Servo might use inexpensive parts with large tolerance leading to inaccurate shaft positioning.
If we turn off the Microcontroller connected to servo then on powerup it won't be able to tell current position of servo shaft.
Any external force applied on servo shaft during it's operation can cause shaft position to change. This change cannot be noticed by Microcontroller Advantages of Analog Feedback Servo:
Advantages of Analog Feedback Servo
This servo is capable of providing closed feedback loop between Microcontroller and Servo which helps to maintain accuracy of servo shaft.
Each position of servo shaft between 0-180 degrees can be represented as a unique Analog voltage. This Analog voltage can be read by Microcontroller having Analog pin.
Any external force applied on shaft is reflected as change in Analog value. Enabling you to know the deflection of servo shaft in real time!
Steps to Obtain Analog Position
Connect the separate 4th wire of servo to Analog pin on Microcontroller and rest of wires as per standard connection.
Open a SWEEP sketch provided in ArduinoIDE under servo section to swing shaft between two extreme position(0-180 degrees).
Modify the above code to read the Analog value and display it on the serial monitor for both extreme positions.
Map this recorded Analog values against 0 to 180 degrees using MAP function. You now have the Servo capable of providing position feedback.
Unique Benefits
You no longer need to save current position of servo shaft into EEPROM every time you move your shaft.
You can monitor Analog value to see deflection of shaft by any external force to take corrective action.
Train your servo manually with hand to rotate shaft at desired angle. Powerful isn't it !