scholarly journals A Robust Adaptive Trajectory Tracking Algorithm Using SMC and Machine Learning for FFSGRs with Actuator Dead Zones

2019 ◽  
Vol 9 (18) ◽  
pp. 3837 ◽  
Author(s):  
Lin Jia ◽  
Yaonan Wang ◽  
Changfan Zhang ◽  
Kaihui Zhao ◽  
Li Liu ◽  
...  
Keyword(s):  
Machine Learning ◽  
Steady State ◽  
Trajectory Tracking ◽  
Dead Zone ◽  
Lyapunov Theory ◽  
Tracking Algorithm ◽  
Convergence Time ◽  
Model Uncertainties ◽  
Friction Forces ◽  
State Error

The actuator dead zone of free-form surface grinding robots (FFSGRs) is very common in the grinding process and has a great impact on the grinding quality of a workpiece. In this paper, an improved trajectory tracking algorithm for an FFSGR with an asymmetric actuator dead zone was proposed with consideration of friction forces, model uncertainties, and external disturbances. The presented control algorithm was based on the machine learning and sliding mode control (SMC) methods. The control compensator used neural networks to estimate the actuator’s dead zone and eliminate its effects. The robust SMC compensator acted as an auxiliary controller to guarantee the system’s stability and robustness under circumstances with model uncertainties, approximation errors, and friction forces. The stability of the closed-loop system and the asymptotic convergence of tracking errors were evaluated using Lyapunov theory. The simulation results showed that the dead zone’s non-linearity can be estimated correctly, and satisfactory trajectory tracking performance can be obtained in this way, since the influences of the actuator’s dead zone were eliminated. The convergence time of the system was reduced from 1.1 to 0.8 s, and the maximum steady-state error was reduced from 0.06 to 0.015 rad. In the grinding experiment, the joint steady-state error decreased by 21%, which proves the feasibility and effectiveness of the proposed control method.

scholarly journals FLS-Based Nonuniform Trajectory Tracking AILC for Uncertain Nonlinear Systems with Nonsymmetric Dead-Zone Input and Initial State Error

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Chunli Zhang ◽  
Xu Tian ◽  
Lei Yan
Keyword(s):  
Target Tracking ◽  
Dead Zone ◽  
Small Neighborhood ◽  
Convergent Series ◽  
Lyapunov Theory ◽  
Uncertain Nonlinear System ◽  
Initial State ◽  
Fuzzy Logic Systems ◽  
Mass Spring ◽  
State Error

This paper proposes an AILC method for uncertain nonlinear system to solve different target tracking problems. The method uses fuzzy logic systems (FLS) to approximate every uncertain term in systems. All closed-loop signals are bounded on 0 , T according to the Lyapunov theory. A time-varying boundary layer and a typical convergent series are introduced to handle initial state error, unknown bounds of errors, and nonuniform target tracking, respectively. The result is that the tracking error’s norm can converge to a small neighborhood along iteration increasing asymptotically. Finally, the simulation results of mass-spring mechanical system show the correctness of the theory and validity of the method.

scholarly journals Fixed-Time Trajectory Tracking Control of Autonomous Surface Vehicle with Model Uncertainties and Disturbances

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Jiawen Cui ◽  
Haibin Sun
Keyword(s):  
Trajectory Tracking ◽  
Tracking Control ◽  
Sliding Mode ◽  
Fixed Time ◽  
Convergence Time ◽  
Model Uncertainties ◽  
External Disturbances ◽  
Trajectory Tracking Control ◽  
Integral Sliding Mode ◽  
Control Scheme

The issue of fixed-time trajectory tracking control for the autonomous surface vehicles (ASVs) system with model uncertainties and external disturbances is investigated in this paper. Particularly, convergence time does not depend on initial conditions. The major contributions include the following: (1) An integral sliding mode controller (ISMC) via integral sliding mode surface is first proposed, which can ensure that the system states can follow the desired trajectory within a fixed time. (2) Unknown external disturbances are absolutely estimated by means of designing a fixed-time disturbance observer (FTDO). By combining the FTDO and ISMC techniques, a new control scheme (FTDO-ISMC) is developed, which can achieve both disturbance compensation and chattering-free condition. (3) Aiming at reconstructing the unknown nonlinear dynamics and external disturbances, a fixed-time unknown observer (FTUO) is proposed, thus providing the FTUO-ISMC scheme that finally achieves trajectory tracking of ASVs with unknown parameters. Finally, simulation tests and detailed comparisons indicate the effectiveness of the proposed control scheme.

