Pneumatic Artificial Muscle (McKibben Muscle)

A tube-shaped actuator that shortens and thickens like a real muscle, pulling with force, when inflated.

The classic form of pneumatic artificial muscle is the McKibben muscle: a rubber inner tube is wrapped in a braided mesh sleeve, and when the tube is inflated, it bulges outward, but the braided sleeve converts that radial expansion into axial shortening, producing a pulling force at both ends — closely resembling how a biological muscle contracts. It's named after physicist Joseph L. McKibben, who designed it in the 1950s for orthotic devices for polio patients. Its advantages are that it's very light, has a high force-to-weight ratio, and is naturally compliant; its disadvantages are that it can only pull, not push, so it needs to be arranged in antagonistic pairs like real muscles, its range of contraction is limited, and it shows significant nonlinearity and hysteresis, making precise modeling and control difficult. It's commonly found in rehabilitation exoskeletons, biomimetic robot arms, and soft-robotics research.

ExampleFesto's Fluidic Muscle is a commercialized pneumatic-muscle product, used in applications such as gripping and tensioning that need compliant pulling force.

Also called

PAM, McKibben Muscle, Pneumatic Muscle

Related

Pneumatic Actuation · Artificial Muscle · Exoskeleton · Soft Robot · Bio-inspired Robot · Hydraulically Amplified Self-Healing Electrostatic Actuator (HASEL)

Sources

Pneumatic artificial muscles - Wikipedia