Dynamic Sliding Mode Control Research Articles

Adaptive sliding mode control for trajectory tracking of nonholonomic mobile robot with uncertain kinematics and dynamics

ABSTRACT This article designs a novel adaptive trajectory tracking controller for nonholonomic wheeled mobile robot under kinematic and dynamic uncertainties. A new velocity controller, in which kinematic parameter is estimated, produces velocity command of the robot. The designed adaptive sliding mode dynamic controller incorporates an estimator term to compensate for the external disturbances and dynamic uncertainties and a feedback term to improve the closed-loop stability and account for the estimation error of external disturbances. The system stability is analyzed using Lyapunov theory. Computer simulations affirm the robustness of the designed control scheme.

Research on Integrated Guidance and Control of Distributed Cooperation of Multi-Interceptor with State Coupling

With the aim of achieving cooperative target interception by using multi-interceptor, a distributed cooperative control algorithm of the multi-interceptor with state coupling is proposed based on the IGC (integrated guidance and control) method. Considering the coupling relationship between the pitch and ya w channels, a state coupling “leader” IGC model is established, an FTDO (finite-time disturbance observer) is designed for estimating the unknown interference of the model, and the “leader” controller is designed according to the adaptive dynamic surface sliding-mode control law. Secondly, the cooperative control strategy of the multi-interceptor is designed with the “leader-follower” distributed network mode to obtain the speed in the three directions of the interceptor in air and transform them to the general flight speed, trajectory inclination angle, and trajectory deflection instruction by using the transformational relation of kinematics. Finally, the “follower” controller is designed with the FTDO and dynamic surface sliding-mode control. The designed multi-interceptor distributed cooperative IGC algorithm with state coupling has good stability according to the simulation results of two different communication topologies.

Dynamic sliding mode-based attitude stabilisation control of satellites with angular velocity and control constraints

This work presents a novel control approach to the attitude stabilisation problem of rigid satellites with external disturbance, control constraint, and angular velocity constraint. The controller is developed in the framework of dynamic sliding mode control. A dynamic sliding mode surface is preliminarily chosen, and then a structure-simple sliding mode control law is synthesised. It is proved that the proposed control law can successfully accomplish the attitude stabilisation manoeuvre. The attitude is exponentially stabilised, and the angular velocity is stabilised with an exponential rate to a ball with a small radius. In comparison with the static sliding mode surface-based controllers, the proposed approach can provide a fast convergence rate. The system convergence time can be shortened by dynamically updating the control parameters in the sliding mode. Simulation results are presented to examine the feasibility of the presented solution.

Adaptive fractional order fast terminal dynamic sliding mode controller design for antilock braking system (ABS)

This article focuses on designing an antilock braking system (ABS) controller to adjust the wheel slip to the preferred value using sliding mode control and fractional calculus. The ABS must be robust against external disturbances such as variations in the friction force between the tire and road caused by changes in the road conditions, loadings and etc. A fractional order PD switching surface is defined, then in order to improve the convergence speed and increase degree of freedom of the controller, a new sliding surface is defined as fast terminal dynamic sliding surface which is formulated using Fractional Calculus. Then, a fractional order fast terminal dynamic sliding mode controller (FOFTDSMC) is designed. Also, for estimating the upper bound value of the lumped uncertainty in the proposed controller, an adaptive FOFTDSMC is designed. The finite time stability of the closed-loop system is guaranteed. Simulation results show the effectiveness of the proposed controller in terms of fast tracking with high robustness when compared to the fractional order sliding mode controller and fractional order fast terminal sliding mode controller.

Adaptive dynamic sliding mode control for space manipulator with external disturbance

ABSTRACTIn this paper, a novel adaptive dynamic sliding mode control(ADSMC) methodology is developed for space manipulator control systems with external disturbance. The proposed ADSMC approach can make the systems stable and accurately track the desired signals in the presence of external disturbances. Firstly, the simplified dynamic model of the manipulator is introduced. Then, the proposed adaptive dynamic sliding mode(ADSM) controller is given, which is proved to be able to guarantee high tracking accuracy via effectively estimating the disturbance boundary. Finally, experimental results show that the dynamic sliding mode controller proposed in this paper can not only track the desired trajectory, but also present strong robustness for external disturbance, meanwhile effectively reduce the chattering phenomenon generated by switching between different sliding mode surfaces.

