Answer / ram

In pid controller P stands for PROPORTIONAL BAND, I for
INTEGRAL MODE & D for DERIVATIVE MODE. We can also use this
mode for controlling purpose as individual mode. Means we
can use P mode alone or I mode or PI mode PD also. But using
this mode individuals will not provide the desired accurate
output.

So we need to use all the three parameters together to get
good accurate control over process variable.
In this PID mode P(ON-OFF) will try to give the output value
as possible as close to the set value but it will never get
the actual output to the set value. it has some limitations.
So to compensate for the errors remain P mode the I mode is
used. it takes the output value to the set point but after
certain time. it takes some time to get the desired output.
some oscillations are there due to I mode.

So finally to eliminate the damped response of I mode we use
the D mode. it will compensate for the offset error occurs
due to I mode. & try to reaches the desired output level fast.

Answer / muthu

to get free oscillated output for given input, PID
controller uses.

in pid setting, the following parameters are considered.

i) proportional gain, kp
ii) integral gain, ki
iii) derivative gain, kd

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