LMI-Based 2-Degrees-of-Freedom Controller Design for Robust Vibration Suppression Positioning

2011 ◽  
Vol 131 (1) ◽  
pp. 93-101 ◽  
Author(s):  
Takanori Kato ◽  
Yoshihiro Maeda ◽  
Makoto Iwasaki ◽  
Hiromu Hirai
Keyword(s):  
Degrees Of Freedom ◽  
Vibration Suppression ◽  
Controller Design

Vibration suppression of wind turbine nacelle with active electromagnetic mass damper systems using adaptive backstepping control

2021 ◽  
pp. 107754632199887
Author(s):  
Sinan Basaran ◽  
Fevzi Cakmak Bolat ◽  
Selim Sivrioglu
Keyword(s):  
Vibration Suppression ◽  
Controller Design ◽  
Wind Load ◽  
Backstepping Control ◽  
Structural Systems ◽  
Adaptive Backstepping ◽  
Electromagnetic Mass ◽  
Flow Induced Vibration ◽  
Adaptive Backstepping Control ◽  
Mass Damper

Many structural systems, such as wind turbines, are exposed to high levels of stress during operation. This is mainly because of the flow-induced vibrations caused by the wind load encountered in every tall structure. Preventing the flow-induced vibration has been an important research area. In this study, an active electromagnetic mass damper system was used to eliminate the vibrations. The position of the stabilizer mass in the active electromagnetic mass damper system was determined according to the displacement information read on the system without using any spring element, unlike any conventional system. The proposed system in this study has a structure that can be implemented as a vibration suppressor in many intelligent structural systems. Two opposing electromagnets were used to determine the instant displacement of the stabilizer mass. The control currents to be given to these electromagnets are determined by using an adaptive backstepping control design. The adaptive controller algorithm can predict the wind load used in the controller design without prior knowledge of the actual wind load. It was observed that the designed active electromagnetic mass damper structure is successful in suppressing system vibrations. As a result, the proposed active electromagnetic mass damper system has been shown to be suitable for structural systems in flow-induced vibration damping.

Active Damping of a Large Flexible Manipulator With a Short-Reach Robot

1996 ◽  
Vol 118 (4) ◽  
pp. 704-713 ◽  
Author(s):  
I. Sharf
Keyword(s):  
Vibration Suppression ◽  
Controller Design ◽  
Reaction Force ◽  
Control Variable ◽  
Active Damping ◽  
Flexible Manipulator ◽  
Design Problems ◽  
Flexible Arm ◽  
Six Degree Of Freedom ◽  
Small Robot

This paper deals with manipulator systems comprising a long-reach manipulator (LRM) with a short-reach dextrous manipulator (SRM) attached to its end. The former, due to its size, is assumed to have significant structural flexibility, while the latter is modeled as a rigid robot. The particular problem addressed is that of active damping, or vibration suppression, of the LRM by using SRM specifically for that purpose Such a scenario is envisioned for operations where the large manipulator is used to deploy the small robot and it is necessary to damp out vibrations in LRM prior to operating SRM. The proposed solution to the problem uses the reaction force from SRM to LRM as a control variable which allows to effectively decouple the controller design problems for the two manipulators. A two-stage controller is presented that involves first, determining the trajectory of the short manipulator required to achieve a desired damping wrench to the supporting flexible arm and subsequently, brings the small manipulator to rest. Performance of the active damping algorithm developed is illustrated with a six-degree-of-freedom rigid manipulator on a flexible mast. Comparison to an independent derivative joint controller is included. The paper also discusses how the proposed methodology can be extended to address other issues related to operation of long-reach manipulator systems.

