Cross-coupled Control Research Articles

Pre-Compensation Strategy for Tracking Error and Contour Error by Using Friction and Cross-Coupled Control

This paper focuses on improving the tracking accuracy for servo systems and increasing the contouring performance of precision machining. The dynamic friction during precision machining is analyzed using the LuGre model. The dynamic and static parameters in the friction model are efficiently and accurately identified using the improved Drosophila swarm algorithm based on cross-mutation. The friction tracking error can be deduced from the friction state space and an expression is derived. To compensate for the tracking error caused by friction, a feedforward compensation control is designed to avoid signal lag in traditional friction controllers. Furthermore, the factors of multi-axis parameter mismatching that impact the machining profile accuracy are analyzed for multi-axis control. An adaptive cross-coupled control-based pre-compensation strategy of contour error is designed to reduce both the tracking error and the contour error. The effectiveness of the proposed method is validated through several experiments, which demonstrate a remarkable improvement in tracking performance and contour accuracy.

Counter-rotating synchronization theory and experiment of tri-rotor actuated with dual-frequency considering adaptive global sliding mode control strategy

In petroleum drilling engineering, self-synchronous vibration screen with single-frequency actuation is difficult to implement the scheduled synchronous behavior caused by its invariance and instability of dynamic characteristics, which usually leads to reduction of the production efficiency. Hence, to solve the problem mentioned above, a dual-frequency counter-rotating synchronization control method among three exciters is presented by combining adjacent cross-coupling control (ACCC) structure with global sliding mode control (GSMC) theory. Firstly, motion differential equation of the vibration system in each direction is derived according to mathematical model of the tri-rotor vibration machine. Secondly, considering exponential reaching law and adaptive control algorithm, the adjacent cross-coupling controller and the vector controller of each induction motor are investigated to achieve the stable zero phase difference synchronization between double-frequency rotors. Subsequently, Runge-Kutta method is introduced to establish the electromechanical coupling control model and prove validity of the control theory. Meanwhile, it is also discussed that the rotors cannot obtain an ideal self-synchronization state since velocity of high-frequency motor is not strictly equal to twice that of low-frequency motor. Finally, based on the experimental test scheme, an experimental prototype related to controlled multi-rotor synchronization vibration system is designed independently, which further verifies the validity of theory and computer simulation. Research shows that the desirable synchronous state of the vibration system can be accurately controlled via the designed control strategy, and the control system can implement diversity of the dynamical characteristics, due to the existence of strong robustness.

Contour error control for the biaxial system based on active disturbance rejection generalised prediction

ABSTRACT For the purpose of contour error control in two-axis systems, a cross-coupled controller utilising auto-disturbance rejection generalised predictive control and nonlinear proportional differentiation is proposed. The contour error components along each axis are estimated by utilising the information from the nearest reference point and its adjacent reference points. The combination of ADRC and GPC is utilised for uniaxial tracking control. The LESO is utilised for estimating and compensating for the total disturbance of the system while simplifying it into two cascaded integrators. Because GPC is designed only for the series form of the integrator, the dependence on mathematical models is reduced. A nonlinear cross-coupled controller is designed utilising the fal function, with compensation control quantities for each axis directly obtained from their respective contour error components. Finally, the results obtained from the simulation demonstrate that the control strategy can availably enhance the performance of single-axis tracking and contour processing.

