Robust control of reaction wheel bicycle robot via adaptive integral terminal sliding mode

Nonlinear Dynamics - In this paper, the modelling of a reaction wheel bicycle robot (RWBR) is identified from a second-order mathematical model which is similar to an inverted pendulum, and an...     

Coupling-observer-based nonlinear control for flexible air-breathing hypersonic vehicles

This paper investigates the nonlinear control problem for flexible air-breathing hypersonic vehicles (FAHVs). The coupling dynamics between flexible and rigid-body parts of FAHVs may cause degradation of control performance or high-frequency oscillations of control input and flexible state. In this paper, the flexible effects produced by the coupling are modeled as a kind of unknown disturbance and included in the new control-design model, for which a coupling observer is constructed to estimate these effects. Thus, a novel nonlinear composite control strategy, which combines a coupling-observer-based feedforward compensator and a dynamic-inversion-based feedback controller, is proposed to reject the flexible effects on pitch rate and track desired trajectories of velocity and flight-path angle. The stability of composite closed-loop system is analyzed by using the Lyapunov theory. Simulation results on a full nonlinear model of FAHVs demonstrate that the presented controller is more effective by comparison with the previous scheme.     

Switched-model-based compound control of hypersonic vehicles with input nonlinearities

Nonlinear Dynamics - Focusing on the large-envelope control problem of air-breathing hypersonic vehicles (AHVs), this paper employs a switched control-oriented model (SCOM) to describe vehicle...     

A robust attitude control strategy with guaranteed transient performance via modified Lyapunov-based control and integral sliding mode control

In this paper, a robust control strategy with guaranteed transient performance is presented for spacecraft attitude maneuvers. Firstly, a Lyapunov-based controller is designed to achieve high-performance attitude control in the absence of disturbance and parameter variation. Unlike most existing designs, the feedback gains in the proposed controller increase with the attitude error convergence. Consequently, the system response can be accelerated without increasing the control torque at large attitude error. The overshooting phenomenon is also avoided by imposing a restriction on the parameter selection. Then, the integral sliding mode control technique is employed to preserve the desired transient characteristics and improve the robustness. Furthermore, by combining an adaptive scheme with the boundary layer method, the conservativeness in the switching gain selection is reduced and the chattering is also suppressed. Theoretical analysis and simulation results verify the effectiveness of the proposed strategy.     

Barrier Lyapunov function-based adaptive control for hypersonic flight vehicles

Nonlinear Dynamics - This paper presents an adaptive control strategy for hypersonic flight vehicles (HFVs) subject to parametric uncertainties, external disturbances and faulty actuators. Besides...     

Fuzzy integral sliding mode controller design for boost converters

We consider the problem of designing an integral sliding mode controller for a nonlinear boost DC–DC converter based on the Takagi–Sugeno (T–S) fuzzy approach. We give an accurate T-S fuzzy model of a boost converter. We derive an existence condition of a sliding surface in terms of linear matrix inequalities (LMIs). We give a parameterization of the sliding surface using the solution matrices of the LMI existence condition. We also give a switching feedback control strategy to guarantee the reachability condition. We show that the proposed method can robustly regulate the output voltage under bounded model uncertainties. Finally, we give some simulation and experimental results to show the practicality and feasibility of the proposed method.     

Adaptive integral sliding mode control with payload sway reduction for 4-DOF tower crane systems

Nonlinear Dynamics - An adaptive integral sliding mode control (AISMC) method with payload sway reduction is presented for 4-DOF tower cranes in this paper. The designed controller consists of...     

Function approximation-based sliding mode adaptive control

For the position tracking in DC motor with unknown bound time-varying dead zone uncertainties, a novel sliding mode adaptive controller is proposed by means of sliding mode and function approximation technique in this paper. First, control law with an uncertain term and another compensative term is obtained using sliding mode technique, and then the function approximation technique is employed to transform the uncertain term into finite combinations of orthonormal basis functions. The concrete expressions of uncertain term and compensative term can thus be derived based on the Lyapunov design. Actual system control experiments of the sliding adaptive control proposed are given.     

