Design and implementation of a PC-based laser tachometer and motor speed controller

Date

4-2002

Degree

Bachelor of Science in Applied Physics

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Demetrio A Yco, Jr.

Abstract

A PC-based laser tachometer was designed and constructed using a diode laser pointer as the medium for measurement. The device (1) measures RPM (Revolutions Per Minute), (2) Controls and stabilizes a servo motor RPM for spin-coating purposes, (3) Measures some peripheral variables involving rotating rigid bodies (linear and angular velocity and centrifugal force) using the obtained RPM. The system determines the various measurements by the use of a diode laser pointer beamed directly on a special light sensor. Both the laser diode and the light sensor are mounted on a probe. A disc with a single slit near its center to its edge is mounted on the shaft of the motor in order to be synchronized with the rotation. As the disc rotates, a laser beam light pulse is generated due to the slit on the disc. The laser beam pulse is received by the light sensor and interprets the light and the dark instances as "high" and "low". The "high" state is considered as one complete revolution. A 16-bit frequency counter directly calculates the RPS and sends it to the computer. The system is interfaced to a computer using a I 6-bit Input/Output card on the ISA bus slot. The data is transferred to the computer in real-time using a 32-bit software program developed under Microsoft Visual Basic 6.0. The software program computes for the actual RPM. The peripheral variables are determined by equations relating RPM to each variable. Data sent to the computer are analyzed, displayed, graphed and stored by the software. A minimum of 0 and a maximum of 9 percentage difference were obtained in the calibration process for the determination of the RPM of various devices and machines and control of a servo motor.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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