Bowden Cable

A flexible cable with an inner wire in an outer sheath, transmitting pull force along a curved path, like a bike brake line.

A Bowden cable consists of an inner wire (or cord) and an incompressible outer sheath around it; the sheath's two ends are fixed in place, and pulling the inner wire at one end moves the other end — the most familiar example is a bicycle brake cable. In robots, it's used to keep a motor in the torso, a backpack, or near the base of an arm, while sending pull force along a curved path out to a finger, wrist, or exoskeleton joint, keeping the far end lighter and lowering its inertia. Its downside is significant friction between the inner wire and sheath that varies with bend angle, plus hysteresis and elastic stretch, so precise force control needs to compensate for these effects. It's a common way of implementing tendon-driven actuation.

ExampleThe soft exoskeleton from Harvard's Wyss Institute keeps its motor at the waist and pulls the ankle joint via a Bowden cable to assist walking.

Also called

Bowden Sheath

Related

Tendon-Driven Actuation · Exoskeleton · Intrinsic vs. Extrinsic Actuation (Proximal Actuator Placement) · Dexterous Hand · Friction Compensation · Tendon Material (UHMWPE)

Sources

Bowden cable - Wikipedia