Optimal Control for Response Reduction of Single Hinged Articulated Tower Using MR-Damper

2019 ◽  
Author(s):  
Kushal Solomon ◽  
Deepak Kumar
Keyword(s):  
Optimal Control ◽  
Structural Control ◽  
Mr Damper ◽  
Linear Quadratic Regulator ◽  
Wave Loads ◽  
Linear Quadratic ◽  
Offshore Structure ◽  
Damping Force ◽  
Optimal Control Strategy ◽  
Sea Bed

Abstract Articulated tower is a compliant offshore structure deployed in deep waters for oil and gas exploration. The base of the tower is connected to the sea bed through universal joint, which allows the tower to rotate about horizontal axis (pitch). Articulated towers attain stability due to large buoyancy forces acting on it. Under extreme wave loads, the response of ALP can exceed the design limit causing discomfort to the occupants and create unfavourable working conditions. Structural control systems can be implemented in order to reduce the response of ALP, thereby protecting the structure from damages and to increase its life span. In this paper, a semi-active optimal control strategy using Magneto-Rheological damper is adopted to reduce the responses of ALP. Bouc-Wen model is used to describe the force generated by MR-Damper. For achieving the optimal performance of the control system, the applied voltage is varied according to the measured feedback at any moment to change the damping force using linear quadratic regulator technique. Several parametric studies have been conducted and the performance of the controller is evaluated. It is observed that the response of ALP is reduced considerably by using MR-damper as a semi-active control device. However, the capacity of the damper required for achieving the desired control is huge.

Elastic-Plastic Time History Analysis of MR Damping Structure Based on LQG Algorithm

2016 ◽  
Vol 858 ◽  
pp. 145-150
Author(s):  
Yu Liang Zhao ◽  
Zhao Dong Xu
Keyword(s):  
Optimal Control ◽  
Time History ◽  
Mr Damper ◽  
Time History Analysis ◽  
Control Force ◽  
Control Effect ◽  
Damping Force ◽  
Optimal Control Strategy ◽  
Elastic Plastic ◽  
History Analysis

This paper discussed an elastic-plastic time-history analysis on a structure with MR dampers based on member model, in which the elastoplastic member of the structure is assumed to be single component model and simulated by threefold line stiffness retrograde model. In order to obtain better control effect, Linear Quadratic Gaussian (LQG) control algorithm is used to calculate the optimal control force, and Hrovat boundary optimal control strategy is used to describe the adjustable damping force range of MR damper. The effectiveness of the MR damper based on LQG algorithm to control the response of the structure was investigated. The results from numerical simulations demonstrate that LQG algorithm can effectively improve the response of the structure against seismic excitations only with acceleration feedback.

Control and Response Characteristics of a Mixed Mode MR Damper for a Multi-Story Structure

2013 ◽  
Vol 284-287 ◽  
pp. 1778-1782
Author(s):  
Kum Gil Sung
Keyword(s):  
Vibration Control ◽  
Mixed Mode ◽  
Excitation Frequency ◽  
Mr Damper ◽  
Linear Quadratic Regulator ◽  
Relative Displacement ◽  
Linear Quadratic ◽  
Damping Force ◽  
Story Structure ◽  
Mr Fluid

This paper presents vibration control responses of a multi-story structure installed with a semi-active magneto-rheological(MR) damper. As a first step, performance characteristics of three different working modes for MR fluid are compared and the mixed mode type of MR damper is chosen as an optimal candidate for the vibration control of the multi-story structure. An appropriate size of the mixed mode MR damper is devised and manufactured on the basis of the field-dependent Bingham model of the MR fluid which is commercially available. The damping force of the mixed mode MR damper is evaluated with respect to the excitation frequency at various magnetic fields. After formulating the governing equation of motion for the small scaled three-story structure associated with the MR damper, the linear quadratic regulator(LQR) controller to effectively suppress unwanted structural vibrations is designed by imposing semi-active actuating conditions. The control algorithm is then empirically implemented under earthquake conditions and the control responses of the horizontal relative displacement and acceleration are evaluated in time and frequency domains through computer simulations.

