Dynamic Coefficients of a Tilting Pad With Active Lubrication: Comparison Between Theoretical and Experimental Results

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Alejandro Cerda Varela ◽  
Ilmar Ferreira Santos
Keyword(s):  
Mathematical Model ◽  
Closed Loop ◽  
Open Loop ◽  
Control Signal ◽  
Experimental Results ◽  
Industrial Grade ◽  
Tilting Pad ◽  
Oil Flow ◽  
Bearing Design ◽  
The Mathematical Model

This paper deals with the validation of the mathematical model for predicting the equivalent stiffness and damping of an active tilting-pad bearing. The active bearing design includes an injection nozzle in the pad and a hydraulic supply system featuring a servovalve, which enables to modify the pressurized oil flow into the bearing clearance. The servovalve is governed by a control signal, obtained in open- or closed-loop configuration. The mathematical model includes the dynamics related to journal, tilting pads, and associated hydraulic system. First, the model results are tested against experimental results from the literature for industrial grade passive tilting pad bearings. This initial validation is followed by a comparison with experimental identification results obtained from a test rig featuring the active bearing design. Good overall agreement is observed in both configurations. The results provide an overview about the feasibility of modifying the bearing impedance by means of the active lubrication system, both in open-loop (fixed control signal), or closed-loop, as a function of the journal position and proportional derivative (PD) controller gains.

Design and Modelling of a Novel Servovalve Actuated by a Piezoelectric Ring Bender

2015 ◽  
Author(s):  
L. Johan Persson ◽  
Andrew R. Plummer ◽  
Christopher R. Bowen ◽  
Ian Brooks
Keyword(s):  
Mathematical Model ◽  
Closed Loop ◽  
Position Control ◽  
Open Loop ◽  
Closed Loop Control ◽  
Hydraulic Fluid ◽  
Loop Control ◽  
Frequency Responses ◽  
Spool Valve ◽  
The Mathematical Model

This paper describes the design, simulation and testing of a piezoelectric spool valve. An actuator has been connected to the valve and tested under closed loop control. A mathematical model of the valve was produced and a prototype of the valve was tested. The mathematical model is validated against the experimental data. Step and frequency responses for both the valve and actuator are presented. It was found that displacement of the hydraulic fluid by the ring bender had an impact on the valve performance. To reduce the effect of the piezoelectric hysteresis, closed loop spool position control was evaluated. A noticeable difference can be observed between open loop and closed loop performance.

The Control of Vibration Transmissibility Using an Electrodynamic Actuator –Close-Loop Solution

2013 ◽  
Vol 436 ◽  
pp. 166-173
Author(s):  
A. Mihaela Mîţiu ◽  
Daniel Constantin Comeagă ◽  
Octavian G. Donţu
Keyword(s):  
Mathematical Model ◽  
Control System ◽  
Mechanical System ◽  
Closed Loop ◽  
Mechanical Systems ◽  
Vibration Transmissibility ◽  
Technical Solutions ◽  
The Mathematical Model

In this paper are presented some aspects of transmissibility control of mechanical systems with 1 DOF so that the effects of vibration on their action to be minimized. Some technical solutions that can be used for this purpose is analyzed. Starting from the mathematical model of an electro-mechanical system with 1 DOF, are identified the parameters which influence the effectiveness of the transmissibility control system using an electrodynamic actuator who work in "closed loop".

scholarly journals Motion Simulation for Triangular-Shaped Autonomous Underwater Vehicle (TAUV) with Controllable Rudder

2021 ◽  
Vol 2107 (1) ◽  
pp. 012046
Author(s):  
I Y Amran ◽  
K Isa
Keyword(s):  
Mathematical Model ◽  
Autonomous Underwater Vehicle ◽  
Research Work ◽  
Underwater Vehicle ◽  
Open Loop ◽  
Vehicle Speed ◽  
Motion Simulation ◽  
Loop Control ◽  
Angular Velocities ◽  
The Mathematical Model

Abstract The dynamic model and motion simulation for a Triangular-Shaped Autonomous Underwater Vehicle (TAUV) with independently controlled rudders are described in this paper. The TAUV is designed for biofouling cleaning in aquaculture cage fishnet. It is buoyant underwater and moves by controlling two thrusters. Hence, in this research work, the authors designed a TAUV that is propelled by two thrusters and maneuvered by using an independently controllable rudder. This paper discussed the development of a mathematical model for the TAUV and its dynamic characteristics. The mathematical model was simulated by using Matlab and Simulink to analyze the TAUV’s motion based on open-loop control of different rudder angles. The position, linear and angular velocities, angle of attack, and underwater vehicle speed are all demonstrated in the findings.

scholarly journals On Numerical Simulation Approach for Multiple Resonance Modes in Servo Systems