Optimization-Based Design of a Leg Mechanism via Combined Kinematic and Structural Analysis

1994 ◽  
Author(s):  
W. B. Shieh ◽  
S. Azarm ◽  
L. W. Tsai ◽  
A. L. Tits
Keyword(s):  
Energy Loss ◽  
Degrees Of Freedom ◽  
Controller Design ◽  
Minimum Energy ◽  
Problem Formulation ◽  
Minimal Energy ◽  
Interactive Optimization ◽  
Joint Forces ◽  
Four Bar Linkage ◽  
Optimization Based Design

Abstract We study a recently proposed compound two degrees of freedom planar leg mechanism consisting of a four-bar linkage and a pantograph. In this mechanism, one degree of freedom is used for normal walking to provide an ovoid path which emulates that of humans while the other is used only when necessary to walk over obstacles. Potential advantages of such a compound mechanism are fast locomotion, minimal energy loss, simplicity in controller design, and slenderness of the leg. To exploit these to the fullest, a multiobjective optimization-based design problem formulation is proposed with the following four design objectives: (i) minimum leg height, (ii) minimum of the maximum joint forces, (iii) minimum leg mass, and (iv) minimum energy loss for a walking cycle. In addition, this problem formulation takes into account a combination of mechanism requirements and structural requirements. Several tradeoff solutions are obtained using the Consol-Optcad interactive optimization-based design package.

Improved disturbance rejection control based on H∞ synthesis and equivalent-input-disturbance for aircraft longitudinal autopilot design

2018 ◽  
Vol 233 (9) ◽  
pp. 3323-3335
Author(s):  
Tong Li ◽  
Huabo Yang ◽  
Jiayi Tian ◽  
Shifeng Zhang
Keyword(s):  
Frequency Domain ◽  
Disturbance Rejection ◽  
Degrees Of Freedom ◽  
Controller Design ◽  
Engineering Application ◽  
Research Attention ◽  
Input Disturbance ◽  
Disturbance Rejection Control ◽  
Frequency Domain Methods ◽  
Equivalent Input Disturbance

Disturbance rejection control has been developed over decades attracting wide interest and research attention. Aiming at providing a potential engineering application of disturbance rejection control to aircraft control system design following traditional frequency-domain methods, this paper presents an improved disturbance rejection control of two degrees of freedom based on [Formula: see text] synthesis and equivalent-input-disturbance for an aircraft longitudinal autopilot design. The mismatched disturbance is transformed as a “total disturbance” in the input channel for compensation through the establishment of an equivalent-input-disturbance system. The [Formula: see text] synthesis based on classical frequency-domain analysis is applied to a disturbance filter and a composite feedback controller design. In terms of the controller design, the system including the filter is considered as a whole in [Formula: see text] optimization process without separate design to guarantee the stability of the overall system. Furthermore, the proposed method is successfully implemented on the autopilot design by modeling nonlinear aircraft longitudinal dynamics as a linear equivalent-input-disturbance formulation of angle of attack. The simulation of tracking performance in comparison with existing renowned methods is conducted in the presence of aerodynamic uncertainties, gust disturbance, actuator characteristics and sensor noise. The results verify the effectiveness of the proposed method with excellent performance and practical prospects.

Multibody Analysis and Control of a Full-Wrist Exoskeleton for Tremor Alleviation

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Jiamin Wang ◽  
Oumar R. Barry
Keyword(s):  
Degrees Of Freedom ◽  
Controller Design ◽  
Wrist Joint ◽  
Three Dimensional ◽  
Design Parameters ◽  
Light Power ◽  
Multibody Modeling ◽  
Flexion Extension ◽  
Reliable Performance ◽  
Rotational Joint

