Showing papers on "Variable structure control published in 2013"
TL;DR: In this paper an adaptation methodology is developed for searching the minimum possible value of control based on evaluations of the, so-called, equivalent control by a low-pass filter based on direct measurements of the first-order low- pass filter.
436 citations
TL;DR: Based on the decentralized sliding mode control, a load frequency controller is designed in this article for multi-area interconnected power systems with matching and unmatched uncertainties, and a proportional and integral switching surface is constructed for each area to improve system dynamic performance in reaching intervals.
Abstract: Based on the decentralized sliding mode control, a load frequency controller is designed in this paper for multi-area interconnected power systems with matching and unmatched uncertainties. The proportional and integral switching surface is constructed for each area to improve system dynamic performance in reaching intervals. The robust controller is proposed by the reaching law method to assure that frequency fluctuation converges to zero after a load and operation point variation. A three-area interconnected power system is studied to illustrate the effectiveness of the proposed decentralized sliding mode control scheme.
248 citations
TL;DR: A new control system, based on field programmable gate array technology, targeting the powertrain control of multi-motor electric vehicles (EVs), and demonstrates a good slip regulation and robustness to disturbances.
Abstract: This paper presents a new control system, based on field programmable gate array technology, targeting the powertrain control of multi-motor electric vehicles (EVs) The control chip builds around a reusable intellectual property core named propulsion control unit, which features motor control functions with field-orientation methods, and energy loss minimization of induction motors In order to improve the EV safety, the control system was extended with a wheel slip controller based on the sliding mode framework The robustness to parametric and modeling uncertainties is the main attraction in this design, thanks to a simple connection that was found between the driving torque request and the model uncertainty To overcome the chattering issue, which arrives from the discontinuous nature of the sliding control, the conditional integrator approach was employed, enabling a smooth transition to a Proportional+Integral control law, with anti-windup, when the tire slip is close to the setpoint The controller asymptotic stability and robustness was analytically investigated through the Lyapunov method Experimental results, obtained with a multi-motor EV prototype under low grip conditions, demonstrate a good slip regulation and robustness to disturbances
151 citations
TL;DR: A controller ensuring exponential exact tracking in the presence of matched and unmatched disturbances for the nonlinear systems in the block controllable form is proposed and combines the feedback linearization technique with the high-order sliding-modes.
Abstract: In this technical note, a controller ensuring exponential exact tracking in the presence of matched and unmatched disturbances for the nonlinear systems in the block controllable form is proposed. The controller is designed using the backstepping procedure and combines the feedback linearization technique with the high-order sliding-modes. The matched and unmatched disturbances are compensated by the injection of a continuous term generated by the robust exact high-order sliding-modes differentiator. The obtained control law is differentiable and can be applied directly to the system. Simulations verify the performance of the proposed controller.
149 citations
TL;DR: A nonlinear position tracking controller with a disturbance observer (DOB) is proposed to track the desired position in the presence of the disturbance for electrohydraulic actuators (EHAs) in order to compensate for the error in disturbance estimation.
Abstract: A nonlinear position tracking controller with a disturbance observer (DOB) is proposed to track the desired position in the presence of the disturbance for electrohydraulic actuators (EHAs). The DOB is designed in the form of a second-order high-pass filter in order to estimate the disturbance. The nonlinear controller is designed for position tracking as a near input-output linearizing inner-loop load pressure controller and a backstepping outer-loop position controller. Variable structure control is implemented in order to compensate for the error in disturbance estimation. The desired load pressure is designed to generate the pressure using the differential flatness property of the EHA's mechanical subsystem. The disturbance within the bandwidth of the DOB can be cancelled by the proposed method. The performance of the proposed method is validated via simulations and experiments.
136 citations
01 Jan 2013
TL;DR: A comprehensive approach to Sliding Mode Design and Analysis in Linear Systems and a practical relative degree approach in sliding- mode control for accurate tracking of Unmatched Perturbed Outputs are presented.
Abstract: Comprehensive Approach to Sliding Mode Design and Analysis in Linear Systems.- Adaptive Sliding Mode Control.- Decentralised Variable Structure Control for Time Delay Interconnected Systems.- On the Second Order Sliding Mode Approach to Distributed and Boundary Control of Uncertain Parabolic PDEs.- Practical relative degree approach in sliding- mode control.- Higher Order Sliding Mode Based Accurate Tracking of Unmatched Perturbed Outputs.- On the Second Order Sliding Mode Approach to Distributed and Boundary Control of Uncertain Parabolic PDEs.- Practical relative degree approach in sliding- mode control.- Higher Order Sliding Mode Based Accurate Tracking of Unmatched Perturbed Outputs.