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Qixin Zhu ◽  
Hongli Liu ◽  
Yiyi Yin ◽  
Lei Xiong ◽  
Yonghong Zhu
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Closed Loop ◽  
Resonance Mode ◽  
Servo Control ◽  
Simulation Approach ◽  
Servo Systems ◽  
Resonance Modes ◽  
Resonant Part ◽  
The Mathematical Model

Mechanical resonance is one of the most pervasive problems in servo control. Closed-loop simulations are requisite when the servo control system with high accuracy is designed. The mathematical model of resonance mode must be considered when the closed-loop simulations of servo systems are done. There will be a big difference between the simulation results and the real actualities of servo systems when the resonance mode is not considered in simulations. Firstly, the mathematical model of resonance mode is introduced in this paper. This model can be perceived as a product of a differentiation element and an oscillating element. Secondly, the second-order differentiation element is proposed to simulate the resonant part and the oscillating element is proposed to simulate the antiresonant part. Thirdly, the simulation approach for two resonance modes in servo systems is proposed. Similarly, this approach can be extended to the simulation of three or even more resonances in servo systems. Finally, two numerical simulation examples are given.

scholarly journals DYNAMIC SIMULATION AND COMPOSITION CONTROL IN A 10 L MIXING TANK

REAKTOR ◽  
2012 ◽  
Vol 14 (2) ◽  
pp. 95
Author(s):  
Yulius Deddy Hermawan ◽  
Gogot Haryono
Keyword(s):  
Mathematical Model ◽  
Dynamic Simulation ◽  
Closed Loop ◽  
Step Function ◽  
Open Loop ◽  
Liquid Volume ◽  
Control Parameters ◽  
Software Environment ◽  
Composition Control ◽  
Volumetric Rate

The open loop experiment of composition dynamic in a 10 L mixing tank has been successfully done inlaboratory. A 10 L tank was designed for mixing of water (as a stream-1) and salt solution (as astream-2 with salt concentration, c2 constant). An electric stirrer was employed to obtain uniformcomposition in tank. In order to keep the liquid volume constant, the system was designed overflow. Inthis work, 2 composition control configurations have been proposed; they are Alternative-1 andAlternative-2. For Alternative-1, the volumetric-rate of stream-1 was chosen as a manipulatedvariable, while the volumetric-rate of stream-2 was chosen as a manipulated variable for Alternative-2. The composition control parameters for both alternatives have been tuned experimentally. Thevolumetric-rate of manipulated variable was changed based on step function. The outlet stream’scomposition response (c3) to a change in the input volumetric-rate has been investigated. Thisexperiment gave Proportional Integral Derivative (PID) control parameters. The gain controllers Kc[cm6/(gr.sec)] for Alternative-1 and Alternative-2 are -34200 and 40459 respectively. Integral timeconstant ( tI) and Derivative time constant (tD) for both alternatives are the same, i.e. tI = 16 second,and tD = 4 second. Furthermore, closed loop dynamic simulation using computer programming wasalso done to evaluate the resulted tuning parameters. The developed mathematical model ofcomposition control system in a mixing tank was solved numerically. Such mathematical model wasrigorously examined in Scilab software environment. The results showed that closed loop responses inPID control were faster than those in P and PI controls.

Mathematical Modeling of Electrochemical Deburring

2010 ◽  
Vol 126-128 ◽  
pp. 545-550 ◽  
Author(s):  
Wen Ji Xu ◽  
W. Wang ◽  
Xu Yue Wang ◽  
Gui Bing Pang
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Influencing Factors ◽  
Applied Voltage ◽  
Experimental Results ◽  
Electrode Gap ◽  
Workpiece Material ◽  
Burr Height ◽  
Object A ◽  
The Mathematical Model

The drilling burr is taken as the research object. A mathematical model of electrochemical deburring (ECD) is established and the effects of main influencing factors, such as inter-electrode gap, applied voltage and deburring time, on burr height have been analyzed. The results show that the deburring time increases with the increase of initial burr height, inter-electrode gap, with the decrease of volume of electrochemical equivalent of the workpiece material, conductivity of electrolyte and applied voltage. The deburring time for various burr heights can be predicted by the mathematical model. The calculated results obtained from the mathematical model are approximately consistent with the experimental results. The results show that initial burr height h0=0.722mm is removed, and the fillet radius R=0.211mm is obtained.

