This research proposes a new system for controlling yarn tension in the winding operation based on active disturbance-rejection control (ADRC) technology, which controls and minimizes the fluctuation of tension during winding. The mechanical structure of the winding machine was analyzed to clarify the main factors affecting the yarn tension. Proportional–integral–derivative (PID) control is the most common control method of the winding machine. In order to compare the control effects of ADRC and PID control, the mathematical model of the yarn-tension control system was established on the MATLAB platform by means of system identification. Through the simulation on this model, the results showed that under the action of disturbance, the overshoot of the yarn tension controlled by the active disturbance-rejection controller was smaller, the adjustment time was shorter, and the steady-state error was smaller. An experimental platform was built to test the control effect of the controller under different parameters, thereby verifying the performance and stability of the active disturbance-rejection controller. The results showed that the controller had good performance and stability.

A conical winding formation and tension control system was proposed in the doubling operation based on the yarn guide mode of a single spindle in this study. Conical winding formation realized the radial unwinding of wound package. An overfeed mechanism was introduced to achieve closed-loop control of yarn tension. The overfeed wheel was driven by a brushless Direct Current motor. The tension control system combined a Proportion Integration Differentiation controller with a radial-basis-function neural network, whose purpose was to meet the control requirements of the brushless DC motor. This system consisted of three main steps: Firstly, the radial-basis-function neural network was used to identify the system online. Secondly, the gradient descent method was used to adjust the node weight, center vector, and baseband width. Finally, incremental PID parameters online were adjusted according to the identified Jacobian information. A mathematical model of a control system was established in Matrix Laboratory. An experimental platform was designed for doubling winder to compare the control effects of Radial-basis-function-PID with traditional PID. The simulation results showed that the RBF-PID had a smaller overshoot of yarn tension, shorter adjustment time, and smaller steady-state error compared with the traditional PID controller in doubling operation by simulating the mathematical model. Experimental results showed the RBF-PID controller had good performance and stability and could be applied to yarns with different average linear velocity, yarn counts and strands . The yarn tension fluctuation will not exceed ±3% of the target value when the experimental materials and the cone angles are unchanged.

Entropy generation rates in two-dimensional Rayleigh–Taylor (RT) turbulence mixing are investigated by numerical calculation. We mainly focus on the behavior of thermal entropy generation and viscous entropy generation of global quantities with time evolution in Rayleigh–Taylor turbulence mixing. Our results mainly indicate that, with time evolution, the intense viscous entropy generation rate $s_u$ and the intense thermal entropy generation rate $S_{\mathsf{\theta }}$ occur in the large gradient of velocity and interfaces between hot and cold fluids in the RT mixing process. Furthermore, it is also noted that the mixed changing gradient of two quantities from the center of the region to both sides decrease as time evolves, and that the viscous entropy generation rate ${⟨S_u⟩}_V$ and thermal entropy generation rate ${⟨S_{\mathsf{\theta }}⟩}_V$ constantly increase with time evolution; the thermal entropy generation rate ${⟨S_{\mathsf{\theta }}⟩}_V$ with time evolution always dominates in the entropy generation of the RT mixing region. It is further found that a “smooth” function ${⟨S_u⟩}_V\sim t^{1/2}$ and a linear function ${⟨S_{\mathsf{\theta }}⟩}_V\sim t$ are achieved in the spatial averaging entropy generation of RT mixing process, respectively.

The contact pressure control issue in the precision winding process significantly affects the yarn package density and overall quality. The following work was done to address this challenge. An analysis of the mechanical structure of precision winding machines was conducted to establish a nonlinear mathematical model of contact pressure in precision winding. MATLAB was used for the simulation, which validated the nonlinear relationship between the contact pressure and yarn package diameter variations during the winding process. A novel contact pressure control algorithm utilizing ant colony optimization (ACO) for proportional–integral–derivative (PID) control was proposed to enhance the stability of the contact pressure and improve the yarn package quality. An experimental platform for a precision winding doubling machine was developed, and the controller’s performance was evaluated for various parameters, including different types and thicknesses of yarn. This approach verified the efficacy of the theoretical model and the control algorithm. The ACO-PID control method exhibited superior accuracy and stability, compared with traditional control methods, improving the yarn package quality and achieving a 20.24% reduction in pressure fluctuations. These results address key technical issues in contact pressure control within the industry, providing an innovative solution for enhancing the quality of precision wound yarn packages.

A mechanical model for the precision winding of yarns was established to address uneven residual tension in wound packages during precision winding. Based on the precision winder, a constant residual tension control method was proposed to ensure uniform residual tension in precision winding, which improved package quality and consistency. A proportional–integral–derivative (PID) control strategy was used to regulate the overfeed roller motor’s speed, and the winding tension was adjusted based on the speed difference between the overfeed and take-up rollers. This ensured consistent circumferential tension of yarns on the inner winding layer, which achieved optimal tensile strength for each layer during precision winding. Compared with constant winding tension control, this method prevented yarn slippage due to negative tension. It also offset the relaxation effect of newly wound yarns on previously wound layers. Packages wound with the constant residual tension had a more stable and uniform winding density than those with the constant winding tension.