Research On Tension PID Control Technology Of Warp Knitting Machine Based On Genetic Algorithm

The tension is an important factor in fishing nets production process and the tension stability affects the quality of nets directly.Excessive tension affects the surface properties of warp wires,and may even leads to the breakage of warp wires,as a result,that seriously affects the production efficiency.The lack of tension causes the warp and mesh to be slack and shapeless.In order to improve the tension stability,the dissertation takes the tension control module of warp knitting machine as the research object in consideration of friction force,pendulum position and winding radius to analyze tension control system.The main work and conclusions are as follows:Firstly,the formation mechanism of the warp knitting machine tension is analyzed to determine the composition of the tension system.The mathematical model of each module of tension system is established,and the influencing factors: friction force,pendulum position and winding radius are analyzed.The control scheme using AC servo motor as the actuator is designed.Secondly,the mathematical model of the system is established,and the transfer functions of the executive motor,the pendulum motor and the system are also obtained.The fuzzy control and genetic algorithm are applied in PID controller to get used in industrial scene.The simulation of three kinds of PID control models are performed by SimuLink module in matlab.The results show that the overshoot of control system which applies GA PID is reduced to 1% and the adjustment time is reduced to 3s after the optimal solution is optimized for the objective function.At the same time,the fuzzy PID steady-state error and dead zone problem are also solved.Thirdly,PLC control interface of tension control is designed in order to realize real-time tension monitoring and visualization.The program of integral separation PID is completed to realize the real-time tension acquisition and online setting.EtherCat fieldbus communication is used between PLC controller and servo driver.The multi-axis synchronization experiment of EtherCat proves that the synchronization error between axis 1 and axis 6 is only 28 ns and this communication method can greatly reduce the synchronization error between multi-axis,so as to reduce the impact on tension control.Finally,experiments are carried out in rewinding and unwinding platform.After the program of tension control is debugged,the AC servo motor speed and torque are calibrated to obtain the initial position of the pendulum and the real-time winding radius.The results show that the fluctuation rate and static error rate of tension control system based on genetic algorithm PID controller are both around 3%.At the same time,the response time during the period of tension setting value changing is only 0.5s,the tension jitter error is controlled within 5%,the stability of the system has been greatly improved,and the system meets the actual demand of nets production.