Development of an automatic arc welding system using an adaptive sliding mode control

This paper develops an automatic welding control scheme for alternating current shielded metal arc welding (SMAW) system. A mathematical model of the welding control system is derived and the system parameters identified. An adaptive sliding mode controller is designed to estimate the bound of the system uncertainties and to modulate the electrode feed rate in such a way that the desired arc length and arc current are maintained as the electrode melts during the welding process. The proposed control method is suitable for any consumed electrode welding technique. The simulation and experimental results show that the automatic welding control system successfully maintains the magnitude of the arc current at the desired value and preserves the arc stability, thereby obtaining an enhanced SMAW control system performance.

a :

Viscous damping coefficient of welding system

e _i :

Error signal between actual and desired output variable

y :

Actual output variable

A :

State gain matrix

B :

Input gain matrix

C :

Output gain matrix

α :

Adaptive gain

λ:

Slope of the sliding surface

ė :

Derivative error between actual and desired output variable

\({\bar{e}}\) :

Bound of the disturbance

\({\overline{\beta}}\) :

Upper bound of the disturbance

k _mr :

Coefficient ratio of melting rate to arc current

k _v :

Coefficient ratio of melting rate to the arc voltage

K _m :

Motor constant

u _eq :

Equivalent control of the sliding mode controller

T _d :

Disturbance

v _fr :

Electrode feed-rate

v _mr :

Electrode multing-rate

V _a :

Arc voltage

s(t):

Sliding surface

sat(s):

Saturation function

E(s):

Error signal between reference input, I _r (s), and welding current, I _a

G(s):

Transfer function of the welding control system

H(s):

Current sensor of the welding control system

V(s):

Output signal of the controller

I_a(s):

Transfer function of arc current, I _a, in welding control system

I_r(s):

Transfer function of reference input to welding control system

V_f(s):

Transfer function of electrode feed rate

This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.

Authors and Affiliations

1. Department of Mechanical Engineering, National Central University, Chung-Li, 320, Taiwan

   Cheng-Yu Wu & Pi-Cheng Tung

2. Department of Mechanical & Mechatronic Engineering, National Taiwan Ocean University, Keelung, 20224, Taiwan

   Chyun-Chau Fuh

Corresponding author

Correspondence to Pi-Cheng Tung.

Open Access This is an open access article distributed under the terms of the Creative Commons Attribution Noncommercial License (https://creativecommons.org/licenses/by-nc/2.0), which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.

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