Order Sliding Mode Controller Design Research Articles

High gain differentiator based neuro-adaptive arbitrary order sliding mode control design for MPE of standalone wind power system.

In this paper, we introduce a novel Maximum Power Point Tracking (MPPT) controller for standalone Wind Energy Conversion Systems (WECS) with Permanent Magnet Synchronous Generators (PMSG). The primary novelty of our controller lies in its implementation of an Arbitrary Order Sliding Mode Control (AOSMC) to effectively overcome the challenges caused by the measurement noise in the system. The considered model is transformed into a control-convenient input-output form. Additionally, we enhance the control methodology by simultaneously incorporating Feedforward Neural Networks (FFNN) and a high-gain differentiator (HGO), further improving the system performance. The FFNN estimates critical nonlinear functions, such as the drift term and input channel, whereas the HGO estimates higher derivatives of the system outputs, which are subsequently fed back to the control inputs. HGO reduces sensor noise sensitivity, rendering the control law more practical. To validate the proposed novel control technique, we conduct comprehensive simulation experiments compared against established literature results in a MATLAB environment, confirming its exceptional effectiveness in maximizing power extraction in standalone wind energy applications.

Fractional Order Sliding Mode Control Design for a Buck Converter Feeding Resistive Power Loads

Standalone DC micro-grid requires highly efficient power converters with high performance robust controllers. This research work deals with the hardware implementation of a load side buck converter and its control system integrated in a DC micro-grid system. This paper presents a novel fractional order sliding mode control (FSMC) method for voltage regulation of a buck converter feeding a constant power load. FSMC controller is derived based on the average state space model of the buck converter and its stability is verified using Lyapunov theorem. Finally, the FSMC controller is implemented using Arduino mega 2560 processor and the obtained results are compared with classical sliding mode control (SMC), proportional, integral, derivative (PID) control and fractional order PID control system (FOPID under constant and variable resistive loading.

A combined control approach for industrial process systems using feed-forward and adaptive action based on second order sliding mode controller design

This paper presents a new method that uses a feed-forward adaptive second order sliding mode control (FF-ASSMC) for a coupled tank process system that is often used in industry. This proposed method is to combine a feedforward action with adaptive feedback for robust performance of the couple tank system for the first time. The reason for using this feedforward action with the feedback sliding mode control (SMC) is to reduce the effect of the measured disturbance on the coupled tank system. In addition to this, an adaptive second-order SMC proposes to track the desired tank’s level trajectories under disturbances and uncertainties. In order to illustrate the efficiency of the proposed FF-ASSMC method, the simulation and real time experimental studies have been realized. The simulation and experimental outcomes strongly verified that the proposed controller gives a quite successful trajectory tracking response and smaller magnitude overshot under external disturbances.

Fractional order sliding mode controller design for large scale variable speed wind turbine for power optimization

Based on wind speed, the operating regions of a wind turbine are divided into two parts: below‐rated wind speed (region II) and above‐rated wind speed (region III). This article presents a new control strategy for a variable speed wind turbine for the below‐rated wind speed category (region II). In this operating region, maximization of the conversion efficiency and capturing the maximum energy available in the wind are desirable. The controller is designed based on sliding mode control techniques and fractional order calculations. The sliding‐mode approach has been widely used in wind turbine systems due to the existence of nonlinearity and uncertainty in wind turbine dynamics. The fractional order sliding mode controller has the capacity to produce better performance in comparison to integer order sliding mode controllers due to higher degrees of freedom for tuning. The generator torque is used as the control input to vary the rotor speed in order to maximize energy conversion. To achieve this goal, the rotor angular speed must track the time variable reference value and, hence, fast variations in wind speed. This requires fast reactions on the part of design control. The fractional‐order sliding mode controller can have a good transition response, a low tracking error, and a very fast reaction against rapid variations in wind speed. The stability analysis of the suggested controller was provided using Lyapunov stability theory. Finally, the numerical simulation results are presented and compared with integer order sliding mode control to illustrate the effectiveness of the proposed method. The results show the better performance of the fractional‐order sliding mode controller in comparison to the integer order sliding mode controllers. © 2018 American Institute of Chemical Engineers Environ Prog, 37: 1901–1907, 2018

Second Order Sliding Mode Controller Design for Pneumatic Artificial Muscle

In this paper, first and second order sliding mode controllers are designed for a single link robotic arm actuated by two Pneumatic Artificial Muscles (PAMs). A new mathematical model for the arm has been developed based on the model of large scale pneumatic muscle actuator model. Uncertainty in parameters has been presented and tested for the two controllers. The simulation results of the second-order sliding mode controller proves to have a low tracking error and chattering effect as compared to the first order one. The verification has been done by using MATLAB and Simulink software.