Estimation of load torque in induction motors via dynamic sliding mode control and new nonlinear state observer

This study conducts load torque estimation in an induction motor (IM) with uncertainty using a dynamic sliding mode controller (DSMC) that suppresses chattering using an integrator or a low-pass filter placed before the control signal of the system. Hence, the dimension of the augmented system in DSMC is larger than the dimension of the original system, thus leading to an increase in the number of system states. These new state variables should be determined to control such a system. To address this problem, a new nonlinear state observer (NSO) is suggested and utilized in this study. The proposed method is independent of the uncertainty bound of the system, but the system output must be accessible. These subjects are important in practical implementations. Lyapunov theory is applied to validate the stability of the proposed DSMC and NSO methods. Then, the boundedness of the closed-loop signals is concluded from the stability of the proposed techniques. The validity of the proposed approach is evaluated using an IM model. By using DSMC and NSO, we can simultaneously control the IM and estimate its load torque. In particular, the external bounded load torque signal is compensated by the input control signal of the motor. Simulation results illustrate the advantages of the proposed approach.

Path Tracking of an Autonomous Ground Vehicle With Different Payloads by Hierarchical Improved Fuzzy Dynamic Sliding-Mode Control

A hierarchically improved fuzzy dynamical sliding-model control (HIFDSMC) is presented to address the autonomous ground vehicle (AGV) path tracking problem. The proposed controller has two portions: one is the virtual desired input (VDI), and the second is the path tracking control (PTC). In addition to the equivalent control in VDI and PTC, an improved fuzzy dynamical sliding-mode control (IFDSMC) is designed to deal with the system uncertainties, e.g., different payloads. Contributions of this paper include the following four parts: 1) Based on the nominal system response, the fuzzy rules and scaling factors of the IFDSMCs in the VDI and PTC are easily chosen. In contrast, a conventional fuzzy logic control approach requires more trial-and-error tuning to obtain a satisfactory performance. 2) The proposed HIFDSMC possesses the tuning mechanism (the coefficients of two sliding surfaces, the scaling factors in indirect and direct modes, and the fine tuning in fuzzy table) such that the uncertainties are tackled without a larger computational burden. 3) The stability of the closed-loop system is verified by the Lyapunov stability with hierarchical concept. 4) Different payloads not at the mass center of the AGV (e.g., greater than 25% in the total weight of the AGV) are tackled by the IFDSMCs to obtain a satisfactory performance. Finally, the application to the assembly line of the AGV with different payloads to track the circular and piecewise straight-line paths by the proposed HIFDSMC is compared with the hierarchical fuzzy decentralized PTC.

New Results on Sliding-Mode Control for Takagi-Sugeno Fuzzy Multiagent Systems.

This paper investigates the sliding-mode control (SMC) problem of Takagi-Sugeno (T-S) fuzzy multiagent systems (MASs). A cooperative fuzzy-based dynamical sliding-mode (SM) controller is designed and the overall closed-loop T-S fuzzy MAS is constructed. A new model transformation method for T-S fuzzy MASs is presented to transform the fuzzy weighting matrix into a set of fuzzy weighting scalars. By applying the method of linear matrix inequality, a general stability analysis approach for T-S fuzzy MASs is proposed. Moreover, the energy-cost constraint problem is studied by using the linear quadratic regulator method. Finally, numerical examples are provided to illustrate the effectiveness of the proposed theoretical approaches and the improved performance compared to existing results.

