1. Design and development of a robot for friction stir welding by Shailesh Bamoriya (Roll No. 154103056) Under guidance of Dr. S. K. Dwivedy and Dr. P. S. Robi 1 DEPARTMENT OF MECHANICAL ENGINEERING INDIAN INSTITUTE OF TECHNOLOGY GUWAHATI July, 2017

2. Content: INTRODUCTION LITERATURE REVIEW PRELIMINARY DESIGN 3-D MODELING FEM ANALYSIS MOTION PLANNING EXPERIMENTAL ANALYSIS CONCLUSION SCOPE OF FUTURE WORK 2

3. INTRODUCTION Introduction of Industrial Robot  Industrial Robot: The industrial robot is a general-purpose, computer-controlled manipulator consisting of several rigid links connected in series by revolute or prismatic joints.  Classification of robots: (Based on DOF) 3 SCARA (three rotary axes) Cartesian coordinates (three linear axes) Cylindrical coordinates (two linear and one rotary axes) Articulated or revolute coordinate (three rotary axes) Spherical coordinates (one linear and two rotary axes)

4. History of industrial robot 4 In 1954- Unimate (4-DOF) In 1978- PUMA -560 (6-DOF) In 1973- Famulus (6-DOF) In 1954- George Devol designed the first programmable robot (Unimate) and coin the term universal Automation, planting the seed for the name of his future company – Unimation. In 1973- German robotics company, KUKA, creates the first industrial robot with six electromechanically-driven axes. It is called the Famulus.

5. Introduction of Friction Stir Welding  Friction Stir Welding: Friction stir is the solid state joining process by utilizing the heat generated by friction between tool and work piece.  Weld properties:  Low distortion  Low shrinkage  No porosity  No lack of fusion  No change in material  Applications:  To manufacture ships  Subway vehicles  Aerospace industry 5 Figure 2: Schematic of Friction stir Welding Process Figure 1: Friction Stir Welding for joining two plates

6. Need and Objective Objective of the present work is to design and develop a low cost robot for Friction Stir Welding.  Literature review to find the parameters required for of Friction Stir Welding.  Kinematic study of the robot to find the desired workspace for FSW.  Dynamic study of the robot using Newton-Euler formulation, to find the joint torque for motion of robot in the given trajectory. This will help to decide the specification of the prime movers (electric motor) to be used in this robot.  Development of 3D model of the robot using Solidworks software.  FEM analysis of the developed 3D model to perform the static and dynamic analysis of the robot for a safe design of robot. Develop a open source controller to control the SCORBOT ER-V plus Robot and experimented to draw different trajectories similar to those in actual welding. 6

7. LITERATURE REVIEW Fu et al. [1] presented the basic fundamentals of the robot manipulator, classification of industrial robot and its kinematic and dynamic characteristics of the of the different robot manipulators. Denavit and Hartenberg [6] showed a general transformation between two joints of robot manipulator requires four parameters. These parameters are known as the Denavit-Hartenberg (D-H) parameters. These are the basic design parameters helps to describe robot kinematics. Wu et al. [14] established a kinematic model of the robot, and a welding trajectory planning method was developed and verified by the experiments. 7

8. Force And torque Analysis on FSW Sonor and Stensson [20] found the problems associated with robotic FSW operation like compliances and rigidity of the robot links are offered by the generated contact forces during welding process. Cook et al. [22] discussed the forces and torques at the joints of the industrial robots for friction stir welding (FSW). From the experimental results, it has been found that with heavy-duty industrial robots with high stiffness, force feedback is important for successful robotic FSW. Methods of implementing force feedback are reviewed. Mitchell et al. [23] designed a force sensing method for a conventional milling machine which is employed to measure the force during the friction stir welding (FSW). By using the FSW tool, which was made-up of H13 tool steel having hardness Rc-48. 8