Terminal sliding mode control for aeroelastic systems

An aeroelastic system is a nonlinear system with two freedoms, i.e., the plunge displacement and the pitch angle, in a dynamic system model. A chaos effect or a limit cycle oscillation is presumably attributed to the nonlinear effect of the pitch angle mentioned above or the interaction between the aerodynamic behaviors. It is that a single trailing edge input in an aeroelastic system is employed as a way to suppress the limit cycle oscillation with an exclusive choice between the plunge displacement and the pitch angle for a control law design. Consequently, the remaining inevitably turns into an internal dynamics, whose stability is adversely affected by the flight speed and structure parameters, a problem improved by no means using a singe control input design. Toward this end, this work presents a controller design criterion with multiple input channels for both the leading and training edges to remove the uncertainty effect of internal dynamics, and render more room for the response design of the plunge displacement as well as the pitch angle. Mostly due to external disturbance and unknown uncertainty, there is a deviation between the intended and implemented system performances for a robust control design, a mainstream research issue in the modern control. As a consequence of a sliding mode control utilized here, the limit cycle oscillation suffered in an aeroelastic system is removed effectively by the use of a terminal sliding mode control, and the chattering phenomenon seen in the control signal is hence eliminated by his method. It is seen from simulations that the control system is stably assured to reach the target within a limited time frame with an addition of a saturation function to the control law.     

Coupling effect-triggered control strategy for hypersonic flight vehicles with finite-time convergence

Nonlinear Dynamics - This paper investigates a novel control strategy of addressing coupling issue for attitude tracking control of hypersonic flight vehicle. By using a defined coupling effect...     

On dynamic sliding mode control of nonlinear fractional-order systems using sliding observer

Nonlinear Dynamics - In this study, a new fractional-order dynamic sliding mode control (FDSMC) for a class of nonlinear systems is presented. In FDSMC, an integrator is placed before the input...     

On the sliding mode control of mechanical systems

We consider the control of mechanical systems based on sliding mode control techniques. Recently developed simplex control methods are shown to converge in a finite time when applied to nonlinear systems under bounded deterministic uncertainty. Applications are considered to the control of mechanical systems in which the control action is provided by monodirectional devices.     

Input-and-measurement event-triggered control for flexible air-breathing hypersonic vehicles with asymmetric partial-state constraints

In this paper, an input-and-measurement event-triggered control scheme considering asymmetric partial-state constraints is proposed for flexible air-breathing hypersonic vehicles (FAHV) subject to lumped disturbances and limited resources. To realize a precise disturbance rejection with decreased communication burden in sensor-to-control channels, intermittent measurement-based extended state observers using switching threshold samplers are developed in altitude and velocity subsystems, while the quantitative relationship between the upper bounds of observation errors and the design parameters of switching triggering mechanism is derived. Subsequently, to ensure the angle of attack (AoA) well within the allowable operational region and simultaneously achieve a reference tracking with expected characteristic, asymmetric constraints imposed on partial states including AoA, velocity, and altitude are embedded in design process, while a one-to-one nonlinear mapping is designed to avoid the violation of state constraint of AoA without enforcing feasibility conditions on virtual control laws, and a modified prescribed performance control is constructed to govern the output constraints of velocity and altitude, releasing the demand on the precise knowledge of initial states. Next, to maintain the resources occupation (energy and communication in controller-to-actuator channel) at low levels and ensure a desirable tracking precision, robust control laws based on switching event-triggered mechanisms are designed for FAHV to circumvent Zeno phenomena and compensate for the sampling error induced by event-triggered conditions. The simulation results and comparisons validate the effectiveness of the proposed scheme.

     

Forced sliding mode control for chaotic systems synchronization

Synchronization of chaotic systems is considered to be a common engineering problem. However, the proposed laws of synchronization control do not always provide robustness toward the parametric perturbations. The purpose of this article is to show the use of synergy-cybernetic approach for the construction of robust law for Arneodo chaotic systems synchronization. As the main method of design of robust control, the method of design of control with forced sliding mode of the synergetic control theory is considered. To illustrate the effectiveness of the proposed law, in this article it is compared with the classical sliding mode control and adaptive backstepping. The distinctive features of suggested robust control law are the more good compensation of parametric perturbations (better performance indexes—the root-mean-square error (RMSE), average absolute value (AVG) of error) without designing perturbation observers, the ability to exclude the chattering effect, less energy consuming and a simpler analysis of the stability of a closed-loop system. The study of the proposed control law and the change of its parameters and the place of parametric perturbation’s application is carried out. It is possible to significantly reduce the synchronization error and RMSE, as well as AVG of error by reducing some parameters, but that leads to an increase in control signal amplitude. The place of application of parametric disturbances (slave or master system) has no effect on the RMSE and AVG of error. Offered approach will allow a new consideration for the design of robust control laws for chaotic systems, taking into account the ideas of directed self-organization and robust control. It can be used for synchronization other chaotic systems.