Improved output‐feedback second order sliding mode control design with implementation for underactuated slosh‐container system having confined track length

In this study, a new second order sliding mode controller is designed through a novel non-linear sliding surface proposal for a slosh-container system. A linear sliding surface based controller using second order sliding mode is also derived for the comparison purpose. Both the controllers need only output measurements. The super-twisting algorithm is employed to ensure the finite time convergence of system trajectories to a second order sliding set. In sliding phase, the asymptotic stability of the system states to a desired origin is proved by proposing a new Lyapunov function for the system. A slosh-container system representing underactuated interconnected non-linear dynamics is considered. It is shown that how the consideration of limited track length of container affects the stability conditions. To generate a position trajectory for container from the control input signal, a new approach is employed for the implementation purpose. It is demonstrated through simulations and experimental results that the proposed controller based on the novel non-linear sliding surface outperforms the other controller based on the linear surface and it is more suitable on various practical aspects. This also validates the theoretical findings of the study.

A class of predefined-time stable dynamical systems

This article introduces predefined-time stable dynamical systems which are a class of fixed-time stable dynamical systems with settling time as an explicit parameter that can be defined in advance. This concept allows for the design of observers and controllers for problems that require to fulfil hard time constraints. An example is encountered in the fault detection and isolation problem, where mode detection in a timely manner needs to be guaranteed in order to apply a recovery action. Furthermore, through the notion of strong predefined-time stability, the approach hereinafter presented permits to overcome the problem of overestimation of the convergence time bound encountered in previous methods for the analysis of finite-time stable systems, where the stabilization time is often an unbounded function of the initial conditions of the system. A Lyapunov analysis is provided together with a detailed discussion of the applications to consensus and first order sliding mode controller design.

Adaptive second order sliding mode control under parametric uncertainties: application to a robotic system

The sliding mode control concept has been extensively investigated during the last decade, where it has been proved that such a control strategy is not so simple to be efficiently applied in dynamical and mechanical systems, because of the too strong sensitivity of such systems to the chattering phenomenon. In this paper, a reformulated second order sliding mode controller has been implemented into a robotic system for a trajectory tracking task, both in the case of ideal operation as well as for real systems submitted to parameter uncertainties. A comparative study performed through the obtained simulation results has been presented. Then, an adaptive extension of the second order sliding mode control has been treated seeking to resolve the challenging problems of real systems reflected by the presence of physical and environmental disturbances and especially parametric uncertainties. The proposed adaptive second order SMC has the advantage that it allows not only to remedy disturbing phenomena but also to retain all properties and system performances. Simulation results performed on a robotic manipulator system have illustrated improved performances with the proposed adaptive second order sliding mode control design.

Third order sliding mode control of a medical robot for tele-echography

This paper deals with the control problem of robotic manipulators, which are always subject to nonlinear uncertainties. In particular, a dynamic system with fast actuators is exposed to many disrupting risks, generally induced by the presence of parametric uncertainties and unmoderated dynamics. So the dynamic model becomes highly nonlinear, which requires the use of a robust stabilising control. In this context, we propose a solution based on the third order sliding mode control (SMC) approach, in order to ensure a performant trajectory tracking motion control for a medical task. The proposed controller is expected to remove the standard sliding mode restrictions, to provide for a higher accuracy and robustness in realisation with respect to the current existence of imperfections. Simulation results confirm the effectiveness of the proposed third order SMC design with respect to disturbances, mainly affecting control systems.

Third order sliding mode control of a medical robot for tele-echography

This paper deals with the control problem of robotic manipulators, which are always subject to nonlinear uncertainties. In particular, a dynamic system with fast actuators is exposed to many disrupting risks, generally induced by the presence of parametric uncertainties and unmoderated dynamics. So the dynamic model becomes highly nonlinear, which requires the use of a robust stabilising control. In this context, we propose a solution based on the third order sliding mode control (SMC) approach, in order to ensure a performant trajectory tracking motion control for a medical task. The proposed controller is expected to remove the standard sliding mode restrictions, to provide for a higher accuracy and robustness in realisation with respect to the current existence of imperfections. Simulation results confirm the effectiveness of the proposed third order SMC design with respect to disturbances, mainly affecting control systems.

Higher order sliding mode controller design for a research nuclear reactor considering the effect of xenon concentration during load following operation

Reactor power control is one of the most important problems in a nuclear power plant. This paper presents the higher order sliding mode controller (H.O.S.M.C.) which is a robust nonlinear controller for a nuclear research reactor considering the effect of xenon concentration during load following operation. Sliding mode controllers for nuclear reactors were developed before. Traditional sliding mode technique has intrinsic problem of chattering. To cope with this problem higher order sliding mode (HOSM) is used. The nonlinear model of a research reactor (Pakistan Research Reactor-1) has been used for higher order sliding mode controller design and performance evaluation. The reactor core is simulated based on the point kinetics equations and three delayed neutron groups. The model assumes feedback from lumped fuel and coolant temperatures. The effect of xenon concentration is also included. The employed method is easy to implement in practical applications and moreover, the higher order sliding mode control exhibits the desired dynamic behavior during the entire output-tracking process. Simulation results show the effectiveness of the proposed controller in terms of performance, stability and robustness against disturbances.