On dynamic sliding mode control of nonlinear fractional-order systems using sliding observer

In this study, a new fractional-order dynamic sliding mode control (FDSMC) for a class of nonlinear systems is presented. In FDSMC, an integrator is placed before the input control signal of the plant, in order to remove the chattering. However, in FDSMC method, the dimension of the resulted system (integrator plus the system) is bigger than the primary system. As a result, the model of the plant is needed to be known completely, in order to stabilize the system. Then, a sliding observer is proposed to extract an appropriate model for the unknown nonlinear system. Then, the chattering free controller can be obtained such that the closed-loop system has the desired properties. Lyapunov theory is used to verify the stability problem of the presented both observer and controller. For practical applications consideration, we have not applied the upper bound of the system dynamic either in controller or in observer. The effectiveness of the proposed method in comparison to the conventional fractional sliding mode control (FSMC) method is addressed. We have utilized a same observer in both control approach, in order to have a valid comparison. The simplicity of the proposed FDSMC method in concept and also in realization can be seen with comparison of the relevant equations. In addition, it is clear that the FDSMC can remove chattering completely, while chattering is the main challenge of the conventional FSMC. Finally, the validity of the proposed method is shown by some simulation examples based on the Arneodo chaotic system.

Adaptive Fuzzy Fault Tolerant Control Using Dynamic Sliding Mode

In this paper, an actuator fault tolerant control (FTC) has been designed using dynamic sliding mode control (DSMC) for single input nonlinear systems which are affected from uncertainty. In DSMC the switching of input control signal is removed due to the integrator which is placed before the input control signal of the plant hence, its result is reducing of chattering. However, in DSMC the augmented system (the system plus the integrator) is one dimension bigger than the actual system and then, the plant model should be completely known. To overcome on this problem, an adaptive fuzzy observer (AFO) has been proposed. Finally, we show the combination result of DSMC and AFO is the compensation of the fault by input control signal of the plant, while the performance and robustness of the closed loop system are reserved. The main property of the proposed approach is its simplicity and we only use system output for FTC and moreover, the fault diagnosis (detection, isolation and reconstruction) is done at the same time. The upper bound of the uncertainty is not used in DSMC and AFO, which is important in practical implementation. Simulation results show the advantages of the proposed approach.

Dynamic Analysis and Adaptive Sliding Mode Controller for a Chaotic Fractional Incommensurate Order Financial System

In this study, the dynamic behavior and chaos control of a chaotic fractional incommensurate-order financial system are investigated. Using well-known tools of nonlinear theory, i.e. Lyapunov exponents, phase diagrams and bifurcation diagrams, we observe some interesting phenomena, e.g. antimonotonicity, crisis phenomena and route to chaos through a period doubling sequence. Adopting largest Lyapunov exponent criteria, we find that the system yields chaos at the lowest order of [Formula: see text]. Next, in order to globally stabilize the chaotic fractional incommensurate order financial system with uncertain dynamics, an adaptive fractional sliding mode controller is designed. Numerical simulations are used to demonstrate the effectiveness of the proposed control method.

Research on the sliding mode control for underactuated surface vessels via parameter estimation

This brief proposes an adaptive sliding mode control law for an underactuated vessel via parameter estimation to follow a desired path. An adaptive continuous PI sliding mode scheme is devoted to enhancing the robustness of the control system and reducing the system oscillation in presence of unknown plant parameters and environmental disturbances. To address model uncertainties and unknown environmental disturbances, an adaptive parameters estimation and an upper bound estimation scheme are incorporated with the control scheme. In addition, a novel virtual control approach based on backstepping and adaptive dynamical sliding mode control is designed to relax the assumption of passive boundedness in sway motion. Under this kind of consideration, a certain nonlinear scheme is proposed to guarantee sway velocity uniformly ultimately bounded by Lyapunov direct method. Finally, numerical simulation results are given to demonstrate the effectiveness of the proposed method.

