When I started to sew with an electric sewing machine
the machine we had had a knee control..the foot control can be mounted so that a lever can be pushed by pressing with a knee to make the machine sew.
Some machines now have a knee lever to raise and lower the foot but this was to make the it work like the foot control..
I have not seen this kind of control on a machine for a long time but I am sure it could be used again.. It let you use both hands to guide the material