Design for Fuzzy Variable Structure Controller of Hybrid Position and Force Control for Dual-arm Coordinated Space Robot Systems

To eliminate the effect of the uncertain disturbances and improve the control accuracy of spacecraft Attitude Control System, a nonlinear control algorithm named nonsingular terminal sliding-mode feedback controller is proposed in this work, which is mainly made up of nonsingular terminal sliding-mode controller and sliding-mode feedback controller. In the first place, nonsingular terminal sliding-mode controller is designed, which guarantees global asymptotic convergence of the attitude in the presence of the uncertain perturbations from the space. Despite that, it is the influence of the uncertain disturbances that hinder the control accuracy. Then, in order to promote the control accuracy, the sliding-mode feedback controller based on the principle of minimum sliding-mode error is proposed, which is used to compensate the control errors of the nonsingular terminal sliding-mode controller caused by the uncertainties. Hence, the determination principle of the weighting matrix in sliding-mode feedback controller is discussed, and the algorithm structure of the sliding-mode feedback controller is also analyzed, which provides the theoretical basis for the sliding-mode feedback controller. By contrast, an adaptive fuzzy algorithm is designed and introduced into the nonsingular terminal sliding-mode controller to improve the control accuracy, which named the nonsingular terminal fuzzy sliding-mode controller. Last but not the least, several numerical examples are presented to demonstrate the efficacy of the proposed nonsingular terminal sliding-mode feedback controller. Simulation results confirm that the control accuracy of the nonsingular terminal sliding-mode feedback controller is higher than the nonsingular terminal sliding-mode controller and the same as nonsingular terminal fuzzy sliding-mode controller. Not only is the calculation of the nonsingular terminal fuzzy sliding-mode feedback controller smaller than nonsingular terminal fuzzy sliding-mode controller, the adjusted parameters are also fewer than nonsingular terminal fuzzy sliding-mode controller obviously. The numerical results clearly indicate that the proposed nonsingular terminal sliding-mode feedback controller based on the principle of minimum sliding-mode error can compensate control errors accurately and quickly; therefore, it can reduce the effect of the uncertainties from the space indirectly.

In this paper, the robust control problem for free-floating dual-arm space robot system with two objects is discussed. Firstly, the kinematics and dynamics of free-floating dual-arm space robot system with two objects are analysed. In order to overcome the difficulty that the dynamic equations of the system are nonlinearly dependent on inertial parameters, the system is modeled as under-actuated robot system, and the idea of augmentation approach is adopted. It is demonstrated that the dynamic equations of the system can be linearly dependent on a group of inertial parameters with augmented inputs and outputs. And then based on the above results, the robust control scheme for dual-arm space robot system with uncertain inertial parameters to track the desired trajectories in joint space is proposed. The proposed control scheme is computationally simple, because we guarantee the controller robust to the uncertain inertial parameters rather than explicitly estimating them online. In addition to this, it need not require controlling the position and attitude of the floating base. Finally, a planar free-floating dual-arm space robot system with two objects is simulated to verify the proposed control scheme

A self-organizing fuzzy controller to augment a sliding-mode control (SOFSMC) scheme for a class of nonlinear systems is proposed. The motivation behind this scheme is to combine the best features of self-organizing fuzzy control and sliding-mode control to achieve rapid and accurate tracking control of a class of nonlinear systems. The chatter encountered by most sliding-mode control schemes is greatly alleviated without sacrificing invariant properties. A stability analysis is presented; the design guidelines and the class of applicable systems are clearly identified. To verify the scheme, the authors performed experiments on its implementation in a magnetic levitation system. The results show that both alleviation of chatter and robust performance are achieved; the advantages of the scheme are indicated in comparison with the conventional sliding-mode design. >

The following topics are dealt with: renewable energy sources; energy conservation; computer aided engineering; thermal power stations; solar power stations; solar absorber-convertors; distributed power generation; photovoltaic power systems; domestic appliances; humidity.

In order to improve the robustness of the sliding mode control algorithm of the four-phase interleaved parallel Buck converter, an improved adaptive non-singular terminal sliding mode PI (ANTSMC-PI) dual closed-loop control strategy based on linearly expanding state observer (LESO) is proposed in this paper. First, two LESO observers are designed to estimate the matched and mismatched disturbance in the system dynamic model, respectively. Second, the estimates of the observers are Integrationed into the outer-loop controller, and an improved sliding-mode controller is proposed to achieve error-free tracking of the output voltage to the reference voltage; while the PI controller is used for the current inner loop to ensure the equal current flow in each phase of the system. Finally, the stability of the designed controller is demonstrated by using the lyapunov stability principle. The simulation in Matlab/Simulink platform shows that the proposed scheme can effectively reduce the output ripple and improve the system dynamic performance compared with the traditional non-singular terminal sliding-mode PI control strategy.

