is through the pressure differential created between the front and rear seals (buckets) of the pig where the instrumented system is placed between the two seals. That means, the motion of the carriage (pig) is due to the static pressure difference between the upstream and downstream of the pig. For this principle of mobility, the pipeline has to be always full of fluid. The magnetic flux characteristics is also affected due to the pig velocity as well as due to the system pressure. Another method of carriage movement is done with the help of DC motor and the storage battery. But such arrangement makes the system bulky and intermittent, due to the discharge of the battery. The instrumented pig is also done mobile with the help of an inbuilt turbine. But for this method of mobility one has to provide continuous supply of fluid through the pipe under inspection. Existence of flow of fluid inside the pipe makes the sensor less reliable and the flow of fluid creates other operational problems. Ultrasonic Wall Thickness measurement tool (UWT) is another type of machine which monitors the health of the pipeline. In this case, one of the manufacture is Nippon Kokan of Japan. This method is very sensitive to fluid and debris and it can not work without water filled pipeline. The locomotion of such class of instrumented pig is also through pressure differential of fluid or battery operated motors and the limitaions are similar to the previous method. Yet, another method of inspection of a pipeline is through cable operated video camera which operates through electrical power and hand operated manouvering of the portable video camera. The instrument is manufactured by RICO of Germany,This is a error visual inspection method and can not be used in hazardous fluid environment. Another method of in-situ inspection of pipeline is possible through Flexible Micro Actuator for miniature robots (FMA). Such work is done in Toshiba, Japan. The method is composed of pneumatic or hydraulic actuation of miniature fibre-reinforced rubber linkages similar to human fingers. The load carrying capacity of such devices is very limited. Fukuda and his team of Nagoya University of Japan has been working on Giant Magnetostrictive Alloy (GMA) to micro mobile robots. Here the drive power is an electromagnet placed on outer surface of the pipe and the follower pig is placed inside the pipe to be inspected. The pig traverses at the actuation of the outer magnetic drive. Because there is no 'positive grip1 between the driver and the driven, more chance of slip is there. In this system load carrying capacity of the pig also less. In this type of device the outer surface of the pipe has to be always available for the placement of the driver electromagnet. One method of monitoring of outer surface of pipe is through the actuation of DC motor and Shape Memory Alloy (SMA) combination. But it is only for the survey of the outer surface and the load earring capacity is also much limited by the function of SMA. Considering the above information available in the public domain and their limitations the present invention of A Pneumatic Inch Worm Robot has been developed for its merits as given in the claims. The main objective of the present invention is to provide a pneumatic inch worm robot. Another objective of the present invention is to provide suitably connected mechanical systems having the capacity to generate inch-worm type crawling motion through pipes/tubes with application of pneumatic pressure. Yet Another objective is to provide mechanical sys terns of the present invention which are suitable for the following movements, i) forward movement of the main piston ii) outward and inward movement of the three radially arranged pistons, located at the front end of the unit iii) backward movement of the main piston iv) outward and inward movement of the three radially arranged pistons, located at the rear end of the unit The programmed synthesis of the above 4 sequences offers the wide spectrum' usefulness of this present inven tion. Some of the existing devices, as explained below are job-specific and are of different design. Use of 'pneumatics' in many specific areas are 'snfo' from firo hazards point of In fig 1(a), fig 1 (b), fig 1 (c) of the drawings accompanying the provisional specifications the assembly drawing showing the various parts of the miniature crawler robot are depicted. Accordingly, the present invention provides a pneumatic inch worm robot which comprises a front gripping unit (1) having at least three radially piston cylinders (2) at 120°apart ,in such a manner so as to provide simultaneous gripping of the inside wall of a pipe/tube (13A) by pads (3), the said pads (3) fixed on curved plates (4) which are fitted at the piston rod ends (5), the said gripping unit having at its front end a conical head (6), the said conical head (6) consisting of at least three radially spring loaded wheels (7) for guiding the crawler robot through a pipe/tube (13A), the rear of the said front gripping unit being connected by a flexible joint (8) to the said piston rod end (9) of driving unit (10), the said driving unit being fitted with a spring (11) connected to the rear gripping unit (12) the three units (1,10,12) being connected to a pneumatic control source such as herein described. In Fig. 2 of the drawings accompanying the provisional specification the schematic of an embodiment of the present invention is shown consists of crawler robot, solenoid valves, and microprocessor kit etc., made to observe the motion of the crawler robot inside a glass tube. The three units (1, 10, 12) are connected to individual solenoid valves (S-l, S-2, S-3, S-4) by means of flexible pipes (13) covered under a PVC (poly vinyl chloride(sheathing (14), the said solenoid valves receive presurized air from the compressor (15) via a distributor (18) and the said air supply in controlled by means of valve (16) after checking the pressure by means of pressure gauge (17), the opening and closing the said solenoid valves are controlled by a 8086 microprocessor kit (19) through relays (20). The detail description of the pneumatically operated miniature crawler robot is given below. This crawler robot consists of three Units, viz i) Front gripper Unit ii) Driver Unit iii) Rear gripper Unit as shown in fig. 1 of the drawings.The Driver unit (10) comprises of a simple cylinder piston arrangement and both the gripper units consist of three radically placed cylinder-piston arrangements at 120°apart. One unit (1) is mounted at piston rod end of the Driver unit and the other one (12) is fitted at the cylinder end of it. Compressible rubber pads (3) glued on curved plates (4) are fitted to the piston rod ends (5) of the gripper