The document describes the design of a manipulator robot for crack detection and welding in process pipes. It discusses two conceptual designs - the first uses a differential drive base with a 3 DOF robotic arm and welding torch but causes loading effects and requires servo motors. The second design uses a linear arm, camera, higher load capacity, and replaces servo motors with lower RPM DC gear motors to reduce complexity, but has less speed control. It further details challenges in flexibility for different pipe sizes, changing the center of rotation, different welding units, crack detection methods, and field requirements.

1. Manipulator Robot for Crack Detection and
Welding in Process Pipes
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978-1-4799-5202-1/14/$31.00 ©2014 IEEE

2. Design
Base body
Detection
unit
Welder arm
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Block diagram. 1
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3. TOP VIEW SIDE VIEW
Conceptual Design
Design 1 main features
Differential drive
Robotic arm with 3 DOF
Welding torch
Feed mechanism
Limitations
Caused loading effects
Required servo motors
arm
arm
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Fig. 1
Fig. 2
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4. Practical Design – Stage 1
Main features
Includes features of design 1
linear arm
Camera
Higher loads
Programming is less complex
Servo motors replaced by dc gear motors
Limitations
Less control over the arm due to high rpm of dc motor
Pulse Width Modulation (PWM) technique alone to control speed was in sufficient
As frequency decreases the load bearing capacity decreases
TOP VIEW SIDE VIEW
arm
arm
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Fig. 3
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5. Practical Design – Stage 2
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To reduce speed we use PWM
PWM reduces the torque of the shaft
Extra gear attached to solve the problem
Fig. 4
Fig. 5
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6. Challenges:
Motor driver
H bridge circuit
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Fig. 6
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7. Flexibility in pipe size
.......Challenges
400 mm
200 mm
650 mm
450 mm
762 mm
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Fig. 7 Fig. 8
Fig. 9
Fig. 10
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8. .......Challenges
Change of centre of rotation
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Fig. 11
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9. STICK ARC WELDING UNIT
GAS WELDING UNIT
MIG WELDING UNIT
.......Challenges
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Fig. 12
Fig. 13
Fig. 14
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10. .......Challenges
Crack detection unit
Dye penetrant inspection
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Fig. 15
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11. Field requirements
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Pipes should laid horizontally
Presence of any inflammable gases should be checked
DPI technique is not economically feasible
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12. Applications
Welding
Crack detection
Painting
Drilling
Cleaning
Operation in hazardous environments
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Fig. 16
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13. Existing robots
Crack detecting robots
Outer surface welding robots
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Fig. 17
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14. Re-engineering
PC interfacing
Replacing DPI with ultrasonic testing
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Fig. 19
Fig. 18
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16. References
[1] Gupta V., " Working and analysis of the H - bridge motor driver circuit designed for wheeled
mobile robots", 2nd International Conference on Advanced Computer Control (ICACC), 2010
[2] http://www.atmel.in/devices/ATMEGA328P.aspx
[3] An Arc Welding Robot Control for a Shaped Metal Deposition Plant: Modular Software Interface
and Sensors Filippo Bonaccorso, Member, IEEE, Luciano Cantelli, and Giovanni Muscato, Senior
Member, IEEE, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 58, NO. 8,
AUGUST 2011.
[4] Hemanand, T. and Rajesh, T. " Speed control of brushless DC motor drive employing hard
chopping PWM technique using DSP", India International Conference on Power Electronics,
2006.
[5] K.L. Moore, D.S. Naidu, R. Yender, J. Tyler, "Gas metal arc welding control-Part I: Modeling and
analysis," Nonlinear Analysis, Theory, Methods and Applications, vol. 30, pp. 3101-3111, 1997.
(Pubitemid 127406978)
[6] Y.M. Zhang and R. Kovacevic, “Real-time sensing of sag geometry for full penetration control in
GTA welding,” ASME J. Eng. Znd., to appear, vol. 118, no. 4, 1996.
[7] http://liquidpenetrant.com/penetrant-inspection-process/
[8] http://www.st.com/st-web-
ui/static/active/en/resource/technical/document/datasheet/CD00000059.pdf
[9] http://www.st.com/web/en/resource/technical/document/datasheet/CD00000240.pdf
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Acknowledgement
 Prof. P. R.Madhava Panicker
Department of Applied Electronics and
Instrumentation
Rajagiri School of Engineering and Technology
Asst. Prof. Naveen N
Department of Applied Electronics and
Instrumentation
Rajagiri School of Engineering and Technology
 SS casting and metal works
Kochupally Nadakkavu PO
Udyamperoor
Ernakulam
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