Intelligent Seam Tracking for Robotic Welding is part of the Advances in Industrial Control series, edited by Professor M.J. Grimble and Dr. M.A. Johnson of the Industrial Control Unit, University of Strathclyde. This publication discusses in depth the development of a seam tracking system for robotic welding. Various topics are covered including the theory of seam tracking, details of the sub-systems comprising the intelligent seam tracker and the operation of the seam tracking system with coordinated interaction amongst the various sub-systems. The sources of various seam tracking errors and existing seam tracking systems operating in both structured and unstructured welding environments are also addressed. The work reported builds upon the research conducted during the course of the project ARTIST (Adaptive, RealTime, Intelligent Seam Tracker) at the Applied Research Laboratory of the Pennsylvania State University. Although the book is presented in the context of seam tracking, issues related to systems integration are general in nature and relate to other applications as well.

Inhalt

1 Introduction.- 1.1 Industrial Robotic Applications.- 1.2 An Overview of Robotic Welding.- 1.3 Outline of the Monograph.- 2 An Overview of Seam Tracking Technology.- 2.1 Introduction.- 2.2 Through-the-Arc Sensing.- 2.3 3D Vision Sensing.- 2.4 Evolution of Seam Tracking Strategies for Vision-based Systems.- 2.5 Summary.- 3 Feature Extraction and Seam Recognition Techniques.- 3.1 Introduction.- 3.2 Intensity Image Preprocessing.- 3.3 Range Image Preprocessing.- 3.4 Feature Extraction and Seam Recognition.- 3.5 Seam Environment Model.- 3.6 Summary.- 4 Coordinate Frames for Realtime Seam Tracking.- 4.1 Introduction.- 4.2 Base Coordinate Frame ([W]).- 4.3 Torchtip Coordinate Frame [T].- 4.4 Sensor Coordinate Frame [S].- 4.5 Seam Coordinate Frame [C(k)].- 4.6 Summary.- A.1 PPV to Range Conversion.- 5 Seam Tracking in an Unstructured Environment: A Case Study with Vee-Groove Joints.- 5.1 Overview.- 5.2 Definitions.- 5.3 Range Image Processing.- 5.4 Seam Environment Model & High-Level Control.- 5.5 Geometric Model of the Seam.- 5.6 Robot Motion Control (Weld Path Generation).- 5.7 Summary.- B.1 Least Squares Approximation Polynomials.- 6 Implementation Concerns in Seam Tracking Systems.- 6.1 Introduction.- 6.2 System Description.- 6.3 System Control Software.- 6.4 System Operation.- 6.5 Synchronizing Concurrent Operations in Seam Tracking.- 6.6 Summary.- C.1 Laser Profiling Gage Calibration.- 7 Tracking Accuracy & Error Analysis.- 7.1 Is The Tracking Error Bounded?.- 7.2 Sources of Error.- 7.3 Minimum Radius of Curvature for the Seam.- 7.4 Summary.- D.1 Robot Accuracy Issues.- 8 Seam Tracking System Prototypes.- 8.1 Ultrasonic Ranging-Based Seam Tracking.- 8.2 Automatix Inc.'s Vision-aided Robotic Welder.- 8.3 PASS-Visual Sensing for Tracking and Online Control.- 8.4 ASEA Robotics' Adaptive Torch Positioner.- 8.5 A Realtime Optical Profile Sensor for Robot Welding.- 8.6 LaserTrak-Seam Tracker for Arc Welding Applications.- 8.7 ESPRIT-Realtime Imaging for Arc Welding.- 8.8 Summary.- 9 Future Directions.- 9.1 Introduction.- 9.2 Scope of Future Enhancements.- 9.3 Error Analysis.- 9.4 Summary.- References.