Integrator Backstepping Technique Research Articles

Nonlinear control of three level NPC inverter used in PV/grid system: comparison of topologies and control methods

With the passage of time, the importance of using renewable energy systems to overcome energy consumption and improve the quality of the grid has emerged through the use of nonlinear control techniques and reliance on advanced types of inverters such as multi-level inverters. This research is focused on comparing two grid-connected converter topologies in a photovoltaic (PV) generation system connected to a three-phase grid that serves a non-linear load. Additionally, the study explores two different control techniques applied to this converter, evaluating their effects on the total harmonic distortion coefficient. A comparison has been made between the traditional inverter and the three-level inverter type neutral point clamped (NPC) inverter, with the use of integral backstepping (IBS) technique which was also compared with the proportional integral (PI) controller. The simulation results in MATLAB/Simulink are presented illustrating the performances and the strong effectiveness of the three-level NPC inverter controlled by the proposed technique (IBS).

Sensorless nonlinear control based on integral backstepping technique for PMSG- based wind energy conversion system

This article addresses the control of the wind energy conversion system (WECS) based on a permanent magnet synchronous generator (PMSG) connected to the grid through a three-phase rectifier and an inverter followed by an L filter. Two observers have been developed to estimate the mechanical torque of the PMSG and the rotor flux. Integral backstepping control (IBC) has been employed to regulate the wind energy conversion system. Its objective is to achieve maximum power point tracking while maintaining the bus voltage at its reference and regulating the injected power into the grid to ensure a unity power factor. The developed control approach has been tested using Matlab/Simulink and compared with the linear PI controller. Simulation results demonstrate, on one hand, the robustness, efficiency, and superiority of the nonlinear technique employed, and on the other hand, the dynamic performance of the developed observers.

Adaptive terminal synergetic-backstepping technique based machine learning regression algorithm for MPPT control of PV systems under real climatic conditions

This paper deals with a comparative evaluation of nonlinear controllers based on the linear regression technique, which is a machine learning algorithm for maximum power point tracking. In the past decade, most photovoltaic systems have been equipped with classical algorithms such as perturb and observe, hill climbing, and incremental conductance. The simplicity of these techniques and their ease of implementation were seen as the main reasons for their utilization in photovoltaic systems. However, researchers’ attention has recently been attracted by artificial intelligence-based techniques such as linear regression, which offer better performance within the bounds of the nonlinearity of photovoltaic system characteristics. An adaptive terminal synergetic backstepping controller is developed in this paper for a single-ended primary inductance converter. This control scheme is based on the combination of a non-singular terminal synergetic technique with an integral backstepping technique and equally a neural network for the approximation of unmeasured or inaccessible variables that guarantees the finite-time convergence. The proposed controller was further verified under virtual and real environmental conditions, and the numerical results obtained from Matlab/Simulink software under various test conditions, including load variations, show that the adaptive terminal synergetic backstepping controller gives satisfactory performance compared to the adaptive integral backstepping controller used in the same climatic conditions.

Prescribed-time constrained feedback control for an uncertain twin rotor helicopter

This article presents a prescribed-time adaptive constraint feedback control strategy for an unmanned twin rotor helicopter system in the presence of parametric uncertainties. The integrator backstepping technique and adaptive estimator are employed to handle these unknown parameters. Additionally, a constrained function is utilized to prevent the possibility of signal amplification as the appointed settling time approaches. Through rigorous mathematical analysis employing Lyapunov theory, we prove that the proposed adaptive time-varying constraint feedback control and parameter estimator ensure the boundedness of all signals in the closed-loop system, promoting stability and preventing erratic behavior. One notable benefit of the proposed approach is that the convergence can be achieved within the time specified in advance. Finally, simulations and experiments are carried out to verify the efficacy of the proposed adaptive prescribed-time constraint feedback control strategy.

Experimental validation of an output feedback controller based on an integral and adaptive backstepping technique for a fuel-cell power system

Experimental validation of an output feedback controller based on an integral and adaptive backstepping technique for a fuel-cell power system

Experimental validation of an output feedback controller based on an integral and adaptive backstepping technique for a fuel-cell power system

Experimental validation of an output feedback controller based on an integral and adaptive backstepping technique for a fuel-cell power system

Finite-Time Orbit Control for Spacecraft Formation with External Disturbances and Limited Data Communication

This work addresses the finite-time orbit control problem for spacecraft formation flying with external disturbances and limited data communication. A hysteretic quantizer is employed for data quantization in the controller-actuator channel to decrease the communication rate and prevent the chattering phenomenon caused by the logarithmic quantizer. Combined with the adding one power integrator method and backstepping technique, a new finite-time tracking control strategy with adaptation law is designed to ensure that the closed-loop system is practical finite-time stable, and that the tracking errors of relative position and velocity are bounded within finite-time despite with limited data communication and external disturbances. Finally, an example is shown to validate the effectiveness of the proposed finite-time tracking controller.

