Design Of Controller Of Resistance Spot Welding Based On ARM

With the development of electronic technology, the welding control is developing to direction of digitization,the intellectualization,the flexibility,the information, traditional control system can't meet the requirement of the development of modern industry network. The rapid development and integration of field bus and internet technology, focusing on the network monitoring system question, the CAN bus control technology is applied to the resistance spot welding, It is adopted that the method of spot welding constant-current Fuzzy Self-adaptive PID control is bring forward to realize the real-time control to the current during the spot welding control process, so a spot welding controller is designed to realize the collection of the welding current and Fuzzy Self-adaptive PID control calculation.In this paper, it is compared every spot welding monitoring and controlling method, and analyzed the ARM characteristic, ultimately determined to develop a set of resistance spot welding intelligent control system based on Samsung S3C2440, it's a low-power, high-performance, a wealth of I/O interface,using the Hall sensor point by point integration method calculated RMS of current. The input of the system is deviation and deviation rate between RMS of the current and setting current. The output is PID parameters of the amendment to the amount of the ? Kp, ? Ki, ? Kd. Through the Fuzzy Self-adaptive PID method, it can maintain welding current at the invariable level finally. Hardware includes the current signal detection circuit, the control of the SCR pulse generation circuits required for constant current control in spot welding, the input and output isolation and interface circuit and so on. The communication circuit we designed achieve the information exchanges among equipments and equipment and host computer, which solved the problem of"isolated island".In software systems, RTOS (Real Time Operating System) was applied to schedule the procedures of Spot welding controlling basied on fuzzy self-adaptive PID. Firstly, in software design, RTOS UC/OS-II was transplanted into EMPU. Secondly, based on the requirement, the Spot welding control system was divided into seven tasks, we designed software modles such as keyboard scan task, LCD display task, sampling of A/D task, data processing task, time and flow task and communication task basied on CAN ,ect. The priority of tasks were different, all of them were real-timely and high effectively scheduled by RTOS.The Spot welding control system proofer this paper brings forward has the function of gathering and dealing with real time data, communicating with the CAN bus and displaying the control results, etc. The control precision is effectively improved to a higher level, and it's is intelligent, has certain theory and project pratical value.