Paul Lin

Comparison on fuzzy logic and PID controls for a DC motor position controller

Fuzzy logic and proportional-integral-derivative (PID) controllers are compared for use in a 486 PC-based DC motor positioning system. A simulation study of the PID position controller for the desired DC motor is performed. The parameters of a standard PID controller for the DC motor position control system under the investigation is tuned and fixed throughout the control. The fuzzy logic controller (FLC) using seven membership functions is also designed and implemented on the same PC and software development system for the same position controller. Fuzzy rules and the inferencing mechanism of the FLC are evaluated in real-time instead of using conventional rule-lookup tables that encode the control knowledge in a numerical form. The performance assessment of the studied position controllers is based on accuracy, resolution and settling time to changes in the command signals. It is shown that the FLC performed better than the PID controller. The hardware and software of the PID and fuzzy logic position controllers are also presented.<<ETX>>

Design of a real-time rotor inertia estimation system for DC motors with a personal computer

Various traditional measurement techniques of moment of inertia were examined. Two computer-based measurement methods using the motors torque constant, back EMF (electromotive force) constant, mechanical time constant, and armature resistance with straightforward formulations were investigated. A PC-based inertia measuring unit was designed by using a multifunction interface card for signal processing and acquisition circuits. This low-cost inertia computation and measurement system can be used to assist in modeling and controlling DC drives in real-time. The system can also be integrated into an existing DC motor measurement or testing laboratory. Experimental results are presented.<<ETX>>

A Corrosion Sensor for Monitoring the Early-Stage Environmental Corrosion of A36 Carbon Steel

An innovative prototype sensor containing A36 carbon steel as a capacitor was explored to monitor early-stage corrosion. The sensor detected the changes of the surface- rather than the bulk- property and morphology of A36 during corrosion. Thus it was more sensitive than the conventional electrical resistance corrosion sensors. After being soaked in an aerated 0.2 M NaCl solution, the sensor’s normalized electrical resistance (R/R0) decreased continuously from 1.0 to 0.74 with the extent of corrosion. Meanwhile, the sensor’s normalized capacitance (C/C0) increased continuously from 1.0 to 1.46. X-ray diffraction result indicates that the iron rust on A36 had crystals of lepidocrocite and magnetite.

A PC-based measurement and control system for DC motors

The design of a personal computer-based measurement and control system for teaching and research in a DC drive laboratory is described. This system uses a personal computer in conjunction with an analog and digital I/O board, a signal sensing and conditioning subsystem for the acquisition and subsequent processing of current, voltage, and speed signals, and a power amplifier module for driving the DC motor under test. The system is shown to improve the reliability and productivity of DC motor measurement in the laboratory and provide such features as speed control, overload identification and protection, and graphics display of measured variables. The software subsystem is written in the C language and is able to perform the tasks associated with the real-time measurement and control of a DC motor. The design considerations and system-related constraints are presented. The hardware and software subsystems are discussed. Some possible practical applications are also discussed.<<ETX>>

Development of fuzzy-logic processing objects for industrial control applications

Object-oriented programming is introduced as a new approach for implementing software to solve fuzzy logic control problems. The object-oriented approach does a better job in supporting rapid prototyping. It allows users to gradually refine a subset of objects and operations. In the initial program testing phase, C++ fuzzy objects were used to generate a control decision table and control motor speed. The authors experienced no difficulty in modifying the C++ object functions into pure C functions for gaining portability and execution speed, which made this approach more attractive than a pure procedure-oriented approach. The object-oriented approach using C++ appears to be the appropriate technology for an FLC (fuzzy logic controller)-based DC motor speed control application. It enables a more flexible programming environment and reduces the efforts for fuzzy-object development and maintenance.<<ETX>>

Implementation of a two-link collision free robot controller

The objective of this paper is to implement a two-link with three-joint robot controller by an 8051 microcontroller system. In order to detect obstacles around the working space, two ultrasonic sensors are attached around the second link. The inverse kinematics of the robot are also derived by a geometry approach and integrated into the system program, so that users are allowed to enter the desired position in Cartesian space. Experimental results indicate that the robot works as expected. This device could be used as a tool for education or industrial applications. Features of this system include high reliability, simplicity, friendly user interface and low cost.<<ETX>>