A success Finally- Low cost DC servo

At last, i am able to successfully control the servo motor with low cost electronics to the finest resolution the encoder can support. This quadrature encoder takes 192 pulses per revolution( PPR)of the motor. The PID values for this motor is P=20, I=20 and D=0.1
Ziegler–Nichols method for PID manual tuning:
Set all gains to 0.
Increase Kd until the system oscillates.
Reduce Kd by a factor of 2-4.
Set Kp to about 1% of Kd.
Increase Kp until oscillations start.
Decrease Kp by a factor of 2-4.
Set Ki to about 1% of Kp.
Increase Ki until oscillations start.
Decrease Ki by a factor of 2-4.