Vibration Reduction by Active Control of Flexible Marine Riser Angle Subjected to Time-Varying Distributed Force

2016 ◽  
Author(s):  
F. Bakhtiari-Nejad ◽  
A. Azimi
Keyword(s):  
Boundary Control ◽  
Closed Loop ◽  
Direct Method ◽  
Surface Current ◽  
Ocean Surface ◽  
Distributed Parameter ◽  
Time Varying ◽  
Parameter System ◽  
Closed Loop System ◽  
Ocean Surface Current

In this research, boundary control is developed at the upper end of the riser based on the Lyapanuv’s direct method to reduce top angle and transverse vibration of the riser subjected to time-varying disturbance. First, ocean surface current is assumed to be linearly declined to zero from the ocean surface to the ocean floor and then it is assumed to be exponentially declined to zero. The riser is modeled as a distributed parameter system with one partial differential equation (PDE) coupled with boundary conditions (ODE). Since all of the control signals can be measured by sensors or can be calculated by a backwards difference algorithm, so the boundary control is practical and implementable with existing instrumentation. The Lyapunov’s direct method is applied to stability analysis of the closed-loop system. Finally, efficiency of the controller is verified and results of linear and exponential profiles are compared to each other.

Design and Simulation of Robust and Adaptive Controls for a Nonlinear String System1

2004 ◽  
Vol 126 (1) ◽  
pp. 54-62
Author(s):  
Weiwei Jin ◽  
Zhihua Qu ◽  
Kuo-Chi Lin
Keyword(s):  
Numerical Simulation ◽  
Vibration Control ◽  
Boundary Control ◽  
Closed Loop ◽  
Direct Method ◽  
Closed Loop System ◽  
Lyapunov Direct Method ◽  
Adaptive Controls ◽  
Control Designs ◽  
Nonlinear String

In this paper, vibration control of a nonlinear string system is considered. The system consists of a nonlinear string, two boundary supporting mechanisms, and a moving transporter at the base. To suppress the vibration, boundary control designs are carried out. A new robust and adaptive boundary controller is designed using the Lyapunov direct method. The proposed control is implemented at the two ends supporting the string to compensate for vibration induced by the base motion. It is shown that the adaptive/robust boundary control can asymptotically stabilize the nonlinear string. Numerical simulation of the closed loop system demonstrates the effectiveness of the proposed control.

Design and Simulation of Robust and Adaptive Controls for a Nonlinear String System

2000 ◽  
Author(s):  
Weiwei Jin ◽  
Zhihua Qu ◽  
Kurt Lin
Keyword(s):  
Numerical Simulation ◽  
Vibration Control ◽  
Boundary Control ◽  
Closed Loop ◽  
Direct Method ◽  
Closed Loop System ◽  
Lyapunov Direct Method ◽  
Adaptive Controls ◽  
Control Designs ◽  
Nonlinear String

Abstract In this paper, vibration control of a nonlinear string system is considered. The system consists of a nonlinear string, two boundary supporting mechanisms, and a moving transporter at the base. To suppress the vibration, boundary control designs are carried out. A new robust and adaptive boundary controller is designed using the Lyapunov direct method. The proposed control is implemented at the two ends supporting the string to compensate for vibration induced by the base motion. It is shown that the adaptive/robust boundary control can asymptotically stabilize the nonlinear string. Numerical simulation of the closed loop system demonstrates the effectiveness of the proposed control.

The Swing Control of Cranes with Variable Rope Length Based on Linear Time Varying System Theory

2012 ◽  
Vol 461 ◽  
pp. 763-767
Author(s):  
Li Fu Wang ◽  
Zhi Kong ◽  
Xin Gang Wang ◽  
Zhao Xia Wu
Keyword(s):  
State Feedback ◽  
Closed Loop ◽  
Linear Time ◽  
Feedback Stabilization ◽  
Time Varying ◽  
Closed Loop System ◽  
Overhead Cranes ◽  
Time Varying Systems ◽  
Time Invariant ◽  
Time Invariant System

In this paper, following the state-feedback stabilization for time-varying systems proposed by Wolovich, a controller is designed for the overhead cranes with a linearized parameter-varying model. The resulting closed-loop system is equivalent, via a Lyapunov transformation, to a stable time-invariant system of assigned eigenvalues. The simulation results show the validity of this method.

The Implementation of the Minimal Control Synthesis Algorithm on a Web Control Problem

1994 ◽  
Vol 208 (1) ◽  
pp. 53-60 ◽  
Author(s):  
D P Stoten ◽  
M G Dye ◽  
M Webb
Keyword(s):  
Closed Loop ◽  
Control Synthesis ◽  
Time Varying ◽  
Closed Loop System ◽  
Synthesis Algorithm ◽  
Time Varying Parameters ◽  
Transport Control ◽  
Adaptive Control Strategy ◽  
Web Control ◽  
Experimental Comparisons

The minimal control synthesis (MCS) algorithm is an adaptive control strategy that requires no prior knowledge of plant dynamic parameters, and yet is guaranteed to provide global asymptotic stability of the closed-loop system. The purpose of this paper is to present MCS as applied to web tension und transport control a class of plant that has highly non-linear dynamics and time-varying parameters. The plant is difficult to control by conventional methods over its full operating range. A typical example and model of such a plant is presented along with the implementation of MCS. Experimental comparisons of MCS with conventional control benchmarks are provided. It will be seen that MCS significantly outperforms the conventional controller.

Stabilization of Nonlinear Strict-Feedback Systems With Time-Varying Delayed Integrators

2011 ◽  
Author(s):  
Nikolaos Bekiaris-Liberis ◽  
Miroslav Krstic
Keyword(s):  
Asymptotic Stability ◽  
Global Asymptotic Stability ◽  
Closed Loop ◽  
Loop System ◽  
Time Varying ◽  
Feedback Systems ◽  
Closed Loop System ◽  
Feedback Form ◽  
Globally Asymptotically Stable ◽  
Strict Feedback

We consider nonlinear systems in the strict-feedback form with simultaneous time-varying input and state delays, for which we design a predictor-based feedback controller. Our design is based on time-varying, infinite-dimensional backstepping transformations that we introduce, to convert the system to a globally asymptotically stable system. The solutions of the closed-loop system in the transformed variables can be found explicitly, which allows us to establish its global asymptotic stability. Based on the invertibility of the backstepping transformation, we prove global asymptotic stability of the closed-loop system in the original variables. Our design is illustrated by a numerical example.

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