In order to realize the high-speed and high-precision movement of the direct drive system, it is important to study the strong robust control strategy of permanent magnet linear synchronous motor (PMLSM) servo system. This article proposes a high-order fast nonsingular terminal sliding mode control strategy for PMLSM based on double disturbance observer. The double disturbance observer is used to observe the mismatched/matched disturbances to reduce the conservativeness of the system to multiple disturbances. In addition, a high-order fast nonsingular terminal sliding mode controller is designed to enhance the robustness of the system. By adding feedback current into the controller, the overall control of current, speed, and position is realized. In addition, the steady-state performance and dynamic performance of position tracking system are improved. The stability and convergence of the closed loop system are proved by the Lyapunov stability theory. Experimental results show that the proposed strategy can effectively improve position tracking accuracy of the system and robustness to uncertain disturbances.
The direct-drive servo system of H-type platform is easily affected by load disturbance and mechanical coupling. In this paper, a discrete-time integral sliding mode position control method based on smooth saturation function is proposed. First, the discrete-time mathematical model of direct-drive servo system with mechanical coupling characteristics is established with the position and speed of mover as state variables. Then, a discrete-time integral sliding mode position controller is designed to reduce the influence of external disturbance, and improve the tracking accuracy of the system. At the same time, in order to weaken the chattering caused by the sign function in the control law, a smooth saturation function is designed to replace the original sign function, and the advantages of the smooth saturation function are analyzed and proved. Finally, the simulation and experimental results show that the proposed method not only improves the position tracking accuracy of the system, weakens the chattering, but also enhances the robustness of the system to load disturbance.
Aiming at the problem that the permanent magnet linear synchronous motor servo system is easily affected by uncertainties such as parameter perturbation, friction and load disturbance, an adaptive nonlinear speed tracking control strategy based on immersion and invariance theory is proposed in this paper. In the control strategy, the first-order dynamic system is taken as the target mode. By establishing the mapping relationship between the kinematic equation and the target system, a nonlinear controller suitable for speed tracking is designed by using the immersion and invariance theory. At the same time, an adaptive law based on the immersion and invariance theory is designed for the time-varying external load disturbance in the servo system, so that the adaptive parameters in the controller can asymptotically track the external load disturbance. By Lyapunov stability theory, it is proved that the closed-loop control system is globally uniformly asymptotically stable at the equilibrium point. Finally, the feasibility of the proposed control method is verified by experiments, and the dynamic performance and robustness of the system can be effectively improved.
The high robustness of the permanent magnet linear synchronous motor (PMLSM) servo system is the key to achieve high-speed and high-precision control of direct drive motion. In this paper, a high-order fast nonsingular terminal sliding mode control strategy for permanent magnet linear synchronous motor based on double disturbance observers (DDO) is proposed. A dual disturbance observer is designed to observe the mismatched /matched disturbances to ensure that the PMLSM system is robust to mismatched/matched disturbances. In addition, a high-order fast nonsingular terminal sliding mode controller (HFNTSMC) is designed to enhance the robustness to disturbance observation errors, and integrate the feedback current into it to realize the overall control of the position, speed and current, and improve the dynamic performance and steady-state performance of the position tracking system. Based on the Lyapunov stability theory, the stability and convergence of the closed-loop system are proved. The experimental results show that the system can effectively improve the tracking accuracy and robustness to uncertainty.
In the dual-motor servo system driven by permanent magnet linear synchronous motor, a synchronous control strategy based on coupling parameter identification algorithm and feedback linearization decoupling controller is proposed to overcome the influence of mechanical coupling on the synchronous control performance of the system. Firstly, the mathematical model of synchronous motion system with mechanical coupling dynamics is established. Secondly, a novel coupling parameter identification structure based on disturbance observer is designed. Additionally, the input excitation adopts relatively smooth sinusoidal position and velocity signals to avoid damage to the mechanical structure. Then the feedback linearization method is used to decouple the coupled synchronous control system, and the integrated sliding mode controller is designed for the linear subsystem to improve the robustness of the system. Finally, the experimental results show that the proposed identification method can accurately identify the coupling parameters of the system, and the feedback linearized sliding mode controller based on the identification parameters can effectively eliminate the influence of mechanical coupling and improve the performance of synchronous control.
In order to improve the position tracking control performance of permanent magnet synchronous linear motor under the influence of parameter perturbation, load disturbance and friction, an adaptive backstepping sliding mode controller based on immersion and invariance theory is proposed. Firstly, the dynamic model of linear servo motor motion system with uncertainty is established, and the backstepping method and the sliding mode control strategy based on the reaching law are designed and applied. Then immersion and invariance theory is introduced into the design of disturbance estimation error manifold. The selection of adaptive law realizes the invariance and attraction of the error manifold to ensure that the estimation error converges to zero. Finally, the simulation results show that this method improves the position tracking accuracy of the system and has a strong ability to suppress the influence of uncertainty such as parameter changes and load disturbances.
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