Adaptive Sliding Mode Control Vibrations of Structures

The sliding mode controller is one of the interesting classical nonlinear controllers in structural vibration control. From its apparition, in the middle of the twentieth century, this controller was a subject of several studies and investigations. This controller was widely used in the control of various semi-active or active devices in the civil engineering area. Nevertheless, the sliding mode controller offered a low sensitivity to the uncertainties or the system condition variations despite the presence of the Chattering defect. However, the adaptation law is one of the frequently used solutions to overcome this phenomenon offering the possibility to adapt the controller parameters according to the system variations and keeping the stability of the whole system assured. The chapter provides a sliding mode controller design reinforced by an adaptive law to control the desired state of an excited system. The performance of the adaptive controller is proved by numerical simulation results of a three-story excited structure.

Nonlinear Cutterhead Pose Control of Large-Diameter Slurry Shields in Complicated Stratum

To replace cutterhead worn tools conveniently or get rid of shield’s jamming effectively in complicated stratum, a new nonlinear cutterhead pose control system of large-diameter slurry shields is especially designed. High precision cutterhead pose control of large-diameter slurry shields is hardly achieved due to the uncertain load force and mass. A nonlinear controller constructed by adaptive robust control based on sliding mode is designed for this parallel mechanism, which includes a special adaptation law to compensate for the uncertainties. The stability of the whole closed loop system is verified based on Lyapunov theory. And the validity of the proposed strategy is proved by Simulink and AMESim co-simulation. The simulation results show that not only in control accuracy but also in parameter uncertainty, the designed nonlinear cutterhead pose control is effective.

Moving-horizon-estimator-integrated adaptive hierarchical sliding mode control for flexible hypersonic vehicles considering aeroservoelastic effect

In order to solve the attitude control problem of flexible hypersonic vehicles with consideration of aeroservoelastic effect, uncertainty and external disturbance, a novel moving-horizon-estimator-integrated adaptive hierarchical sliding mode control scheme is presented in this paper. First, the measurement model considering flexibility is established and the influence of aeroservoelastic effect on system stability is analyzed. Then moving horizon estimator is developed to reconstruct full state information from sensor measurements, while sliding mode disturbance observer and gain adaptation law is proposed to enhance the robustness and attenuate the chattering. Via combining moving horizon estimator, sliding mode disturbance observer, gain adaptation law and baseline hierarchical sliding mode controller, the moving-horizon-estimator-integrated adaptive hierarchical sliding mode control scheme that is able to achieve the control objective of both precise attitude control and active flexible vibration suppression is developed. Finally, Lyapunov theory is used to prove the stability of the proposed control scheme, and the numerical simulations are carried out, which further verify the effectiveness of the proposed control scheme against aeroservoelastic effect, uncertainty and external disturbance.

Motion Control of Small Autonomous Underwater Vehicle in Presence of Parameters Uncertainties

A dynamic model of the underwater vehicle is usually established with parameters uncertainties due to the non-linear and time-varying nature of hydrodynamic forces from the surrounding fluid and external environmental disturbances. The paper investigates the motion control problem of the vehicle in tridimensional space based on model reference adaptive control. A developed autopilot consists of three independent controllers with a parameter adaptation law implemented. A control performance is guaranteed by suitably choosing design parameters. The effectiveness and robustness of the proposed control scheme for trajectory tracking in surge, depth and yaw dynamics is tested through simulations studies.

An intermittent controller for robotic manipulator with uncertain dynamics in task space

An intermittent controller for robotic manipulator in the presence of dynamic uncertainties was developed in this paper. The adaptation law is designed to deal with the dynamic uncertainties. In task space, for given a desired position, the robot end-effector is able to reach the desired position under the designed intermittent controller. Different from most of the existing works on control of robotic manipulator, the designed controller only needs to receive the information of the desired position in some interval time, but not continuously. In addition, the intermittent control of robotic manipulator is discussed in task space instead of joint space. Based on an extended Barbalat’s Lemma, some simple control gains are obtained. As a direct application, we implement the proposed controller on a two-link robotic manipulator. Numerical simulations demonstrate the effectiveness of the proposed control strategy.

Adaptive fuzzy Jacobian control of spacecraft combined attitude and Sun tracking system

Purpose The paper aims to address the combined attitude control and Sun tracking problem in a flexible spacecraft in the presence of external and internal disturbances. The attitude stabilization of a flexible satellite is generally a challenging control problem, because of the facts that satellite kinematic and dynamic equations are inherently nonlinear, the rigid–flexible coupling dynamical effect, as well as the uncertainty that arises from the effect of actuator anomalies. Design/methodology/approach To deal with these issues in the combined attitude and Sun tracking system, a novel control scheme is proposed based on the adaptive fuzzy Jacobian approach. The augmented spacecraft model is then analyzed and the Lyapunov-based backstepping method is applied to develop a nonlinear three-axis attitude pointing control law and the adaptation law. Findings Numerical results show the effectiveness of the proposed adaptive control scheme in simultaneously tracking the desired attitude and the Sun. Practical implications Reaction wheels are commonly used in many spacecraft systems for the three-axis attitude control by delivering precise torques. If a reaction wheel suffers from an irreversible mechanical breakdown, then it is likely going to interrupt the mission, or even leading to a catastrophic loss. The pitch-axis mounted solar array drive assemblies (SADAs) can be exploited to anticipate such situation to generate a differential torque. As the solar panels are rotated by the SADAs to be orientated relative to the Sun, the pitch-axis wheel control torque demand can be compensated by the differential torque. Originality/value The proposed Jacobian control scheme is inspired by the knowledge of Jacobian matrix in the trajectory tracking of robotic manipulators.

Inverse Jacobian Adaptive Tracking Control of Robot Manipulators with Kinematic, Dynamic, and Actuator Uncertainties

In this paper, we mainly solve the adaptive control problem of robot manipulators with uncertain kinematics, dynamics, and actuators parameters, which has been a long-standing, yet unsolved problem in the robotics field, because of the technical difficulties in handling highly coupled effect between control torque and the mentioned uncertainties. To overcome the difficulties, we propose a new Lyapunov-based adaptive control methodology, which effectively fuses the inverse Jacobian technique and the actuator adaptation law, with which the chattering in tracking errors caused by actuator parameter perturbation is well suppressed. It is demonstrated that the asymptotic convergence of all closed-loop signals is guaranteed. Moreover, the effectiveness of our control scheme is illustrated through simulation studies.