Observer-based robust control for flexible-joint robot manipulators: A state-dependent Riccati equation-based approach

2020 ◽  
Vol 42 (16) ◽  
pp. 3135-3155
Author(s):  
Neda Nasiri ◽  
Ahmad Fakharian ◽  
Mohammad Bagher Menhaj
Keyword(s):  
Robust Control ◽  
Control Problem ◽  
Riccati Equation ◽  
Power Transmission ◽  
Control Method ◽  
Main Idea ◽  
Robotic Systems ◽  
Flexible Joint ◽  
State Dependent ◽  
Highly Nonlinear

In this paper, the robust control problem is tackled by employing the state-dependent Riccati equation (SDRE) for uncertain systems with unmeasurable states subject to mismatched time-varying disturbances. The proposed observer-based robust (OBR) controller is applied to two highly nonlinear, coupled and large robotic systems: namely a manipulator presenting joint flexibility due to deformation of the power transmission elements between the actuator and the robot known as flexible-joint robot (FJR) and also an FJR incorporating geared permanent magnet DC motor dynamics in its dynamic model called electrical flexible-joint robot (EFJR). A novel state-dependent coefficient (SDC) form is introduced for uncertain EFJRs. Rather than coping with the OBR control problem for such complex uncertain robotic systems, the main idea is to solve an equivalent nonlinear optimal control problem where the uncertainty and disturbance bounds are incorporated in the performance index. The stability proof is presented. Solving the complicated robust control problem for FJRs and EFJRs subject to uncertainty and disturbances via a simple and flexible nonlinear optimal approach and no need of state measurement are the main advantages of the proposed control method. Finally, simulation results are included to verify the efficiency and superiority of the control scheme.

Proton Exchange Membrane Fuel Cell System Identification and Control: Part II — H-Infinity Based Robust Control

2006 ◽  
Author(s):  
F. C. Wang ◽  
Y. P. Yang ◽  
H. P. Chang ◽  
Y. W. Ma ◽  
C. W. Huang ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Robust Control ◽  
System Identification ◽  
Control Method ◽  
Cell Voltage ◽  
Pem Fuel Cell ◽  
Cell System ◽  
Proton Exchange ◽  
Fuel Cell System ◽  
Highly Nonlinear

This paper applies robust control strategies to a PEM fuel-cell system. In Part I of this work [17], a PEM fuel cell was described as a two-input-two-output system with the inputs of hydrogen and air flow rates, and the outputs of cell voltage and current. From the responses, system identification techniques were adopted to model the system transfer function matrix. Then adaptive control methods were applied to control the system with encouraging results. In this paper, the H∞ robust control strategy is proposed due to the highly nonlinear and time-varying characteristics of the system. From the results, it is illustrated to be an efficient control method for the fuel cell systems.

Vibration suppression and attitude control for the formation flight of flexible satellites by optimally tuned on-off state-dependent Riccati equation approach

2020 ◽  
Vol 42 (15) ◽  
pp. 2984-3001
Author(s):  
Hossein Rouzegar ◽  
Alireza Khosravi ◽  
Pouria Sarhadi
Keyword(s):  
Riccati Equation ◽  
Attitude Control ◽  
Vibration Suppression ◽  
Pso Algorithm ◽  
Formation Flight ◽  
Equation Approach ◽  
Coordination Control ◽  
Suggested Approach ◽  
State Dependent ◽  
Highly Nonlinear

In this paper, vibration suppression and attitude control for the formation flight of flexible satellites using optimally tuned on-off SDRE (state-dependent Riccati equation) approach is discussed. A formation consisting of flexible satellites has highly nonlinear dynamics and the corresponding satellites are subject to vibrations as well as uncertainties due to the practical conditions. Vibrations that are mainly caused by flexible modes of the satellites disorganize the coordination and hinder the formation stability as well as decreasing its performance and lifetime. Hence, flexibility should be considered in formation model and the coordination control needs to address such challenges. Owing to capabilities of SDRE approach for nonlinear systems, it is used as the coordination control. Satellites are assumed to be equipped with thrusters as their actuators which requires the control to be applied as on-off pulses. To this end, an algorithm is suggested to efficiently convert SDRE control into on-off pulses. For optimal tuning of the controller, the particle swarm optimization (PSO) algorithm is employed. Stability of the system has also been analyzed via a Lyapunov-based approach utilizing the region of attraction concept. The proposed on-off SDRE approach has shown to effectively suppress the vibrations in the presence of uncertainties leading to the accurate coordination of the whole formation while consuming less energy. Simulation results show the capability, efficiency, robustness and stability of the suggested approach.

State Dependent Riccati Equation (SDRE) Control Method Applied in Cancellation of a Parametric Resonance in a Magnetically Levitated Body

2011 ◽  
Author(s):  
Fa´bio Roberto Chavarette ◽  
Jose´ Manoel Balthazar ◽  
Ce´lia Aparecida dos Reis ◽  
Nelson Jose´ Peruzzi
Keyword(s):  
Riccati Equation ◽  
Control Method ◽  
Equations Of Motion ◽  
Control Design ◽  
Inertial Force ◽  
The Body ◽  
State Dependent ◽  
Oscillatory Movement ◽  
Magnetically Levitated ◽  
Static Equilibrium State

Here, a simplified dynamical model of a magnetically levitated body is considered. The origin of an inertial Cartesian reference frame is set at the pivot point of the pendulum on the levitated body in its static equilibrium state (ie, the gap between the magnet on the base and the magnet on the body, in this state). The governing equations of motion has been derived and the characteristic feature of the strategy is the exploitation of the nonlinear effect of the inertial force associated, with the motion of a pendulum-type vibration absorber driven, by an appropriate control torque [4]. In the present paper, we analyzed the nonlinear dynamics of problem, discussed the energy transfer between the main system and the pendulum in time, and developed State Dependent Riccati Equation (SDRE) control design to reducing the unstable oscillatory movement of the magnetically levitated body to a stable fixed point. The simulations results showed the effectiveness of the (SDRE) control design.