Multiple-time scale smooth second order sliding mode controller design for flexible hypersonic vehicles

A nonlinear robust control strategy is proposed for flexible hypersonic vehicles with aerodynamic parameters uncertainties. Firstly, the longitude dynamics of this vehicle are divided into velocity subsystem, altitude and flight path angle subsystem, angle of attack, and pitch rate subsystem. Then the smooth second order sliding mode controller and disturbance observer are designed to ensure the finite time stability for each subsystem. Furthermore, the stability of the whole system is guaranteed via the assumption of multiple-time scale characteristic. Moreover, the effect of flexible modes on rigid-body states can be estimated exactly using the disturbance observer. In addition, two representative simulations are carried out to analyze the effect of elevator deflection and canard on the dynamics of velocity, flight path angle, and angle of attack. Finally, the Monte Carlo simulations are provided to verify the effectiveness of the proposed control strategy.

Continuous high order sliding mode controller design for a flexible air-breathing hypersonic vehicle

This paper investigates the problem of tracking control with uncertainties for a flexible air-breathing hypersonic vehicle (FAHV). In order to overcome the analytical intractability of this model, an Input–Output linearization model is constructed for the purpose of feedback control design. Then, the continuous finite time convergence high order sliding mode controller is designed for the Input–Output linearization model without uncertainties. In addition, a nonlinear disturbance observer is applied to estimate the uncertainties in order to compensate the controller and disturbance suppression, where disturbance observer and controller synthesis design is obtained. Finally, the synthesis of controller and disturbance observer is used to achieve the tracking for the velocity and altitude of the FAHV and simulations are presented to illustrate the effectiveness of the control strategies.

Design Higher Order Sliding Mode Controller for a Class of SISO Uncertain Nonlinear System

A higher order sliding mode control design is considered for a class of uncertain nonlinear systems with unknown bounded uncertainties. This method can be viewed as the finite time stabilization based on integral sliding mode control and geometric homogeneity. Based on the Lyapunov theory, the system trajectory is guaranteed to approach the sliding surface. Only one adaptive gain parameter is required. The stability and the robustness of the control system are proven. Numerical experiments illustrate the satisfactory performance of the proposed control methodology.

Fractional order sliding mode controller design for antilock braking systems

Antilock braking system (ABS) is a highly nonlinear system including variation and uncertainties in the parameters due to changes in vehicle loadings, road condition, etc. It is a difficult task to design an ideal controller for ABS. In this paper, a novel robust controller named fractional order sliding mode controller (FOSMC) is proposed for ABS to regulate the slip to a desired value. The proposed FOSMC combines sliding mode controller (SMC) with fractional order dynamics, in which fractional order proportional-derivative (FOPD) sliding surface is adopted. FOSMC can not only deal with the uncertainties in ABS system but also track the desired slip faster than conventional integer order SMC with proportional or proportional-derivative sliding surface. Experimental results demonstrate the effectiveness of the proposed method.

Adaptive High Order Sliding Mode Controller Design for Hypersonic Vehicle with Flexible Body Dynamics

This paper describes the design of a nonlinear robust adaptive controller for a flexible hypersonic vehicle model which is nonlinear, multivariable, and unstable, and includes uncertain parameters. Firstly, a control-oriented model is derived for controller design. Then, the model analysis is conducted for this model via input-output (I/O) linearized technique. Secondly, the sliding mode manifold is designed based on the homogeneity theory. Then, the adaptive high order sliding mode controller is designed to achieve the tracking for hypersonic vehicle where the upper bounds of the uncertainties are not known in advance. Furthermore, the stability of the system is proved via the Lyapunov theory. Finally, the Monte-Carlo simulation results on the full-order nonlinear model with aerodynamic uncertainties are provided to demonstrate the effectiveness of the proposed control strategy.

Model validation and higher order sliding mode controller design for a research reactor

The paper pertains to model validation and novel higher order sliding mode controller design for a nuclear research reactor. Sliding mode controllers for nuclear reactors were reported before but higher order sliding mode controllers have added advantage of reduced chattering. As a first step of model development a simulation model of control rod drive mechanism (CRDM) has been developed using SIMULINK ®. This model has been validated with a lab based CRDM model, which is similar to Pakistan Research Reactor-1 (PARR-1) CRDM system. The nonlinear model of PARR-1 has been tuned and validated with experimental data. This model has been subsequently used for higher order sliding mode controller design and performance evaluation. Certain parameter values have also been recalculated to ensure model accuracy. Based on the validated model a robust nonlinear controller for controlling output power by manipulating control rod position has been developed and simulated. The new controller showed improved performance as compared to the classical PID controller.