Servomotors have been around for a long time and are used in many applications. They are small in size but have a great impact and are very energy efficient. These features allow them to be used to operate toy vehicles, robots and remote controlled or radio controlled aircraft. Servomotors are also used in industrial applications, robotics, online manufacturing, pharmaceuticals and food services. The servo circuits are built into the motor unit and have a shaft that can be placed, which is normally equipped with a gear. The motor is controlled with an electrical signal that determines the amount of movement of the shaft.
A servomotor is operated by applying the voltage signal at regular intervals. The servo is sensitive to time variations. A pulse of specific width should be applied at specific time intervals. Typically the pulse duration varies from 0 ms to 2.2 ms and the repetition rate is from 50 Hz to 60 Hz. For precise position control, the chosen controller must have timers having the required resolution. In addition, if more than one motor has to be controlled simultaneously, the processor clock must be fast enough. For a single motor control, an 8051 can be used as an AT89s51 or a P89v51RD2. But for more than one engine, we must use a PIC, such as a PIC18F or an ATMEGA, so that its internal PWM can be used. However, the microcontroller selection depends entirely on the designer and the project requirements.