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In this paper, an indirect filtering fault‐tolerant control method is proposed for interconnected time‐delay systems with multiple sensor and actuator faults. As is well known, directly utilizing the state information obtained from sensors with faults to constrain the actual state poses great challenges. This article utilizes conservative sensor fault loss information to indirectly apply time‐varying asymmetric constraints to the actual state while ensuring compliance with fault state constraints. In addition, the conservatism requirement of the initial state is reduced by utilizing carefully constructed delay constraint functions. To solve the problem of "explosion of complexity," the derivative of the output signal of the filter is used to replace the derivative of the virtual control rate. The Nussbaum function can effectively alleviate the impact of multiple actuator failures and unknown control directions on the system. The effectiveness of the proposed control strategy is verified through simulation examples. [ABSTRACT FROM AUTHOR]

Summary: As the nonlinearities of many real physical controlled systems become stronger and stronger, they are difficult to be described by accurate mathematical models. For a class of nonlinear single‐input single‐output systems with all‐state constraints and actuator faults, an event‐triggered adaptive fuzzy ABLF function fixed‐time tracking control method is proposed. The asymmetric barrier Lyapunov function (ABLF) combined with backward step technique is used to ensure the boundedness of the closed‐loop system output. In order to solve the problem of limited bandwidth resources, this paper adopts the event trigger mechanism and fuzzy control technology to approximate the unknown function to ensure the convergence of the system in a fixed time. After theoretical analysis, it is proved that the tracking error of the system converges in the small neighborhood of the origin, and it still has good tracking performance when the actuator faults. Finally, by comparing the proposed method with the asymmetric barrier Lyapunov function, which verifies the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Summary: This article addresses an adaptive fuzzy practical fixed‐time tracking control for nonlinear systems with unknown actuator constraints and uncertainty functions. First, fuzzy logic systems (FLSs) are used to identify uncertain functions. Then, by utilizing FLSs, backstepping technique, and finite‐time stability theory, an adaptive fuzzy practical fixed‐time control is proposed to obtain satisfactory tracking performance even when the actuator faults. The theoretical analysis verified that the closed‐loop systems is practical fixed‐time stable under the proposed control strategy, the tracking error converges to a small neighborhood of the origin in a fixed time, and the convergence time is independent of the state conditions. Finally, both numerical simulation and physical example demonstrates the effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

The traditional direct torque control system of permanent magnet synchronous motor has many problems, such as large torque ripple and variable switching frequency. In order to improve the dynamic and static performance of the control system, a new torque control idea and speed sensorless control scheme are proposed in this paper. First, by deriving the equation of torque change rate, an improved torque controller is designed to replace the torque hysteresis controller of the traditional direct torque control. The improved direct torque control strategy can significantly reduce the torque ripple and keep the switching frequency constant. Then, based on the improved direct torque control and considering the sensitivity of the stator resistance to temperature change, a speed estimator based on the model reference adaptive method is designed. This method realizes the stator resistance on-line identification and further improves the control precision of the system. The performance of the traditional direct torque control and the improved direct torque control are compared by simulation and experiment under different operating conditions. The simulation and experimental results are presented to support the validity and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]