scholarly journals Fixed-Time Adaptive Neural Network Tracking Control for Output-Constrained High-Order Systems Using Command Filtered Strategy

2021 ◽  
Author(s):  
Lian Chen ◽  
Qing Wang
Keyword(s):  
Tracking Control ◽  
Initial Conditions ◽  
Tracking Error ◽  
Fixed Time ◽  
Growth Conditions ◽  
High Order ◽  
Adding A Power Integrator ◽  
Time Control ◽  
Uncertain Dynamics ◽  
Power Integrator

Abstract This paper proposes a fixed time adaptive neural command filtered controller for a category of high-order systems based on adding a power integrator technique. Different from existing research, the presented controller has the following distinguishing advantages: i) fixed-time control framework is extended to the tracking control problem of high-order systems. ii) the error compensation mechanism eliminates filter errors that arise from dynamic controllers. iii) growth assumptions about unknown functions are relaxed with the help of adaptive neural networks. iv) more general systems: the developed controller can apply to high-order systems subject to uncertain dynamics, unknown gain functions and asymmetric constraints. Stability analysis shows that all states are semi-globally bounded, and the convergence rate of tracking error is independent of initial conditions. The main innovation of our work is that the presented controller considers simultaneously filter errors, fixed-time convergence, growth conditions and asymmetric output constraint for the tracking control issue of high-order systems. Finally, the simulation results validate the advantages and efficacy of the developed control scheme.

Fixed-time trajectory tracking control for multiple nonholonomic mobile robots

2020 ◽  
pp. 014233122096641
Author(s):  
Meiying Ou ◽  
Haibin Sun ◽  
Zhenxing Zhang ◽  
Lingchun Li
Keyword(s):  
Mobile Robots ◽  
Trajectory Tracking ◽  
Tracking Control ◽  
Initial Conditions ◽  
Fixed Time ◽  
Nonholonomic Mobile Robots ◽  
Trajectory Tracking Control ◽  
Adding A Power Integrator ◽  
Time Control ◽  
Power Integrator

This paper investigates the fixed-time trajectory tracking control for a group of nonholonomic mobile robots, where the desired trajectory is generated by a virtual leader, the leader’s information is available to only a subset of the followers, and the followers are assumed to have only local interaction. According to fixed-time control theory and adding a power integrator technique, distributed fixed-time tracking controllers are developed for each robot such that all states of each robot can reach the desired value in a fixed time. Moreover, the settling time is independent of the system initial conditions and only determined by the controller parameters. Simulation results illustrate and verify the effectiveness of the proposed schemes.

Output tracking control of high-order nonlinear systems with dynamic uncertainties

2019 ◽  
Vol 42 (8) ◽  
pp. 1511-1520
Author(s):  
Zong-Yao Sun ◽  
Yu-Jie Gu ◽  
Qinghua Meng ◽  
Wei Sun ◽  
Zhen-Guo Liu
Keyword(s):  
Nonlinear Systems ◽  
Tracking Control ◽  
Tracking Error ◽  
High Order ◽  
Approximation Technique ◽  
Zero Dynamic ◽  
Adding A Power Integrator ◽  
Output Tracking ◽  
Output Tracking Control ◽  
Dynamic Uncertainties

This paper investigates the output tracking control problem for a class of nonlinear systems with zero dynamic. On the basis of adding a power integrator method and approximation technique, an appropriate controller is proposed to guarantee that the tracking error turns to a preassigned neighborhood of the origin. The systems under investigation allow unmeasurable dynamic uncertainties, unknown nonlinear functions and unknown high-order terms. As an application, two examples are provided to illustrate the effectiveness of a control strategy.

scholarly journals Fixed-Time Bounded H Infinity Tracking Control of a Single-Joint Manipulator System with Input Saturation

2021 ◽  
Author(s):  
ming chen
Keyword(s):  
Tracking Control ◽  
Initial Conditions ◽  
Tracking Error ◽  
Input Saturation ◽  
Small Neighborhood ◽  
Fixed Time ◽  
H Infinity ◽  
Finite Time Stability ◽  
Control Objective ◽  
H Infinity Control

Abstract Based on Lyapunov finite-time stability theory and backstepping strategy, we put forward a novel fixed-time bounded H infinity tracking control scheme for a single-joint manipulator system with input saturation. The main control objective is to maintain that the system output variable tracks the desired signal at fixed time. The advantages of this paper are the settling time of the tracking error converging to the origin is independent of the initial conditions, and its convergence speed is more faster. Meanwhile, bounded H infinity control is adopted to suppress the influence of the external disturbances on the controlled system. At the same time, the problem of input saturation control is considered, which effectively reduce the input energy consumption. Theoretical analysis shows that the tracking error of the closed-loop system converges to a small neighborhood of the origin within fixed time. In the end, a simulation example is presented to demonstrate the effectiveness of the proposed scheme.

scholarly journals Approximation-Based Fixed-Time Adaptive Tracking Control for a Class of Uncertain Nonlinear Pure-Feedback Systems

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Cheng He ◽  
Jian Wu ◽  
Jiyang Dai ◽  
Zhe Zhang ◽  
Libin Xu ◽  
...  
Keyword(s):  
Tracking Control ◽  
Tracking Error ◽  
Fixed Time ◽  
Mean Value ◽  
Design Parameters ◽  
Mean Value Theorem ◽  
Feedback Systems ◽  
Adaptive Tracking Control ◽  
Adaptive Tracking ◽  
Time Control

