If you can't pull an "Upa" escape by bridging out and to the side to roll your opponent because you're getting caught in an armbar, you might be pulling the escape wrong. If the person on top is riding you well enough to avoid the Upa, then pull an Elbow escape to put your opponent in guard or half-gaurd.
If you're looking to sweep, I would definitely encourage you to start your sweep from the half-gaurd. This is actually a real good position to sweep from, and not to many people work off their back that way. If you can't pull the sweep from half-gaurd, then you should still be able to create anough space to pull the elbow escape again and pull full gaurd.
If you want a step by step, just ask and I'll try to respond in a timely manner.
It doesn't matter if you agree or disagree
... As long as I don't bore you and I spark a moment of thought, my goal is achieved
Queng leon queng tigre ecu tacacut, queca pa? - Pampangan Mandarigma Motto