A modular pneumatic robotic actuator, including a first elongated hollow structure and a second elongated hollow structure connected to each other at a moveable joint; an inflatable bladder comprised of an elastomeric material disposed at the joint and immobilized between the first and second hollow structures, wherein the inflatable bladder inflates preferentially away from the joint; and a restraining membrane comprised of an elastomeric material disposed over the bladder and connecting the first and second hollow structures, wherein the restraining membrane is relaxed when the bladder is deflated.