You can use the trapezoid membership function with the limits as limits as [a, b, above +range, above +range]. This is equivalent to x been aways 1 until yoiu reach the limit.
Barp - Control, Simulation, RTT and HIL - National Instruments
Yep, that's what I did. I put in something remarkably high and it worked. It would be nice to be able to put in infinity if possible. I'm trying to generalize the contoller as much as possible.