Papers by Keyword: Lyapunov Stability

Abstract: The speed control system of DC motor normally uses increasing of electric current and voltage for obtaining required speed and torque with regardless of effects from variable of load torque to system. Including that noise will make some errors in speed and torque control. This research aims to present a method for developing the high accuracy in speed control of DC motor by a technique of adaptive torque compensation that is evolved on Lyapunov stability and using Kalman filter for screening out the evident noises in the system. Results reveals that the adaptive torque compensator evolved from the Lyapunov stability can compensate a stable torque and when it is worked with Kalman filter, it can compensate torque correctly and can control more accuracy of motor speed.

Abstract: Based on the characteristics of releasing loads for many times, the attitude dynamics model of MIRV has established by using the Rodrigues representation, and we proposed a method of indirect multi-model adaptive attitude control. It was proved that the adaptive controller we designed can ensure the control system globally uniformly and bounded stable according to the Lyapunov stability theory, and the effectiveness of the controller was demonstrated by the numerical simulation results.

Abstract: This paper constructs a sliding mode observer of fixed long delay network control system with an augmented modeling method, and then proves the feasibility of system residuals converging to zero by Lyapunov stability theorem. The network control system fault diagnosis is discussed in depth by detecting changes in the residuals. In addition, this paper takes Gradient faults and mutation faults of actuator as examples to conduct fault diagnosis simulation, and the simulation results show that this method can detect the system faults effectively.

Abstract: This paper studies the stability analysis of discrete time-varying system with parameter uncertainties and disturbances. The system under consideration is subject to time-varying non-bounded parameter uncertainties in both the state and measured output matrices. To facilitate the stability analysis, the T-S fuzzy model is employed to represent the discrete-time nonlinear system. A fuzzy observer is used to guarantee the Lyapunov stability of the closed-loop system and reduces the effect of the disturbance input on the controlled output to a prescribed level for all admissible uncertainties. The control and observer matrices can be obtained by directly solving a set of linear matrix inequality (LMI) via the existing LMI optimization techniques. Finally, an example is provided to demonstrate the effectiveness of the proposed approach.

Abstract: In this paper, an adaptive backstepping type design is proposed to control the complex nonlinear behavior of the wing rock phenomenon. This method, based on Lyapunov stability theory, can simultaneouslyachieve parameters identification and control.Finally numerical simulations are presented to justify the effectiveness of the proposed controller.

Abstract: This paper proposes a multi-link algorithm to analyze the walking stability of a self-fabricated, full-size, biomimic, android robot. The stepping trajectory is prescribed and navigated along a horizontal plane without slipping motions and variable center of gravity. However, it may encounter different circumstances for less number of LDOF. Traditionally, walking equilibrium can be assured based on the stabilizable conditions of the dynamic structure of 5-7 leg-degrees of freedom (LDOF). Various kinks of the walking structure are analyzed with the loading effects of the upper-body on the robot. The multi-link fuzzy-logic controller (MLFLC) is also proposed to stabilize the multi-LDOF walking system. Finally, Lyapunov stability can be successfully assured using the proposed controller under the assumption of the theory of the dynamic zero-moment points

Abstract: Based on the sliding mode control (SMC) technique, a design of the sliding surface for the dual-excited and steam-valving control of the synchronous generators with matched and mismatched perturbations is proposed in this paper. By utilizing some constant gains designed in the sliding surface function, not only are the mismatched perturbations overcomed during the sliding mode, but also the property of asymptotical stability of the rotor angle and the voltage is achieved at the same time. Simulations have demonstrated that the control scheme is robust against the disturbances.

Abstract: Stabilization and tracking control of nonlinear uncertain underactuated systems are always challenging problems because underacturated systems have fewer independent control actuators than degrees of freedom to be controlled. For a class of second order underactuated mechanical systems, a robust finite time control strategy is developed in this paper. The robust finite time controller is to drive the tracking error to be zero at the fixed final time. In fact, finite time convergence implies nonsmooth or non-Lipschitz continuous autonomous systems with nonuniqueness of solution. In order to prove the stability, we present a generalized Lyapunov stability proof for the second order underactuated mechanical system. By utilizing a Lyapunov stability theorem, we can achieve finite time tracking of desired reference signals for underactuated systems, which is subject to both external disturbances and system uncertainties. The proposed control scheme is demonstrated by actual experiments on a Furuta pendulum system. Based on the experiment results, the finite time convergence of system errors can be assured.

Abstract: This paper proposes a new method for designing both nonlinear observer and adaptive controller for a class of non-affine nonlinear systems with unknown functions of the system. The states of the nonlinear system are assumed to be unavailable for measurement. The merits of this paper is as: asymptotic convergence of the observer and tracking error to zero, boundedness of all signals involved, and robustness. The simulation results illustrate the promising performance of the proposed algorithm.

Abstract: This paper proposes a new method for designing a fuzzy adaptive controller for a class of non-affine nonlinear chaotic systems in which functions of the systems are unknown. The proposed method is aimed on a class of non-canonical non-affine nonlinear chaotic systems. The stability of the closed loop system is guaranteed based on Lyapunov’s theory. The proposed controller is robust against uncertainties and external disturbances. The simulation results show the effectiveness of the proposed method.