Steady-State and transient assessments of integral back-stepping current controllers in high-voltage direct current transmission systems

In the last five decades, proportional-integral (PI) controller remains dominant in control of high-power converters in industrial and utility power systems despite its bandwidth, hence, the performance is coupled to power circuit parameters and degrades in parts of operating range. Consequently, further mitigation measures such as fine-tuning or loop reshaping might be needed. In contrast, integral back-stepping (IBS) decouples controller bandwidth and performance from the system parameters; hence, leads to consistent performance throughout the operating range and simplifies tuning of controllers with complex structures with multiple loops. Therefore, this paper investigates the suitability of IBS for implementation of inner current controllers of the voltage source converter (VSC)-based high-voltage direct current (HVDC) transmission systems. The paper presents step-by-step synthesis of back-stepping current controller and supporting theoretical bases, and assesses its performance against the conventional PI current controller. Theoretical analysis and discussions and comparative simulations reveal that the characteristics of IBS technique enjoys unique characteristics: decouples the controller gains from the converter parameters; restricts closed loop poles to real axis; and exhibits larger closed loop bandwidth than the PI counterpart. It has been shown that the gains of IBS current controllers are explicitly specified in terms of the desired natural frequency and damping ratio, which are advantageous compared to that of the PI equivalent, in which the closed loop bandwidth are limited by converter parameters. For ease of illustration of similarities and differences, only inner current controllers of the converter stations were designed using integral back-stepping technique and compared against PI equivalents. The outer control loops such as dc link voltage, active and reactive power controllers are designed based on proportional-integral controllers. MATLAB-SIMULINK models of the point-to-point VSC-HVDC system, in which the current controllers implemented using integral back-stepping and proportional-integral controllers (active/reactive power and DC link voltage controllers) have been developed and subsequently used for performance comparison. Results of the one-to-one comparison show that the integral back-stepping current controller can match and even outperform its proportional-integral equivalent during normal and abnormal conditions, including current limitation during ac faults. Selected experiments conducted on grid connected voltage source converter that employs IBS current controller have confirm its viability.

Distributed secondary control of islanded microgrids using modified integral backstepping technique

Distributed secondary control of islanded microgrids using modified integral backstepping technique

Finite‐time optimal control for interconnected nonlinear systems

SummaryThis work addresses the finite‐time optimal control problem for a class of interconnected nonlinear systems with powers of positive odd rational numbers. A series of homogeneous controllers, which are capable of guaranteeing the local finite‐time stability of the closed‐loop systems, are first developed using the adding one power integrator method and backstepping technique. Then, the nested saturation controllers are further proposed to achieve global finite‐time stability. Furthermore, the corresponding design parameters are optimized, and thus, an optimal controller is obtained. A numerical simulation example is finally given to illustrate the effectiveness of the proposed control strategy.

Adaptive Finite-Time Control for High-Order Nonlinear Systems With Multiple Uncertainties and its Application

The globally finite-time control issue is concerned in this note for high-order nonlinearly parameterized systems with unknown control gain and external disturbances. A novel control strategy combining adaptive control technique with sign function can well deal with serious uncertainties and unknown control gain. Without any nonlinear growth assumptions, a unified and systematic design procedure is employed to derive an adaptive state-feedback controller with the help of the adding a power integrator method and backstepping technique. Then, by finite-time stability analysis and Lyapunov functions, the proposed controller ensures that the closed-loop system is globally practically finite-time stable (PFTS). Two simulation examples, including a mass-spring mechanical system and a numerical example, are applied to verify the performance and effectiveness of the designed schemes.

Adaptive NN Backstepping Control Design for a 3-DOF Helicopter: Theory and Experiments

This paper presents an adaptive neural network backstepping control design for an experimental helicopter with three rotational degrees of freedom. The helicopter system is described by a state-space model with unmodeled dynamics and external disturbances. By resorting to radial basis function neural networks with online gradient descent training, such unmodeled dynamics and external disturbances can be compensated in real time. With the help of Lyapunov stability criteria, it is proved that the desired trajectories can be boundedly tracked by the corresponding attitude angles of the helicopter under the proposed adaptive neural network backstepping controller. Compared with robust adaptive integral backstepping technique, our approach has smaller root mean squared error. Finally, four sets of contrastive experiment results are, respectively, given to show the effectiveness and advantages of the proposed control scheme.

Active Queue Management Algorithm for TCP Networks with Integral Backstepping and Minimax

A novel active queue management (AQM) approach is considered for a class of TCP network systems in this paper. A sufficient condition is given and the corresponding control is obtained based on integral back-stepping technique (IB) and minimax method. The presented results not only are used to deal with the disturbances produced by UDP flows, but also can shorten the convergent time of the signals. Simulation examples are carried out to verify the effectiveness and superiority of the proposed algorithm.

Congestion tracking control for uncertain TCP/AQM network based on integral backstepping

An H∞ congestion tracking control problem for nonlinear transmission control protocol/active queue management (TCP/AQM) network is proposed in this paper. Inspired by the existing network models, a modified TCP/AQM network model with external disturbance and modelling uncertainty is first introduced. And then, a novel function for the desired queue length is defined for the first time, which can simulate the changes in the queue length during a day. Next, a novel AQM scheme is presented to control network congestion by combining H∞ theory and integral backstepping technique. The proposed method guarantees that the better tracking performance of the queue is achieved, and all the signals are asymptotically stable in the closed-loop system in probability. Finally, the effectiveness of the presented algorithm is tested by simulation results.

