Adaptive integral terminal sliding mode control algorithm for hydraulic transformer inner loop position control system based on sensitivity analysis

Synchronization of angular velocities of chaotic leader-follower satellites using a novel integral terminal sliding mode controller

An integral terminal sliding mode control scheme for speed control system using a double-variable hydraulic transformer

To overcome the mutual constraints between the system chattering and the arrival time in conventional sliding mode control in this paper, a tangent excitation function (tansig) type nonlinear extended state observer (NLESO)-based integral terminal sliding mode control is proposed to solve the trajectory tracking control task of the modular robot manipulators (MRMs) possessing strong coupling and complex time-varying properties. Through the joint torque feedback technology, the MRM system dynamic model is formulated; on this basis, the proposed NLESO based on tansig is utilized to estimate and compensate the system uncertain information, which are consisted of the friction, interconnected dynamic coupling, and external disturbance. The proposed NLESO can simplify the traditional extended state observer design parameters for theoretical analysis and practical application. The proposed tansig-type NLESO-based integral terminal sliding mode control integrated adaptive term exponential reaching law for MRMs is designed to diminish the arrival time when the system state converges to the equilibrium point. The presented algorithm improves the robotic system antidisturbance ability. Furthermore, the Lyapunov theory is utilized to verify stability of the proposed NLESO and closed-loop robotic system. Finally, the availability of the proposed algorithm is demonstrated by experiments.

The recursive integral terminal sliding mode control with combined extended state observer (ESO) and adaptive Kalman filter (AKF) is proposed in this article for micromechanical system gyroscopes. To accurately estimate the unmeasured system states in the presence of measurement noises, external disturbances and system uncertainties, the special combination of ESO and AKF is proposed. The AKF is employed to deal with measurement noises and prepare necessary signals for the ESO, while the ESO constantly provides the updated estimate of the lumped disturbance for the AKF. Furthermore, a robust control scheme is designed by using the recursive integral terminal sliding mode variable. Simulation results verify that more accurate unmeasured state estimation and higher tracking accuracy are achieved under the proposed method.

This paper focuses on the trajectory tracking control of unmanned underwater vehicles (UUVs) in the presence of dynamic uncertainties and time-varying external disturbances. Two adaptive integral terminal sliding mode control schemes, namely, adaptive integral terminal sliding mode control (AITSMC) scheme and adaptive fast integral terminal sliding mode control (AFITSMC) scheme are proposed for UUVs based on integral terminal sliding mode (ITSM) and fast ITSM (FITSM), respectively. Each control scheme is double-looped: composed of a kinematic controller and a dynamic controller. First, a kinematic controller is designed for each of the two control schemes. The two kinematic controllers are based on ITSM and FITSM, respectively. These kinematic controllers yield local finite-time convergence of the position tracking errors to zero meanwhile avoid the singularity problem in the conventional terminal sliding mode control (TSMC). Then, using the output of the kinematic controller as a reference velocity command, a dynamic controller is developed for each of the two control schemes. The two dynamic controllers are also based on ITSM and FITSM, respectively. An adaptive mechanism is introduced to estimate the unknown parameters of the upper bound of the lumped system uncertainty which consists of dynamic uncertainties and time-varying external disturbances so that the prior knowledge of the upper bound of the lumped system uncertainty is not required. The estimated parameters are then used as controller parameters to eliminate the effects of the lumped system uncertainty. The convergence rate of the integral terminal sliding variable vector is investigated and the local finite-time convergence of the velocity tracking errors to zero in the ITSM or FITSM is obtained. Finally, based on the designed kinematic and dynamic controllers, the finite-time stability of the full closed-loop cascaded system is shown. The two proposed control schemes improve the tracking accuracy over the existing globally finite-time stable tracking control (GFTSTC) and adaptive nonsingular TSMC schemes, and enhance the robustness against parameter uncertainties and external disturbances over the GFTSTC scheme. Compared with the conventional adaptive integral sliding mode control (AISMC) scheme, the two proposed control schemes offer faster convergence rate and stronger robustness against dynamic uncertainties and time-varying external disturbances for the trajectory tracking control of UUVs due to involving the fractional integrator. Comparative numerical simulations are performed on the dynamic model of the Omni Directional Intelligent Navigator UUV for two trajectory tracking cases. The convergence rate and robustness to uncertainties and disturbances are quantified as the convergent time and bounds of the steady-state position and velocity tracking errors, respectively. The results show that the two proposed control schemes improve at least 20s in convergence rate and enhance about 2% robustness in position tracking and 20% robustness in velocity tracking over the AISMC scheme.

The hydraulic CPR (Common Pressure Rail) system has some advantages (i.e. modularization and energy saving), which can be integrated with the characteristics of networked control system (NCS) to enhance the control performance. However, the strong nonlinearity and parameter uncertainty issues of the CPR system based on HT (hydraulic transformer) must be addressed. Moreover, the time-varying time delay and packet loss induced by NCS should be solved at the same time. In the paper, an adaptive fuzzy sliding mode controller based on Pi-sigma fuzzy neural network combining with Pade approximation is proposed to solve these problems. By constructing an appropriate Lyapunov function, the stability of the controller is proved. Finally, the simulation is proceeded to show the proposed controller can guarantee the robustness and compensate the input delay and packet loss in presence of external disturbance and parameter uncertainty.