9. Experimental analysis on Robotic FSW Santosh et al. [8] proposed modeling and fabrication of friction welding end-effector for ABB IRB1410 robot. The Friction welding has been applied to Aluminium sheets of 2 mm thickness. A prototype setup was developed to monitor the developed axial forces and tool temperature during the operation. It was found that pressure of a gripper plays a significant role in tool rotation and developing torque. Mendes et al. [9] proposed a design of a setup for friction stir welding of a polymeric material by using an industrial robot and found it advantageous over common FSW machine. The presented system shown in Fig. 2.1 is also responsible for supporting a force/torque (F/T) sensor and a servo motor that transmits motion to the tool. During the process, a hybrid force/motion control system adjusts the robot trajectories to keep a given contact force between the tool and the welding surface Callegari et al. [17] performed Friction Stir Welding operation on AA5754 Aluminum alloy sheets, having 2.5 mm thickness, in two different temper states (H111 and O- annealed). A six axes robot with a hybrid structure, characterized by an arm with parallel kinematics and a roll-pitch-yow wrist with serial kinematics, was used. The effect of the process parameters on the macro- And micromechanical properties and microstructure of joint was analyzed. 9

10. Design and Analysis Cristina et al. [10] proposed a comprehensive Computer Aided Engineering (CAE) procedure to do the analysis of the industrial robot. Presented a simplified model of the six-axis industrial KUKA robot [12] and done CAE analysis on it and the Results obtained from the static, modal analysis and an extended kinematic study are presented and coupled with FEM optimization procedure. All results were analyzed in respect with the influence of the static and dynamic behavior on the positioning accuracy of the robot. 10

11. PRELIMINARY DESIGN OF ROBOT Robot Kinematics  Forward or Direct kinematics : Forward or direct kinematics is used to find the end-effector position (P) and orientation (Q) from the joint parameters (θ1, θ2 ….).  Inverse kinematics : In inverse kinematics, the joint parameters are determined from the known position and orientation of the end-effector. 11 Where, P- End-effector position Q - End-effector orientation θ1, θ2 ….- joint parameters

12. Forward kinematics 12  Link coordinate system and D-H parameters. ai = distance along xi from Oi to the intersection of the xi and zi−1 axes. di = distance along zi−1 from Oi−1 to the intersection of the xi and zi−1 axes. di is variable if joint i is prismatic. αi= the angle between zi−1and zi measured about xi (see Figure 3.4). θi= the angle between xi−1 and xi measured about zi−1 (see Figure 3.4). θi is variable if joint i is revolute. Figure 4: link co-ordinate system

13. Important relations 13 D-H Parameters Joint iθiθi αiαi aiai didi 1θ1θ1 -90 a1a1 d1d1 2θ2θ2 0a2a2 d2d2 3θ3θ3 90 a3a3 d3d3 4θ4θ4 -90 a4a4 d4d4 5θ5θ5 90 a5a5 d5d5 6θ6θ6 0 a6a6 d6d6 The D-H parameter has been specified for each link and joint. The homogeneous transformation arm matrix D-H matrix which relates ith coordinate frame w.r.t. (i-1)th coordinate frame is developed by four successive transformations as given below. Last column vector P3×1 of this homogenous transformation matrix T in Eq. 3.2 represents position vector of the end-effector with respect to the base coordinate frame. The R3×3 represents the orientation. Table 1: Arm link coordinate (D-H) parameters

14. Robot Dynamics The dynamic equation of motion of a manipulator is a mathematical equation describing the dynamic behavior of the manipulator. Former part of manipulator control problems: Modeling and evaluating the dynamic properties and behavior of computer controlled robots. Actual dynamic model can be obtained from known physical laws such as, 1. The law of Newtonian mechanics 2. Lagrangian mechanics In the presented work MATLAB code are made using Newton-Euler formulation for dynamic modeling. We will verified by PUMA robot. Final expression of joint torque,at ith joint. 14

