What are the arguments Yogacara makes to deny the reality of sensory objects? Yogacara and Vasubandhu etc deny that matter exists by itself but rather that is comes from awareness and is merely a perception of the mind.what are the arguments Yogacarins make to prove their main thesis?
They don't believe that.  That's an almost universal misunderstanding.  Yogacara doesn't make any ontological statements about the universe, perception, reality, and so forth.  Their approach was strictly soteriological.  They were exclusively concerned with liberating the mind, not with describing things as they are.  What Yogacara is concerned about is how the mind (store house consciousness and &quot;I-making&quot; consciousness) &quot;perfumes&quot; and &quot;transforms&quot; the sensory gates and how that in turn impacts perception.  You aren't seeing a chair, for instance, but rather your entire life history, memories, prejudices, etc. dealing with chairs.  That means that the chair you see isn't the same chair that someone at, say, the Buddha's time would see even if you were looking at the same object.  Something that you might take to be a pretty shoddy looking recliner, after all, might be a veritable throne to them!
This has very real implications when it comes to liberation.  Our personal histories impact not just our existential lives but even the very way we deal with and perceive the world.  Our habituated, unenlightened perception makes us miss so much of what's actually there.  We don't see the spaces between things, we don't perceive the energy, and we are wholly negligent of the emptiness that is always there.  Hell, we don't even hear properly.  Yogacara training (especially as manifested in Zen koan study) seeks to reacquaint us with what we are missing...not to assert any concepts regarding the nature of reality.