This paper demonstrates a fuzzy sliding mode control (FSMC) scheme for a static reactive power (VAR) compensator (SVC) to improve the damping of a synchronous generator. A robust sliding regime is derived to guarantee the stability of the FSMC with parameter uncertainties. Two types of FSMC-fuzzy switching gain compensation and fuzzy control signal compensation, are recommended to regulate the reactive power of the SVC. A synchronous generator system with the proposed FSMC-SVC has been studied and its dynamic responses are simulated. And the results show that the suggested FSMC possesses the advantages of fuzzy control and sliding mode control, e.g., insensitivity to parameter variations and load disturbances. The dynamic performance of the synchronous machine system can be improved dramatically over a wide range of operating condition. In these control schemes, the reducing switches control are adopted for simplification. >

A new adaptive fuzzy sliding-mode control (FSMC) scheme was proposed, which incorporated the fuzzy logic into sliding-mode control using fuzzy logic to approximate the equivalent control and the upper bound of uncertainty which involved the disturbance and approximation error, thus the influence of modeling error was reduced and the gain of sliding-mode control part was more fitting, such that the chattering effects could be alleviated . Besides, inspired by the thought of fully tuned RBF neural networks, a fully tuned fuzzy logic was proposed which enhanced the approximating ability of fuzzy logic system. Lyapunov stability theorem was used to prove the stability of the system and the adaptive laws were deduced. Finally, simulation results of some BTT missile were included to illustrate the effectiveness of the adaptive fuzzy sliding-mode control scheme.

ABSTRACTIn this paper, a fault estimation and fault-tolerant control problem for a class of T-S fuzzy stochastic time-delay systems with actuator and sensor faults is investigated. A novel sliding mode observer is proposed, which can simultaneously estimate the system states, actuator and sensor faults with good accuracy. Based on the state and actuator fault estimation, a new sliding mode control scheme is developed, which can effectively eliminate the influence of actuator fault. Sufficient conditions for the existence of the proposed observer and fault-tolerant sliding mode controller are provided in terms of linear matrix inequality, and moreover, the reachability of the sliding mode surface can be guaranteed under the proposed control scheme. The propose sliding mode observer and fault-tolerant sliding mode controller can overcome the restrictive assumption that the input matrix of all local modes is the same. Finally, a numerical example is provided to verify the effectiveness of the proposed sliding mode observer and fault-tolerant sliding mode control technique.

This paper presents a non-linear Sliding Mode Control (SMC) strategy based on continuous switching law for large-power (10MW) Permanent Magnet Synchronous Generator (PMSG) based Wind-Energy Conversion System (WECS). The WECS model consists of a wind turbine, PMSG, rectifier fed boost converter, PWM inverter and the filter. The controller is used to maintain the DC-link voltage constant and to generate controlled active and reactive power for grid. For verification of validity of proposed control scheme and model, the proposed system's dynamic model is simulated in MATLAB/Simulink. SMC has the promising features of: fast switching, insensitivity to parameter uncertainty, disturbance rejection quality, and more robustness than the conventional linear controllers. The proposed continuous control compelled the states trajectories of the system onto the surface in error space (sliding surface) for the system behavior to obtain design specifications. Simulation results demonstrate that the proposed SMC is effective and gives superior performance than conventionally tuned PI controller.

This paper presents a comparison study of performances and characteristics of two types of state observer based state feedback control schemes, including Sliding Mode Observer (SMO) based Sliding Mode Controller (SMC) scheme and Luenberger observer (LO) based Sliding Mode Control scheme. The effectiveness of the schemes are simulated and implemented on Two Conical Tank Interacting Level System (TCTILS) which exhibits dynamic nonlinearity and coupling dynamics. The results show that, over all, the SMO based SMC scheme is much superior in dealing with dynamic uncertainties, disturbances and sensor noise.