15. Kinematic Analysis Workspace Analysis: 15 Joint i θiθi αiαi aiai didi range 1 θ1θ1 -90 00 -160 to +160 2 θ2θ2 0431.8mm149.09mm -225 to 45 3 θ3θ3 90 20.32mm0 -45 to 225 4 θ4θ4 -90 0433.07mm -110 to 170 5 θ5θ5 90 00 -100 to 100 6 θ5θ5 0056.25 0 Table 2: Arm link coordinate (D-H) parameters for a PUMA robot Figure 5: 3D workspace plot of PUMA 560 robot

16. Dynamic analysis 16 Link m i (kg) r i,x r i,y (m) r i,z I i,xx I i,xy I i,xz (kg-m 2 ) I i,yy I i,yz I i,zz 110.521000.0541.61200 00.5091 215.7610.292000.4898008.078308.2672 38.7670.020-0.1973.376800 00.3009 41.0520-0.05700.181000.127300.181 51.05200-0.0070.0735000.127300.0735 60.351000.019.007100 00.0141 Table 3: Mass and inertia parameters of PUMA robot Expressions for the joint trajectory on each joint. i=1,2…n n=no. of degree of freedom of the robot = 6 θ (0) = i th joint rotation at (t=0) = 0  MATLAB code validation of dynamic analysis :

17. Result & discusion When no external forces applied at end-effector: 17 Figure 6: Joint toque developed in PUMA robot manipulator without external load on end-effector (a) First joint torque vs. time graph. (b) Second joint torque vs. time graph.

18. (c) Third joint torque vs. time graph. (d) Fourth joint torque vs. time graph (e) Fifth joint torque vs. time graph. (f) Sixth joint torque vs. time graph. 18

19. When external forces and torque are applied at the end-effector Here considering the axial load in z direction Fz =50kN, Fx= Fy= 20kN, and torque Tz=500N-m, the real time dynamic analysis has been carried out and joint torques are determined. 19 Figure 7: Joint toque developed in PUMA robot manipulator with external load on end- effector (a) First joint torque vs. time graph. (b) Second joint torque vs. time graph.

20. (c) Third joint torque vs. time graph. (d) Fourth joint torque vs. time graph. (e) Fifth joint torque vs. time graph. (f) Sixth joint torque vs. time graph. 20

21. 3-D Modeling First CAD model of Robot using Solidworks. 21 Servo motor (joint 1,2) Figure 8:First Solidworks model of robot for FSW Joint i θiθi αiαi aiai didi 1 θ1θ1 -90 0675mm 2 θ2θ2 01150mm250mm 3 θ3θ3 90 50mm0 4 θ4θ4 -90 01000mm 5 θ5θ5 90 00 6 θ6θ6 0090mm Table 4.1:Arm link coordinate (D-H) parameters for a designed robot (6- DOF)for FSW All the dimension as shown in figures are in millimeter (mm)

22. CAD models of the individual links 22 Figure 9: Base of the robotFigure 10: Shoulder of the robot (link 1) Figure 11: Inner arm of robot (link 2) Figure 12:Forearm of robot (link 3)Figure 13:Roll part of robot (link 4)

23. Figure 14:Pitch part of robot (link 5)Figure 15:Yaw part of robot (link 6) 23

24. Modified 2 nd CAD model of Robot 24 Figure 16:Modified first link of previous design Figure 17:Second Solidworks model of robot for FSW

25. Workspace plot of Designed robot Workspace analysis using MATLAB code 25 Joint i θiθi αiαi aiai didi 1 θ1θ1 -90 0630mm 2 θ2θ2 01150mm5mm 3 θ3θ3 90 50mm0 4 θ4θ4 -90 01000mm 5 θ5θ5 90 00 6 θ6θ6 0090mm Table 4.2: Arm link coordinate (D-H) parameters for a designed robot for FSW Figure 4.9: 3D workspace plot of robot Designed for FSW.