Dynamic global proportional integral derivative sliding mode control using radial basis function neural compensator for three-phase active power filter

An adaptive dynamic special global sliding mode controller that is based on proportional integral derivative (PID) sliding surface using radial basis function (RBF) neural network (NN) for a three- phase active power filter (APF) was presented in this paper. To overcome the problems associated with the schemes of the conventional sliding mode control, a global PID sliding manifold is introduced to realize the whole process of robustness and inhibition of the steady state error, accelerating the system response meanwhile. In addition, the nested dynamic sliding mode controller can reduce the influence of chattering that may lead to malfunction of the insulated gate bipolar transistor (IGBT) caused by sign function in the control law, achieving a better property. Moreover, owing to the parameter uncertainties and the external disturbances, a RBF neural estimator is added to eliminate the chattering phenomenon that further optimizes the performance of the system. Eventually, simulation studies in the MATLAB/SimPower Systems Toolbox verify the outstanding performance of the designed RBFNN dynamic global PID sliding mode controller in three different conditions, and some comparisons are made at the same time to demonstrate the excellent properties of the raised control method.

Turning control of a mobile robot for greenhouse spraying based on dynamic sliding mode control

The road of a greenhouse is both damp and narrow, and there are both ground obstacles and space obstacles in a greenhouse, which easily cause the instability problem for a four-wheel independent driving greenhouse spraying mobile robot turning in the greenhouse. In order to improve the steering performance of the greenhouse spraying mobile robot, based on the characteristics that each wheel torque of the robot can be separately controlled, the dynamic model of the four-wheel independent steering system is firstly established using D’Alembert’s principle and choosing the sideslip angle and the yaw velocity as the state variables. Then, based on the theory of sliding mode control, a dynamic sliding mode control strategy with exponential approaching rate is proposed by adopting the sideslip angle and the yaw velocity as the joint control variables in order to make the sideslip angles be in the stable range and make the yaw velocity track the desired value well. Finally, the simulation of the steering performance is performed using MATLAB/Simulink. The control response curves of the yaw velocity and the sideslip angle of the robot’s mass center in a step input and in a sinusoidal input are obtained, respectively. It is shown from the simulation results that compared with the feedforward–feedback control method, the proposed dynamic sliding mode control strategy based on the established dynamic model is effective to improve the turning control stability of the mobile robot for greenhouse spraying. The experiment results further verify the feasibility of the proposed turning control strategy.

Dynamic Adaptive Sliding Mode Control of Large Erecting Mechanism

In this paper, a dynamic adaptive sliding mode control algorithm is proposed to overcome the nonlinearities, uncertainties and circumstance disturbances that exist in the process of mechanism erecting. The backstepping methodology is applied in developing the Lyapunov-based controller. Then the dynamic surface control which using first integral filter to evaluate the derivative of virtual control item combined with sliding mode control is introduced to realize nonlinear control. Furthermore, adaptive algorithm is adopted to estimate the uncertainty parameters, and the control law and adaptive scheme are also presented. By Lyapunov stability theorem, the system is proven to be asymptotically stable. Simulation results show that compared to the PID controller and conventional sliding mode controller, the proposed control method has nicer robustness and more accurate tracking ability, and the stability of the erecting process has improved

Boosted Flight Controller for Quadrotor Navigation under disturbances

Lightweight Unmanned Aerial Vehicles (UAV) are usually very sensitive to the external disturbances during outdoor experimentations. These adverse conditions make both the dynamic modeling and the control tasks more complex. Thus, it is necessary to employ an efficient control technique with acceptable performance without a complete knowledge of the disturbed model. This is because, in the classic feedback linearization control, the deviations between the model and the real plant may produce poor performance. Throughout the present paper, Dynamic Sliding Mode Control (DSMC) technique is designed to deal with the disturbances and which has never been used for quadrotors. Unlike the existing sliding mode techniques, the designed one uses an input-dependent sliding surface in order to enhance the robustness level of the classical feedback linearization control law. The effectiveness of this approach that ensures 3D trajectory tracking of quadrotor is demonstrated through numerical simulations.

