A servo motor is a rotary actuator or linear actuator that allows for precise control of angular or linear position, velocity and acceleration. These motors are classified into different types based on their application like Brushless DC , AC , continuous rotation, linear and positional rotation, etc. Typical servo motors contain of three wires such as, power control and ground. The outline and dimension of these motors depend on their applications.
The motor which is used as a DC servo motor generally have a separate DC source in the field of winding & armature winding. The control can be archived either by controlling the armature current or field current. Field control includes some particular advantages over armature control. In the same way armature control includes some advantages over field control. Based on the applications the control should be applied to the DC servo motor. DC servo motor provides very accurate and also fast respond to start or stop command signals due to the low armature inductive reactance. DC servo motors are used in similar equipments and computerized numerically controlled machines.
AC servo motor is an AC motor that includes encoder is used with controllers for giving closed loop control and feedback. This motor can be placed to high accuracy and also controlled precisely as compulsory for the applications. Frequently these motors have higher designs of tolerance or better bearings and some simple designs also use higher voltages in order to accomplish greater torque. Applications of an AC motor mainly involve in automation, robotics, CNC machinery, and other applications a high level of precision and needful versatility.
Positional rotation servo motor is a most common type of servo motor. The shaft’s output rotates in about 180 degree. It includes physical stops located in the gear mechanism to stop turning outside these limits to guard the rotation sensor. These common servos involve in radio controlled water, radio controlled cars, aircraft, robots, toys and many other applications.
Continuous rotation servo motor is quite related to the common positional rotation servo motor, but it can go in any direction indefinitely. The control signal, rather than set the static position of the servo, is understood as the speed and direction of rotation. The range of potential commands sources the servo to rotate clockwise or anticlockwise as preferred, at changing speed, depending on the command signal. This type of motor is used in a radar dish if you are riding one on a robot or you can use one as a drive motor on a mobile robot.
This type offers more gears than the positional rotation servo, but is otherwise very similar. It uses a rack and pinion mechanism to change the output back and forth instead of circularly. This servo is rare, but can be found in larger hobby planes and robots.
