Research On Servo Control Techniques For Welding Feed Table

With the backdrop of welding automation technology, this paper's research major in the servo control of the machine's feed system based on self-constructed welding feed table. According to the problems which would be faced when the table is running actually, such as the detection of touch state for workpiece and welding pole, the low velocity smooth properties, and synchronized driving for dual-motor on the vertical direction, the solving scheme is opened out and given, so the theory basic is founded for realization of the feed table.On the foundation of the designed collectivity program of the control system and the analysis of mathematics model for the feed transmission system, the paper would solve the actual problem one by one. Firstly, a method of measuring motor output torque is raised to insure the close touch state of workpiece and downer welding pole, and a kind of new strain gauge torsion sensor which bases on force and counterforce is designed to achieve the function.Then, the measured torque signal is further used to analysis the friction status while the table is on low-speed operation, the Stribeck friction model is established in order to design the PID control algorithm based on friction feedforward compensation. From Matlab simulation study, the results prove that friction feedforward compensation for the servo control system can improve the operation of low-speed stability, and reduce the creeping phenomenon.Finally, against the dual-motor synchronized driving problem which is caused by large span of workpiece on the vertical direction, the velocity error feedback is proposed and analyzed to get its effect on static and dynamic performance of the system. The simulation results make know that the velocity error feedback method which is adopted PI control can make the dual-motor system keep pace synchronous while tracking speed step signal, even make it track uniform accelerate signal in some specific circumstances. The experiment also validate the velocity error feedback is valid and feasible.