Dexterous wrists

A rotatable wrist for placement and manipulation of an actuatable device, the rotatable wrist comprising:

• a wrist hub non-rotatably coupled to a distal end of a positioning shaft;
• a wrist capstan rotatably connected to the wrist hub and non-rotatably connected to the actuatable device;
• and
• a flexible wire loop extending through the wrist hub and partially contacting the wrist capstan, wherein linear movement of the flexible wire loop through the positioning shaft causes rotation of the wrist capstan due to friction between the flexible wire loop and the wrist capstan,
• wherein the wrist hub includes a first groove and a second groove, wherein the first groove is positioned at an angle relative to the positioning shaft, and wherein a first end of the flexible wire loop is positioned within the first groove such that the first groove guides linear movement of the first end of the flexible wire loop.