Optimized Back-Stepping Controller For Position Tracking Of Electro-Hydraulic Actuators

Electro-hydraulic actuator servo system is commonly found in various types of force and position tracking applications. Nonlinearities of the system come from either the system itself or external disturbance signals. These dynamic characteristics make the controller design for the system to be quite challenging. In order to provide satisfactory system performance for high accuracy trajectory tracking, this thesis presents a model of electro-hydraulic actuator servo system with external disturbance included to the actuator of the system. Backstepping controller is proposed in formulating position tracking control algorithm for this system. The designed controller is integrated with Particle Swarm Optimisation (PSO) and Gravitational Search Algorithm (GSA) techniques as an adaptation method such that the controller adjusts its performance automatically based on the dynamic requirement of the system. The combination of the designed controller with these optimization techniques is verified by giving different types of known perturbation signals to the system’s actuator. Then, the performance of the system with this controller is compared in terms of its tracking output, tracking error and Sum of Squared Error (SSE) as performance indices for each algorithm. The simulation results show that the output of the system tracked the reference input given with both integration of backstepping with PSO and GSA. However, backstepping-PSO produces smaller value of SSE which is around 0.5 as compared to SSE generated by backstepping-GSA

Estimator and Controller Design for a Didactic Liquid Level system by System Identification Approach

This manuscript is a piece of report on the identification of Didactic Liquid Level Systems. The term didactic is used as to enlighten the purpose of proto-typing liquid level system for educational use. A liquid level system with unknown mathematical characteristic is identified using ARX (Auto-Regressive with Exogenous Input) model. The determination of such system, on the basis of experimental data is conducted to obtain the discrete transfer function as well as state space representation of it. The identification process which exploits the advantage of linear parametric ARX gives beneficial information such as correlation, best fit and poles-zeros location. The Linear Quadratic Regulator (LQR) is tested for such liquid level system before the estimator is designed. Literal analysis of the estimator performance is conducted as a preliminary insight to the next investigation on the self tuning Proportional – Integral – derivative (PID) algorithm

MODELING AND CONTROLLER DESIGN FOR A COUPLEDTANK LIQUID LEVEL SYSTEM: ANALYSIS & COMPARISON

The system under investigation is a coupled-tank apparatus which is a laboratory bench top emulation of a common process in industrial control. The basic control principle of the coupled-tank system is to maintain a constant level of the liquid in the tank when there is an inflow and outflow of water in the tank and outflow of water out of the tank respectively. Classification of this system using system identification technique involved the transient response analysis, the pseudorandom binary sequence (PRBS) analysis and the least square method. The main objective of this project is to determine the mathematical model of a coupled-tank system using these techniques. It follows by designing a controller consists of a PID and a Fuzzy Logic controllers for the system. At the final stage of this project, the usage of both controllers in industrial applications is compared and analyze

Image Reconstruction Algorithm for Electrical Charge Tomography System

Abstract: Problem statement: Many problems in scientific computing can be formulated as inverse problem. A vast majority of these problems are ill-posed problems. In Electrical Charge Tomography (EChT), normally the sensitivity matrix generated from forward modeling is very ill-condition. This condition posts difficulties to the inverse problem solution especially in the accuracy and stability of the image being reconstructed. The objective of this study is to reconstruct the image cross-section of the material in pipeline gravity dropped mode conveyor as well to solve the ill-condition of matrix sensitivity. Approach: Least Square with Regularization (LSR) method had been introduced to reconstruct the image and the electrodynamics sensor was used to capture the data that installed around the pipe. Results: The images were validated using digital imaging technique and Singular Value Decomposition (SVD) method. The results showed that image reconstructed by this method produces a good promise in terms of accuracy and stability. Conclusion: This implied that LSR method provides good and promising result in terms of accuracy and stability of the image being reconstructed. As a result, an efficient method for electrical charge tomography image reconstruction has been introduced

New robust bounded control for uncertain nonlinear system using mixed backstepping and lyapunov redesign

