In friction stir welding (FSW) processes, force control can be used to achieve good welding quality. This paper presents the systematic design and implementation of FSW force controllers. The axial and path forces are modeled as nonlinear functions of the FSW process parameters (i.e., plunge depth, tool traverse rate, and tool rotation speed). Equipment models, which include communication delays, are constructed to relate the commanded and measured actuator signals. Based on the dynamic process and equipment models, nonlinear feedback controllers for the axial and path forces are designed using the polynomial pole placement technique. The controllers are implemented in a Smith predictor-corrector structure to compensate for the inherent equipment communication delays, and the controller parameters are tuned to achieve the best closed loop response possible given equipment limitations. In the axial force controller implementation, a constant axial force is maintained, even when gaps are encountered during the welding process. In the path force controller implementation, a constant path force is maintained, even in the presence of gaps, and wormhole generation during the welding process is eliminated by regulating the path force.

1.
Kalya
,
P.
, 2007, “
Modeling and Control of Friction Stir Welding
,” Ph.D. thesis, University of Missouri–Rolla, Rolla, MO.
2.
Chen
,
L.
,
Stango
,
R. J.
, and
Cariapa
,
V.
, 2001, “
A Force-Control Model for Edge-Deburring With Filamentary Brush
,”
ASME J. Manuf. Sci. Eng.
1087-1357,
123
(
3
), pp.
528
532
.
3.
Viswanathan
,
V.
,
Kinsey
,
B.
, and
Cao
,
J.
, 2003, “
Experimental Implementation of Neural Network Springback Control for Sheet Metal Forming
,”
ASME J. Eng. Mater. Technol.
0094-4289,
125
(
2
), pp.
141
147
.
4.
Liang
,
S. Y.
,
Hecker
,
R. L.
, and
Landers
,
R. G.
, 2004, “
Machining Process Monitoring and Control: The State-of-the-Art
,”
ASME J. Manuf. Sci. Eng.
1087-1357,
126
(
2
), pp.
297
310
.
5.
Xu
,
C.
, and
Shin
,
Y. C.
, 2007, “
Control of Cutting Force for Creep-Feed Grinding Processes Using a Multi-Level Fuzzy Controller
,”
ASME J. Dyn. Syst., Meas., Control
0022-0434,
129
(
4
), pp.
480
492
.
6.
Mason
,
M. S.
,
Huang
,
T.
,
Landers
,
R. G.
,
Leu
,
M. C.
, and
Hilmas
,
G. E.
, 2006, “
Freeform Extrusion of High Solids Loading Ceramic Slurries, Part II: Extrusion Process Control
,”
17th Annual Solid Freeform Fabrication Symposium
, Austin, TX, Aug. 14–16.
7.
Smith
,
C. B.
,
Hinrichs
,
J. F.
, and
Crusan
,
W. A.
, 2003, “
Robotic Friction Stir Welding: The State of the Art
,”
Proceedings of the Fourth International Symposium of Friction Stir Welding
, Park City, UT , May 14–16.
8.
Von Strombeck
,
A.
,
Schilling
,
C.
, and
Dos Santos
,
J. F.
, 2000, “
Robotic Friction Stir Welding: Tool, Technology and Applications
,”
Proceedings of the Second International Symposium of Friction Stir Welding
, Gotherburg, Sweden, Jun. 26–28.
9.
Cook
,
G. E.
,
Smart
,
H. B.
,
Mitchell
,
J. E.
,
Strauss
,
A. M.
, and
Crawford
,
R.
, 2003, “
Controlling Robotic Friction Stir Welding
,”
Weld. J. (Miami, FL, U.S.)
0043-2296,
82
(
6
), pp.
28
34
.
10.
Chao
,
Y. J.
,
Qi
,
X.
, and
Tang
,
W.
, 2003, “
Heat Transfer in Friction Stir Welding: Experimental and Numerical Studies
,”
ASME J. Manuf. Sci. Eng.
1087-1357,
125
(
1
), pp.
138
145
.
11.
Ulysse
,
P.
, 2002, “
Three-Dimensional Modeling of the Friction Stir Welding Process
,”
Int. J. Mach. Tools Manuf.
0890-6955,
42
(
14
), pp.
1549
1557
.
12.
Heurtier
,
P.
,
Jones
,
M.
,
Desrayaud
,
C.
,
Driver
,
J.
,
Montheillet
,
F.
, and
Allehaux
,
D.
, 2006, “
Mechanical and Thermal Modeling of Friction Stir Welding
,”
J. Mater. Process. Technol.
,
171
(
3
), pp.
348
357
. 0924-0136
13.
Zhao
,
X.
,
Kalya
,
P.
,
Landers
,
R. G.
, and
Krishnamurthy
,
K.
, 2007, “
Empirical Dynamic Modeling of Friction Stir Welding Processes
,”
ASME International Conference on Manufacturing Science and Engineering
, Atlanta, GA, Oct. 15–18.
14.
Arbegast
,
W. J.
, and
Hartley
,
P. J.
, 1998, “
Friction Stir Weld Technology Development at Lockheed Martin Michoud Space System—An Overview
,”
Proceedings of the Fifth International Conference on Trends in Welding Research
, Pine Mountain, GA, June 1–5, pp.
541
546
.
15.
Åström
,
K. J.
, and
Wittenmark
,
B.
, 1997,
Computer-Controlled Systems: Theory and Design
,
3rd ed.
,
Prentice-Hall
,
Upper Saddle River, NJ
, pp.
110
111
and
183
185
.
16.
De Silva
,
C. W.
, 2004,
Mechatronics: An Integrated Approach
,
CRC
,
Boca Raton, FL
, pp.
1032
1034
.
17.
Ogata
,
K.
, 2002,
Modern Control Engineering
,
4th ed.
,
Prentice-Hall
,
Upper Saddle River, NJ
.
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