26. Modified 3 rd CAD model of Robot 26 Figure 19:Third Solidworks model of robot for FSW Figure 18:Modified base of robot for FSW

27. FEM ANALYSIS Transient structural analysis: A transient analysis involves loads that are a function of time. In mechanical application that analysis can perform on either a flexible structure or a rigid assembly. FEM model of the first robot model 27 Material: Structural Steel Yield Strength (250 MPa) Number of total nodes = 14337 Number of contact elements = 500 Number of spring elements = 0 Number of solid elements = 7622 Number of total elements = 8142 Solid elements type = SOLID 187 Using default Mesh size Figure 20: FEM model of the first robot model.

28. Connections: All the joints of the robot manipulator are revolute. Base of the robot manipulator is fixed to the ground. Loading conditions: Joint rotations are been given to the 1st, 2nd, 3rd, 4th and 5th joint as shown in Fig. 5.2. Self-Weight of the robot links has been considered by applying the gravity in negative y- direction. 28 Figure 21: Transient structural analysis loading. Link6Link 5Link 4Link 3Link 2 Link 1 Base Volu me 3.1494e +005 mm³ 2.3766e +006 mm³ 1.077e+ 007 mm³ 5.1937e +007 mm³ 5.0488e +007 mm³ 4.1207e +007 mm³ 5.3298e +007 mm³ Mass 2.4723 kg 18.657 kg 84.542 kg 407.7 kg 396.33 kg 323.47 kg 418.39 kg Centr oid X 130.85 mm 128.54 mm 146.65 mm 249.68 mm 505.95 mm 293.18 mm 262.99 mm Centr oid Y 801.2 mm 892.12 mm 906.18 mm 905.82 mm 906.18 mm 696.2 mm 320.52 mm Centr oid Z -1465.4 mm -1461.4 mm -1328.8 mm -482.96 mm 85.838 mm 687.29 mm 691.5 mm Mom ent of Inerti a Ip1 2479.3 kg·mm² 74496 kg·mm² 7.9609e +005 kg·mm² 2.9547e +007 kg·mm² 2.7506e +006 kg·mm² 1.433e+ 007 kg·mm² 1.1076e +007 kg·mm² Mom ent of Inerti a Ip2 2479.5 kg·mm² 64095 kg·mm² 1.3236e +006 kg·mm² 2.6289e +007 kg·mm² 6.0758e +007 kg·mm² 4.0422e +006 kg·mm² 1.9683e +007 kg·mm² Mom ent of Inerti a Ip3 4595.5 kg·mm² 43612 kg·mm² 8.1168e +005 kg·mm² 7.2711e +006 kg·mm² 6.198e+ 007 kg·mm² 1.3675e +007 kg·mm² 1.1075e +007 kg·mm² Table 5.1 link parameters of the first robot model

29. Analysis result: Equivalent stress () vs. time (s) 29 Time (s) Figure 22:von-Mises stress (σ) vs. time(s) plot for first robot model. Figure 23:Maximum von-Mises stress on first robot model

30. Ansys simulation of first model (Transient structural anlysis) 30

31. Rigid body dynamic analysis of first robot model To determine the end-effector position of the robot, the analysis of the intermediate joint position has to be performed. This type of analysis precedes any static or dynamic calculation and has a steadfast solver, which is the rigid dynamics module. Following loading conditions are applied. 31 Figure 25: rigid dynamics analysis loading Figure 24: total displacement during RBD analysis.

32. Reaction torque in the joint due to the motion of the robot frame 32 Time (s) (a) Joint probe 1 (b) Joint probe 2  Torque is taken in Newton-mm (N-mm)

33. 33 Time (s) Figure 26: Torque reactions (τ) of joints over time:((c) Joint probe 3

34. Reaction forces in the joint due to the motion of the robot frame 34 Time (s) (a) Joint 1(b) joint 2

35. 35 Time (s) Figure 27: Total Force reactions (F) on joints vs. time on:(e) Joint 5 (c) Joint 3 (d) Joint 4

