Design and construction of a microstepping control system using pulse width modulation

The use of motors such as actuators is very common in the area of robotics. There are AC and DC motors, and the so called step motors, these revolve in discrete way and no continuous as the others. A step motor is mainly characterized because its rotor moves angularly a certain amount of degrees when applies a pulse of voltage in their bobines (step of the motor), and therefore does not require a feedback to know its actual position and does not require a braking device. One of its limitations is the size of the step for which they are designed: 0.9 degrees is the smallest step that can be found commercially. The present work shows the design and construction of a microstepping control system to increase the resolution, i.e. to reduce the step of the motor. This system has a user interface implemented in Visual Basic that receives instructions, these are sent to a PIC16F877A microcontroller, which determines the amount of current to be supplied to the bobines of the motor using a Pulse Width Modulation technique (PWM). The result is a system capable of controlling the sense of rotation, positioning and the angular velocity of three motors simultaneously, and with independent values for each motor, with a microstep of 0.225 degrees.