Thermal Management of Single- and Dual-Tank Fuel-Flow Topologies Using an Optimal Control Strategy

2018 ◽  
Vol 10 (4) ◽  
Author(s):  
P. G. Huang ◽  
D. B. Doman
Keyword(s):  
Heat Transfer ◽  
Optimal Control ◽  
Control Strategy ◽  
Linear Quadratic Regulator ◽  
Operating Conditions ◽  
Adjoint Equations ◽  
Linear Quadratic ◽  
Optimal Control Strategy ◽  
Flow Topology ◽  
Operation Conditions

The effect of fuel topology and control on thermal endurance of aircraft using fuel as a heat transfer agent was studied using an optimal dynamic solver (OPT). The dynamic optimal solutions of the differential equations governing the heat transfer of recirculated fuel flows for single- and dual-tank arrangements were obtained. The method can handle sudden jumps of operating conditions across different operating zones during mission and/or situations when control parameters have reached their physical limits. Although this method is robust in providing an optimal control strategy to prolong thermal endurance of aircrafts, it is not ideal for practical application because the method required iterative procedures to solve expensive nonlinear equations. The linear quadratic regulator (LQR), the feedback controller, can be derived by linearizing the adjoint equations at trim points to offer a simple control strategy, which can then be implemented directly in the feedback control hardware. The solutions obtained from both OPT and LQR were compared, and it was found two solutions were almost identical except in regions having sudden jump of operation conditions. Finally, a comparison between single- and dual-tank arrangements was made to demonstrate the importance of the flow topology. The study shows the dual-tank arrangement allows flexibility in how energy is managed and can release energy faster than a single-tank topology and hence provides improved aircraft thermal endurance.

scholarly journals Modeling and Optimal Shift Control of a Planetary Two-Speed Transmission

2019 ◽  
Vol 10 (3) ◽  
pp. 53
Author(s):  
Zhao ◽  
Tang
Keyword(s):  
Optimal Control ◽  
Control Strategy ◽  
Linear Quadratic Regulator ◽  
Gear Ratio ◽  
Bench Test ◽  
Bldc Motor ◽  
Linear Quadratic ◽  
Optimal Control Strategy ◽  
Rotation Direction ◽  
Engagement Process

To improve the efficiency of electric vehicles (EVs), a planetary two-speed transmission is proposed, which consists of a brushless direct current (BLDC) motor, a turbo-worm reducer, two multi-disc wet brakes, and a Simpson planetary gearset. Based on the devised electronic actuator for shifting, the rotation direction of the BLDC shaft determines the gear ratio of the transmission. For acquiring smooth shift, the state-space equations with control variables of transmission are derived, and a three-stage algorithm is suggested. During the brake engagement process, the optimal control strategy has been developed using linear quadratic regulator control, considering the jerk and friction work of the brake. The simulation results show that the proposed optimal control strategy could reduce the slipping friction work of the brake and improve the shifting quality of EVs. The optimal control trajectory of the BLDC motor was conducted on the electronic shifting actuator bench test.

Optimal Design of Forging Processes With Deformation and Temperature Constraints

1993 ◽  
Author(s):  
R. V. Grandhi ◽  
H. Cheng ◽  
S. S. Kumar
Keyword(s):  
Thermal Analyses ◽  
State Space Model ◽  
Linear Quadratic Regulator ◽  
Parameter Design ◽  
Linear Quadratic ◽  
Optimal Control Strategy ◽  
Time Control ◽  
Systematic Methodology ◽  
Element Approach ◽  
Nonisothermal Conditions

Abstract This paper presents a systematic methodology for the design of process parameters for nonisothermal forgings. The finite element approach is used for deformation and thermal analyses, and an optimal control strategy is used for the process parameter design. A state-space model is developed for representing the coupled deformation and thermal behavior using rigid viscoplastic formulation. Design constraints on strain-rates and temperature variation are imposed for achieving the desired forging conditions. The linear quadratic regulator (LQR) theory for finite time control is used in designing the ram velocity and initial die temperature. The approach is demonstrated on an axisymmetric disc forging and a plane strain channel section forging, under nonisothermal conditions.