An anti-windup rate-varying integral control applied to electromechanical actuator

2014 ◽  
Vol 229 (4) ◽  
pp. 692-702
Author(s):  
Mohammad Reza Sabaapour ◽  
Esmaeel Khanmirza ◽  
Siamak Ghadami
Keyword(s):  
Steady State ◽  
Trajectory Tracking ◽  
Position Control ◽  
Nonlinear Modeling ◽  
External Disturbance ◽  
Error Signal ◽  
Integral Control ◽  
Electromechanical Actuator ◽  
Good Agreement ◽  
State Error

This paper introduces a novel integral-based controller to correct steady-state error as well as to improve trajectory tracking in position control of a rotary actuator. For this aim, linear and nonlinear modeling of a rotary electromechanical actuator via conventional P-D controller has been described followed by investigation of nonlinear element's effects. The model has very good agreement with experimental results. Then, for trajectory tracking improvement and especially to reduce steady-state error induced by external disturbance, different integral based controllers such as PID, PI-D, and I-PD have been considered. Moreover, the problem of integrator saturation (integral wind-up) has been solved by modified rate varying integral method. It has been showed that a PI-D controller with modified rate varying integral can best match controlling requirements, as well as having enough simplicity for analogue implementation. Also, as a new method, it was suggested that for rate-varying integral calculation, the error rate signal could be replaced by error signal. Doing so, not only former advantages were hold, but more simplicity in controller implementation was gained. Simulation results have shown the effectiveness of the proposed method.

scholarly journals Piecewise fast multi-power reaching law: Basis for sliding mode control algorithm

2020 ◽  
pp. 002029402096424
Author(s):  
Guang-Yu Yang ◽  
Si-Yi Chen
Keyword(s):  
Steady State ◽  
Sliding Mode Control ◽  
Sliding Mode ◽  
Nonlinear Function ◽  
Convergence Time ◽  
Pendulum System ◽  
Reaching Law ◽  
Mode Control ◽  
Inverted Pendulum System ◽  
State Error

A piecewise fast multi-power reaching law (PFMPRL) is proposed aiming at the problems of chattering and slow convergence in the reaching phase of sliding mode control (SMC). In this paper, the fast power reaching law and the double power reaching law are combined, and a nonlinear function is introduced to design the exponential term in PFMPRL. The proposed method ensures the characteristic of fast convergence of the system at all the phases of tendency. The characteristic of fixed-time convergence has also been satisfied. The study proves that the system state can converge to steady-state error bounds within a finite time in the presence of system uncertainty and bounded external disturbance. Compared with the existed methods, the proposed method has shorter convergence time and smaller steady-state error bound. To suppress the influence of model uncertainty and disturbance in system control, a non-linear disturbance observer (NDO) is introduced, and combined with the reaching law-based non-singular terminal sliding mode control (NTSMC), is applied to the cart inverted pendulum system. Simulation results and numerical analysis verify the effectiveness and superiority of this approach.

scholarly journals ENHANCEMENT OF STABILITY ON AUTONOMOUS WAYPOINT MISSION OF QUADROTOR USING LQR INTEGRATOR CONTROL

2022 ◽  
Vol 23 (1) ◽  
pp. 129-158
Author(s):  
Oktaf Agni Dhewa ◽  
Tri Kuntoro Priyambodo ◽  
Aris Nasuha ◽  
Yasir Mohd Mustofa
Keyword(s):  
Steady State ◽  
Trajectory Tracking ◽  
Control Method ◽  
Linear Quadratic Regulator ◽  
System Specification ◽  
Linear Quadratic ◽  
Environmental Disturbances ◽  
Essential Requirement ◽  
Lqr Control ◽  
State Error

