sliding manifold
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The stabilization and disturbance rejection of the translational oscillator with a rotating actuator (TORA) are considered in this paper. To deal with the control issues, a novel continuous sliding mode control method is designed for the TORA system. Compared with existing sliding mode control methods for the TORA system, the proposed method here is continuous. Specifically, first, a global diffeomorphism is introduced for the model of the TORA system. Then, an elaborate sliding manifold is constructed, and a continuous sliding mode control scheme is developed to ensure the convergence of the sliding manifold. Furthermore, rigorous theoretical analysis is given. Finally, simulation tests are carried out, and the obtained simulation results demonstrate that the proposed method exhibits superior stabilization control performance and strong robustness.

This paper synthesizes a continuous, multivariable, finite-time-convergent, super-twisting attitude and rate controller for rotorcraft with the objective of providing desired handling qualities and robustness characteristics. A sliding manifold is defined in the system state space to represent ideal attitude and rate command response dynamics of relative degree one with respect to the command input. Subsequently, robust command tracking is achieved via the synthesis of a multivariable super-twisting flight controller, which renders the plant states convergent on to the defined sliding manifold in finite-time and in the presence of matched external disturbance input. To validate the efficacy of the controller, simulation results are presented based on a nonlinear, higher-order rotorcraft model operating in turbulence. True system convergence to the sliding manifold from an untrimmed state is shown to lie within the theoretically predicted finite-time convergence bound. Furthermore, simulations with a linear quadratic flight controller are also presented for performance comparison with the proposed super-twisting flight controller.

Abstract This paper addresses an adaptive fault-tolerant tracking control for robot manipulators. By fully considering the effects of uncertainties and actuator effectiveness faults (UAEFs), a robust fault-tolerant tracking control combining with an auxiliary function and an integral sliding manifold is first developed for uncertain robot manipulators. Then, an adaptive law for unknown parameters of the upper bounded uncertainties is constructed to obtain a robust fault-tolerant approach with the elimination of the reaching phase of sliding mode control (SMC). The stability of the proposed approaches is accomplished by Lyapunov stable theory. The key contributions of the proposed approach are as follows: i) the reaching phase of SMC is removed in the control design and then the sliding mode starts at very beginning; (ii) the nominal control term is eliminated in the design of integral sliding surface and then the algebraic loop problem is also avoided in the proposed approach for robot manipulators; (iii) the simple control structure with an adaptive law is obtained for improving chattering-restraining ability of the proposed approach and then the effects of time delay and computational burden are also restrained from the proposed approach. Simulation and experimental comparisons have been accomplished for verifying the effectiveness of the proposed approach.

A terminal synergetic control (TSC) is designed in this work for a rotor side converter (RSC) of asynchronous generator (ASG)-based dual-rotor wind power (DRWP) systems. The design is based on a novel sliding manifold and aims at improving the ASG performance while minimizing active and reactive power undulations. The method performance and its effectiveness were studied under harmonic distortion (THD) of current, parameter variations and power undulations. Simulation results, carried out using Matlab software, confirmed the system’s robustness against parameter variations and its effectiveness in power undulations. The performance of the designed technique was further compared to that of integral-proportional (PI) controllers in terms of parameter variations, power undulations and THD value of current. While both controllers were able to reduce the effects of power undulations and protect the rotor circuit against over-currents, the proposed TSC was shown to be more effective than the classical PI controller in tracking power and minimizing the undulations effect.

Abstract This work proposes a new class of controllers for mobile manipulators subject to both undesirable forces exerted on the end-effector and slip reaction forces acting on the platform wheels, unknown friction forces coming from joints directly driven by the actuators as well as undesirable forces caused by kinematic singular configurations appearing on the mechanism trajectory. Based on suitably defined task space non-singular terminal sliding manifold (TSM) and the Lyapunov stability theory, we derive a class of estimated extended transposed Jacobian controllers which seem to be effective in counteracting the unstructured forces. Moreover, in order to eliminate (or to alleviate) undesirable chattering effects, the proposed control law involves second order sliding technique. The numerical computations closely related to an experiment, which are carried out for a mobile manipulator consisting of a platform of (2, 0) type and holonomic manipulator of two revolute kinematic pairs, illustrate the performance of the proposed controllers.

This study considers the design of a modified high-order sliding mode (HOSM) controller using a PI sliding surface to the attitude control of a ground vehicle. A robust-modified HOSM controller is derived, so that the lateral velocity and yaw rate tracks the desired trajectory despite the environment actions acting on the ground vehicle and parameter variations. The stability is guaranteed with Lyapunov’s stability theorem function. The performance of the dynamic controllers is evaluated using the CarSim simulator considering a challenging double steer maneuver.