Servo Motor Literature Review

This project is about servo motor controller. It is a circuit that is used to control the position of a servo motor. A servomotor is a rotary actuator or linear actuator that allows for exact control of sharp or linear position, velocity and acceleration. It consists of a suitable motor joined to a sensor for position feedback. It also requires a relatively complex controller, often a dedicated element designed especially for use with servomotors.

Servomotors are not a specific class of motor although the term servomotor is often used to refer to a motor suitable for use in a closed-loop control system.

Servos are controlled by sending an electrical pulse of variable width, or pulse width modulation (PWM), through the control wire. There is

DC motors are widely used in many applications that we use in our daily life. They can be found everywhere, from house appliances to our vehicles, desktops and laptops, and industrial applications such as production lines, remote control airplanes, automatic navigation systems and many other applications.

There are two types of positional rotation servo motor which are DC servo motor that is controlled by DC, and Alternating Current (AC) servo motor which is controlled by AC. The servo motor “internal” positional feedback consists of either encoder feedback or voltage feedback.

The built-in encoder inside the servo motor provides a pulse signal that is processed by the servo controller to get the position feedback. The voltage feedback consists of a built-in potentiometer which is coupled with the servo motor axis to get the relative angular position depending on the value of the potentiometer. In particular, the DC servo motor is mostly utilized in the field of electronic, robotics and automation system, especially for special types of applications where the rotation of the motor only requires a certain angular movement such as for robot arm, robot gripper, and

Volta, 1800), the electro magnet (W. Sturgeon, 1825) and the discovery of a magnetic field from electric current (H. C. Oersted, 1820). The first working rotating electric motor was introduced in May 1834 by Moritz Jacobi. In 1838, Jacobi reintroduced an improved and more powerful motor. However, these electric motors were large and weak compared those we use today. Servo motors works within a closed-loop control system. These motors provide precise control of position (angular or linear), velocity, and acceleration. These devices are rarely seen but an average person uses them daily : The sliding doors at the supermarket; the power windows in a car; the elevator at the office, and the ice delivery system on a refrigerator. Servo motors are so sophisticated that they are used in robotic manufacturing, such as those used to assemble automobiles. [3]

2.2 Types of Servo Motor

These motors are classified into different types based on their application like Brushless DC, AC, continuous rotation, linear and positional rotation, etc. [4]

2.2.1 DC Servo Motor

Generally, this motor has a distinct DC source in the winding and the armature winding field.it can be controlled by adjust the field or armature current. Field control has some profits over armature control. Similarly, armature control comprises some benefits over field control

2.2.2 Synchronous DC Motor

Encoder which is used with controllers in