36. Transient structural analysis of second Robot model FEM model of the second robot model Material: Structural Steel (Yield strength= 250 MPa) 36 Figure 28: FEM model of the second robot model first robot model.  Number of total nodes = 15351  Number of contact elements = 419  Number of spring elements = 0  Number of solid elements = 8208  Number of total elements = 8647  Solid element type = SOLID 187  Using default Mesh Size

37. Figure 29: Transient structural analysis loading second Robot model.  Connections: All the joints of the robot manipulator are revolute. Base of the robot manipulator is fixed to the ground.  Loading conditions: Joint rotations are been given to the 1st, 2nd, 3rd, 4 th,5 th and 6th joint as shown in Fig. 5.6. Self-Weight of the robot links has been considered by applying the gravity in negative y-direction. (g=9805.6mm/s2) Joint rotations are given in the figure. 37

38. Simulation result: Equivalent stress vs. time (s) 38 Time (s) Figure 30:von-Mises stress (σ) vs. time(s) plot for second robot model. Figure 31:Maximum von-Mises stress on second robot model

39. Ansys simulation of second model(Transient structural analysis) 39

40. Preliminary Design Figure 33: 3D Solid model of the robot. Figure 32: Schematic D-H coordinate system of the proposed robot. Figure 6. 1: D-H parameters of the robot. In preliminary design of the robot main focus is given to determine the D-H parameters of the robot. Maximum reach of robot is assumed for 6 DOF robot and based on it D-H parameters are decided. Other link dimensions of the robot are decided by hit and trial.

41. Workspace analysis The workspace is dependent on the DOF angle/translation limitations, the arm link lengths, the angle at which something must be picked up at, etc. The workspace is highly dependent on the robot configuration. The robot workspace (sometimes known as reachable space) is all position in the space around the robot that the end effector (gripper) can reach. Homogeneous Transformation matrix. Global Transformation matrix. Figure 34: workspace of designed robot

42. FEM analysis of robot for FSW Rigid Body Dynamics analysis BaseLink 1Link 2Link 3Link 4Link 5Tool Mass (kg) 29.429.871.849.2623.95.08.07 Loading conditions are gravity force in –Y direction and the remote force of 2 kN in axial direction. 1 kN force is acting on the two lateral directions of the tool (End- effector) and the joint rotational velocity as joint trajectory for each joint is given by the equation. Rigid dynamics tool box in ANSYS Workbench is very efficient to determine the dynamic behavior of multi body system in real time. Table :Mass of the links of designed robot Figure 35: Loading and boundary conditions for rigid body dynamic analysis

43. Joint moment Developed at the joints Figure 36: Variation of moment reaction for joint 1 with time. Figure 37: Variation of moment reaction for joint 2 with time. (1)Moment reaction in the x direction. (2) Moment reaction in the y direction. (3) Moment reaction in the z direction. (4) Resultant moment reaction

44. Joint moment Developed at the joints Figure 38: Variation of moment reaction for joint 3 with time. Figure 39: Variation of moment reaction for joint 4 with time. Figure 40: Variation of moment reaction for joint 5 with time.

45. Reaction Forces Developed at the joints Figure 41: Variation of force reaction for joint 1 with time. Figure 42: Variation of force reaction for joint 2 with time. Figure 44: Variation of force reaction for joint 4 with time. Figure 43: Variation of force reaction for joint 3 with time.

46. Reaction Forces Developed at the joints Figure 45: Variation of force reaction for joint 5 with time. (1)Force reaction in the x direction. (2) Force reaction in the y direction. (3) Force reaction in the z direction. (4) Resultant Force reaction

47. Dynamic Stress analysis Figure 46 FEM model of the designed robot for FSW. BaseLink 1Link 2Link 3Link 4Link 5Tool Node314816181547118415861536393 Element1478761803592771840187 Table 6.3: Number of nodes and elements in FEM model  Dynamic stress analysis was done by using transient structural analysis tool box in ANSYS Workbench  In the transient structural analysis of the robot design maximum equivalent or von- Mises stress (  ) has been calculated for each link.  Material of robot model is structural steel. yield strength of the material 250 Mpa

48. Stress analysis Result Figure 47: Variation of equivalent stress ( ) with time for link 1. Figure 48: Variation of equivalent stress ( ) with time for link 2.

