Zdenko Kovacic

Fuzzy Controller Design : Theory and Applications

The book presents clear, practical, easy-to-use methods for designing and implementing fuzzy control systems. It addresses the heuristic nature of fuzzy controller design and methods to overcome the resulting problems. It examines the design of hybrid, adaptive, and self-learning fuzzy control structures. It explains original concepts and methods such as phase-plane-based initial presetting, sensitivity model-based self-organization, and PLC-based implementation. It provides easy-to-follow worked examples in MATLAB. The final chapter explores industrial applications with emphasis on techniques for fuzzy controller implementation and different implementation platforms for various applications.

Sensitivity-based self-learning fuzzy logic control for a servo system

Describes an experimental verification of a self-learning fuzzy logic controller (SLFLC). The SLFLC contains a learning algorithm that utilizes a second-order reference model and a sensitivity model related to the fuzzy controller parameters. The effectiveness of the proposed controller has been tested by experiment in the position control loop of a chopper fed DC servo system in the presence of a gravity-dependent shaft load and fairly high static friction. The experimental results prove that the SLFLC provides closed-loop behavior as desired and eliminates a steady-state position error.

An implementation of the matrix-based supervisory controller of flexible manufacturing systems

Deals with an implementation of a new matrix-based supervisory controller of flexible manufacturing system (FMS). A design method is applied to the laboratory setup of a finite-buffer multiple reentrant flowline FMS which contains one 5-degree of freedom (DOF) robot, few transporters, pistons, and other elements (sensors, programmable logic controller, and personal computers). Control of the FMS is based on a matrix model approach which significantly reduces a computational effort and simplifies conversion of dispatching rules to the software program. The results obtained during experiments have confirmed effectiveness of the matrix-based FMS controller.

Trajectory planning algorithm based on the continuity of jerk

This paper presents a trajectory planning method that provides a continuity of position, velocity, acceleration and jerk. The method combines fifth-order and fourth-order polynomials in order to satisfy the continuity of jerk and give smooth accelerations on all segments of the planned trajectory. The proposed method was tested for movements of the three-axes planar articulated robot. The method includes limits of the velocities, accelerations, and jerks of each robot joint. Simulation results are presented and compared with the results obtained by the original Ho and Cook spline-interpolation method.

Design and stability of self-organizing fuzzy control of high-order systems

The paper describes a model reference-based self-organizing fuzzy control scheme which is suitable for high-order systems of well-known structure. The conditions for stability of the learning process, which may be used for determination of the learning coefficient values, have been worked out. The way of improving the system response in the initial stage of learning by using the referent model-based method of presetting a fuzzy control surface is described. The proposed fuzzy control method has been tested in the angular speed control loop of a DCM servo drive. The results obtained have shown the feasibility and marked effectiveness of the self-organizing fuzzy control scheme indicating a better performance of the system with the preset fuzzy controller than with a blank fuzzy rule-table in the initial stage of learning.

Fuzzy rule-based model reference adaptive control of permanent magnet synchronous motor drive

The paper presents a model reference adaptive control scheme using fuzzy logic adaptation mechanism to generate additional signal to the system input. The proposed method has been applied to the linearized model of the angular speed control system of a vector controlled chopper-fed permanent magnet synchronous motor (PMSM) drive. Simulation results indicate that a good adaptation is achieved even for large parameter variations. Marked simplicity and digital character of the method make it very suitable for microcomputer implementation.<<ETX>>

The Application of Spline Functions and Bezier Curves to AGV Path Planning

The paper describes a path planning method for an automated guided vehicle (AGV). The method consists of two steps, the calculation of a path by using Bezier curves and the calculation of a path trajectory by using a Ho and Cook spline-interpolation algorithm. The generation of parallel path curves for left-hand and right-hand AGV wheels is elaborated. The solution for the generation of sharp curves is derived. The proposed path planning method has been tested on tricycle-type AGVs with a front stabilization wheel and two rear powered wheels.

A matrix approach to an FMS control design [flexible manufacturing systems]

This article presents advantages of using new technologies and design methods for control of flexible manufacturing systems (FMS). For this purpose, a matrix-based description of FMS operations is adopted, as it generates the form of the FMS supervisory controller that is directly convertible into the programmable logic controller (PLC) program. An accent is given to the program tool FlexMan which enables elegant setting of complex FMS configurations by using virtual reality models and a matching matrix-based dynamic simulator. We demonstrate how this tool has been used for design, dynamic simulation, and visualization of a two-robot, material handling cell. It is shown how phenomena like operation conflicts and deadlocks can be observed and analyzed within a virtual reality environment before switching to the real world application. A comparison of results indicates large match-ups of phenomena in both environments.

Fuzzy rule-based adaptive force control of a single DOF mechanisms

A position/force control with completely fuzzified adaptive force control system for the single degree of freedom mechanisms is presented. The proposed force control scheme contains are adaptive fuzzy force controller and a subordinated fuzzy velocity controller. By using a second-order referent model, a model reference-based fuzzy adaptation mechanism is able to keep the error between the model and system output responses within the desired limits. The results obtained by computer simulations indicate a stable performance of the force control system for a wide range of environment stiffness variations. The proposed adaptive force control method is efficient in the case of contact with the rough surface or the complex form workpiece.<<ETX>>

Sensitivity-based self-learning fuzzy logic controller as a PLC super block

In this article, implementation of a self-learning fuzzy logic controller (SLFLC) in a form of PLC super block is described. The SLFLC contains a learning algorithm that utilizes a second-order reference model and a sensitivity model related to the fuzzy controller parameters. The effectiveness of the PLC super block has been tested by experiment in the position control loop of an electronically commutated servo system in the presence of a gravity-dependent shaft load. The experimental results have proved that the SLFLC implemented in PLC provides desired closed-loop behavior.