Missile Angle of Attack Tracking Using Integrator Backstepping

This paper deals with missile longitudinal dynamics control. The angle of attack tracking problem is considered for an unpowered flight phase of a short range tail-controlled missile with the zero engine thrust. For the control synthesis, a simplified missile dynamics model that includes the actuator dynamics is used. The tracking control law is designed using the integrator backstepping approach. The aerodynamic polynomials dependence on absolute values of the angle of attack is considered from the perspective of applying the integrator backstepping technique.

Real-Time Integral Backstepping with Sliding Mode Control for a Quadrotor UAV

This paper presents a nonlinear control of a quadrotor unmanned aerial vehicle(UAV) for trajectory tracking. The dynamical model is obtained by the Euler- Lagrange methodology. In this paper, the proposed control strategy is based on the integral backstepping technique with sliding mode control (SMC) for altitude and lateral motion. In addition, an inner loop control is used to stabilize the vehicle orientation. The implementation is applied to the Qball-X4 prototype of Quanser Inc. which has OptiTrackTM cameras to provide the vehicle lateral position and a sonar sensor gives the altitude measurement. The experimental test results illustrate the effectiveness on the quadrotor of the proposed control scheme.

Integral Backstepping Approach for Mobile Robot Control

This paper presents the trajectory tracking problem of a unicycle-type mobile robots. A robust output tracking controller for nonlinear systems in the presence of disturbances is proposed, the approach is based on the combination of integral action and Backstepping technique to compensate for the dynamic disturbances. For desired trajectory, the values of the linear and angular velocities of the robot are assured by the kinematic controller. The control law guarantees stability of the robot by using the lyapunov theorem. The simulation and experimental results are presented to verify the designed trajectory tracking control.

Advanced Nonlinear Control of Single-Phase Grid Connected PV Generator

In this article, we address the problem of the controlling PV generators connected to the single-phase grid is addressed. The PV system presented consists of a PV generator, a DC_AC inverter, an LCL filter and a single-phase grid. The main advantages of the studied system are: the abundance of the use of a DC_DC converter, the minimization of the total harmonic distortion of the current injected into the grid, the stabilization of the system, the great reliability and high efficiency. In this paper, we seek to achieve the following objectives: (i) extracting the maximum power from the PV generator, (ii) setting the DC-link voltage to its reference voltage vp,ref, (iii) injecting a sinusoidal and in phase current with the grid voltage (unit power factor UPF), while ensuring a total harmonic distortion (THD) less than 5%. To fulfill the above objectives, a nonlinear controller based on a nonlinear state model is proposed. This controller is realized by the Integral Backstepping technique. The results of the simulation showed that the extraction of the maximum power and the injection of the current with the unit power factor (UPF) are obtained whatever the climatic conditions.

Straight-line path following for asymmetric unmanned platform with disturbance estimation

The problem of straight-line path following for asymmetric unmanned platform exposed to unknown disturbances was addressed in this paper. The mathematical model of asymmetric unmanned platform was established and the inputs in sway and yaw directions were decoupled, which facilitated the establishment of control strategy of path following. The guidance law and the cross-track error were derived from the classical line-of-sight (LOS) guidance principle. And the equilibrium point of the cross-track error was proven to be uniformly semiglobally exponentially stable (USGES), which guaranteed the exponential convergence to zero. A new disturbance estimation law was developed by adding a linear item of the estimation error into the classical one, which improved the principle’s precision and sensitivity dramatically. The control strategy was developed based on the integrator backstepping technique and the new disturbance estimation law, which made the equilibrium system to be uniformly globally asymptotically stable (UGAS). Computer simulations were conducted to verify the effectiveness of the estimation and control laws during straight-line path following for asymmetric unmanned platform in the presence of unknown disturbances.

Dynamic adjustment of queue levels in TCP Vegas‐based networks

Transmission control protocols (TCPs) are used to control the congestion in the Internet. Various types of TCP protocols have been proposed including TCP Reno, TCP Tahoe and TCP Vegas. Although TCP Reno is widely used for wired communications, TCP Vegas is proved to have better performance in wireless environments. In TCP Reno, to achieve a certain queue level at the intermediate routers, active queue management (AQM) schemes are used. An AQM scheme marks the packets at the intermediate routers and TCP Reno source uses that mark to adjust its speed. However, in TCP Vegas, such scheme is not useable. Consequently, the queue level adjustment is not achievable. A scheme which is employed at the source and adjusts the TCP Vegas parameters dynamically to achieve a certain queue level at the intermediate router is proposed. To the best of the knowledge, this is the first attempt to dynamically adjust the queue levels when TCP Vegas is employed. Our proposed scheme plays the role of AQM in TCP Reno for TCP Vegas. The control scheme presented is designed based on integral backstepping technique and will be applied to the linearised model of TCP Vegas.