This paper examines approximation-based fixed-time adaptive tracking control for a class of uncertain nonlinear pure-feedback systems. Novel virtual and actual controllers are designed that resolve the meaninglessness of virtual and actual controllers at the origin and in the negative domain, and the sufficient condition for the system to have semiglobal fixed-time stability is also provided. Radial basis function neural networks are introduced to approximate unknown functions for solving the fixed-time control problem of unknown nonlinear pure-feedback systems, and the mean value theorem is used to solve the problem of nonaffine structure in nonlinear pure-feedback systems. The controllers designed in this paper ensure that all signals in the closed-loop system are semiglobally uniform and ultimately bounded in a fixed time. Two simulation results show that appropriate design parameters can limit the tracking error within a region of the origin in a fixed time.

scholarly journals Fixed-time output tracking control for extended nonholonomic chained-form systems with state observers

2020 ◽  
Vol 53 (3-4) ◽  
pp. 400-408 ◽  
Author(s):  
Hua Chen ◽  
Huilin Li ◽  
YiWen Yang ◽  
Lulu Chu
Keyword(s):  
Tracking Control ◽  
Estimation Error ◽  
Tracking Error ◽  
Fixed Time ◽  
Structure Characteristic ◽  
Initial State ◽  
Time Control ◽  
Output Tracking Control ◽  
State Observers ◽  
Control Scheme

This paper deals with the fixed-time tracking control problem of extended nonholonomic chained-form systems with state observers. According to the structure characteristic of such chained-form systems, two subsystems are considered to design controllers, respectively. First of all, using the fixed-time control theory, a controller is proposed to make the first tracking error subsystem converge to zero in bounded time independent initial state. Second, a state observer is proposed to estimate the unmeasurable states of the second subsystem. And the precise state estimation can be presented from the observer within finite time; moreover, the upper bound of time is a constant independent on the initial estimation error. Third, a fixed-time controller is designed to drive all states of the second chained-form subsystem to zero within pre-calculated time. Finally, the effectiveness of the proposed control scheme is validated by simulation results.

scholarly journals Fixed-Time Trajectory Tracking Control for Nonholonomic Mobile Robot Based on Visual Servoing

2021 ◽  
Author(s):  
OU Meiying ◽  
Haibin Sun ◽  
Zhenxing Zhang ◽  
Shengwei Gu
Keyword(s):  
Mobile Robot ◽  
Tracking Control ◽  
Visual Servoing ◽  
Tracking Error ◽  
Fixed Time ◽  
Camera Model ◽  
Trajectory Tracking Control ◽  
Control Laws ◽  
Time Control ◽  
Time Simulation

Abstract This paper aims to discuss fixed-time tracking control problem for a nonholonomic wheeled mobile robot based on visual servoing. At first, by making use of the pinhole camera model, the robot system model with uncalibrated camera parameters is given. Then, the tracking error system between the mobile robot and desired trajectory is proposed. Thirdly, on the basis of fixed-time control theory and Lyapunov stability analysis, fixed-time tracking control laws are proposed for the robot, which can make the robot achieve the desired value in a fixed time. Simulation results are given at the end.

scholarly journals Fixed-Time Sliding-Mode Fault-Tolerant Control of Waste Heat Power Generator Systems

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Zhi Wang ◽  
Yateng Bai ◽  
Jin Xie ◽  
Zhijie Li ◽  
Caoyuan Ma ◽  
...  
Keyword(s):  
Fault Tolerant ◽  
Waste Heat ◽  
Sliding Mode ◽  
Dynamic Performance ◽  
Tracking Error ◽  
Fixed Time ◽  
Fault Estimation ◽  
Actuator Fault ◽  
Heat Power ◽  
Time Control

In order to overcome disturbances such as the instability of internal parameters or the actuator fault, the time-varying proportional-integral sliding-mode surface is defined for coordinated control of the excitation generator and the steam valve of waste heat power generation units, and a controller based on sliding-mode function is designed which makes the system stable for a limited time and gives it good performance. Based on this, a corresponding fault estimation law is designed for specific faults of systems, and a sliding-mode fault-tolerant controller is constructed based on the fixed-time control theory so that the systems can still operate stably when an actuator fault occurs and have acceptable performance. The simulation results show that the tracking error asymptotically tends to be zero, and the fixed-time sliding-mode fault-tolerant controller can obviously improve the dynamic performance of the system.

Global fixed-time stabilization for a class of uncertain high-order nonlinear systems with dead-zone input nonlinearity

2018 ◽  
Vol 41 (7) ◽  
pp. 1888-1895
Author(s):  
Fangzheng Gao ◽  
Yanling Shang ◽  
Yuqiang Wu ◽  
Yanhong Liu
Keyword(s):  
Nonlinear Systems ◽  
State Feedback ◽  
Closed Loop ◽  
Dead Zone ◽  
Fixed Time ◽  
High Order ◽  
Closed Loop System ◽  
Sign Function ◽  
Input Nonlinearity ◽  
Power Integrator

This paper considers the problem of global fixed-time stabilization for a class of uncertain high-order nonlinear systems. One distinct characteristic of this work is that the system under consideration possesses the dead-zone input nonlinearity. By delicately combining the sign function with a power integrator technique, a state feedback controller is designed such that the states of the resulting closed-loop system converge to the origin within a fixed time. A simulation example is provided to illustrate the effectiveness of the proposed approach.

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