49. Figure 49: Variation of equivalent stress ( ) with time for link 3. Figure 50: Variation of equivalent stress ( ) with time for link 4.

50. Stress analysis result Figure 51: Variation of equivalent stress ( ) with time for link 5.

51. Motion Planning DH Parameters SCORBOT ER-V Plus Joint iθiθi α i (degree) a i (mm)d i (mm) 1θ1θ1 90100200 2θ2θ2 01200 3θ3θ3 0 0 4θ4θ4 -9000 590 00 6θ6θ6 00150 Figure 52: Schematic D-H coordinate system of the SCORBOT ER- V Plus robot. Table 7.1: D-H parameters of scorbot  Inverse Kinematics.  Trajectory Planning. I.Cubic spline trajectory. II.4 th order polynomial trajectory. III.6 th order polynomial trajectory.

52. Inverse kinematics for SCORBOT ER-V plus robot Here we used a geometric approach to solve the inverse position problem. Robot is assumed as 6 DOF robot when there is no yaw motion it is taken as 90 degree(constant). After decouple the kinematics arm joint angle ( and wrist rotation ( ) are calculated individually.

53. Inverse kinematics for SCORBOT ER-V plus robot

54. Trajectory Planning Joint-space trajectory generation is in common usage in robotics to provide smooth, continuous motion from one set of joint angles to another. Trajectory planning has been done for SCORBOT ER-V Plus by utilizing the inverse kinematics. For N point interpolation (N-1) cubic segments are generated. Triadigonal matrix (known) Velocities at via points Matrix containing joint variables (known)

55. 4 th order polynomial

56. 6 th order polynomial

57. Nature of trajectory for Cubic, 4 th order and 6 th order polynomial through single via point Figure 53: Joint trajectory for horizontal straight line motion through single via point.

58. Nature of trajectory for Cubic spline through 5 via point Figure 55: Space trajectory for horizontal straight line motion through 5 via points. Figure 54: Joint trajectory for horizontal straight line motion through 5 via points.

59. Nature of trajectory for Cubic spline through 11 via point Figure 57: trajectory for horizontal straight line motion through 11 via points. Figure 56: Joint trajectory for horizontal straight line motion through 11 via points.

60. Experimental Analysis Figure 58: Open Robot control system wiring Parts:  SCORBOT ER-V Plus  Arduino Mega 2560 Microcontroller  Motor Driver  Rotary type Linear Potentiometer Robot control system:

61. Parts Figure 61: SCORBOT ER-V Plus Robot Figure 60: linear potentiometer EN61058 by VDE Figure 62: 8V-28V, 5Amp Dual DC Motor Driver with Current Sense Figure 59: Arduino Mega 2560 Microcontroller

62. Controller Design From the trajectory planning the desired, is available. The control law can then be expressed as, The Simulink® Support Package for Arduino® Hardware enables the possibility to create and run Simulink models on Arduino boards. A Simulink model accessing the Analog Output (D/A) and Analog Input (A/D) of the Arduino with the sampled time (5ms) trajectory generator was developed. The controller was implemented in the same model.

63. Block diagram of proposed Controller Figure 63: Block diagram of the proposed controller

64. Figure 64: SIMULINK Model of a single joint

65. Hardware setup

66. Cubic spline trajectory tracking ( with single via point)

67. 6 th order polynomial trajectory tracking ( with single via point)

68. Actual error in joint and Cartesian space trajectory for 6 th order polynomial through single via points Figure 65: Error of joints at different time instance (6 th order, single via point) Figure 66: Actual vs. desired space trajectory (6 th order, single via point)

69. Cubic spline trajectory tracking ( with 11 via point)

70. Actual error in joint based trajectory tracking for cubic spline through 11 via points Figure 67: Error of joints at different time instance (cubic spline, 11 via points)