86 citations
TL;DR: Two guidance laws are proposed to solve the problem of automatic path tracking by autonomous farming vehicles subject to wheel slips, and both explicitly take into account the constraints on the steering angle and ensure tracking an arbitrarily curved path.
85 citations
TL;DR: A novel switching surface is proposed and its finite-time stability to the origin is proved and a robust fractional control law is proposed to ensure the existence of the sliding motion in finite time.
Abstract: This paper investigates the problem of robust control of nonlinear fractional-order dynamical systems in the presence of uncertainties. First, a novel switching surface is proposed and its finite-time stability to the origin is proved. Subsequently, using the sliding mode theory, a robust fractional control law is proposed to ensure the existence of the sliding motion in finite time. We use a fractional Lyapunov stability theory to prove the stability of the system in a given finite time. In order to avoid the chattering, which is inherent in conventional sliding mode controllers, we transfer the sign function of the control input into the fractional derivative of the control signal. The proposed chattering-free sliding mode technique is then applied for stabilisation of a broad class of three-dimensional fractional-order chaotic systems via a single variable driving control input. Simulation results reveal that the proposed fractional sliding mode controller works well for chaos control of fractional-ord...
83 citations
TL;DR: In this paper, a new nonsingular terminal sliding manifold is proposed to design a robust finite-time controller, and a novel fractional sliding mode control law is introduced to guarantee the occurrence of the sliding motion in finite time.
Abstract: This paper introduces a finite-time control technique for control of a class of non-autonomous fractional-order nonlinear systems in the presence of system uncertainties and external noises. It is known that finite-time control methods demonstrate better robustness and disturbance rejection properties. Moreover, finite time control methods have optimal settling time. In order to design a robust finite-time controller, a new nonsingular terminal sliding manifold is proposed. The proposed sliding mode dynamics has the property of fast convergence to zero. Afterwards, a novel fractional sliding mode control law is introduced to guarantee the occurrence of the sliding motion in finite time. The convergence times of both reaching and sliding phases are estimated. The main characteristics of the proposed fractional sliding mode technique are (1) finite-time convergence to the origin; (2) the use of only one control input; (3) robustness against system uncertainties and external noises; and (4) the ability of control of non-autonomous fractional-order systems. At the end of this paper, some computer simulations are included to highlight the applicability and efficacy of the proposed fractional control method.
79 citations
TL;DR: It is proved that any given level of gain attenuation from external disturbance/parametric estimation error to system output is achieved with the developed control law.
Abstract: Adaptive-based integral sliding mode control scheme is developed to solve the actuator fault-tolerant compensation problem for linear time-invariant system in the presence of unknown actuator faults and external disturbances. A nonlinear integral-type sliding manifold is first presented that incorporates a virtual nominal control to achieve prescribed specifications of the perturbed system, and an adaptive sliding mode controller is constructed to automatically compensate for external disturbances and unknown time-invariant faults. It is shown that the proposed controller has the capability to guarantee that the resulting closed-loop system is asymptotically stable. Control design methodology is then extended to tackle with the unknown time-varying actuator faults. It is proved that any given level of gain attenuation from external disturbance/parametric estimation error to system output is achieved with the developed control law. The closed-loop performance of the new control solution derived here is evaluated extensively through numerical simulations in which the flexible spacecraft attitude control under both the external disturbances and actuator faults are considered.
69 citations
TL;DR: In this article, the optimal control law for a single nonlinear point absorber in irregular sea states is derived, and proven to be a closed-loop controller with feedback from measured displacement, velocity and acceleration of the floater.
TL;DR: An observer-based forward kinematics solution of a 6-6 Stewart platform is proposed and this algorithm is applied to implement an output feedback sliding mode control to control the posture in Cartesian domain directly.
Abstract: In this paper, an observer-based forward kinematics solution of a 6-6 Stewart platform is proposed and this algorithm is applied to implement an output feedback sliding mode control. The conventional forward kinematics solutions take too much computational load or are too complex to be carried out in the online control scheme. The proposed nonlinear observer-based algorithm provides a simple method to obtain a real-time forward kinematics solution. With this solution, 6-degrees-of-freedom posture control of the moving platform can be achieved without installation of any external sensor after applying an output feedback control. In contrast with the conventional control scheme which aims to control individual leg length in actuator domain, the output feedback controller is proposed here to control the posture in Cartesian domain directly. The stability of the whole system is thoroughly proved to ensure convergence of the control errors. Simulations and experimental results are presented to validate the feasibility of the hereby proposed results.
