Linkage Transmission

连杆传动Common

Using rigid, hinged rods to transmit power from a motor to a joint.

A linkage transmission connects several rigid rods with hinges (a common example is the four-bar linkage) to carry motion from a motor or electric cylinder to a joint some distance away, with the rod lengths engineered to produce the desired motion relationship. Its advantages are high stiffness and the ability to handle large forces, and it lets designers place heavy motors closer to the torso to reduce the mass at the limb's far end. Its downsides are that the range of motion is limited by the geometry of the rods, and the mechanism takes up space. On humanoid robots, linkages are common in parallel ankle and knee joints; in dexterous hands, linkage drive and tendon drive are the two dominant approaches — linkages are sturdier and easier to maintain, while tendons are lighter and more flexible.

ExampleIn many humanoid robots, the ankle places two motors in the shin and uses two linkages to push and pull the foot plate for pitch and roll motion.

Also called: Linkage Drive
Related: Four-Bar Linkage · Tendon-Driven Actuation · Parallel Ankle Mechanism · Dexterous Hand · Linear Actuator (Electric Cylinder) · Parallel Mechanism
Sources: Linkage (mechanical) - Wikipedia