A force transmission with means for winding a first cable onto a first capstan and a second cable onto a second capstan with a first axis of rotation. The first and second cables wound such that when one of the two cables is payed out, the other of the two cables is payed in. The force transmission further includes means for passing the first and cables over an idler pulley in opposite directions. The idler pulley has a second axis of rotation substantially perpendicular to the first axis of rotation. The force transmission further includes means for coupling the first cable to a lever to rotate the lever in a first direction and means for coupling the second cable to the lever to rotate the lever in a second direction opposite the first direction, the lever having a third axis of rotation substantially parallel to the second axis of rotation.
