Robust control of single input multi outputs systems

In this paper combination of standard and second order sliding mode controller are used and investigated for congestion control problem of differentiated Services (Diff-Serv) networks. Robustness against modeling uncertainties and disturbances are major features of sliding mode controller. Chattering phenomenon affects sliding mode congestion control; to overcome this problem, second order sliding mode control (SOSMC) is proposed as a congestion controller but this controller has slower response to SMC. Combination SMC and SOSMC gives better response. There are three types of traffics in Diff-Serv networks; i.e. three types of queues and based on that, the quality of their services are categorized. Each of these types of traffic has its own congestion control mechanisms. Stability of each controller is proved by Lyapunov stability law. To evaluate the capabilities of our proposed robust control strategy, simulation results are provided for both sliding mode controllers and second order slide mode controllers and their corresponding efficiencies are compared.

The work carried out in this paper proposes an improvement of the direct torque control (DTC) of induction machine by the design of modern, robust and more efficient controllers than the conventional PI controllers commonly used for speed control. A comparative study has been carried out using five controllers, i.e. PI anti-windup, first-order sliding mode control (SMC), second order sliding mode control (SOSMC), fuzzy logic controller (Fuzzy-PI) and hybrid Fuzzy second-order sliding mode controller (FSOSMC). An advanced optimization technique based on the particle swarm optimization (PSO) algorithm has been utilized to optimize all of these controllers, the use of PSO for the determination of the different gains used in all controllers gives on the one hand a high accuracy performance and ensures on the other hand a reliable comparison between the different controllers in their optimal states. The simulation and analysis of each method with respect to robustness to disturbances was performed externally under various operating conditions and variations of the machine parameters.

This article presents design, analysis and implementation of second order sliding mode controller (SOSMC) for DC-DC buck converter. Firstly, second order sliding mode controllers with prescribed convergence law is designed using the buck converter model. The necessary bounds on the parameter variations for designing the SOSM are obtained. The closed loop stability condition is also derived using Lyapunov function. The SOSM controller is implemented with digital signal controller STM32F407VG based on ARM cortex M4 controller. The converter performance is assessed in simulation as well experimentally with the SOSMC and compared with classical sliding mode control. The effects of varying controller parameters and load disturbances are also analysed to endow the robust performance of the converter and efficacy of the algorithm.

In this paper, the robust control problem of general nonlinear multi-input multi-output (MIMO) systems is proposed. The robustness against unknown disturbances is considered. Two algorithms based on the Sliding Mode Control (SMC) for nonlinear coupled multi-input multi-output (MIMO) systems are proposed: the first order sliding mode control (FOSMC) with saturation (sat) function and the FOSMC with sat combined with integrator controller. Those algorithms were simulated and implemented on the three tanks test-bed system and the exprimental results confirm the effectiveness of our control design.

This paper presents Second Order Sliding Mode Controller using Super Twisting algorithm for the two-wheeled inverted pendulum (TWIP). A mathematical model incorporating the dynamics of LEGO EV3 TWIP is considered here. A Sliding Mode Control (SMC) is designed first, then switching surface is synthesized by converting the state space model into regular form. The corresponding system response is plotted, the problem encountered in SMC is that the control input suffers from Chattering. To overcome the drawback a Second Order Sliding Mode Controller (SOSMC) using super twisting algorithm is designed. The contribution of this paper is real time implementation of Super Twisting SOSMC algorithm to balance the lego TWIP in an upright position. The performance and merit of the SOSMC are exemplified by conducting simulations and real-time validation on the LEGO Mindstorms EV3. The issues related to hardware implementation is discussed.

This paper presents an adaptive PID sliding surface-based second order sliding mode control algorithm for uncertain nonlinear systems using an adaptive PID controller and second order sliding mode control (SOSMC). In the adopted control algorithm, the SOSMC, which is published recently in the literature for linear systems, is extended to nonlinear systems and combined with an adaptive PID sliding surface. The PID sliding surface parameters are adapted online using an adaptation algorithm. The proposed control algorithm (APID-SOSMC) is derived based on Lyapunov stability criterion such that the stability of the overall system is guaranteed. Numerical simulations with dynamical model of the nonlinear inverted pendulum system are presented to demonstrate the effectiveness of the designed controller and proof the system robustness against parameters uncertainty and external load disturbances.

In this paper sliding mode controllers (SMCs)' techniques are used and investigated for congestion control problem of differentiated Services (Diff-Serv) networks. Robustness against modeling uncertainties and disturbances are major features of sliding mode controller. Chattering phenomenon affects sliding mode congestion control; to overcome this problem, second order sliding mode control (SOSMC) is proposed as a congestion controller. There are three types of traffics in Diff-Serv networks; i.e. three types of queues and based on that, the quality of their services are categorized. Each of these types of traffic has its own congestion control mechanisms. Stability of each controller is proved by Lyapunov stability law. To evaluate the capabilities of our proposed robust control strategy, simulation results are provided for both sliding mode controllers and second order slide mode controllers and their corresponding efficiencies are compared.

