# Main: TAU - APMonitor Option

 Type: Floating Point, Input
Default Value: 60.0
Description: Time constant for controlled variable response


The time constant is a tuning parameter for the speed of response of a reference trajectory. When the set point is stepped to a new value, the time constant (TAU) adjusts the speed of response with SP_tr = (1-exp(-t/TAU)) (SPnew - SPold) + SPold where SPold is the prior set point, SPnew is the new set point, t is the time, TAU is the time constant, and SP_tr is the resultant trajectory.