Trajectory planning and control strategy optimization design of double electric cylinder erecting device

The transition of the rocket from a horizontal to an erect state before its launch on the offshore platform is a crucial stage. Compared with erecting the rocket on the ground, higher servo control and synchronization accuracy are required for erecting it on the offshore platform. Most rocket erecting devices on offshore platforms rely on hydraulic drive systems, posing challenges due to their lower servo control accuracy and difficulties in achieving high-precision synchronization. The erecting process, trajectory planning, control system, and control strategies of rockets driven by a double electric cylinder erecting device are studied, aiming at the requirement of erecting rocket devices on offshore platforms. This paper commences by establishing the kinematic model of erecting the rocket with a double electric cylinder erecting device. It delves into the process and trajectory of the erection rocket with a double electric cylinder erecting device. Subsequently, the focus shifts toward designing the control system, while inclination and angular velocity sensors monitor the erection process. Finally, designing and demonstrating control strategies for a double electric cylinder erecting device, three different control strategies, master control, master-slave control, and cross-coupling control, are analyzed, and the cross-coupling control strategy is selected as the control strategy of the double electric cylinder offshore platform rocket erecting device.

Nonlinear model predictive control—Cross-coupling control with deep neural network feedforward for multi-hydraulic system synchronization control

This paper studies a multi-hydraulic system (MHS) synchronization control algorithm. Firstly, a general nonlinear asymmetric MHS state space entirety model is established and subsequently the model form is simplified by nonlinear feedback linearization. Secondly, an entirety model-type solution is proposed, integrating a nonlinear model predictive control (NMPC) algorithm with a cross-coupling control (CCC) algorithm. Furthermore, a novel disturbance compensator based on the system's inverse model is introduced to effectively handle disturbances, encompassing unmodeled errors and noise. The proposed innovative controller, known as nonlinear model predictive control—cross-coupling control with deep neural network feedforward (NMPC-CCC-DNNF), is designed to minimize synchronization errors and counteract the impact of disturbances. The stability of the control system is rigorously demonstrated. Finally, simulation results underscore the efficacy of the NMPC-CCC-DNNF controller, showcasing a remarkable 60.8% reduction in synchronization root mean square error (RMSE) compared to other controllers, reaching up to 91.1% in various simulations. These results affirm the superior control performance achieved by the NMPC-CCC-DNNF controller.

Research on electro-hydraulic position servo synchronous control system based on adaptive robust control

A control method combining adaptive robust control with cross-coupling control is designed to address the issues of model uncertainty, nonlinear friction, and external interference in electro-hydraulic servo systems. We have established a nonlinear model of the system and designed an adaptive robust controller. Further simulation studies have shown that the control method designed in this paper has better control performance and stronger anti-interference ability than PID control and still has good control performance under continuous interference.

Tangential velocity tracking-based cross-coupled control method with variable feedrate for biaxial parametric curve following

To address the inaccurate contour error calculation problem in traditional cross-coupled control (CCC) methods for biaxial motion systems, this paper presents a novel CCC method based on a recently developed tangential velocity tracking (TVT) strategy. It has the advantage that existing high-precision algorithms for searching the foot point can be directly integrated to obtain the excellent estimation accuracy of contour error. The cumbersome parameter tuning for position controllers of each axis is unnecessary. Moreover, a velocity interpolator for parametric curves is developed to extend the TVT strategy to the variable feedrate case. The stability of the TVT-based CCC system is proved using a quadratic Lyapunov function. Comparative experiments are carried out, and the results indicate that the estimation deviation of contour error in the TVT-based CCC method can be constrained within 1 μm. The maximum contour error is significantly reduced by 65.32% and 50.10% compared with the traditional CCC methods based on tangential and circular approximations, respectively.

Collocated control of double electric pushrod in a harvester header based on an improved gray wolf PID algorithm

In order to further enhance energy conservation and emission reduction, the header lifting structure of a harvester is studied. First, a double electric pushrod structure is used to replace the oil cylinder and air cylinder lifting structure of a traditional header to reduce fuel consumption and harmful gas emission. Furthermore, a mathematical model and a simulation model of the electric pushrod are established. To enhance the control effect of the header lifting structure, an improved version of the traditional gray wolf optimization (GWO) algorithm is designed. The nonlinear convergence factor, Kent chaotic mapping and convergence surrounding and spiral updating operations are introduced to increase the convergence speed and optimization accuracy of this algorithm. The improved GWO (IGWO) algorithm is applied to optimize the proportional-integral-derivative (PID) controller of the double pushrod coordinated control system. Then, a new IGWO-PID control algorithm is also designed. The cross-coupling control strategy of header’s double pushrods is then studied. Results of the simulation and bench test show that the IGWO-PID control algorithm and the cross-coupling control strategy can effectively enhance controlling effect of the harvester header. The left and right pushrods can achieve good synchronous and coordinated movements.

