Design and Construction of PIC-Based DC Motor Speed Controller for Small Robots

Abstract

Because of their good speed control and high torque, DC motors are widely used in many industrial and robotic applications. Robotic application of DC motors often required, in addition to driving loads at constant speed or torque, the ability to vary the speed of the motor. An efficient and economically feasible intelligent DC motor speed controller is designed and constructed based on the rules of closed loop feedback control system. There are two main parts in the hardware development: PIC16F873A microcontroller and its support circuitries and external interface circuitries between motors and microcontrollers. Data processing and control program (firmware program) was run on PIC microcontroller and its on-chip A/D converter, PWM module and external circuitry was used to send and receive the data signal from the motor for control application. The firmware program was written in assembly language and converted to machine language (Hex code) by using Microchip MPASM macro assembler. These machine codes are downloaded into the PIC microcontroller by using EPIC microcontroller programmer. Through prototyping and implementing on a PIC microcontroller, the system was then be tested and used to control the speed of a small DC motor until the required criteria were achieved.