Grammatical Aspect

So I was looking at: http://en.wikipedia.org/wiki/Grammatical_aspect#Examples_of_various_aspects_rendered_in_English and I saw no examples that relate to can, could, should, must, might, and may. For example, "I should go home," "I could go home," and "I may go home." Are there specific names that relate to these English constructions? Are these constructions various aspects or is there a different term for them? 


x-posted to conlangs