71. Vertical trajectory testing 71

72. 72

73. CONCLUSION Result obtained from the validation of the code for real time dynamic analysis of PUMA robot we have concluded that design of robot must be such that it should not offer any joint reaction torque then there is no external force (on end-effector) is applied. After modification of the design maximum equivalent stresses in the modified robot are less than the yield strength of the structural steel (Robot material). From this modification of the design, i have concluded that bending effect of link has to be minimizing over lower link to reduce the stress and trajectory planning also affected the stresses induced in the links. From the result of the rigid dynamics analysis found some position of the robot end-effector where the reaction torque is very high so we can design the smooth trajectory which will reduce the reaction torque induced. Designed control is no sufficient for the position control. Dynamic control is required to increase the positional accuracy. Controller can be modified by put controller at individual joint. 73

74. FUTURE WORK In next phase of work will to devolve foolproof model of robot and its transmission assembly, find the motor rating by dynamic analysis of the final robot design for planned trajectory suitable for the Friction Stir Welding operation will do. Optimize the robot design. Search the suitable gear drives according to our design and motor ratings. After complete this work we will be going to start fabrication of the robot. Apart from the design and analysis, smoothening of trajectory planning will do and test it experimentally on 5- axis industrial robot available in the MECHATRONICS & ROBOTICS LAB. 74

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76. BIBLIOGRAPHY 76 [1] Fu K. S., Gonzalez R. C. and Lee C. S. G., “ROBOTICS: control, sensing, vision, and Intelligence”, Tata McGraw-Hill, Edition 2008. [2] Cook, G., Crawford, R., Clark, D., and Strauss, A., “Robotic friction stir welding”, Industrial Robot, vol. 31, no. 1, pp. 55–63, 2004. [3] Strombeck A. V., Shilling C., and Santos J. F. D., “Robotic friction stir welding – tool technology and application” 2nd Friction Stir Welding International Symposium, Gothenburg, Sweden, 2000. [4] Smith C. B., “Robotic Friction Stir Welding using standard industrial robot”,2nd Friction Stir Welding International Symposium, Gothenburg, Sweden, 2000. [5] Bres, A., Monsarrat, B., Dubourg, L., Birglen, L., Perron, C., Jahazi, M., and Baron, L., “Simulation of friction stir welding using industrial robots”,Industrial Robot: An International Journal, vol. 37, no.1, pp.36–50, 2010. [6] Denavit, J. and Hartenberg, R. S., “A kinematic notation for lower-pair mechanisms based on matrices”, Journal of Applied Mechanics, vol. 1 pp. 215-221, June 1955. [7] Singh, S., and Singla, E., “Realization of task-based designs involving DH parameters: A modular approach”, Intelligent Service Robotics, vol. 9(3), pp. 289-296, 2016.

77. [8] Santosh, V., Rao, V.R. and Ch, V.K., "Design and fabrication of friction stir welding automatic end-effector for industrial ABB IRB1410", Journal of Chemical and Pharmaceutical Sciences, vol. 9, no. 4, pp. 2582-2586, 2016. [9] Mendes, N., Neto, P., Simão, M. A., Loureiro, A., and Pires, J. N., “A novel friction stir welding robotic platform: Welding polymeric materials”, International Journal of Advanced Manufacturing Technology, 85(1-4), pp. 37-46, 2016. [10] Cristina PUPAZA, George CONSTANTIN, and Stefan NEGRILA, “Computer aided Engineering of industrial robots”, Proceedings in Manufacturing System, vol. 9, issue2, pp. 87-92, 2014. [11] Luo, H., Fu, J., Yu, M., Yu, C. and Wang, P., "Static simulation analysis on friction stir welding (FSW) robot", 6th Annual IEEE International Conference on Cyber Technology in Automation, Control and Intelligent Systems, IEEE-CYBER 2016, pp. 327, 2016. [12] Luo, H., Wang, T., Fu, J., Chen, Z. and Leng, Y., "Analytical kinematics and working- condition simulation for friction stir welding (FSW) robot", 2015 IEEE International Conference on Information and Automation, ICIA 2015 - In conjunction with 2015 IEEE International Conference on Automation and Logistics, pp. 1992, 2015. [13] Li, Q., Wu, W., Xiang, J., Li, H. and Wu, C., "A hybrid robot for friction stir welding", Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, vol. 229, no. 14, pp. 2639-2650, 2015. 77