This paper proposes an approach of hybrid control that is based on the concept of combining fuzzy logic and the methodology of sliding mode control (SMC). In the present works, a first‐order nonlinear sliding surface is presented, on which the developed control law is based. Mathematical proof for the stability and convergence of the system is presented. In order to reduce the chattering in sliding mode control, a fixed boundary layer around the switch surface is used. Within the boundary layer, since the fuzzy logic control is applied, the chattering phenomenon, which is inherent in a sliding mode control, is avoided by smoothing the switch signal. Outside the boundary, the sliding mode control is applied to driving the system states into the boundary layer. Experimental studies carried out on a coupled Tanks system indicate that the proposed fuzzy sliding mode control (FSMC) is a good candidate for control applications.

The control of nonlinear systems has been the subject of extensive research. This interest is mainly due to its potential for real applications. In this paper, we investigated discrete sliding mode control for a class of nonlinear time-delay systems represented by T–S fuzzy models. In most existing fuzzy sliding mode control, a common input matrix is considered for all subsystems. This assumption is very restrictive. Therefore, we proposed a new sliding surface, which takes account of the system state and the control input in order to exclude the restrictive assumption. Furthermore, we have improved the latter sliding mode control scheme, by adding delayed states. Based on formulation of linear matrix inequalities, the parameters of the sliding function are obtained. Therefore, to further reduce the conservatism in the existing results, the Wirtinger-based integral inequality and Jensens inequality are employed. To show the applicability and effectiveness of the proposed controller design methodology, a numerical example is given for illustration.

—Stability, robust and reliability are the main objectives to design a controller for highly nonlinear spherical motor. Most of linear and nonlinear controllers are stable, model-base controllers are reliable but in this group sliding mode controller is a robust controller. Therefore in this research sliding mode controller is used to design stable, robust and reliable controller. For intelligence part, the minimum rule base Proportional Integral Derivative (PID) Fuzzy hybrid guidance Controller for three dimensions spherical motor is presented in this research. Guidance control in a three dimensions spherical motor is performed by the robust sliding mode controllers producing the control signals which are applied to systems torque. Sliding mode controller has an important problem, namely chattering. In this research, chattering-free sliding mode controller is design as a robust guidance controller to their robust performance in a wide range of operating conditions. In this research the PID-like fuzzy controller can be constructed as a parallel structure of a PD-like fuzzy controller and a PI-like controller to have the minimum rule base. Nonlinear type robust sliding mode controller is used to modify PID fuzzy logic theory to design robust and reliable hybrid guidance methodology. This research is used to reduce or eliminate the fuzzy and conventional sliding mode controller problem based on minimum rule base fuzzy logic theory and modified it by sliding mode method to control of spherical motor system.

This study introduces a novel sliding mode control method that combines generalized T-S fuzzy systems and quantized feedback to enhance control efficiency and robustness in complex systems. Existing methods often perform poorly in environments with incomplete information and system uncertainties, making them ill-suited to the dynamic characteristics of complex systems. To address this issue, we propose a sliding mode control method that incorporates both static and dynamic quantizers (with adjustable quantization parameters). Our approach employs a sliding mode variable structure controller designed with traditional linear switching surfaces to ensure that the system approaches the desired sliding mode surface, thereby enhancing the asymptotic stability of the closed-loop system. This quantized feedback sliding mode control strategy effectively ensures the stability and robustness of generalized T-S fuzzy systems under conditions of incomplete information and system uncertainties. Simulation results demonstrate that the system exhibits good control performance under experimental conditions. In summary, our research provides an effective improvement, enhancing the adaptability of generalized T-S fuzzy systems in complex real-world environments and laying a solid foundation for future applications and expansions.

This paper suggests a new hybrid control strategy, called Optimal Type II Fuzzy Sliding Mode (OT2FSM) control scheme, to realize the control of general uncertain chaotic systems. The proposed controller not only guaranties the stability and robustness against the lumped uncertainties caused by unmodeled dynamics and external disturbances, but also can significantly reduce the control chattering inherent in conventional sliding mode control. In the proposed controller, a novel heuristic algorithm namely particle swarm optimization with random inertia weight (RNW–PSO) is employed. To achieve an optimal performance, the parameters of the proposed controller as well as the input and output membership functions are optimized simultaneously by RNW–PSO. The globally asymptotic stability of the closed-loop system is mathematically proved. To evaluate the performance of the proposed controller, the results are compared with those obtained by Optimal H-infinity Adaptive PID (OHAPID) controller and an optimal Type-2 fuzzy proportional integral derivative (OT2FPID), which are the latest researches in the problem in hand. Simulation results show the effectiveness of the OT2FSM controller.