My foot pedal slipped around on our carpet no matter what I used under it.
So my husband took a piece of pegboard that we had around and cut it to length as follows.... the foot pedal was where I wanted it for comfort and the edge of the board was under the edge of the pedal and the far edge of the pegboard reached to the baseboard. Then he glued velcro to the bottom of the foot pedal (two places) and stapled the matching velcro piece to the pegboard. This holds the pedal securely.
My intent for travelling was to take the pedal off and put some spare velcro over the foot pedal stuff to keep it clean. But when I went to a retreat recently I just took the whole shebang as it fit easily in my travel bag.
If you need pictures please let me know and I'll see if I can get some and transfer them to the computer to send.