Design Of Real-Time Monitoring System For The Automatic Welding Manipulator Circuit Fault

The Chinese car factory would take a great share in the future world. The Chinese car industry has a strong rising in last ten years, which will lead a technical reformation in car manufacturing, especially in the welding area. A better quality and efficiency need better manufacturing equipments. The main welding mode of the car body for a home subcompact factory is the traditional manual spot welding while the automatic welding must be introduced, to improve the welding quality and decrease the labor costs, with the rising sales volume.Compared with welding robot, the specific welding units for specific position have been adopted in a large scale because of a lower cost, a shorter development cycle and a simpler training process. But the mass applying has lead to a rising electrical fault along with growing work hours. It is a large number waste of economic losses because of the long maintenance time once the fault causes shutting down of a product line. Thus it is necessary to study monitoring the fault.This paper mainly discusses some researches as follows:1. The monitoring design of electrical fault based on boundary scan. This paper applies boundary scan, which usually used in PCB test, on the simple four-axis-linkage welding mechanical arm, whose control system is NC Central, to detect the open circuit and short circuit. The electrical line of the mechanism is possibly been open and short as a result of the complicate motion such as rectilinear one and rotating one, plus other worse work conditions. The traditional detect method with only manual test will cost plenty of time so a real-time monitoring system has a important role to play.2. The real-time tracking of TAP FSM. The TAP controller controls the scan vector of boundary scan and the testing principle is a16-bit state machine. We can only detect the electrical level of the periphery circuit while the flow state of the TAP state machine is unknown to us. This paper uses MATLAB Stateflow to simulate the TAP state machine, which is included into the software interface to provide a clear observation of the work sate for works, while the usual means to simulate the sate machine with hardware description language.3. The GUI interface design. MALAB has a powerful ability to deal with data and rich material for GUI interface, and these two abilities are combined in this paper. This paper analyses the scanning algorithm to assure the accuracy, then designs the software interface so the workers can observe the real-time state of every monitoring point and operate the system if necessary.4. The preliminary discussion about welding quality monitoring. This paper has a preliminary discussion about IEEE1149.4for the measurement of welding holder dynamic resistance, and it provides a means for studying welding quality.