The control of Doubly-Fed induction generator (DFIG), used in wind energy conversion, has been given a great deal of interest. Frequently, this control has been dealt with ignoring the magnetic saturation effect in the DFIG model. The aim of the present work is twofold: firstly, the magnetic saturation effect is accounted in the control design model; secondly, a new second order sliding mode control scheme using adjustable-gains (AG-SOSMC) is proposed to control the DFIG via its rotor side converter. This scheme allows the independent control of the generated active and reactive power. Conventionally, the second order sliding mode control (SOSMC) applied to the DFIG, utilize the super-twisting algorithm with fixed gains. In the proposed AG-SOSMC, a simple means by which the controller can adjust its behavior is used. For that, a linear function is used to represent the variation in gain as a function of the absolute value of the discrepancy between the reference rotor current and its measured value. The transient DFIG speed response using the aforementioned characteristic is compared with the one determined by using the conventional SOSMC controller with fixed gains. Simulation results show, accurate dynamic performances, quicker transient response and more accurate control are achieved for different operating conditions.

Quadrotor has been widely applied on tethered transportation due to its advantages of safety, low cost, easy operation and high mobility. However, a precise trajectory tracking control is hard to achieve due to the long tether and tethered payload, specially during the maneuvering motion, which is a classical underactuated system. Based on the above questions, a new double-loops observer-based second order sliding mode control(OBSOSMC) scheme is proposed for tethered quadrotor transportation. The dynamics equation of the quadrotor was established based on Newton's Second Law and Euler-Lagrange mechanic. The payload is regarded as disturbance, and observers are designed in both position loop and attitude loop under which the disturbance can be precisely and directly compensated in the designed second order sliding mode control(SOSMC). The asymptotic stability of the closed loop system based on proposed OBSOSMC is theoretically proved by the Lyapunov stability method. The effectiveness of the proposed OBSOSMC scheme is proved by comparing Classical PID and SOSMC in two different practical experiments.

In this study, a reduced-order fast proportional integral (PI) observer with a fast convergence function based on the equivalent control notion is developed to estimate the side slip angle β. An unknown state can be discovered by forcing the PI term on the state error, which is the difference between the real and estimated states. A second order sliding mode control (SOSMC) based on a proposed nonlinear sliding manifold is designed to achieve improved transient response and control performance by robustness. The proposed sliding manifold ensures the convergence of the roll angle in finite time. To validate the assertion regarding the proposed SOSMC, classical SOSMC and proportional integral derivative (PID) SOSMC are simulated both in the absence and presence of disturbances. The simulation results show that the proposed SOSMC over-performs in terms of achieving the desired response in both cases. Additionally, a numerical analysis is also performed for both scenarios to evaluate the effectiveness of the proposed controller in terms of the power consumption of the control law and burden on the aileron control surface. Finally, Monte Carlo simulations are performed to demonstrate the robustness of the proposed controller against external disturbances.

This paper presents a novel Second Order Sliding Mode (SOSM) control algorithm for a class of nonlinear systems subject to matched uncertainties. By virtue of its Event-Triggered nature, it can be used as a basis to construct robust networked control schemes. The algorithm objective is indeed to reduce the number of state transmissions over the network, in order to alleviate the network congestion and reduce possible packet loss, jitter and delays, while guaranteeing satisfactory performance in terms of stability and robustness. The proposed Event-Triggered Second Order Sliding Mode control strategy is theoretically analyzed in the paper, showing its capability of enforcing the robust ultimately boundedness of the sliding variable and its first time derivative, and consequently the practical stability of the uncertain nonlinear system, in spite of the significant reduction of the number of state transmissions with respect to a conventional SOSM control approach. The satisfactory performance of the proposed scheme are also assessed in simulation.

This paper is concerned with design of second order sliding mode controller (SOSMC) with linear dynamic sliding surface. The sliding surface consists of a gain matrix having a variable damping ratio and settling time. The methodology explained is suggested to design systems with desired dynamic behaviour and robust for process uncertainties. In this study sliding mode control (SMC) and SOSMC are designed with linear dynamic sliding surface. The SOSMC proved that output response of process is effectively improved with smooth and reduced control efforts. For effectiveness of the SOSMC strategy, it is verified by simulation of an illustrative example of second order process with delay time (SOPDT).

Choice of control function in magnetically-coupled full bridge DC-DC power controller for arc welding: A Practical Approach

Comparison of robust and adaptive second order sliding mode control in PEMFC air-feed systems

The conventional Direct Torque Control (DTC) strategy using PI regulators has certain disadvantages such as significant flux, torque ripples and sensitivity to parametric variations. To overcome these drawbacks, we apply a new type with more robust regulators such as the Second Order Sliding Mode Control (SOSMC) based on Super Twisting algorithm and fuzzy second order sliding mode control. This work deals with the modeling and performance improvement study of the DTC of a Double Star Permanent Magnet Synchronous Machine (DSPMSM) using a hybrid FUZZY-SOSMC speed regulator. The torque ripple, speed and currents will be evaluated and compared by the classical PI-DTC and SOSMC-DTC. Simulation results demonstrate the feasibility and validity of the proposed FUZZY-SOSMC-DTC system by effectively accelerating system response, reducing torque and a very satisfactory performance has been achieved.