Cabbie21
We have some grippers but they don’t really work. It helps if you can anchor the rug down with furniture.
I put a heavy solid wood coffee table on top of my creeping rug, (which is on top of carpet). It STILL moves, taking the coffee table with it, even if no-one even enters that room. I didn't use the room at all for a couple of weeks, but when I went in later, it had moved a least a foot.. I had left it touching the edge of the hearth.
That room faces south and gets the sunsine, so I think it must be some effect of expansion and contraction, by day and night. Maybe the pile of the carpet underneath it assists the creeping.
Either that or I have a poltergeist.