A servo motor is an electrical device which can push or rotate an object with great precision. If you want to rotate an object at some specific angles or distance, then you use a servo motor. It is just made up of a simple motor which runs through a servo mechanism. If a motor is used is DC powered then it is called a DC servo motor, and if it is an AC powered motor then it is called an AC servo motor. We can get a very high torque servo motor in a small and lightweight package. Servo motors are rated in kg/cm (kilogram per centimeter) most hobby servo motors are rated at 3kg/cm or 6kg/cm or 12kg/cm. This kg/cm tells you how much weight your servo motor can lift at a particular distance.
The position of a servo motor is decided by an electrical pulse and its circuitry is placed beside the motor.
It consists of three parts:
- Controlled device
- Output sensor
- Feedback system
It is a closed loop system where it uses the positive feedback system to control motion and final position of the shaft. Here the device is controlled by a feedback signal generated by comparing output signal and reference input signal.
Here reference input signal is compared to a reference output signal and the third signal is produced by the feedback system. And this third signal acts as an input signal to control device. This signal is present as long as the feedback signal is generated or there is a difference between the reference input signal and reference output signal. So the main task of servomechanism is to maintain the output of a system at a desired value at the presence of noises.
A servo consists of a Motor (DC or AC), a potentiometer, gear assembly, and a controlling circuit. First of all, we use gear assembly to reduce RPM and to increase the torque of the motor. Say at the initial position of servo motor shaft, the position of the potentiometer knob is such that there is no electrical signal generated at the output port of the potentiometer. Now an electrical signal is given to another input terminal of the error detector amplifier. Now the difference between these two signals, one comes from the potentiometer and another comes from another source, will be processed in the feedback mechanism and output will be provided in term of the error signal. This error signal acts as the input for motor and motor starts rotating.
Now motor shaft is connected with a potentiometer and as the motor rotates so the potentiometer and it will generate a signal. So as the potentiometer’s angular position changes, its output feedback signal changes. After some time the position of potentiometer reaches at a position that the output of potentiometer is the same as the external signal provided. At this condition, there will be no output signal from the amplifier to the motor input as there is no difference between externally applied signal and the signal generated at potentiometer, and in this situation, the motor stops rotating.
- Toy Car
- Helicopters and planes