01 Jan 2013
TL;DR: In this article, an adaptation methodology is discussed for obtaining the minimum possible value of control based on two approaches developed in recent publications: Adaptive Sliding Mode Control (ASCC).
Abstract: The main obstacles for application of Sliding Mode Control are two interconnected phenomena: chattering and high activity of control action. It is well known that the amplitude of chattering is proportional to the magnitude of a discontinuous control. These two problems can be handled simultaneously if the magnitude is reduced to a minimal admissible level defined by the conditions for the sliding mode to exist. Here an adaptation methodology is discussed for obtaining the minimum possible value of control based on two approaches developed in recent publications:
TL;DR: Choosing the missile's lateral acceleration (latax) to enforce sliding mode on a switching surface defined by the line-of-sight angle leads to a guidance law that allows the achievement of the desired terminal impact angle.
Abstract: In this brief, variable structure systems theory based guidance laws, to intercept maneuvering targets at a desired impact angle, are presented. Choosing the missile's lateral acceleration (latax) to enforce sliding mode, which is the principal operating mode of variable structure systems, on a switching surface defined by the line-of-sight angle leads to a guidance law that allows the achievement of the desired terminal impact angle. As will be shown, this law does not ensure interception for all states of the missile and the target during the engagement. Hence, additional switching surfaces are designed and a switching logic is developed that allows the latax to switch between enforcing sliding mode on one of these surfaces so that the target can be intercepted at the desired impact angle. The guidance laws are designed using nonlinear engagement dynamics for the general case of a maneuvering target.
TL;DR: In this article, a sliding mode controller for a class of mismatched uncertain systems is proposed for slosh-free motion of a partially filled liquid container, which is representative of a broader class of systems to which the proposed methodology is applicable.
Abstract: A new nonlinear switching surface is proposed for the design of a sliding mode controller for a class of mismatched uncertain systems. A control system for slosh-free motion of a partially filled liquid container is sought. This is representative of a broader class of systems to which the proposed methodology is applicable. A fundamental mode of lateral slosh is considered. A simple pendulum model is used to represent the lateral slosh. Given the difficulty of measuring the slosh states directly, a sliding mode observer is used for implementation of the resulting sliding mode control. The effectiveness of the theoretical developments is demonstrated via both simulation and experimental results.
01 Nov 2013
TL;DR: Investigating a permanent magnet synchronous motor drive controlled by a second-order variable structure control technique, known as the super-twisting sliding modes (STSM) control, presents theoretical aspects for the STSM control, several design and implementation details, and comparative experimental results with all three schemes.
Abstract: This paper investigates a permanent magnet synchronous motor drive controlled by a second-order variable structure control technique, known as the super-twisting sliding modes (STSM) control. The STSM controller is designed as a direct torque and flux controller and it works in the stator flux reference frame, rather than the rotor frame, as a regular vector control scheme. Another second-order sliding mode controller (SMC) was developed and compared with the STSM controller. Also for comparison, a similar direct torque control scheme based on linear PI controllers was developed and tested. The tests show that the STSM controller displays very robust behavior, like any SMC, and it works without notable chattering, like the linear PI-based controller. The paper presents theoretical aspects for the STSM control, several design and implementation details, and comparative experimental results with all three schemes.
TL;DR: Two adaptive fault-tolerant control laws are developed by adopting the nonlinear analytical model to describe the system, which can guarantee global asymptotic convergence of the attitude control error with the existence of unknown external perturbations.
TL;DR: A novel second-order fast terminal sliding mode control scheme is proposed to suppress the chaotic motion of a micro-mechanical resonator with system uncertainty and external disturbance and employs the finite-time technique to obtain the properties of fast response and high precision.
TL;DR: The SMV SC simulation should be of interest to design engineers who wish to demonstrate and investigate sophisticated position-control methods and their applications and may also serve as a basis for further applications of SMVSC in other engineering fields.
TL;DR: On the basis of the finite-time stability theory and the differential inequality principle, it is proved that the resulting closed-loop system is stable and the trajectory tracking error converges to zero in finite time.
Abstract: An adaptive nonsingular fast terminal sliding mode control scheme consisting of an adaptive control term and a robust control term for electromechanical actuator is proposed in this article. The adaptive control term with an improved composite adaptive law can estimate the uncertain parameters and compensate for the modelled dynamical uncertainties. While the robust control term, which is based on a modified nonsingular fast terminal sliding mode control method with fast terminal sliding mode TSM reaching law, provides fast convergence of errors, and robustifies the design against unmodelled dynamics. Furthermore, the control method eliminates the singular problems in conventional TSM control. On the basis of the finite-time stability theory and the differential inequality principle, it is proved that the resulting closed-loop system is stable and the trajectory tracking error converges to zero in finite time. Finally the effectiveness of the proposed method is illustrated by simulation and experimental study.
