In this article, a novel adaptive sliding mode control strategy is presented for attitude and altitude stabilization of a quadrotor unmanned aerial vehicle (UAV), where the input saturation is taken into consideration. The nonlinear dynamic model of quadrotor UAV subject to system uncertainty and external disturbance is first derived using the Euler–Lagrange mechanical equation. To ensure system stability, as well as eliminating the negative effects of saturation features, a saturated adaptive sliding mode control law (ASMCSAT) is proposed, which takes advantages of the sliding mode control and the adaptive control. Compared with conventional control strategies, better tracking performance and disturbance and uncertainty rejection can be achieved with the root mean square of the tracking error being reduced by 34.91% in vertical takeoff and 30.11% in trajectory tracking. Simulations and experiments are provided to verify the effectiveness and practicability of the proposed control method.

Model-based strategies are a promising solution to the grand challenge of equipping continuum soft robots with motor intelligence. However, finite-dimensional models of these systems are inherently inaccurate, thus posing pressing robustness concerns. Moreover, the actuation space of soft robots is usually limited. This article aims at solving both these challenges by proposing a robust model-based strategy for the shape control of soft robots with system uncertainty and input saturation. The proposed architecture is composed of two key components. First, we propose an observer that estimates deviations between the theoretical model and the soft robot, ensuring that the estimation error converges to zero within finite time. Second, we introduce a sliding mode controller to regulate the soft robot shape while fulfilling saturation constraints. This controller uses the observer's output to compensate for the deviations between the real system and the established model. We prove the convergence of the closed-loop with theoretical analysis and the method's effectiveness with simulations and experiments.

In this article, a novel fractional-order nonsingular terminal sliding mode (FONTSM) control scheme is developed, which guarantees the desired deployment performance of space tethered satellite (STS) system. The presented control scheme is to stabilize the underactuated deployment mission with only tension regulation. Based on the underactuated model, a practicable integer-order nonsingular terminal sliding mode (IONTSM) controller is designed to realize the deployment of the STS system, with the finite-time stability. Then, to improve the deployment performance, the fractional-order calculus is introduced to raise the FONTSM controller, whose Mittag-Leffler-based uniform ultimate boundedness is proved to ensure the finite-time convergence and steady-state performance. In the FONTSM controller, a fractional-order disturbance observer and a fractional-order adaptive compensation law are proposed, to eliminate the adverse impacts of external disturbances and input saturation, respectively. Moreover, compared to the reported fractional-order sliding mode control strategy of the STS system, a better deployment performance can be obtained by the IONTSM and FONTSM controllers in this work. Finally, the effectiveness of the proposed controllers is verified by groups of deployment simulations of the STS system.