Modeling and Control of a 2-D Membrane Mirror With a PZT Bimorph

Aerospace ◽  
2006 ◽  
Author(s):  
Eric J. Ruggiero ◽  
Daniel J. Inman
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Structural Control ◽  
Shape Control ◽  
Actuation Voltage ◽  
Linear Quadratic Regulator ◽  
Element Model ◽  
Optical Quality ◽  
Active System ◽  
Linear Quadratic

The future of space satellite technology lies in ultra-large mirrors and radar apertures for significant improvements in imaging and communication bandwidths. The availability of optical-quality membranes drives a parallel effort for structural models that can capture the dominant dynamics of large, ultra-flexible satellite payloads. Unfortunately, the inherent flexibility of membrane mirrors wrecks havoc with the payload's on-orbit stability and maneuverability. One possible means of controlling these undesirable dynamics is by embedding active piezoelectric ceramics near the boundary of the membrane mirror. In doing so, active feedback control can be used to eliminate detrimental vibration, perform static shape control, and evaluate the health of the structure. In the present work, a piezoceramic wafer was attached in a bimorph configuration near the boundary of a tensioned rectangular membrane sample. A finite element model of the system was developed to capture the relevant system dynamics from 0 – 500 Hz. The finite element model was compared to experimental results with fair agreement. Using the validated finite element models, structural control using Linear Quadratic Regulator (LQR) control techniques were then used to demonstrate effective vibration control. Typical results show that less than 12 V of actuation voltage is required to eliminate detrimental vibration of the membrane samples in less than 15 ms. The functional gains of the active system are also derived and presented. These spatially descriptive control terms dictate favorable regions within the membrane domain to place sensors.

LQR for State-Bounded Structural Control

1996 ◽  
Vol 118 (1) ◽  
pp. 113-119 ◽  
Author(s):  
C.-H. Chuang ◽  
D.-N. Wu ◽  
Q. Wang
Keyword(s):  
Structural Control ◽  
Vibration Amplitude ◽  
Gain Control ◽  
Linear Quadratic Regulator ◽  
Matching Condition ◽  
High Gain ◽  
Time Instant ◽  
Linear Quadratic ◽  
Earthquake Excitation ◽  
High Gain Control

In order to prevent structural damages, it is more important to bound the vibration amplitude than to reduce the vibration energy. However, in the performance index for linear quadratic regulator (LQR), the instantaneous amplitude of vibration is not minimized. An ordinary LQR may have an unacceptable amplitude at some time instant but still have a good performance. In this paper, we have developed an LQR with adjustable gains to guarantee bounds on the vibration amplitude. For scalar systems, the weighting for control is switched between two values which give a low-gain control when the amplitude is inside the bound and a high-gain control when the amplitude is going to violate the given bound. For multivariable systems, by assuming a matching condition, a similar controller structure has been obtained. This controller is favored for application since the main structure of a common LQR is not changed; the additional high-gain control is required only if the vibration amplitude fails to stay inside the bound. We have applied this controller to a five-story building with active tendon controllers. The results show that the largest oscillation at the first story stays within a given bound when the building is subject to earthquake excitation.

Active Control for Power-Train Vibration of Automotive Using Active Mounts

2013 ◽  
Vol 330 ◽  
pp. 598-601
Author(s):  
Guo Chun Sun ◽  
Li Meng He
Keyword(s):  
Optimal Control ◽  
Vibration Isolation ◽  
Linear Quadratic Regulator ◽  
Active System ◽  
Linear Quadratic ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Engine Vibration ◽  
Active Vibration ◽  
Piezoelectric Stack Actuator

In this work, a new active mount featuring piezostack actuators and a rubber element is proposed and applied to a vibration control system. After describing the configuration and operating principle of the proposed mount, an appropriate rubber element and appropriate piezostacks are designed. Through the analysis of the property of the rubber and piezoelectric stack actuator, a mechanical model of the active vibration isolation system with the active mounts is established. An optimal control algorithm is presented for engine vibration isolation system. the controller is designed according to linear quadratic regulator (LQR) theory. Simulation shows the active system has a better consequence in reducing the vibration of the chassis significantly with respect to the ACM and the optimal control than that in the passive system.

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