1. Servo Motors # A servo is a motor that you can position at any angle very accurately. # Servos have a limited servo range; most servos have a range of 180 degrees, some have a range of 90, 120, 150, or 210. # Servos are very powerful for their sizes. There exist servos that provide a torque of 4kg-cm from a 50 gram servo!!!!!!

2. Servo Motors Servos have a rather large torque for their size and run on a relatively low voltage (4.5 – 6 Volts). There are several types of servos in terms of driving like the AC servo motors used for industries. Now we explains the only DC servo motors.

3. Application For Servo Servo used in man things in our life like : 1) Robotics Because it’s angle is so accurate.

4. Application For Servo 2) Automation 3)CNC machine (Computer Numerical Control )

5. How Does a Servo Motor Work ? 3 wires >> 1)+ve voltage (4.5 – 6 Volts). 2)-ve or GND 3)signal

6. How Does a Servo Motor Work ? The signal wire expects input from a pulse width modulator. The period should be 20 milliseconds long and the duty cycle “encodes” the position of the motor. If the duty cycle is 1 millisecond, the servo is positioned at 0 degrees. If the duty cycle is 2 milliseconds, the servo is positioned at the maximum possible angle (180 degrees, 270 degrees, or whatever is the maximum limit).

7. Internals of a Servo # DC Motor # Controlled Circuit # Internal Gears

8. Internals of a Servo When the shaft of the motor is at the desired position, power supply to the motor is stopped. The desired position is sent in through the signal wire. As long as the signal wire has a position, the servo will ensure that the motor’s shaft remains at the correct position.

9. Internals of a Servo Now for the electronics part. The circuit contains a chip, M51660L (or another proprietary chip of the manufacturer). This chip compares the error in positioning the motor. The chip contains a timer that produces pulse signals from the potentiometer. These signals are similar to the ones you supply. These two pulse signals (the ones you are sending and the ones generated by the potentiometer) are fed into a pulse width comparator. This comparator produces the signals indicating which direction the motor should turn in. These are fed into an H-bridge (a big H Bridge – L293D) to drive the motor.

10. Servo Motor

11. References 1)http://www.anaheimautomation.com/manuals/forms/servo- motor-guide.phphttp://www.anaheimautomation.com/manuals/forms/servo- motor-guide.php 2) http://www.aishack.in/2010/07/how-servo-motors-work/http://www.aishack.in/2010/07/how-servo-motors-work/ 3) http://www.youtube.com/watch?v=-XSXfqd1N58http://www.youtube.com/watch?v=-XSXfqd1N58 By mahmoud abu khader 0094339 Electrical drive