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In this paper, we consider the stabilization of the translational oscillator with a rotational actuator (TORA) system. Existing control methods for the TORA system are developed on the basis of the assumptions that full state feedback is available, and the actuator can supply control torques with any bounded amplitudes or system parameters are exactly known. In order to relax these assumptions, an amplitude‐saturated output feedback controller is proposed for the TORA system. Compared with existing control methods, the proposed method exhibits four remarkable features: free of plant parameters, bounded amplitude, output feedback, and unwinding behavior prevention. Specifically, the passivity of the TORA system is analyzed first. Then, a constructive energy‐like function is introduced and a corresponding amplitude‐saturated output feedback control law for the TORA system is proposed on the basis of the constructed energy‐like function. Lyapunov‐based analysis and LaSalle's invariance principle are used to prove the boundedness and convergence of the closed‐loop signals. Finally, numerical simulations with comparisons to previous reported methods are implemented to demonstrate the superior performance of the proposed method.

In this paper, we consider the control issues of the two-dimensional translational oscillator with rotational actuator (2DTORA) system, which has two translational carts and one rotational rotor. An output feedback controller for the 2DTORA system is proposed, which can prevent the unwinding behaviour. In addition, the velocity signal unavailability and actuator saturation are taken into account, simultaneously. In particular, the dynamics of the 2DTORA system are given first. On the basis of the passivity and control objectives of the 2DTORA system, an elaborate Lyapunov function is constructed. Then, based on the introduced Lyapunov function, a novel output feedback control method is proposed straightforwardly for the 2DTORA system. Lyapunov theory and LaSalle’s invariance principle are utilized to analyse the stability of the closed-loop system and the convergence of the states. Finally, simulation results are provided to illustrate the excellent control performance of the proposed controller in comparison with the existing method.

This article is motivated by the control issues of the translational oscillator with rotational actuator system in the existence of uncertain disturbances. A nonlinear disturbance observer and a global sliding mode control method are proposed for the disturbance estimation and stabilization of the translational oscillator with rotational actuator system. Compared with the existing control methods, uncertain disturbances are estimated by the proposed nonlinear disturbance observer. In addition, the sliding mode control method is continuous and global robustness with respect to disturbances. Specifically, to facilitate the controller design, the dynamics of the translational oscillator with rotational actuator system are rearranged as the cascade form first. Then, a virtual signal is constructed and corresponding error dynamics are derived. Subsequently, a nonlinear disturbance observer and a continuous global sliding mode control method are proposed for the disturbance rejection and stabilization of the translational oscillator with rotational actuator system. Finally, simulation results are provided to verify the effectiveness and robustness of the proposed controller.

The corrosion behavior and mechanism of CoCrFeNi HEA under AC application were systematically studied in 3.5 wt.% NaCl solution containing different concentrations of NaHSO 3 . The results showed that the existence of HSO 3 − increased the defect density within the passivation film on the surface of the HEA. With the increase of HSO 3 − concentration, the passivation zone became narrow, E p shifted negatively, and i p increased, which indicated that the corrosion resistance of the HEA was weakened. When the HSO 3 − concentration increased to 0.1 M, a clear transition zone appeared, indicating that the increase in concentration reduced the passivity of the HEA, and its corrosion behavior changed from the typical passivation characteristic to the activation state with increasing i AC . The imposed AC promoted the nucleation of metastable pitting, which was indicated by a remarkable increase in the average pitting number density (N avg ) from 5 to 17 mm −2 with the enhancement of i AC .