Second-Order Dynamic Sliding-Mode Control for Nonminimum Phase Underactuated Hypersonic Vehicles

This paper deals with the second-order dynamic sliding-mode control (SODSMC) problem for nonminimum phase underactuated hypersonic vehicles. First, the underactuated hypersonic vehicle attitude control model is introduced. The normal form and the nonminimum phase nature for the vehicle are discussed. Thus, the nonminimum phase system is divided into the minimum phase subsystem and the nonminimum phase subsystem via the system decomposition approach. Second, the SODSMC scheme is developed. The conventional sliding-mode controller and the second-order dynamic sliding-mode controller are designed for the two subsystems. Besides, the dynamic sliding manifold is provided for the nonminimum phase subsystem. Simulation results for the nonminimum phase underactuated hypersonic vehicle are presented to demonstrate the effectiveness and robustness of the proposed control scheme.

Speed tracking control of pneumatic motor servo systems using observation-based adaptive dynamic sliding-mode control

This study aims to develop an adaptive high-precision control system for controlling the speed of a vane-type air motor (VAM) pneumatic servo system. In practice, the rotor speed of a VAM depends on the input mass air flow, which can be controlled by the effective orifice area (EOA) of an electronic throttle valve (ETV). As the control variable of a second-order pneumatic system is the integral of the EOA, an observation-based adaptive dynamic sliding-mode control (ADSMC) system is proposed to derive the differential of the control variable, namely, the EOA control signal. In the ADSMC system, a proportional–integral–derivative fuzzy neural network (PIDFNN) observer is used to achieve an ideal dynamic sliding-mode control (DSMC), and a supervisor compensator is designed to eliminate the approximation error. As a result, the ADSMC incorporates the robustness of a DSMC and the online learning ability of a PIDFNN. To ensure the convergence of the tracking error, a Lyapunov-based analytical method is employed to obtain the adaptive algorithms required to tune the control parameters of the online ADSMC system. Finally, our experimental results demonstrate the precision and robustness of the ADSMC system for highly nonlinear and time-varying VAM pneumatic servo systems.

Robust control design for path tracking of non-affine UAV

ABSTRACTPath tracking of Unmanned Aerial Vehicles (UAVs) with three degrees of freedom is studied in this paper with approach of dynamic sliding mode control. For this purpose, the equations of UAV are written. The difficulty and complexity of these equations is that they are non-affine with respect to control inputs. Moreover, they are not directly in the inertial coordinate system while the desired flight path is given in the inertial coordinate system. These two major problems add complexity to the design procedure. Therefore, it is necessary that equations be rewritten in the inertial coordinate system. By definition of virtual inputs; the equations convert to affine structure with respect to virtual inputs and the transformation between the real and virtual inputs has been obtained. After that, the Input/output (I-O) equations of the system are written and converted into controller canonical form. The dynamic sliding mode control law is then designed based on (I-O) equations. Optimal coefficients are also achieved numerically by considering an appropriate cost function. Finally, computer simulation is utilized to illustrate the performance of the designed controller.

Adaptive Fuzzy Dynamic Sliding Mode Control of Nonlinear Systems

Two phenomena can produce chattering: switching of input control signal and the large amplitude of this switching (switching gain). To remove the switching of input control signal, dynamic sliding mode control (DSMC) is used. In DSMC switching is removed due to the integrator which is placed before the plant. However, in DSMC the augmented system (system plus the integrator) is one dimension bigger than the actual system and then, the plant model should be completely known. To overcome on this difficulty, a fuzzy system is employed to identify the unknown nonlinear function of the plant model and then, a robust adaptive law is developed to train the parameters of this fuzzy system. The other problem is that the switching gain may be chosen unnecessary large to cope on the unknown uncertainty. To solve this problem, another fuzzy system is proposed which does not need the upper bound of the uncertainty. Moreover, to have a suitable small enough switching gain an adaptive procedure is applied to increase and decrease the switching gain according to the system circumstances. Then, chattering is removed using the DSMC with a small adaptive switching gain (ASG). As a case study, nonlinear chaotic Duffing-Holmes system is selected.