Krzysztof Jaroszewski

Design of a multivariable neural controller for control of a nonlinear MIMO plant

Abstract The paper presents the training problem of a set of neural nets to obtain a (gain-scheduling, adaptive) multivariable neural controller for control of a nonlinear MIMO dynamic process represented by a mathematical model of Low-Frequency (LF) motions of a drillship over the drilling point at the sea bottom. The designed neural controller contains a set of neural nets that determine values of its parameters chosen on the basis of two measured auxiliary signals. These are the ship’s current forward speed measured with respect to water and the systematically calculated difference between the course angle and the sea current (yaw angle). Four different methods for synthesis of multivariable modal controllers are used to obtain source data for training the neural controller with parameters reproduced by neural networks. Neural networks are designed on the basis of 3650 modal controllers obtained with the use of the pole placement technique after having linearized the model of LF motions made by the vessel at its nominal operating points in steady states that are dependent on the specified yaw angle and the sea current velocity. The final part of the paper includes simulation results of system operation with a neural controller along with conclusions and final remarks.

Classical Versus Fractional Order PI Current Controller in Servo Drive

In the paper a fractional order PI current controller of the servo drive is compared with its classical counterpart. The main focus is put on structures of such a fractional order controller without as well as with different antiwindup blocks. Results of simulations carried out in Matlab/Simulink are presented and discussed.

Neural networks for a dynamic decoupling of a nonlinear MIMO dynamic plant

In the paper a method of synthesis of a neural controller which goal is to reduce effects of coupling of the nonlinear multi-input multi-output (MIMO) plant inputs and outputs is presented. The designed neural controller contains a set of neural nets that determine values of parameters of linear decoupling controllers calculated for the adopted nonlinear plant model at its operating points. A known dynamic decoupling technique is used to generate training and evaluation data for the synthetized neural nets. The resulting neural (gain-scheduling) controller varies its parameters depending on the current plant operating point.

A Comparative And Experimental Study On Gradient And Genetic Optimization Algorithms For Parameter Identification Of Linear MIMO Models Of A Drilling Vessel

Abstract The paper presents algorithms for parameter identification of linear vessel models being in force for the current operating point of a ship. Advantages and disadvantages of gradient and genetic algorithms in identifying the model parameters are discussed. The study is supported by presentation of identification results for a nonlinear model of a drilling vessel.

Study of the efficiency of an algorithm that improves the accuracy of slow-motion control of a servo drive

The paper describes methods of improving motion quality of servo drive in case of set a very small motion changes. Servo drive as well as control problems connected with static friction are described. Solutions of such problems are offered. First one is integration zeroing, second one based on a unique idea introduced by authors and finally feeding into the system an insensibility. All that methods were verified on the base of simulation as well as practical validation, what was described.

Improving the quality of the classic servo drive by modifying the motion control algorithm

Frequently CNC machines use rotary servo drives and a kinematic chain in the form of pulling screw with a nut. The disadvantage of that structure is: non-linear and falling friction, the susceptibility of the pulling screw to the torsion deformation and the backlash. In [3-5] outlines ways to modify the servo drive structure to minimize frictional effects and pulling screw elasticity in order to achieve better motion quality. The present paper presents modified structure of the digital servo drive control system to eliminate the oscillations of the servo drive position with backlash.

The workspace of industrial manipulator in case of fault of the drive

In the paper very preliminary idea of fault tolerant industrial robot is presented. It is noticed that, the most natural way of fault tolerance - redundancy, is not appropriate in case of the robotics area. Using on the production line redundant robots (treated overall as the actuators) is unprofitable from economic point of view. Moreover, redundancy of the actuators (seeing as the parts of the robot) is mostly impossible from construction point of view. Hence, the solution of fault tolerance is offered in the way of adequate control system. In the first chapter problem statement is done and the general idea of solving it is presented. Following, idea of control system is briefly mentioned. In the next unit simple graphs presents the robot’s workspace in selected case of the fault. The wider idea of fault tolerance control in case of industrial manipulator is given in the summary.

Fractional order controller in a servo drive — Case of cogging moment

Results of using fractional order PI current controller, and classical one, in case of cogging effect in servo drive are presented in the paper. The general cascade control system of the servo drive and motor model with dry friction are presented. The most significant result in case of using fractional order current controller (FOCC) observed for starting servo drive in the presence of cogging moment are presented and commented.

Fracional order current controller in servo drive control system

In the paper results of using fractional order PI current controller in comparison with using classical one in case of servo drive cascade control system are presented. The issue of modelling static friction, that is the most important factor having a huge influence on the motion and current characteristic especially in case of slow motion and small movements, were also described. The most significant result in case of using fractional order current controller observed for starting servo drive are presented and commented.

Comparison of improving servo drive position accuracy methods.

The main aim of this paper is to present a new start-aid method to control servo drive in case of very small velocity and distance changes are required. Using resetting of integration in the position controller and friction compensation as well as the initial phase correction - start-aid methods are compared and results of simulations are presented. Moreover, models of the drive and friction are delivered and schemas of control systems are presented.