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Force Ripple Modeling and Minimizing of an Ironless Permanent-Magnet Linear Synchronous Motor
Shengchao Zhen,Panpan Chen,Xianmin Chen,Feifei Qin,Huixing Zhou 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.6
A force ripple model considering both non-ideal magnetic field and windings was developed to study methods for the suppression of the force ripple in an ironless permanent-magnet linear synchronous motor (PMLSM) to improve its low speed stability and position tracking performance. With this new model, which uses the d-q reference frame, the force ripple information could be calculated at discrete positions using the winding features and magnetic flux density (MFD). A PMLSM with two movers and one stator was designed to measure the air gap MFD and force ripple at different positions. The reliability of the model was validated through a comparison of the force ripple data obtained with the new model and practical measurements. The error ratio between the theoretical calculations and measured forces was less than ± 4%. Force constants were available from the model using the measured MFD, and these force constants were then used as force compensation coefficients to adjust the current in terms of the mover’s position. The force ripple, particularly the periodic force ripple causing resonance of the mechanical system, was significantly reduced with compensation. The theoretical analysis and experimental results show the effectiveness of the improved model.
Kang Huang,Mianhao Wang,Shengchao Zhen 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.7
A new adaptive robust control method based on Udwadia-Kalaba(U-K) approach which can be applied to the underactuated system is designed and used to a two-wheeled inverted pendulum system in this paper. We separate this typical underactuated system into two subsystems(forward subsystem and yaw subsystem), which are fully underactuated and actuated. For these different subsystems, we use different control methods. We apply an adaptive robust control method which has been proved many times to the fully actuated subsystem. Based on thisadaptive robust method, a new control strategy can be redesigned and applied to the underactuated subsystem by modifying the adaptive law and other things. This adaptive robust control with a leakage-type adaptive law could guarantee the uniform boundedness and uniform ultimate boundedness of the system. Finally, the simulation is executed to demonstrate the advantage and simplicity of the proposed method.
Feifei Qin,Han Zhao,Shengchao Zhen,Hao Sun,Yan Zhang 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.1
This study designs a control of two-degree of freedom lower limb rehabilitation robot (LLRR) for the patient who needs the proper physical therapy after a spinal cord injury (SCI), stroke, or a surgical operation. The robot manipulator can perform specified passive exercises as well as copy exercise motions and perform them without the physiotherapist. Specifically, the uncertainties including the model uncertainty, initial condition deviation and the external disturbance are also considered. Firstly, a unilateral man-robot dynamical model is proposed based on Lagrange method. Then, we propose a Lyapunov based robust control to suppress the effect of uncertainties. The control algorithm consists of a PD feedback component and a piecewise function component. Theoretical analysis is provided to demonstrate that the controller can guarantee the uniform boundedness and uniform ultimate boundedness of the system. Moreover, the joint angle trajectory of a healthy person is explicitly obtained by the experimental platform and used as the pre-specified trajectory of the LLRR. Finally, numerical simulation is presented to illustrate the effectiveness and the trajectory-tracking control performance of the control.