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《ISA transactions》2014,53(6):1892-1900
Two-dimensional gyroscopic torque can be produced by tilting the rotor shaft of the active magnetically suspended momentum wheel. The nonlinear magnetic torque is analyzed and then an adaptive back-stepping tracking method is proposed to deal with the nonlinearity and uncertainty. The nonlinearity of magnetic torque is represented as bounded unknown uncertainty stiffness, and an adaptive law is proposed to estimate the stiffness. Combined with back-stepping method, the proposed method can deal with the uncertainty. This method is designed by Lyapunov stability theory to ensure the stability, and its effectiveness is validated by simulations and experiments. These results indicate that this method can realize higher tracking precision and faster tracking velocity than the conventional cross feedback method to provide high precision and wide bandwidth outputting torque. 相似文献
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A novel prescribed performance neural controller with unknown initial errors is addressed for the longitudinal dynamic model of a flexible air-breathing hypersonic vehicle (FAHV) subject to parametric uncertainties. Different from traditional prescribed performance control (PPC) requiring that the initial errors have to be known accurately, this paper investigates the tracking control without accurate initial errors via exploiting a new performance function. A combined neural back-stepping and minimal learning parameter (MLP) technology is employed for exploring a prescribed performance controller that provides robust tracking of velocity and altitude reference trajectories. The highlight is that the transient performance of velocity and altitude tracking errors is satisfactory and the computational load of neural approximation is low. Finally, numerical simulation results from a nonlinear FAHV model demonstrate the efficacy of the proposed strategy. 相似文献
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This paper investigates the problem of spatial curvilinear path following control of underactuated autonomous underwater vehicles (AUVs) with multiple uncertainties. Firstly, in order to design the appropriate controller, path following error dynamics model is constructed in a moving Serret–Frenet frame, and the five degrees of freedom (DOFs) dynamic model with multiple uncertainties is established. Secondly, the proposed control law is separated into kinematic controller and dynamic controller via back-stepping technique. In the case of kinematic controller, to overcome the drawback of dependence on the accurate vehicle model that are present in a number of path following control strategies described in the literature, the unknown side-slip angular velocity and attack angular velocity are treated as uncertainties. Whereas in the case of dynamic controller, the model parameters perturbations, unknown external environmental disturbances and the nonlinear hydrodynamic damping terms are treated as lumped uncertainties. Both kinematic and dynamic uncertainties are estimated and compensated by designed reduced-order linear extended state observes (LESOs). Thirdly, feedback linearization (FL) based control law is implemented for the control model using the estimates generated by reduced-order LESOs. For handling the problem of computational complexity inherent in the conventional back-stepping method, nonlinear tracking differentiators (NTDs) are applied to construct derivatives of the virtual control commands. Finally, the closed loop stability for the overall system is established. Simulation and comparative analysis demonstrate that the proposed controller exhibits enhanced performance in the presence of internal parameter variations, external unknown disturbances, unmodeled nonlinear damping terms, and measurement noises. 相似文献
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针对Boost变换器中负载的不确定性或干扰不满足匹配条件的情况,设计了鲁棒反步滑模控制器,可使Boost电路的输出电压快速达到期望值,且稳态误差很小。最后用仿真结果验证了本文所提方法的可行性。 相似文献
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A variable-displacement pump controlled pitch system is proposed to mitigate generator power and flap-wise load fluctuations for wind turbines. The pitch system mainly consists of a variable-displacement hydraulic pump, a fixed-displacement hydraulic motor and a gear set. The hydraulic motor can be accurately regulated by controlling the pump displacement and fluid flows to change the pitch angle through the gear set. The detailed mathematical representation and dynamic characteristics of the proposed pitch system are thoroughly analyzed. An adaptive sliding mode pump displacement controller and a back-stepping stroke piston controller are designed for the proposed pitch system such that the resulting pitch angle tracks its desired value regardless of external disturbances and uncertainties. The effectiveness and control efficiency of the proposed pitch system and controllers have been verified by using realistic dataset of a 750 kW research wind turbine. 相似文献
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Nonlinear adaptive torque control of electro-hydraulic load system with external active motion disturbance 总被引:1,自引:0,他引:1
《Mechatronics》2014,24(1):32-40
This paper develops a high performance nonlinear adaptive control method for electro-hydraulic load simulator (EHLS). The tracking performance of EHLS is mainly affected by the following factors: actuator’s active motion disturbance, flow nonlinear and parametric uncertainties, etc. Most previous studies on EHLS pay too much attention on actuator’s active motion disturbance, while deemphasize the other two factors. This paper concerns EHLS as a motion loading system. Besides actuator’s motion disturbance, both the nonlinear characteristics and parametric uncertainties of the loading system are addressed by the present controller. First, the nonlinear model of EHLS is developed, and then a Lyapunov-based control algorithm augmented with parameters update law is developed using back-stepping design method. The stability of the developed control algorithm is proven via Lyapunov analysis. Both the co-simulation and experiment are performed to validate the effectiveness of the developed algorithm. 相似文献
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针对共振破碎机频率控制系统的不确定性问题,提出基于动态递归模糊神经网络的自适应反推控制策略。建立了破碎机频率控制系统的数学模型,在忽略不确定性项的前提下,设计了基于自适应Back-stepping方法控制律。其次将电液系统中影响频率控制性能的不确定性因素定义为待估计项,采用动态递归模糊神经网络对其进行实时估计,给出了基于动态递归模糊神经网络的参数自适应律,并通过了Lyapunov的稳定性分析。仿真实验和车载测试结果表明,对于系统参数的不确定性,该方法具有较好地频率控制性能。 相似文献
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A compensation control strategy based on adaptive back-stepping technique is presented to address the problem of attitude adjustment for a quad-rotor unmanned aerial vehicle (QR- UAV) with inertia parameter uncertainties, the limited airflow disturbance and the partial loss of rotation speed effectiveness. In the design process of control system, adaptive estimation technique is introduced into the closed loop system in order to compensate the lumped disturbance term. More specifically, the designed controller utilizes “prescribed performance bounds” method, and therefore guarantees the transient performance of tracking errors, even in the presence of the lumped disturbance. Adaptive compensation algorithms under the proposed closed loop system structure are derived in the sense of Lyapunov stability analysis such that the attitude tracking error converge to a small neighborhood of equilibrium point. Finally, the simulation results demonstrate the effectiveness of the proposed controller. 相似文献