Study of Multi-motor Synchronous Operation Based on Sliding Mode Virtual Spindle Adjacent Cross-coupling Control

Aiming at the problems of uneven parameter differences and load torque distribution, which cause the tracking accuracy and synchronization performance of the multi-motor control system to be reduced, a multi-motor system control strategy with sliding mode virtual spindle adjacent cross-coupling control is proposed. First, the feedback torque of each motor is regulated by establishing a virtual spindle to improve the coordination of the system. Secondly, a speed compensator is designed to couple each motor to improve the system synchronization. Meanwhile, the sliding mode control strategy is used for the control of a single motor. The robustness and tracking accuracy of the system are tuned up. The simulation experiment results show that compared with the sliding mode cross-coupling control, sliding mode adjacent deviation coupling control, and PI virtual spindle-adjacent deviation coupling control, the system has a small synchronization error, strong anti-interference ability, and realizes high-precision coordinated control of multiple motors.

A double-iterative learning and cross-coupling control design for high-precision motion control

A double-iterative learning and cross-coupling control design for high-precision motion control

Adjacent Cross-coupling Control for Magnetic Levitation System with Ultra-local Sliding Mode Algorithm

Adjacent Cross-coupling Control for Magnetic Levitation System with Ultra-local Sliding Mode Algorithm

Research on Multiple-Axis Contour Error Suppression Method Based on Composite Layered Control

With the widespread application of multi-axis machining in the industrial manufacturing, aerospace, and military equipment sectors, the demand for machining ultra-precision components has been steadily increasing. Contour errors directly impact the quality of machined parts. In conventional multi-axis motion control systems based on cross-coupling, it is conventionally assumed that all individual axes are of equal significance during machine processing. However, in practical machining scenarios, diverse machining trajectories and accuracy requirements give rise to distinct control necessities for each axis. This complication leads to challenges in ensuring a consistent single-plane contour, thereby constraining the elevation of the overall contour accuracy. To address this issue, this study proposes a multi-axis contour error suppression method based on composite hierarchical control. The approach advocated in this paper initially ensures the precision of single-axis position control through the development of an advanced S-shaped function-based sliding-mode disturbance observer. Building on this foundation, the three-dimensional spatial contour is segregated into upper and lower layers. Subsequently, dedicated fuzzy PID cross-coupling controllers are devised for each layer. The experimental outcomes substantiate that in comparison to conventional cross-coupling control methods, the method introduced in this study, rooted in composite hierarchical control, not only guarantees the accuracy of single-plane contours but also further enhances the overall contour precision.

Cross-coupling control design of a flexible dual rotor wind turbine with enhanced wind energy capture capacity

In order to improve the reliability of wind turbine grid connection and reduce the cost of wind power generation, this paper studies a counter-rotating dual rotor wind turbine (DRWT) which consists of decoupled driven-train subsystems, a triple-terminal converter and a dual rotor generator. For this new-type wind energy conversion system, its modeling and control strategy need to be studied. Firstly, mechanism model of the DRWT with a new structure is constructed. By investigating the effects of pitch angles and rotor speeds on output power, respectively, the maximum power output condition of the DRWT is obtained. Considering the overall energy conversion efficiency and mechanical load constraints, the optimal regime of the DRWT is established. Based on the optimal torque algorithm and cross-coupling control strategy, this paper presents a novel cross-coupling control strategy for the DRWT to track maximum power. The proposed strategy can regulate the rotor speed of the front and rear rotors, enabling DRWT to operate on the optimal speed combination curve. Finally, the hardware-in-the-loop experiment is built to test the performance of the proposed strategy under various wind conditions. The simulation results verify that the proposed strategy can improve power generation, and analysis shows that the proposed strategy fundamentally alters the energy capture ratio between the front and rear wind turbines to optimize total output power.

