Study On Jacquard Control Technology For Multi-Color And Multiheight Tufting Machine

The introduction of multi-color and multi-height tufting technology is a leap in the history of tufted carpets.The multi-color and multi-height tufted carpet produced by this technology is more delicate in color and clearer in pattern texture and make further promotion to the development of tufted carpet industry.The international mainstream of multi-color and multi-height tufted carpet can achieve 6 kinds of colors,the pile height can be set as any value between 1-16mm(that is,"infinite pile height"),but at present,the pattern resolution of multi-color and multi-height tufted carpet is very difficult to achieve the accuracy to one pin.Moreover,the production efficiency is relatively low.There are three main factors that restrict the product quality and production efficiency of tufted carpet machine.The first is the “rigid-flexible” dynamic coupling relationship between individual actuators and the yarn in the jacquard control system.During the operation of the mechanism,mechanical parts such as jacquard rollers,aluminum rollers,and needle bars act on the yarn speed and tension.It directly affects the inherent characteristics of the yarn,in which the dynamic performance of the needle shifting system has a significant effect on the yarn vibration.The second is the synchronization capability of the multi-motor stitch control system.The needle bar shifting system controls the needle bar to move according to the set cam profile.The tension and needle rate of the backing material is controlled by the backing material feed system.The stitch rate on the surface of multi-color and multi-height tufted carpets,the synchronization effect of the multi-motor stitch control system affects the needle position on the carpet surface and the precision of stitch rate.The third is the control precision and synchronization ability of the large-scale electronic roller yarn feed system.The yarn feed system adjusts the speed of the electronic roller in real time according to the spindle signal,and dynamically realizes the control of the amount of yarn feeding and yarn tension.This article focuses on the factors affect the accuracy and production efficiency of multi-color and multi-height tufted carpets,the nonlinear vibration characteristics of the yarns in the jacquard control system,the dynamic performance of the needle shifting system,and the synchronization ability of the multi-motor stitch control system and the synchronization control strategy of large-scale electronic roller yarn feed systems and other issues were studied:Firstly,the dynamic mechanical behavior of high denier viscoelastic yarns,which is the control object of the multi-color and multi-height tufting carpet machine jacquard control system,is studied.In the process of weaving tufted carpets,the high denier viscoelastic yarns combine the deformation characteristics of elastic solids and viscous fluids,and there are transmission characteristics of tension change and deformation delay.In view of the viscoelastic characteristics of high denier yarn,the yarn constitutive model is established based on the improved linear viscoelastic method and nonlinear viscoelastic method,and the validity of the model is verified by experiments.In view of the problem that yarn is very sensitive to outside interference at high speed,such as the vibration of the needle bar shifting system,the fluctuation of the speed of jacquard electronic roller,the synchronous motion effect of multi-motor in jacquard control system will lead to the change of yarn axial motion speed and tension.The vibration characteristics of viscoelastic yarn bundles are deeply studied.It is concluded that the change of yarn tension and speed has great influence on yarn vibration,and the key to the pattern resolution of tufted carpet is the precise control of yarn feeding and dynamic tension.On the basis of deeply studying the dynamic characteristics of yarn,the vibration control technology is studied in this paper,and the mathematical model of needle bar shifting system of tufted carpet machine is established,aiming at the exciting source of yarn vibration-needle bar shifting system.According to the frequency domain characteristic of the system,the system is corrected and compensated,and a double T notch filter is designed for the specific resonance point of the system.In order to be practical,different methods are used to discretize the notch filter,and a comparative analysis is made: the gain and phase margin distortion will exist when the zero order hold and the first order hold are discretized.The pre-deformed bilinear approximation method is closer to the control effect of continuous notch filter in frequency domain.The model simulation and experiments show that the method has a good effect on suppressing the natural vibration frequency of the needle bar shifting system,and the amplitude of the system vibration is greatly reduced.It can be predicted that this method can also be applied to the vibration suppression of yarn and other mechanisms such as jacquard roller.When the vibration of a single mechanism is restrained and the dynamic performance is improved,the precise position control of multiple motors is considered,and the multi-motor stitching control problem in the jacquard control system of multicolor and multi-height tufting carpet machine is considered.This paper presents a SOAPID self-tuning control strategy based on seeker optimization algorithm,which simplifies the tuning procedure of PID controller,improves the parameters optimization effect,and improves the dynamic response ability and tracking accuracy of multi-motor.In order to eliminate the synchronization error quickly,a speed compensator based on wavelet neural network is designed,which combines the approximation accuracy and learning ability of wavelet neural network to arbitrary function.Compared with the fixed gain compensator,the experimental results show that the intelligent control algorithm based on wavelet neural network can obtain strong synchronization tracking ability and robustness,and can improve the synchronization accuracy of multi-motor needle control system.Furthermore,the position of tufted needle and stitch rate of carpet surface are controlled accurately.In order to improve the control accuracy and production efficiency of the jacquard control system,multi-motor cooperative control of yarn feeding system is needed after the rapid and accurate control of carpet stitch in multi-color and multi-height tufted carpet.In this paper,two high performance intelligent control algorithms are proposed for the synchronization control strategy of multi-motor systems,but these algorithms are relatively complex and have a relatively large amount of computation.And with the increase of servo axis,the controller and control network hardware performance will put forward very high requirements.Due to the large number of jacquard electronic rollers,in order to analyze and solve the control accuracy and synchronization ability of the large scale electronic roller yarn feeding system,a dynamic model of the group control coupling system of the jacquard electronic roller is established in this paper.Considering the technological requirements of the jacquard control system of tufted carpet machine in the actual production process and considering the minimum cost of the traction control node to make the system achieve the control goal,a pinning synchronous control strategy for cluster electronic roller group control coupling system is proposed.The simulation results show that each node in the system can quickly converge to the set synchronization state by using the proposed pinning synchronization control strategy.The dynamic model of group control coupling system of jacquard electronic roller and the synchronous control strategy of pinning control provide a theoretical basis for improving the resolution of multi-color and multi-height tufted carpet.In this paper,a series of theoretical and experimental studies have been carried out on the jacquard control accuracy and production efficiency of the jacquard control system of multi-color and multi-height tufting carpet machine.The related control techniques can effectively improve the precision and production efficiency of the jacquard control.It can provide theoretical guidance for the design,manufacture and process development of high efficiency and high precision tufted carpet machine in China.