This paper presents a new robust bounded control law to stabilize uncertain nonlinear system with time varying disturbance. The design idea comes from the advantages of backstepping with Lyapunov redesign, which avoid the needs of fast switching of discontinuous control law offered by its counterpart - a variable structure control. We reduce the conservatism in the design process where the control law can be flexibly chosen from Lyapunov function, hence avoiding the use of convex optimization via linear matrix inequality (LMI) in which the feasibility is rather hard to be obtained. For this work, we design two type control algorithms namely normal control and bounded control. As such, our contribution is the introduction of a new bounded control law that can avoid excessive control energy, high magnitude chattering in control signal and small oscillation in stabilized states. Computation of total energy for both control laws confirmed that the bounded control law can stabilize with less enegry consumption. We also use Euler's approximation to compute average power for both control laws. The robustness of the proposed controller is achieved via saturation-like function in Lyapunov redesign, and hence guaranting asymptotic stability of the closed-loop system

Robust controller design for position tracking of nonlinear system using back stepping-GSA approach

Electro-hydraulic actuator (EHA) system is highly non-linear system with uncertain dynamics in which the mathematical representation of the system cannot sufficiently represent the practical system. Nonlinearities of the system come from either the system itself or external disturbance signals. These dynamic characteristics are the reasons that cause the controller design for the system to be quite challenging. In this paper, back-stepping controller design for tracking purpose of this system is presented based on Lyapunov stability condition. Gravitational Search Algorithm (GSA) technique is then used to optimize the control parameters in order to achieve a predefined system performance. The performance is evaluated based on the tracking output and the tracking error between reference input and the system output. The results show that the system's output follow the reference input given but the tracking performance is influenced by the condition of the system and number of agents and iteration in the algorithm

Optimization of Modified Sliding Mode Control for an Electro-Hydraulic Actuator System with Mismatched Disturbance

This paper presents a modified sliding mode controller (MSMC) for tracking purpose of electro-hydraulic actuator system with mismatched disturbance. The main contribution of this study is in attempting to find the optimal tuning of sliding surface parameters in the MSMC using a hybrid algorithm of particle swarm optimization (PSO) and gravitational search algorithms (GSA), in order to produce the best system performance and reduce the chattering effects. In this regard, Sum square error (SSE) has been used as the objective function of the hybrid algorithm. The performance was evaluated based on the tracking error identified between reference input and the system output. In addition, the efficiency of the designed controller was verified within a simulation environment under various values of external disturbances. Upon drawing a comparison of PSOGSA with PSO and GSA alone, it was learnt that the proposed controller MSMC, which had been integrated with PSOGSA was capable of performing more efficiently in trajectory control and was able to reduce the chattering effects of MSMC significantly compared to MSMC-PSO and MSMC-GSA, respectively when the highest external disturbance, 10500N being injected into the system's actuator

DESIGN OF ADAPTIVE BACKSTEPPING WITH GRAVITATIONAL SEARCH ALGORITHM FOR NONLINEAR SYSTEM

Adaptive backstepping controller is designed for tracking purpose of nonlinear system with unknown parameter is injected to it. Gravitational search algorithm (GSA) is integrated with the designed controller in order to automatically tune its control parameters and adaptation gain since the tracking performance of the controller relies on these parameters. Performance evaluation is observed based on the tracking output and the tracking error between reference input and the system’s output. The effectiveness of the adaptive backstepping controller is verified by looking at the lowest amount value of Sum of Squared Error (SSE) attained from the simulation process. The results show that the system’s output follow the reference input given with remarkably small tracking error

Linearization - Advantages and Shortcomings Toward Control System Design

This brief manuscript discusses the necessity to linearize nonlinear systems. Thorough review on nonlinear phenomena in dynamical and numerical system is presented. The methodology to linearize nonlinear system in Jacobian approach is shown in didactic manner. Numerical and dynamical example of nonlinear system is provided to enhance understanding. Afterward, the comparison between both linearized and non-linearized system is literally discussed. The outcomes concluded that linearization process is a linear approximation of a nonlinear system that is only valid in a small region around an operating point.