Stability boundary analysis of highly flexible aircraft with control saturation and structural flexibility

2020 ◽  
Vol 234 (6) ◽  
pp. 1195-1208
Author(s):  
Liang Xu ◽  
Yuping Lu ◽  
Boyi Chen ◽  
Haidong Shen ◽  
Zhen He
Keyword(s):  
Closed Loop ◽  
Stability Boundary ◽  
Open Loop ◽  
Loop System ◽  
Control Signal ◽  
Stable Region ◽  
Structural Flexibility ◽  
Flexible Aircraft ◽  
Control Saturation ◽  
Loop Stability

In this work, a method has been presented to analyze the influence of control saturation and structural flexibility on the stable radius of highly flexible aircraft. A dynamic model of aircraft is constructed followed by the analysis of kinetic characteristics. In this paper, the closed-loop stability boundary of highly flexible aircraft with open-loop instability is studied. The amplitude limit and bandwidth limit of the control signal are considered in the closed-loop stability boundary calculation. Our analysis shows that the boundary is related to the left eigenvector corresponding to the unstable poles and the amplitude constraint of the control signals. Stability of the boundary of feedback control system further reduces the limitation of the bandwidth of actuators. Focused on the phugoid instability of highly flexible aircraft, computational formulation of the closed-loop stable boundary is achieved. The Monte Carlo analysis has been employed to validate the stable region, under the LQR controller. Both the theory and simulations have nice correlations with each other which verify the stability of the closed-loop system, restricted by the open-loop system, and the influence of control signal bandwidth constraints.

scholarly journals Commissioning tests of the first hydro-generator of the Bajo de Mina HPP (Panama)

2020 ◽  
Vol 175 ◽  
pp. 05044
Author(s):  
Andrey Zuikov
Keyword(s):  
Mathematical Model ◽  
Free Surface ◽  
Empirical Data ◽  
Thrust Bearing ◽  
Third Party ◽  
Engineering Practice ◽  
Vertical Distributions ◽  
Oil Flow ◽  
The Mathematical Model

A mathematical model has been developed for calculating the distribution of azimuthal velocities and the shape of the free surface of oil in the compartments of an oil bath of a hydro-generator. The mathematical model of oil flow is verified by comparing the calculated radial-vertical distributions of normalized azimuthal velocities obtained on its basis with the free surface of the oil with the empirical data of third-party authors. The verification showed a good fit between the calculated and experimental distributions, which allows recommending the developed mathematical model for use in engineering practice. Calculations were carried out for the modes of the oil movement in the thrust bearing and the guide bearing of the hydro-generator of the Bajo de Mina HPP. Recommendations are made for the elimination of emergency modes associated with oil overflow through the fencing of the thrust bearing oil bath, which separate oil bath from the shaft of hydro-generator.

The Application of Double Closed-Loop Unit Gain Negative Feedback and BP Neural Network Controller in Single Inverted Pendulum

2012 ◽  
Vol 490-495 ◽  
pp. 1723-1727
Author(s):  
Jun Ting Wang ◽  
Guo Ping Liu ◽  
Wei Jin ◽  
Gen Fu Xiao
Keyword(s):  
Neural Network ◽  
Mathematical Model ◽  
Negative Feedback ◽  
Bp Neural Network ◽  
Closed Loop ◽  
Inverted Pendulum ◽  
Root Locus ◽  
Neural Network Controller ◽  
Network Controller ◽  
The Mathematical Model

In the paper the mathematical model of the single inverted pendulum is established, on the base of the root locus and the control tasks the control system is made up of double closed-loop unit gain negative feedback and BP neural network controller. The results show that the inverted pendulum is efficiently controlled.

Performance Simulation and Analysis of the Progressive Distributor of the Oil-Air Lubrication by AMEsim

2013 ◽  
Vol 395-396 ◽  
pp. 1227-1232
Author(s):  
Qi Guo Sun ◽  
A Li Cai ◽  
Hong Bo Lv ◽  
Zheng Hui Zhou
Keyword(s):  
Mathematical Model ◽  
Friction Coefficient ◽  
Viscous Friction ◽  
Simulation Method ◽  
Analytic Method ◽  
Performance Simulation ◽  
Air Lubrication ◽  
Oil Flow ◽  
The Stability ◽  
The Mathematical Model

The mathematical model and the simulation model of the progressive distributor are established using an analytic method and AMEsim, a kind of simulation platform, respectively in this paper. The influences of the progressive structure, the viscous friction coefficient, the flow and pressure of the system and the size of throttle orifice on the performance of the progressive distributor are analyzed by the numerical simulation method. The results show that the fluctuations of the flow and pressure of the system are produced due to the overlapping motion of the three pistons, the oil-flow of the progressive distributor can be stabilized by choosing a reasonable viscous friction coefficient, and motion stability of the pistons of the progressive distributor, and the stability of the flow and pressure for the system are influenced by the size of throttle orifice. These conclusions will provide bases for the design of the oil-air lubricating system and the improvement of the structure of the progressive distributor.

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