Explore Program > Dynamic Analyst > Control Input

Available in v12.0 and higher
Available in Dynamic Analyst
Updated in v14.3

PID control consists of three components:

•Proportional (P)

•Integral (I)

•Derivative (D)

The equation for the PID controller looks like:

C(S) = Kp + Ki +Kd

where KP = proportional gain, KI = integral gain, and KD = derivative gain

How the PID controller works

•Tracks the error between the desired input and actual output

•Using the error and the Kp; KI; and KD terms, the correction is calculated

•The correction is added (or subtracted) from the actual output

•Go back and repeat

•Direct product of gain and measured error

•Present time,

•Low Kp leas to large error

•High Kp increases oscillatory behavior and repetitive overshooting

•Summation of error over time

•Past time,

•Low Ki increases rise time

•High Ki increases oscillatory behavior and repetitive overshooting

•Considers the rate of change of the error,

•Future time,

•Higher Kd decreases overshoot and dampens the system.

1.Set Ki and Kd to zero, and increase Kp until output oscillates

2.Then increase Ki until oscillation is minimal (note that sometimes Ki is not used and will make the system more oscillatory),

3.Next increase Kd until the output is acceptably quick in reaching the desired reference curve.

•Each PID controller acts differently for each system.

•Each PID component does not have to be used.

•Increasing any PID component too high may make the system unstable.