Block that outputs true if the Real input u
is greater than a threshold t, optionally within a hysteresis h.
The parameter h ≥ 0 is used to specify a hysteresis.
For any h ≥ 0, the output switches to true if u > t,
where t is the threshold,
and it switches to false if u ≤ t - h.
Note that in the special case of h = 0, this produces the output y=u > t.
To disable hysteresis, set h=0.
Enabling hysteresis can avoid frequent switching.
In simulation, adding hysteresis is recommended to guard against numerical noise.
Otherwise, numerical noise from a nonlinear solver or from an
implicit time integration algorithm may cause the simulation to stall.
Numerical noise can be present if an input depends
on a state variable or a quantity that requires an iterative solution,
such as a temperature or a mass flow rate of an HVAC system.
In real controllers, adding hysteresis is recommended to guard against measurement noise.
Otherwise, measurement noise may cause the output to change frequently.