Individual drive cross-coupled control system to compensate for measurement time-delay for roll-to-roll contact pressure uniformization

Individual drive cross-coupled control system to compensate for measurement time-delay for roll-to-roll contact pressure uniformization

Research on self-coupling PID for multi-driven synchronization control with ring adjacent compensation

Multi-motor synchronous drive system is increasingly widely used in industry and manufacturing, where its control structure and control strategy affect the quality and efficiency of production. In order to solve the contradiction between fastness and overshoot, and the difficulty in determining the compensation law in the conventional PID, cross-coupling control, and master-slave control strategies used in multi-motor control, this paper proposes a self-coupling PID control strategy based on ring adjacent compensation to reduce the complexity of the control structure. Furthermore, this paper analyzes the self-coupling PID parameter tuning rules and establishes the control structure of the ring coupling strategy, and proves its validity mathematically. The simulation results verify that the proposed strategy provides a fast response speed, high control precision, good disturbance rejection, and synchronization performance.

Toward a sustainable transition in automated production: enabling the vision-based approach and synchronous control for textile surface inspection systems

The textile and apparel industry is one of the largest industries in the world, with significant environmental and social impacts, such as manual labor in poor working conditions and resource depletion and environmental degradation due to ineffective production. As a result, there is an increasing need for sustainable practices and a transition toward a more circular and responsible industry. In this paper, we introduce the proposed approach in the context of a sustainable transition for the industrial textiles. Instead of human labor, the automated solution to detect defects is proposed for the 4.0 revolution in general and the textile industry in particular. Specifically, the mechanical design of a three-dimensional model for small- and medium-sized fabric rolls is portrayed. Some computational mechanics are created to ensure a stable mechanism and proper actuators. For acquiring accurate data and measuring the machine state, several installations, that is, a digital camera, load cell, and positioning sensor, and the layout of the light source are improved to intensify the image quality. The control theme, such as the cross-coupling controller, offers superior performance in synchronization and vibration-less motion. Lastly, the excellent detection method is provided by the convolutional neural network scheme for offline training to distinguish defects on products. Instead of a manual check or low rate of defect detection on products, the contributions of this research are as follows: (a) analyzing the mechanical design of the textile machining system in terms of dynamic characteristics; (b) implementing a smooth scheme based on motion control synchronization; and (c) integrating various strategies, including vision-based computation and control topology, to demonstrate superior performance. These results highlight that our approach can be widely adapted to address sustainability challenges not only in the textile field but also in global manufacturing practices.

Synchronization control of blanket remote maintenance robot based on MPC-CCC algorithm

AbstractThis paper studies the synchronization control of the blanket remote maintenance robot (BRMR) of the China fusion engineering test reactor (CFETR). First, the general state space mathematical model of BRMR was established by using a physical-based method. Second, based on the receding horizon optimization of model predictive control (MPC) and cross-coupling error reduction in cross-coupling control (CCC), the innovative MPC-CCC controller was proposed to realize the single-system and multisystem error convergence and high accuracy transportation of blanket through the high accuracy synchronization control of BRMR. Third, to verify the control effectiveness of the MPC-CCC controller, two types of simulations and experiments were implied compared with the original proportional-integral (PI) controller in Mover. Results showed that simulation and experiments were highly consistent. It is found that the use of an MPC-CCC controller can result in up to a 70% reduction in displacement error and up to a 59% reduction in synchronization error compared to the PI controller. And the accuracy of the MPC-CCC controller satisfies the real requirement of the maintenance process of the blanket. This work provides the theoretical basis and practical experience for the highly stable, safe, and efficient maintenance of blankets in the future.