units to ensure proper grip against the inside wall of the tube. The three pistons of a particular gripper unit move simultaneously. A flexible joint (8) such as ball and socket is provided in between the front gripper unit and Driver unit for negotiating bends, if any, having a radius of curvature greater than 250 mm. A spring (11) is incorporated in the system for smoothness of operation. Three number of spring loaded wheels (7) are attached at front end (6) of the crawler for guiding it properly along the length of the tube. As shown in Fig. 2 of the drawings, all the pneumatic cylinders are connected to individual solenoid valves (S-l,S-2,S-3,S-4) by means of flexible pipes (13) and a polythene sheathing, (14) . Pressurized air is allowed to flow from the comprosoor (15) to the solenoid valves via a distributor /l6)). A valve (17)and a pressure gauge ((18)../ is provided in between the compressor and the distributor. The opening and closing of solenoid valves are controlled by a 8086 microprocessor kit (19) through relays (20). The sequence of motion of the crawler robot, is described below. At first, the crawler robot is to be introduced inside a tube under inspection and held at a desired starting position by hand support. Then valve S-l is turned on. As a result, the three pistons of the rear gripper unit move radially outwards by compressed air flow and the rubber pads fitted at the ends press against the wall of the tube. At this stage support is with drawn and the robot is allowed to remain in that equilibrium position. Then turning valve S-2 on, makes pressurized air to flow into the Driver unit (10) and as a consequence, the Front gripper unit (1) moves forward. Next, valve S-2 is turned off, (after the full stroke) and valve S-4 is turned on. This causes the three pistons of the Front gripper unit to move out radially and press the ends against the wall of the tube. In the next sequence, valve S-l is turned off and valve S-3 is turned on. As a result, the three radially arranged pistons of the Rear gripper unit contracts inwards and this unit, as a whole, is pulled forward by the reverse stroke of the Driver unit. Lastly, valve S-l is turned on again causing the rear gripper unit to get hold onto the inside wall of the tube. In this way, the crawler robot moves in the forward direction. The backward motion, too, can be achieved just by reversing the above mentioned sequence of operations. That is, activating the front gripper first. This sequence of operation of solenoid valves for horizontal forward motion of the robot can be represented in a tabular form, as shown below :- (Table Removed) These steps are repeated until it reaches to the desti nation. The program for the microprocesser is so written that its motion can be interrupted in intermediate positions also. The crawler robot can proceed along horizontal direction as well as along any inclined or vertical direction, depending upon the orientation of the tube. This additional feature of motion is possible by employing the same sequence of operations as shown in the Table I above. Similar to the horizontal motion, these steps are repeated until it reaches its desti nation. Its motion can be stopped at any position just by pressing a key in microprocessor kit. At this instant, only S-l and S-4 will be in ON position, thus keeping the robot gripped inside the tube. Alteration of the speed of the robot is not possible during a single stroke of the driving piston. The average opoecl can bo changed by increasing the delay in the program or by changing the value of applied air pressure. This miniature robot can be used to carry an inspection probe (pay-load) for examination of defects inside a tube or may be used for some other pur poses also like cleaning, fixing something inside the tube where the access of the human being is limited. Miniature camera also can be fitted for visual inspection. ADVANTAGES : 1) The unit is simple in design and can be manufactured at a very low cost in comparison to the existing systems used for similar tasks. 2) The actuation has been done by using compressed air which is cheap and almost readily available at workplaces and it is safe to work within hazardous environment. 3) The unit is a rugged one and can be reused for many a no. of times with very little amount of checking and maintenance in between consecutive runs. 4) The materials used for manufacturing the unit are also cheap and readily available. 5) Though the unit can move through a tube as narrow as 56 mm dia., even further miniaturisation is possible. 6) It removes some limitations of other devices for the same duty, such as higher 'pay-load' can be carried. We Claims; 1. A pneumatic inch worm robot which comprises a front gripping unit (1) having at least three radially piston cylinders (2) at 120°apart, in such a manner so as to provide simultaneous gripping of the inside wall of a pipe/tube (13A) by pads (3), the said pads (3) fixed on curved plates (4) which are fitted at the piston rod ends (5), the said gripping unit having at its front end a conical head (6), the said conical head (6) consisting of at least three radially spring loaded wheels (7) for guiding the crawler robot through a pipe/tube (13A), the rear of the said front gripping unit being connected by a flexible joint (8) to the said piston rod end (9) of driving unit (10), the said driving unit being fitted with a spring (11) connected to the rear gripping unit (12) the three units (1,10,12) being connected to a pneumatic control source such as herein described . 2. A pneumatic inch worm robot as claimed in claim 1 where in the said pneumatic control source used such as individual solenoid valves (S-1, S-2, S-3, S-4) connected to the front gripper unit (1), rear gripper unit (2) & driving unit (3) by means of flexible pipes (13) covered under a PVC (poly vinyl chloride) sheathing (14), the said solenoid valves being connected to a compressor (15) via a distributor (18), the said air supply being controlled by means of valve (16). 3. A pneumatic inch worm robot as claimed in claim 2 wherein solenoid valves are controlled by a 8086 microprocessor kit (19) through relays (20). 4. A pneumatic inch worm robot substantially as herein with reference to figs. 1 and 2 of the drawings accompanying the provisional specification.

Documents:

686-del-1996-abstract.pdf

686-del-1996-claims.pdf

686-del-1996-complete specification (granted).pdf

686-del-1996-correspondence-others.pdf

686-del-1996-correspondence-po.pdf

686-del-1996-description (complete).pdf

686-del-1996-description (provisional).pdf

686-del-1996-drawings.pdf

686-del-1996-form-1.pdf

686-del-1996-form-2.pdf

686-del-1996-form-3.pdf

686-del-1996-form-4.pdf

686-del-1996-form-6.pdf