The ability of the quadrotor in the waypoint trajectory tracking becomes an essential requirement in the completion of various missions nowadays. However, the magnitude of steady-state errors and multiple overshoots due to environmental disturbances leads to motion instability. These conditions make the quadrotor experience a shift and even change direction from the reference path. As a result, to minimize steady-state error and multiple overshoots, this study employs a Linear Quadratic Regulator control method with the addition of an Integrator. Comparisons between LQR without Integrator and LQR with Integrator were performed. They were implemented on a quadrotor controller to track square and zig-zag waypoint patterns. From experimental results, LQR without Integrator produce of 2 meters steady-state error and -1.04 meters undershoot average with an accuracy of 64.84 % for square pattern, along 3.19 meters steady-state error, and -1.12 meters undershoot average with an accuracy of 46.73 % for a zig-zag way. The LQR method with integrator produce of 1.06 meters steady-state error with accuracy 94.96 % without multiple-overshoot for square pattern, the 1.06 meters steady-state error, and -0.18 meters undershoot average with an accuracy of 86.49 % for the zig-zag way. The results show that the LQR control method with Integrator can minimize and improve steady-state error and multiple overshoots in quadrotor flight. The condition makes the quadrotor able to flying path waypoints with the correct system specification. ABSTRAK: Kemampuan quadrotor dalam pengesanan lintasan waypoint menjadi syarat penting dalam menyelesaikan pelbagai misi pada masa kini. Walau bagaimanapun, besarnya ralat keadaan mantap dan banyak kelebihan kerana gangguan persekitaran menyebabkan ketidakstabilan pergerakan. Keadaan ini menjadikan quadrotor mengalami pergeseran dan bahkan mengubah arah dari jalur rujukan. Oleh itu, kajian ini menggunakan kaedah kawalan Linear Quadratic Regulator dengan penambahan integrator dalam meminimumkan ralat keadaan mantap dan banyak kelebihan. Perbandingan antara LQR tanpa Integrator dan LQR dengan Integrator dilakukan. Mereka dilaksanakan pada pengawal quadrotor untuk mengesan corak titik jalan persegi dan zig-zag. Dari hasil eksperimen, LQR tanpa Integrator menghasilkan ralat keadaan mantap 2 meter dan -1.04 meter rata-rata undur tembak dengan ketepatan 64.84% untuk corak persegi, sepanjang ralat keadaan tetap 3.19 meter, dan -1.12 meter rata-rata undur bawah dengan ketepatan 46.73 % untuk cara zig-zag. Kaedah LQR dengan integrator menghasilkan ralat keadaan mantap 1.06 meter dengan ketepatan 94.96% tanpa tembakan berlebihan untuk corak segi empat sama, ralat keadaan mantap 1.06 meter, dan rata-rata undur tembak -0.18 meter dengan ketepatan 86.49% untuk zig-zag cara. Hasilnya menunjukkan bahawa kaedah kawalan LQR dengan Integrator dapat meminimumkan dan memperbaiki ralat keadaan mantap dan banyak overhoot dalam penerbangan quadrotor. Keadaan tersebut menjadikan quadrotor dapat terbang ke titik jalan dengan spesifikasi sistem yang betul.

scholarly journals Robust Stable Control Design for AC Power Supply Applications

Electronics ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 419 ◽  
Author(s):  
En-Chih Chang ◽  
Sung-Chi Yang ◽  
Rong-Ching Wu
Keyword(s):  
Steady State ◽  
Power Supply ◽  
High Performance ◽  
Sliding Mode ◽  
Convergence Time ◽  
Control Technology ◽  
Grey Prediction ◽  
Terminal Sliding Mode ◽  
Ac Power ◽  
State Error

This paper applies modified feedback technology to carry out the exact steady-state and fast transient in a high-performance alternating current (AC) power supply. The presented scheme displays the virtues of a finite-time convergence control (FTCC) and a discrete grey prediction model (DGPM). The FTCC, derived from a terminal sliding-mode (TSM) design principle, can produce the finite system-state convergence time and evade the singularity. It is noteworthy that the chattering/steady-state error around the FTCC may occur because of the overestimated or underestimated uncertainty bound. The DGPM with the bound estimate ability is integrated into the FTCC to cope with internal parameter variations and external load disturbances. The less chattering and steady-state error can be obtained, providing more robust performance in the AC power supply. The combination of the FTCC and the DGPM extends the standard TSM design for the purpose of faster singularity-free convergence, as well as introducing the grey modeling method in the case of a more exact uncertainty estimate. The modified control technology has a high-precision tracking performance and a fast convergent speed. Simulated and experimental results point out that the modified control technology can effectuate low total harmonic distortion (THD) and fast dynamic response in the presence of rectifier loads and abrupt step load changes.

Extention of Strongly Stable GPC for Improvement of Steady State Error

2018 ◽  
Vol 138 (5) ◽  
pp. 498-505 ◽  
Author(s):  
Toyoaki Tanikawa ◽  
Tomohiro Henmi ◽  
Akira Inoue ◽  
Akira Yanou ◽  
Shinich Yoshinaga
Keyword(s):  
Steady State ◽  
State Error

FCS-MPC without Steady-State Error Applied to a Grid-Connected Cascaded H-Bridge Multilevel Inverter

2021 ◽  
pp. 1-1
Author(s):  
Carlos R. Baier ◽  
Roberto Ramirez ◽  
Esteban Ignacio Marciel ◽  
Jesus de la Casa Hernandez ◽  
Pedro Eduardo E. Melin Coloma ◽  
...  
Keyword(s):  
Steady State ◽  
Multilevel Inverter ◽  
State Error
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