Mechanical capstan amplifier

A biomimetic joint comprising:

• a first skeletal element;
• a second skeletal element rotationally coupled to the first skeletal element;
• a third skeletal element positioned away from the first skeletal element and rotationally coupled to the second skeletal element;
• and
• a mechanical capstan amplifier configured to move the first skeletal element and the third skeletal element with respect to the second skeletal element, the mechanical capstan amplifier comprising:
• a first tensioner;
• a first actuating rod extending away from the first tensioner, the first tensioner configured to rotate the first actuating rod;
• a second tensioner;
• a second actuating rod extending away from the second tensioner, the second tensioner configured to rotate the second actuating rod;
• a drive motor;
• a single drive rod extending away from the drive motor, the drive motor configured to rotate the single drive rod;
• a first cord having a first end coupled to the first actuating rod and a second end coupled to the first skeletal element, wherein the first cord extends at least partially around the single drive rod;
• and
• a second cord having a first end coupled to the second actuating rod and a second end coupled to the third skeletal element, wherein the second cord extends at least partially around the single drive rod at a position on the single drive rod that is different from a position of the first cord,
• whereby actuation of the first tensioner causes the first cord to tighten around the single drive rod thereby causing the first skeletal element to rotate with respect to the second skeletal element, and actuation of the second tensioner causes the second cord to tighten around the single drive rod thereby causing the third skeletal element to rotate with respect to the second skeletal element.

A method of moving a first load and a second load, the method comprising:

• providing a first cord that extends at least partially around a single drive rod and to the first load;
• providing a second cord that extends at least partially around the single drive rod and to the second load, the second cord at least partially surrounding the single drive rod at a position on the single drive rod that is different from a position of the first cord;
• rotating the single drive rod while the first cord and the second cord are loosely coupled thereto;
• and
• tightening the first cord and the second cord about the single drive rod such that continued rotation of the single drive rod creates friction between the single drive rod and the first cord and between the single drive rod and the second cord so that the first load and the second load are moved.