Adaptive Robust Control of Circular Machining Contour Error Using Global Task Coordinate Frame

2013 ◽  
Author(s):  
Tyler A. Davis ◽  
Yung C. Shin ◽  
Bin Yao
Keyword(s):  
Robust Control ◽  
Control Problem ◽  
Research Work ◽  
Approximation Error ◽  
Adaptive Robust Control ◽  
Contour Error ◽  
Coordinate Frame ◽  
Tool Deflection ◽  
Machining Processes ◽  
Highly Nonlinear

The contour error of machining processes is defined as the difference between the desired and actual produced shape. Two major factors contributing to contour error are axis position error and tool deflection. A large amount of research work formulates the contour error in convenient locally defined task coordinate frames that are subject to significant approximation error. The more accurate global task coordinate frame (GTCF) can be used, but transforming the control problem to the GTCF leads to a highly nonlinear control problem. An adaptive robust control (ARC) approach is designed to control machine position in the GTCF, while directly accounting for tool deflection, to minimize the contour error. The combined GTCF/ARC approach is experimentally validated by applying the control to circular contours on a three axis milling machine. The results show that the proposed approach reduces contour error in all cases tested.

scholarly journals Adaptive Critic Learning-Based Robust Control of Systems with Uncertain Dynamics

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Jun Zhao ◽  
Qingliang Zeng ◽  
Bin Guo
Keyword(s):  
Optimal Control ◽  
Robust Control ◽  
Control Problem ◽  
Control Method ◽  
System Modeling ◽  
Uncertain System ◽  
Nonsmooth Dynamics ◽  
Adaptive Critic ◽  
Uncertain Dynamics ◽  
Critic Neural Network

Model uncertainties are usually unavoidable in the control systems, which are caused by imperfect system modeling, disturbances, and nonsmooth dynamics. This paper presents a novel method to address the robust control problem for uncertain systems. The original robust control problem of the uncertain system is first transformed into an optimal control of nominal system via selecting the appropriate cost function. Then, we develop an adaptive critic leaning algorithm to learn online the optimal control solution, where only the critic neural network (NN) is used, and the actor NN widely used in the existing methods is removed. Finally, the feasibility analysis of the control algorithm is given in the paper. Simulation results are given to show the availability of the presented control method.

Fractional Order LQR for Optimal Robust Control of a Simple Structure

2007 ◽  
Author(s):  
Abdollah Shafieezadeh ◽  
Keri Ryan ◽  
YangQuan Chen
Keyword(s):  
Robust Control ◽  
Control Problem ◽  
Fractional Order ◽  
Simple Structure ◽  
Control Method ◽  
Linear Quadratic Regulator ◽  
Linear Quadratic ◽  
Fractional Damping ◽  
Fractional Order Control

This study combines fractional order control with linear quadratic regulator (LQR) for optimal robust control of a simple civil structure. As a first attempt, the purpose of this paper is to demonstrate that, when fractional damping is introduced, additional benefits can be obtained over the best traditional control method. The control problem of this paper can be used as a simple benchmark example to test new control ideas before applying to more complicated models.

Vibration Control of Redundant Flexible-Joint Manipulators

1997 ◽  
Vol 119 (1) ◽  
pp. 119-125
Author(s):  
Fengfeng Xi
Keyword(s):  
Numerical Simulations ◽  
Vibration Control ◽  
Control Method ◽  
Optimization Technique ◽  
Main Idea ◽  
The Other ◽  
Control Law ◽  
Flexible Joint ◽  
Flexible Joint Manipulator

Presented in this paper is a method for controlling vibrations of a redundant flexible-joint manipulator. The main idea behind this method is to utilize joint redundancy to minimize the change in the manipulator inertia, so that a simple gain-fixed control law can be used to control joint vibrations. For this purpose, two optimal joint trajectory generators are proposed; one is based on the extended Jacobian method and the other is based on an optimization technique. Numerical simulations are provided to demonstrate the effectiveness of the proposed control method.

scholarly journals Nonlinear Optimal Tracking For Missile Gimbaled Seeker Using Finite-Horizon State Dependent Riccati Equation

2014 ◽  
Vol 60 (2) ◽  
pp. 165-171 ◽  
Author(s):  
Ahmed Khamis ◽  
D. Subbaram Naidu ◽  
Ahmed M. Kamel
Keyword(s):  
Riccati Equation ◽  
Finite Horizon ◽  
Change Of Variables ◽  
Dc Motors ◽  
State Dependent ◽  
Highly Nonlinear ◽  
Wide Range ◽  
Nonlinear Tracking ◽  
Lyapunov Differential Equation ◽  
Operating Points

Abstract The majority of homing guided missiles use gimbaled seekers. The equations describing seeker gimbal system are highly nonlinear. Accurate nonlinear control of the motion of the gimbaled seeker through the attached DC motors is required. In this paper, an online technique for finite-horizon nonlinear tracking problems is presented. The idea of the proposed technique is the change of variables that converts the nonlinear differential Riccati equation to a linear Lyapunov differential equation. The proposed technique is effective for wide range of operating points. Simulation results for a realistic gimbaled system with different engagement scenarios are given to illustrate the effectiveness of the proposed technique.

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