Frequency-multiplying synchronous control of the multiple counter-rotating exciters in vibration system

Frequency-multiplying synchronization vibration system is beneficial to diverse the material screening and improve the screening efficiency. In order to solve the problems of insufficient frequency-multiplying synchronous theory and low synchronization precision of the multiple exciters in vibration systems, the dynamic model of the frequency-multiplying synchronous vibration system with multi-vibration exciters is first established. A combined control strategy including the master-slave control and the adjacent cross-coupling control strategy is then proposed, together with the adaptive sliding mode algorithm to realize the frequency-multiplying synchronous control for the multiple exciters in vibration system. The stability of the proposed multiple exciters under frequency-multiplying synchronous control is proved by Lyapunov theorem and Barbalat Lemma. The performance of the proposed controller of frequency-multiplying synchronization is illustrated by comparing the simulation analysis with the vibration synchronization method at double frequency. The results show that the proposed controller of frequency-multiplying synchronization can effectively control the multiple exciters in vibration system to achieve the frequency-multiplying synchronous motion with improved control precision. The influence of different parameters on the performance of the frequency-multiplying synchronization is discussed, which shows that the controller of frequency-multiplying synchronization has good robustness against the system parameter disturbance. On this basis, the synchronization performance of the multiple exciters under different multiplied frequencies are analyzed and explained. The proposed combined control strategy can control the frequency-multiplying synchronization of the multiple exciters in the vibration system to achieve the required stable vibration trajectory.

Speed Synchronization Control of Dual-SRM Drive With ISMC-Based Cross-Coupling Control Strategy

To improve the speed synchronization performance of dual switched reluctance motor (SRM) drive with traditional sliding mode control (TSMC), the improved sliding mode control (ISMC) based cross-coupling control strategy is proposed. Firstly, the overall control structure of the dual-SRM drive is represented. Secondly, the state variable is introduced to reduce the torque fluctuation and adjustment time of the dynamic process of each SRM drive in the system based on the traditional sliding surface and sliding mode reaching law. The adaptive law is introduced into the sliding mode controller to avoid the load torque observation. Thirdly, the ISMC-based cross-coupling control method for the speed synchronization of the dual-SRM drive is designed. The novel sliding surface is proposed considering the speed synchronization deviation. The novel sliding mode reaching law is represented by introducing the state variables. Then the ISMC-based cross-coupling control method is realized for speed synchronization. The stability is proved by Lyapunov function. Simulations and experiments are implemented to verify the effectiveness of the proposed method.

Design of a trajectory contour controller for a dual‐axis precision motion stage based on improved iterative learning

AbstractTo solve the problem of contour error (CE) arising from the dual‐axis coupling of the X–Y coordinate planar motor stage under reciprocating motion conditions in integrated circuit (IC) manufacturing, the following two perspectives are considered: indirect intervention from a single‐axis servo tracking error (TE) control and direct intervention from a dual‐axis cross‐coupling control (CCC). An improved motion controller is designed using the iterative learning control (ILC) principle in conjunction with the motion characteristics of the dual‐axis mechanism. Specifically, the variable gain iterative learning controller with a variable forgetting factor (VFF‐VGILC) is designed to address the characteristics of single‐axis trajectory repetition and variable velocity planning in dual‐axis coupling. The significance of the VFF‐VGILC is to increase the servo control bandwidth of a single axis. On the other hand, the cross‐coupled iterative learning controller (CCILC) is designed on the dual‐axis cross‐coupling, while a pre‐compensation strategy is introduced in the CCC structure to form the pre‐CCILC. After experimental designing and testing are performed, the X–Y coordinate planar motor stage can effectively reduce the CE under various trajectory movements compared with the traditional controller. The trajectory curves drawn can meet the motion control requirements better and effectively enhance the motion control capability of the mechanism.