## 1 Introduction
The servovalves are directly installed on the ring sides of the tension cylinders, and the feedforward calculation method of the servovalve flow can effectively eliminate the influence of pump pressure fluctuation and the pipeline effect, which significantly improves the tension control accuracy. However, this method is reliant on the accurate prediction of forward and backward slip. If the predictions of forward and backward slip are inaccurate, there will be large tension deviation. The forward and backward slip are related to the material, reduction rate, friction coefficient, and roller diameter, among many other factors. This makes accurate prediction difficult, especially when variable gauge rolling is carried out [11]. The uncertainty of forward and backward slip greatly affects the accuracy of tension control. Furthermore, there has also been much research on extraneous force compensation in electric-hydraulic load simulators. [PERSON] et al. derived the exact mathematical model of the control system, proposed the parameter-adaptive sliding-mode force control based on the reaching law and carried out experimental research. Their results fully demonstrated the effectiveness of the control method [12]. [PERSON] and [PERSON] proposed an innovative multilayer neuroadaptive controller to further improve the output force tracking performance of electro-hydraulic load simulators with uncertainty rejection, where closed-loop stability is guaranteed, and extensive comparative application results were achieved [13]. [PERSON] et al. proposed a novel system for dynamic surface disturbance rejection control with synchronous compensation to improve the torque tracking performance of electro-hydraulic load simulators, resulting in a closed-loop system with high precision and robustness [6]. [PERSON] et al. proposed an almost disturbance decoupling control strategy for solving the force control problem of an electro-hydraulic load simulator containing mechanical backlash. Both their simulation and experimental results demonstrated the advantages of the proposed control method [5]. However, the stiffness of the clamped object in the electro-hydraulic load simulator remained unchanged during the entire working process. The stiffness of the CRPM workpiece constantly changes at both the exit and the entry side of the rolling mill. In addition, forward and backward tension are established by the rolling mill and two tension cylinders, respectively, so the uncertainty of forward and backward slip in the rolling process results in a more complicated tension control process than in electro-hydraulic load simulators. Therefore, it is difficult to achieve the ideal tension control effect in CRPMs when using the method applied in electro-hydraulic load simulators. As can be seen, the robustness of the existing techniques is not strong, and the control results are unsatisfactory. It is therefore essential to propose a new strategy for improving the robustness and control precision of tension control. In this paper, tension models are first established, and the difficulties of tension control are analyzed in Section 2. Then, a new type of tension control strategy is proposed in Section 3. Next, simulation analysis and the field application are carried out to prove the effectiveness and advancement of the proposed control strategy in Sections 4 and 5. Finally, the conclusions are drawn in Section 6.