Papers by Keyword: Optimal Control

Abstract: The purpose of this research is to point out a controlled vibration quarter car model of a human body in seated position. Its importance is mostly due to the vertical accelerations impact of the human body and be able to control these vibrations. This paper marks these vertical accelerations based on a concentrated mass mathematical damped model. This is first established mathematically and then simulated in Matlab software, its results clarifying the differences between accelerations at different parts of the model and their range. Then the study focuses on the controller built in Simulink. The first part of the study de-scribes the quarter car model with concentrated masses depicting also mass, stiffness, damping and forces repartition.

Abstract: This paper’s purpose is analyzing a problem of optimal control of vitrifying polymers cooling process. A solution methodology is suggested targeting at decreasing technological residual stresses, which predetermine major operating characteristics of polymer structures. The criteria function to be minimized is maximum intensity of technological residual stresses under minimum cooling process time. To determine technological residual stresses, a problem of thermoviscoelasticity is solved in finite-elemental formulation. The chosen mathematical model of mechanical behavior of viscoelastic bodies under thermorelaxation transition allows to formulate and to solve the problem of cooling process optimal control. Obtained results show that application of optimal control methods to vitrifying polymers cooling process lead to tenfold decrease of technological residual stresses when compared to an uncontrolled process.

Abstract: In this paper, a linear quadratic Gaussian controller is proposed to achieve the robust temperature stability of the fuser system against measurement noise and system disturbance. The proposed controller is fitted to replace the PI controller and relative mathematical derivation is described. The system is implemented using MATLAB and SIMULINK with adding the noise and disturbance. Improvement of performance is verified by comparison with conventional PI controller results on several key factors of the fuser system.

Abstract: In this study we investigated the dynamical behavior of aircraft wings and using piezoelectric actuation we implemented active vibration control. The aircraft wing is modeled as a thin-walled composite beam having a cross section of diamond shaped. The dynamic response of the beam under varying proportional and velocity feedback gain parameters is obtained and shown to be enhanced with optimal control procedure, minimizing the control effort and response.

Abstract: Switched mode DC-DC converters are electronic circuits which convert a voltage from one level to a higher or lower level voltage. This paper presents a new solution approach to controller and observer controller of DC-DC Buck converter. The designs in this paper of DC-DC Buck converter is input voltage 20V step down to 12V output voltage. For control the system simulation investigation into development of controller and observer controller using MATLAB Simulink® software. The simulation develops of the controller and observer controller with mathematical model of DC-DC Buck converter. This paper also providing LQR controller to compare the performance of the system. Finally, the performance output voltage of DC-DC Buck converter is analyzed in terms of time response, overshoot and steady state error.

Abstract: One of the most widespread methods of heating is induction mass heating because it offers certain advantages over similar technologies, including convectional and electrical heating. A significant economical effect can be achieved through optimization of heating modes and design parameters of induction heaters on the basis of modern optimal control theory for distributed parameters systems. The paper is devoted to the numerical simulation and optimal with respect to typical quality criteria control of thermal modes for metals induction heating before hot forming operations. Two-dimensional non-linear time-optimal control problem, problem of maximum heating accuracy and problem of minimum energy consumption are formulated and reduced to the mathematical programming problems. Optimization procedures are based on the developed at SamSTU alternance method of optimal control theory for distributed parameters systems. 2D FLUX code provides FEM analysis of interrelated electromagnetic and temperature fields during induction heating of a cylindrical billet before its hot forming. The model integrated into optimization procedures provides options for variation of the heating system parameters or billet geometry, and for evaluating the process optimization abilities. Computational results for optimal heating of aluminum cylindrical billets are shown and analyzed.

Abstract: This paper presents a method for the estimation of unknown disturbances for high precision gimbal systems. Alternative to the classical methods of model inversion and filtering, we employ an asymptotically stabilizing controller which achieves the estimation process even in the presence of unstable zeros. The architecture provides an input equivalent disturbance which can be thought to capture all real disturbances in the system as well as virtual ones such as unmodelled dynamics and nonlinearities. The proposed method is illustrated on a 2-axis gimbal system where system identification is followed by the design on an integral linear quadratic regulator as the stabilizing controller which forms the base of the disturbance observer. It is seen that a random unknown disturbance is estimated successfully in the presence of additional gyro noise.

Abstract: In this paper, game and optimization theory is applied to the marine navigation in congested waters. The process of game ship control is mentioned first, and then the base model and the approximated models are described with the simulation results. For each approximated model of the dynamic game, an appropriate method of safe control to support the navigator decision in a collision situations has been assigned. The considerations have been illustrated an examples of a computer simulation of several algorithms to determine the safe ship's trajectory in situations of passing many of the ships encountered, recorded on the radar screen in real navigational situation at sea.

Abstract: In order to improve quality and productivity of polymeric composites production we suggest the technique of process simulation and optimization for large parts manufactured by compression molding. Optimal process design includes coupled heat transfer / thermo kinetic cure process formulation, its three-dimensional finite element model (FEM) implementation, its transient analysis at the parameterized thermal control law, and Pareto-based optimization, at which we determine control law parameters ensuring minimum standard deviations of the degree of cure within the cured body. We illustrate this approach via examples of two distinct cases of closed mould design concepts: one for moulds heated in autoclaves by the pressurized heated gas, which acts on the mould surface almost uniformly, and another for moulds with independently controlled built-in electrical heaters such as strip heaters or heated platens that are positioned along the length of the die at locations determined by structural features of the cured part. The suggested approach makes the process design more predictable, easier, faster, and more reliable. It can be adapted to specific manufacturing conditions and allows optimizing tools design and processing conditions before the mould and process control are made.

Abstract: For elastic frames authors offer a method of solving the tasks of optimal control of the stress state, when the boundary loads are the controlling parameters. In difference from other papers it is offered to use deformation energy as a merit functional. This functional estimates the deviation between two functions: optimal function and given function. Examples of the solution are given.