TL;DR: An approach to robust stability of linear systems from the consideration of the saturating control is proposed, which would work only if the slope of the continuous nonlinear function within the boundary layer is low enough.
Abstract: It has been a widely accepted notion that approximation of discontinuous control by certain continuous function in a boundary layer results in chattering elimination in sliding mode control systems. It is shown through three different types of analysis that in the presence of parasitic dynamics, this approach to chattering elimination would work only if the slope of the continuous nonlinear function within the boundary layer is low enough, which may result in the deterioration of performance of the system. A few examples are provided. An approach to robust stability of linear systems from the consideration of the saturating control is proposed.
TL;DR: It is seen that the proposed method exhibits a considerable improvement in terms of a faster dynamic response and lower IAE and ITAE values as compared with the existing decoupled control methods.
TL;DR: In this article, a robust fractional variable structure controller is proposed to ensure the existence of the sliding motion in finite time. But the control inputs are free of chattering and practical.
Abstract: This paper concerns the problem of robust control of uncertain fractional-order nonlinear complex systems. After establishing a simple linear sliding surface, the sliding mode theory is used to derive a novel robust fractional control law for ensuring the existence of the sliding motion in finite time. We use a nonsmooth positive definitive function to prove the stability of the controlled system based on the fractional version of the Lyapunov stability theorem. In order to avoid the chattering, which is inherent in conventional sliding mode controllers, we transfer the sign function of the control input into the first derivative of the control signal. The proposed sliding mode approach is also applied for control of a class of nonlinear fractional-order systems via a single control input. Simulation results indicate that the proposed fractional variable structure controller works well for stabilization of hyperchaotic and chaotic complex fractional-order nonlinear systems. Moreover, it is revealed that the control inputs are free of chattering and practical.
TL;DR: In this paper, a second-order terminal sliding control (2TSMC) is proposed for the velocity and altitude tracking control of a hypersonic vehicle (HSV) in the presence of parameter uncertainties and external disturbances.
Abstract: This paper focuses on the design of nonlinear robust controller and disturbance observer for the longitudinal dynamics of a hypersonic vehicle (HSV) in the presence of parameter uncertainties and external disturbances. First, by combining terminal sliding mode control (TSMC) and second-order sliding mode control (SOSMC) approach, the secondorder terminal sliding control (2TSMC) is proposed for the velocity and altitude tracking control of the HSV. The 2TSMC possesses the merits of both TSMC and SOSMC, which can provide fast convergence, continuous control law and high-tracking precision. Then, in order to increase the robustness of the control system and improve the control performance, the sliding mode disturbance observer (SMDO) is presented. The closed-loop stability is analyzed using the Lyapunov technique. Finally, simulation results illustrate the effectiveness of the proposed method, as well as the improved overall performance over the conventional sliding mode control (SMC).
28 May 2013
TL;DR: The integral sliding-mode control law is modified for linear as well as nonlinear systems with matched disturbance replacing the discontinuous part of the feedback control by a super-twisting control.
Abstract: The integral sliding mode control, existing in literature is a combination of nominal control and a discontinuous feedback control Discontinuity in feedback control, is not suitable for many practical applications due to the practical limitations of actuators, known as chattering In this paper, the integral sliding-mode control law is modified for linear as well as nonlinear systems with matched disturbance replacing the discontinuous part of the feedback control by a super-twisting control Replacement is possible due to the unique feature of disturbance observation property of the super-twisting algorithm The proposed controller is continuous due to the combination of two continuous controls The effectiveness of the modified control law is shown by the simulation on a practical setup-Quanser SRV-02 for position control
01 Jan 2013
TL;DR: Simulation results demonstrated the validity of the Mamdani parallel fuzzy-optimization control with asymptotic and stable tracking at different position inputs and a well synchronized control signal at different excitation conditions.
