Feed-Forward Control of a Cracked Simply Supported Beam

2011 ◽  
Author(s):  
Sudhir Kaul
Keyword(s):  
Crack Propagation ◽  
Control Algorithm ◽  
Control Algorithms ◽  
Transverse Displacement ◽  
Control Force ◽  
Simply Supported Beam ◽  
Feed Forward ◽  
Simply Supported ◽  
Crack Location ◽  
Feed Forward Control

This paper demonstrates the use of two feed-forward control algorithms in order to mitigate crack propagation in a simply supported beam with a pre-existing crack. The main objective of the control algorithms is to minimize or reduce transverse deflection at the crack location so as to contain the damage resulting from the pre-existing crack and, thereby, reduce the rate of crack propagation. A point-load sinusoidal excitation, from a known disturbance, is used as the input load acting on the beam. Two control algorithms are used — the first control algorithm computes a control force to eliminate transverse displacement at the crack location resulting from the excitation force, and the second control algorithm minimizes the mean square transverse displacement over a section of the beam that contains the crack. Both the control algorithms are a-causal and assume that the excitation input is completely known a-priori. Simulation results for a simply supported beam are presented and discussed in detail. It is observed that the rate of crack propagation can be significantly reduced by implementing the proposed feed-forward control algorithms, increasing the useful life of the damaged beam. Also, it is found that the transverse displacement over a significant length of the beam can be substantially reduced when the beam response is dominated by a specific mode.

scholarly journals Active Actuating of a Simply Supported Beam with the Flexoelectric Effect

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1735
Author(s):  
Mu Fan ◽  
Hequn Min
Keyword(s):  
Coupling Effect ◽  
Rank Order ◽  
Transverse Displacement ◽  
Control Force ◽  
Engineering Structures ◽  
Simply Supported Beam ◽  
Mechanical Coupling ◽  
Simply Supported ◽  
Flexoelectric Effect ◽  
Probe Location

Piezoelectric materials with the electro-mechanical coupling effect have been widely utilized in sensors, dampers, actuators, and so on. Engineering structures with piezoelectric actuators and sensors have provided great improvement in terms of vibration and noise reduction. The flexoelectric effect—which describes the coupling effect between the polarization gradient and strain, and between the strain gradient and electric polarization in solids—has a fourth-rank order tensor electro-mechanical coupling coefficient, and in principle makes the flexoelectricity existing in all insulating materials and promises an even wider application potential in vibration and noise control. In the presented work, a flexoelectric actuator was designed to actuate a simply supported beam. The electric field gradient was generated by an atomic force microscopy probe. Flexoelectric control force and moment components could be induced within the flexoelectric control layer. As flexoelectricity is size-dependent, the key parameters that could affect the actuating effect were examined in case studies. Analytical results showed that the induced flexoelectric control moment was strongly concentrated at the probe location. The controllable transverse displacement of the simply supported beam was calculated with the modal expansion method. It was found that the controllable transverse displacement was dependent on the probe location as well.

scholarly journals Smooth Tracking Trajectory Generation of Large Antenna

2016 ◽  
Vol 53 (1) ◽  
pp. 24-33 ◽  
Author(s):  
S. Upnere ◽  
N. Jekabsons ◽  
U. Locans
Keyword(s):  
Pid Control ◽  
Control Algorithm ◽  
Case Analysis ◽  
Control Algorithms ◽  
Control Methods ◽  
Antenna Feed ◽  
Feed Forward Control ◽  
Order Polynomial ◽  
Smooth Tracking ◽  
Tracking Trajectory

Abstract The current paper presents an engineering approach for studies of the control algorithm designed for a mechanically robust large antenna. Feed-forward control methods with the 3rd-order polynomial tracking algorithm are supplemented to the original feed-back PID control system. Dynamical model of the existing servo system of 32m radio telescope has been developed to widen a case analysis of observation sessions and efficiency of the control algorithms due to limited access to an antenna. Algorithms along with the results from the system implemented on a real antenna as well as model results are presented.

