Closed-circuit TV camera is mounted parallel to electrode and moves along with it. Camera is scanned along seam so seam is viewed parallel with scan lines on TV monitor. Two fiber optics illuminators are attached to guidance system; they illuminate seam for TV camera

Avery, R. M.

Smith, H. E.

Stephens, D. L.

Taylor, R. A.

Wall, W. A.

Wunsch, H. P.

English

NASA Technical Reports Server

.September 1974	
.	 B74-10150' 
NASA TECH BRIEF 
Marshall Space Flight Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Closed-Circuit-Television Welding-Electrode Guidance System 
Welding-Electrode Guidance System Block Diagram 
A closed-circuit-television welding-electrode guidance 
system was developed and evaluated. The guidance 
system shown in the illustration is designed to guide 
a welding electrode along the weld seam within a 
10.76-mm accuracy. A closed-circuit TV camera is 
mounted parallel to the electrode and moves along with 
it. The camera is scanned along the seam so that the 
seam is viewed parallel with the scan lines on the TV 
monitor. Two fiber optics illuminators are also attached 
to the guidance system; they illuminate the seam for 
the TV camera. 
In operation, the composite video signal from the TV 
camera is routed to both the waveform and TV monitors 
and from there to a special blanking circuit for the 
removal of unwanted portions of the signal. Next, the S
signal is amplified to raise its voltage and power to a 
level that can be used by the logic section. Logic circuits 
separate the video information from the synchronizing 
pulses to feed a binary counter. The control in the logic 
is such that the counter will begin receiving pulses at 
the top of the IV scan, and it will count each successive 
horizontal scan line until the bright line of the illumi-
nated weld joint is sensed. This stops the counter on 
that particular horizontal line number. The number is 
stored in a flip-flop register until new information is fed 
into it during the next scan. 
The stored horizontal line number in the register is 
periodically fed to a digital-to-analog converter (DAC) 
for conversion into a proportional dc voltage. This dc 
voltage analog of the stored number is then algebraically 
(continued overleaf) 
This document was prepared under the Sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19740000150 2020-03-17T13:50:15+00:00Z
Im 
summed with a reference voltage. If the output dc 
voltage level is either less than or greater than the 
reference voltage level, a positive or negative dc error 
signal is transmitted to the servoamplifler, which drives 
the motor to position the camera electrode holder 
horizontally until, the error difference is canceled. The 
sign of this error signal to the servoamplifier determines 
the direction of the horizontal movement. 
The dynamics of the servomotor are such that new 
error information is received much more rapidly than 
the vertical movement of the electrode holder. Since 
the TV field is scanned 60 times per second, the DAC 
receives new tracking data each 1/60th of a second. 
This rapid supply of position information allows the 
servosystem to guide the welding torch accurately along 
the weld centerline.
Note: 
Requests for further information may be directed to 
Technology Utilization Officer 
Marshall Space Flight Center 
Code ATO1 
Marshall Space Flight Center, Alabama 35812 
Reference: B74.10150 
Patent status: 
NASA has decided not to apply for a patent. 
Source: H. E. Smith, D. L. Stephens, R. A. Taylor,
W. A. Wall, and R.M.Avery

Marshall Space Flight Center

and H. P. Wunsch of
Hayes International Corp.

under contract to
Marshall Space Flight Center

(MFS-23026)
. 
B74-10150	 Category 07,02,04


Closed-circuit television welding- electrode guidance system

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server