78. [14] Wu, J., Zhang, R. and Yang, G., "Design and experiment verification of a new heavy friction-stir-weld robot for large-scale complex surface structures", Industrial Robot, vol. 42, no. 4, pp. 332-338, 2015. [15] Mendes, N., Neto, P., Loureiro, A. 2014, "Robotic friction stir welding aided by hybrid force/motion control", 19th IEEE International Conference on Emerging Technologies and Factory Automation, ETFA 2014. [16] Imani, Y., Guillot, M., "Axial force reduction in friction stir welding of AA6061-T6 at right angle", ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 2014. [17] Callegari M., Forcellese A., Palpacelli M., Simoncini M., "Robotic Friction Stir Welding of AA5754 Aluminum Alloy Sheets at Different Initial Temper States", Key Engineering Materials, vol. 622-623, pp. 540-547, 2014. [18] Zaeh, M.F., Voellner, G., "Three-dimensional friction stir welding using a high payload industrial robot", Production Engineering, vol. 4, no. 2, pp. 127-133, 2010. [19] Soron M., "Quantifying the Usability of a Robot System for Friction Stir Welding ", Materials Science Forum, vol. 638-642, pp. 1255-1260, 2010. [20] Soron, M. and Stensson, P., "Evaluating control solutions for robotic Friction Stir Welding", welding in the World, vol. 53, no. Special issue, pp. 59-64, 2009. [21] Yavuz, H., "Function-oriented design of a friction stir welding robot", Journal of Intelligent Manufacturing, vol. 15, no. 6, pp. 761-775, 2004. [22] Cook, G.E., Crawford, R., Clark, D.E. and Strauss, A.M., "Robotic friction stir welding", Industrial Robot, vol. 31, no. 1, pp. 55-63, 2004. 78

79. [23] Mitchell, J.E., Cook, G.E. and Strauss, A.M., "Force Sensing in Friction Stir Welding", ASM Proceedings of the International Conference: Trends in Welding Research, pp. 235, 2002. [24] Hong, T.S., Ghobakhloo, M. and Khaksar, W., "Robotic Welding Technology" in Comprehensive Materials Processing, pp. 77-99, 2014. [25] Axel Fehrenbacher, Christopher B. Smith, Neil A. Duffie, Nicola J. Ferrier, Frank E. Pfefferkorn, Michael R. Zinn, “Combined Temperature and Force Control for Robotic Friction Stir Welding,” ASME Journal of Manufacturing Science and Engineering, accepted September, 2013. [26] Saha S. K., “Introduction to Robotics”, Tata McGraw-Hill, 2008. [27] Roy J. and Whitcomb L. L., “Adaptive force control of position/velocity controlled robot: Theory and experiment”, IEEE Trans. on Robotics and Automation, vol. 18(2), pp. 121-136, 2002. [28] Schmidt H., Hattle J., Wert J., “An analytical model for heat generation in friction stir welding”, Modelling and Simulation in Material Science and Engineering, vol. 12, pp. 143- 157, 2004. [50] [29] Kazi, Arif and Merk, Günther and Otter, Martin and Fan, Hui, “Design optimisation of industrial robots using the Modelica multi-physics modeling language”, In: Proceedings of the 33rd ISR 2002, pp. 347-352, 2002. [30] KUKA Robots, Specification, KR6-2, KUKA Roboter GmbH, taken from: http://www.kuka-robotics.com/en/products/industrial_robots/low/kr6_2/start.htm. 79