How to obtain funding for independent research after graduating from undergrad? I just graduated with BS from undergrad and am employed as a research associate staff by a research team at the university. 

I would like to ask for suggestions about how to obtain research funding for my independent project. Most of the funding opportunities are only available for registered students. I am not a U.S. citizen eligible for national grants. 

I am working in the field of social science and human-robot interaction and have 2-3 advisors from undergrad research and courses who encourage me to carry on my undergraduate projects and are willing to provide advising. However, they did not specifically offer me guidance of how to resolve the need for funding. It seems like I need to take the initiative to present this research opportunity to them.
I'll make three suggestions, but these are a bit difficult to obtain. 

First, if you intend to return to the country of which you are a citizen, then you might explore funding from there, since your skills would eventually benefit them. This is actually available in some places. 

Second, you might be able to obtain funding indirectly. Suppose you can convince one of your professors to apply for a grant that will fund your research and permit him/her to support you under the grant, even though you are not a citizen. If you don't need personal support, but only research support, this would be much easier, of course. But you would probably have to do the actual grant writing so that your advisor(s) can submit it with little effort on their own. This, in itself, can be a valuable skill, though obtained with a bit of pain. 

Third, you might explore private funding from some interested corporation. These have no real limitations, though the money might be relatively small. But if you have skills that the company might find valuable, perhaps you could work with them, without pay, but obtain a grant for research. I've done this sort of thing, but was in a different (more advanced) situation. In my case the grant didn't support me directly, but paid for such things as travel and equipment. But there might be legal issues that you would need to resolve through the university if you were directly supported.