Finite-time adaptive super-twisting sliding mode control for autonomous robotic manipulators with actuator faults

This study aims to develop an advanced integral terminal sliding-mode robust control method using a disturbance observer (DO) to suppress the forced vibration of a large space intelligent truss structure (LSITS). First, the dynamics of the electromechanical coupling of the piezoelectric stack actuator and the LSITS, based on finite element and Lagrangian methods, are established. Subsequently, to constrict the vibration of the structure, a novel integral terminal sliding-mode control (ITSMC) law for the DO is used to estimate the parameter perturbation of the LSITS based on a continuous external disturbance. Simulation results show that, under a forced vibration and compared with the ITSMC system without a DO, the displacement amplitude of the ITSMC system with the DO is effectively reduced. In the case where the model parameters of the LSITS deviate by ±50%, and an unknown continuous external disturbance exists, the control system with the DO can adequately attenuate the structural vibration and realize robust control. Concurrently, the voltage of the employed piezoelectric stack actuator is reduced, and voltage jitter is alleviated.

In this paper, the fast integral terminal sliding mode control for spacecraft formation flying system is concerned subjected to external disturbances and parametric uncertainties. First, a novel modified fast integral terminal sliding mode control law is designed, which contains the advantages of fast terminal sliding mode. Then, for estimating the external disturbances in the system, the control law based on the reduced-order disturbance observer is proposed which not only reduce the order of the observer but also guarantee the tracking errors converge in finite time. Further, to identify the unknown parameters accurately, by introducing an adaptive parametric updating law, the adaptive fast integral terminal sliding mode control law is proposed, which has better robustness against external disturbances and parameter uncertainties simultaneously. Finally, the effectiveness of the proposed control laws is demonstrated by the simulation results.

Control issue is the key for applying hydraulic hybrid system, especially for common pressure rail (CPR) system which has the huge potential to enhance efficiency. In the paper, the mathematical model of hydraulic cylinder speed control system using new hydraulic transformer is established. Then an adaptive fuzzy sliding mode controller based on Pi-sigma fuzzy neutral network is designed to solve the problem of parameter uncertainty and nonlinearity without establishing the precise model. Furthermore, compared to PID and conventional adaptive fuzzy system, the controller proposed can achieve good control performance and strong robustness in the presence of time-varying uncertainty.

A hybrid UAV, like a biplane quadrotor, has many applications in agriculture, disaster management, and relief operation. In this chapter, we designed a dual observer, (i) an Extended state observer (ESO) for the state approximation and (ii) a Nonlinear Disturbance Observer (DO) for the exterior disturbance estimation. There are three different nonlinear controllers; (i) Backstepping Controller (BSC), (ii) Integral Terminal Sliding Mode Controller (ITSMC), and Hybrid Controller (ITSMC \(+\) BSC) are designed, and ESO (with and without DO) are applied for the trajectory tracking to evaluate the results. Mass change during the flight despite wind gusts is also handled using the Adaptive Backstepping controller (ABSC) and Adaptive hybrid controller with ESO and DO.

Energy-saving research of hydraulic system has become a central issue recently. This paper has made a comprehensive review of the hydraulic transformer (HT) which is the key component in common pressure rail (CPR) hydraulic energy-saving system. First, the invention process and basic working principle of the HT are introduced. Then, HTs are divided into three categories to discuss the current development in accordance with the different structures for realizing the control angle regulation. In addition, the problems existing in the research of HTs are summarized and a new variable displacement HT is proposed for the first time. Finally, the future development of the HT is discussed.

An integral terminal sliding mode controller is proposed in order to control chaos in a rod-type plasma torch system. In this method, a new sliding surface is defined based on a combination of the conventional sliding surface in terminal sliding mode control and a nonlinear function of the integral of the system states. It is assumed that the dynamics of a chaotic system are unknown and also the system is exposed to disturbance and unstructured uncertainty. To achieve a chattering-free and high-speed response for such an unknown system, an adaptive neuro-fuzzy inference system is utilized in the next step to approximate the unknown part of the nonlinear dynamics. Then, the proposed integral terminal sliding mode controller stabilizes the approximated system based on Lyapunov’s stability theory. In addition, a Bee algorithm is used to select the coefficients of integral terminal sliding mode controller to improve the performance of the proposed method. Simulation results demonstrate the improvement in the response speed, chattering rejection, transient response, and robustness against uncertainties.

Permanent magnet synchronous motor (PMSM) has been widely used in position control applications. Its performance is not satisfactory due to internal uncertainties and external load disturbances. To enhance the control performance of PMSM systems, a new method that has fast response and good robustness is proposed in this study. First, a modified integral terminal sliding mode controller is developed, which has a fast-sliding surface and a continuous reaching law. Then, an extended state observer is applied to measure the internal and external disturbances. Therefore, the disturbances can be compensated for in a feedforward manner. Compared with other sliding mode methods, the proposed method has faster response and better robustness against system disturbances. In addition, the position tracking error can converge to zero in a finite time. Simulation and experimental results reveal that the proposed control method has fast response and good robustness, and enables high-precision control.

In the context of chaotic secure communication, this paper is concerned with the predefined-time polynomial-function-based synchronization of chaotic systems via sliding mode control. Firstly, a novel hybrid synchronization scheme among multiple chaotic systems based on polynomial function is defined. Subsequently, based on a new predefined-time stability criterion, a novel multi-power integral terminal sliding mode control algorithm is designed to realize the predefined-time polynomial-function-based synchronization. Finally, the secure communication simulation is presented to verify the feasibility and efficiency of the proposed synchronization scheme. The polynomial-function-based synchronization not only uses the addition and subtraction of vectors, but also uses the power multiplication of vectors, which makes the nonlinear structure of the composed drive system more complex, so that the communication scheme is more secure. Applying the sliding mode control algorithm designed in this work, the synchronization time can be preset off-line without estimation, moreover, the ratio between the formation time and the convergence time of sliding mode can also be distributed in advance, which is more flexible.