Abstract: The focus of this research is on the development, modeling and high precision robust control of an electro-mechanical continuum robot manipulator that serves as a sensing and motion system for hybrid testing. In this research parallel fuzzy logic theory is used to compensate the system dynamic uncertainty controller based on sliding mode theory. This design resulted in strongly non-linear and coupled dynamics as well as an inertial moving platform that attracted model-based control strategies. A novel non-linear control technique based on sliding mode Lyapunov based was selected to meet the multiple simultaneous specification control of nonlinear, uncertain and asymptotic tracking. Sliding mode controller (SMC) is a significant nonlinear controller under condition of partly uncertain dynamic parameters of system. This controller is used to control of highly nonlinear systems especially for continuum robot manipulator, because this controller is robust and stable in presence of partly uncertainties. Sliding mode controller was used to achieve a stable tracking, while the parallel fuzzy-logic optimization added intelligence to the control system through an automatic tuning of the sliding mode methodology uncertainties. Simulation results demonstrated the validity of the Mamdani parallel fuzzy-optimization control with asymptotic and stable tracking at different position inputs. This compensation demonstrated a well synchronized control signal at different excitation conditions.
TL;DR: In this article, an adaptive robust attitude tracking control law based on switched nonlinear systems is presented for a variable structure near space vehicle (VSNSV) in the presence of uncertainties and disturbances.
TL;DR: This paper expands a Multi Input Multi Output (MIMO) fuzzy baseline variable structure control (VSC) which controller coefficient is off-line tuned by gradient descent algorithm which provides an optimal setting for other factors which crated by PID baseline method.
Abstract: This paper expands a Multi Input Multi Output (MIMO) fuzzy baseline variable structure control (VSC) which controller coefficient is off-line tuned by gradient descent algorithm. The main goal is to adjust the optimal value for fuel ratio (FR) in motor engine. The fuzzy inference system in proposed methodology is works based on Mamdani-Lyapunov fuzzy inference system (FIS). To reduce dependence on the gain updating factor coefficients of the fuzzy methodology, PID baseline method is introduced. This new method provides an optimal setting for other factors which crated by PID baseline method. The gradient descent methodology is off-line tune all coefficients of baseline fuzzy and variable structure function based on mathematical optimization methodology. The performance of proposed methodology is validated through comparison with fuzzy variable structure methodology (FVSC). Simulation results signify good performance of fuel ratio in presence of different torque load and external disturbance.
TL;DR: This paper examines single input single output (SISO) chattering free variable structure control (VSC) which controller coefficient is on-line tuned by fuzzy backstepping algorithm which effectively combines the design technique from variable structure controller is based on Lyapunov and fuzzy estimator to estimate the nonlinearity of undefined system dynamic in backste stepping controller.
Abstract: This paper examines single input single output (SISO) chattering free variable structure control (VSC) which controller coefficient is on-line tuned by fuzzy backstepping algorithm. VSC methodology is selected as a framework to construct the control law and address the stability and robustness of the close loop system based on Lyapunove formulation. The main goal is to guarantee acceptable fuel ratio result and adjust. The proposed approach effectively combines the design technique from variable structure controller is based on Lyapunov and fuzzy estimator to estimate the nonlinearity of undefined system dynamic in backstepping controller. The input represents the function between variable structure function, error and the rate of error. The outputs represent fuel ratio, respectively. The fuzzy backstepping methodology is on-line tune the variable structure function based on adaptive methodology. The performance of the SISO VSC which controller coefficient is on-line tuned by fuzzy backstepping algorithm (FBSAVSC) is validated through comparison with VSC and proposed method. Simulation results signify good performance of trajectory in presence of uncertainty torque load. DOI: http://dx.doi.org/10.11591/ijece.v3i2.2092
TL;DR: The proposed PID control law has the following characteristics: it can be straightforwardly applied to any process regardless of its complexity since, for its development, a generalized transfer function process model is employed consisting of n poles and m zeros plus unknown time delay d.
Abstract: The problem of designing PID type-III control loops is investigated. On a theoretical basis and if frequency domain modeling of the control loop is followed, type-III control loops are characterized by the presence of three pure integrators in the open-loop transfer function. Therefore, such a control scheme has the advantage of tracking fast reference signals since it exhibits zero steady-state position, velocity, and acceleration error. This advantage is considered critical in many industry applications, i.e., control of electrical motor drives and control of power converters, since it allows the output variable, i.e., current or speed, to track perfectly step, ramp, and parabolic reference signals. The proposed PID control law has the following characteristics: 1) it consists of analytical expressions that involve all modeled process parameters; 2) it can be straightforwardly applied to any process regardless of its complexity since, for its development, a generalized transfer function process model is employed consisting of n poles and m zeros plus unknown time delay d; and 3) it allows for accurate investigation of the performance of the control action to exogenous and internal disturbances in the control loop and investigation of different operating points. For justifying the potential of the proposed control law, several examples of process models met in many industry applications are investigated.