Abstract Uncontrollable shaking in the human wrist, caused by pathological tremor, can significantly undermine the power and accuracy in object manipulation. In this paper, the design of a tremor alleviating wrist exoskeleton (TAWE) is introduced. Unlike the works in the literature that only consider the flexion/extension (FE) motion, in this paper, we model the wrist joint as a constrained three-dimensional (3D) rotational joint accounting for the coupled FE and radial/ulnar deviation (RUD) motions. Hence TAWE, which features a six degrees-of-freedom (DOF) rigid linkage structure, aims to accurately monitor, suppress tremors, and provide light-power augmentation in both FE and RUD wrist motions. The presented study focuses on providing a fundamental understanding of the feasibility of TAWE through theoretical analyses. The analytical multibody modeling of the forearm–TAWE assembly provides insight into the necessary conditions for control, which indicates that reliable control conditions in the desired workspace can be acquired by tuning the design parameters. Nonlinear regressions are then implemented to identify the information that is crucial to the controller design from the unknown wrist kinematics. The proposed analytical model is validated numerically with V-REP and the result shows good agreement. Simulations also demonstrate the reliable performance of TAWE under controllers designed for tremor suppression and movement assistance.

Structural Control of an Ultra-Large Semi-Submersible Floating Offshore Wind Turbine

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Zhixin Zhao ◽  
Wenhua Wang ◽  
Dongdong Han ◽  
Wei Shi ◽  
Yulin Si ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Dynamic Model ◽  
Structural Control ◽  
Degrees Of Freedom ◽  
Vibration Suppression ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Floating Offshore Wind Turbine ◽  
Proposed Model

Abstract A braceless semi-submersible floating platform is proposed for a Technical University of Denmark (DTU) 10-MW wind turbine at moderate water depths with reference to an existing National Renewable Energy Laboratory (NREL) 5-MW braceless semi-submersible floating platform, and a servo control system for a 10-MW semi-submersible floating offshore wind turbine (FOWT) is introduced. To control the ultimate and fatigue loads of the FOWT, a fore-aft tuned mass damper (TMD) installed in the nacelle of the 10-MW semi-submersible FOWT was investigated for vibration alleviation and load reduction. Considering the hydrodynamic and mooring effect, a four degrees-of-freedom (DOFs) (platform surge and pitch motions, tower fore-aft bending, and TMD translation) simplified dynamic model for the 10-MW semi-submersible FOWT is established based on D’Alembert’s principle. Then, the parameter estimation is conducted based on the Levenberg–Marquardt (LM) algorithm, and the simplified dynamic model was further verified by comparing the output responses with FAST and the proposed model. Furthermore, the exhaustive search (ES) and genetic algorithm (GA) are embedded into the simplified dynamic model to optimize the TMD parameters. Finally, a fully coupled time-domain simulation for all the selected environmental conditions is conducted in FAST, and the vibration suppression performance of the optimized TMD design for the 10-W semi-submersible FOWT was further examined and analyzed.

Kullback-Leibler Divergence, Cost Density-Shaping, Stochastic Optimal Control With Applications to Vibration Suppression

2010 ◽  
Author(s):  
Matthew Zyskowski ◽  
Michael Sain ◽  
Ronald Diersing
Keyword(s):  
Degrees Of Freedom ◽  
First Generation ◽  
Vibration Suppression ◽  
Design Method ◽  
Target Selection ◽  
Active Mass ◽  
Multiple Degrees Of Freedom ◽  
Control Paradigm ◽  
Leibler Divergence ◽  
Mean And Variance

The “k cost cumulant” (kCC) control performs competitively with other structural controllers in protecting buildings from natural disasters. These applications constitute vibration suppression problems involving lightly-damped structures with multiple degrees of freedom. While kCC control has delivered excellent performance in such applications, it gives the designer little direct influence over the shape of the cost’s density. The goal of this work is to present the Minimum Kullback-Leibler Divergence Cost Density-Shaping (MKLD-CDS) control paradigm, which enables the designer to shape the cost’s density according to a pre-specified target mean and variance. This new theory is applied to the first-generation Active Mass Driver (AMD) benchmark problem, where the application of MKLD-CDS with the Statistical Target Selection (STS) design method enables a family of stablizing MKLD-CDS controllers to be computed based on parametric targets. MKLD-CDS controllers are found that exceed the performance of a nominal 2CC controller while not compromising this controller’s robust stability.

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