Research On The Intelligent Seam Tracking Control System

A multi-processor intelligent seam tracking control system with functions of adjusting parameters and real time control for locomotive welding robot is designed and implemented in this research.The whole system is consisted of the PLC central control system, the seam image processing system and the human-machine interface system. The key part of the PLC central control system which makes real-time tracking control steadily and exactly with fuzzy control algorithm is a Siemens S7-200 PLC. The seam image processing system processes seam images and identifies positions seam by DM642EVM develop board. The key part of the human-machine interface system is a PIC16F877A processor, its functions are makeing real-time adjusting of parameters and controlling actions of the robot. These three parts are connected by an open end distributed control RS-485 network system with the master slaver topological structure to make exchange between data and instructions.In order to make better effect of real-time control, the author brings forward a fuzzy logic seam tracking control algorithm based on leading error expressions.The leading error expressions provides accumulated enor of the whole track process, and the fuzzy logic control algorithm provided the error changing trend, so the system can make real time tracking control with steadier and smaller overshoot. The error modified by leading error expressions and the margin between error and modified-error are used as input of the fuzzy logic control algorithm; it outputs the controlling quantity of the left-right orientation step motor. Seam tracking control experiments show that the system with fuzzy algorithm can implement the smooth regulation of tracking process.