scholarly journals Peridynamic Higher-Order Beam Formulation

2020 ◽  
Author(s):  
Zhenghao Yang ◽  
Erkan Oterkus ◽  
Selda Oterkus
Keyword(s):  
Finite Element Method ◽  
Cantilever Beam ◽  
Higher Order ◽  
Point Load ◽  
Transverse Displacement ◽  
Lagrange Equations ◽  
Concentrated Load ◽  
Simply Supported Beam ◽  
Simply Supported ◽  
Good Agreement

Abstract In this study, a novel higher-order peridynamic beam formulation is presented. The formulation is obtained by using Euler-Lagrange equations and Taylor’s expansion. To demonstrate the capability of the presented approach, several different beam configurations are considered including simply supported beam subjected to distributed loading, simply supported beam with concentrated load, clamped-clamped beam subjected to distributed loading, cantilever beam subjected to a point load at its free end and cantilever beam subjected to a moment at its free end. Transverse displacement results along the beam obtained from peridynamics and finite element method are compared with each other and very good agreement is obtained between the two approaches.

Active Wing Load Alleviation with an Adaptive Feed-forward Control Algorithm

2006 ◽  
Author(s):  
Andreas Wildschek ◽  
Rudolf Maier ◽  
Falk Hoffmann ◽  
Matthieu Jeanneau ◽  
Horst Baier
Keyword(s):  
Control Algorithm ◽  
Feed Forward ◽  
Feed Forward Control ◽  
Wing Load

scholarly journals Feed-forward control of a building’s heating system

2018 ◽  
Vol 226 ◽  
pp. 04014
Author(s):  
Valery V. Fomin
Keyword(s):  
Air Temperature ◽  
Temperature Rise ◽  
Control Algorithm ◽  
Weather Conditions ◽  
Heating System ◽  
System Control ◽  
Feed Forward ◽  
Feed Forward Control ◽  
Practical Task

In the heating of buildings during positive dynamics of weather conditions a problem is encountered of air temperature rise in the rooms of the building. Solution of the problem given the buildings are equipped with heating system controllers is a practical task using update algorithms in the operation of controllers. The proposed method offers an option of a heating system control algorithm to attain stable temperatures in the rooms of the building.

Trajectory Control of a Tethered Underwater Robot System

2018 ◽  
Author(s):  
Jiaming Wu ◽  
Dongjun Chen ◽  
Ying Xu ◽  
Yuqing Chen ◽  
Lihua Lu
Keyword(s):  
Pid Control ◽  
Control Algorithm ◽  
Trajectory Control ◽  
Underwater Robot ◽  
Robot System ◽  
Feed Forward ◽  
Feed Forward Control ◽  
Robot Trajectory ◽  
Umbilical Cable ◽  
And Control

A three-dimensional hydrodynamic and control model to simulate tethered underwater robot system is proposed. The fluid motion around the moving robot main body with running control ducted propellers is governed by Navier-Stokes equations, and multiple sliding mesh technique is applied to solve the governing equations. The governing equation of umbilical cable connected to the robot is based on the Ablow and Schechter method. The six-degrees-of-freedom equations of motion for underwater vehicle simulations proposed by Gertler and Hargen are adopted to estimate the hydrodynamic performance of the underwater robot. In the model, the feed-forward control algorithm is applied to adjust the length of the umbilical cable according to the robot trajectory control target, the incremental PID control algorithm is adopt to regulate the rotating speeds of the ducted propellers producing appropriate thrusts for the robot control. With the proposed hydrodynamic and control model, hydrodynamic behaviors of the robot under definite trajectory control manipulations are observed numerically. The numerical results of robot trajectory control simulations indicate that the feed-forward control algorithm for adjusting the length of the umbilical cable, and the incremental PID control algorithm for regulating the rotating speeds of the propellers are feasible and effective, the adjusting the length of the umbilical cable with feed-forward control technique is largely responsible for the vertical trajectory control to the robot, while regulating the rotating speeds of the propellers by the PID control algorithm play a leading role in the horizontal trajectory manipulation, the deviation between the designated trajectory and the control one at each time step is acceptable.

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