Klann linkage

Underwater walking robot, using Klann leg linkages in laser-cut and anodised aluminium.

The Klann linkage is a planar mechanism designed to simulate the gait of legged animal and function as a wheel replacement, a leg mechanism. The linkage consists of the frame, a crank, two grounded rockers, and two couplers all connected by pivot joints. It was developed by Joe Klann in 1994 as an expansion of Burmester curves which are used to develop four-bar double-rocker linkages such as harbor crane booms. It is categorized as a modified Stephenson type III kinematic chain.

The proportions of each of the links in the mechanism are defined to optimize the linearity of the foot for one-half of the rotation of the crank. The remaining rotation of the crank allows the foot to be raised to a predetermined height before returning to the starting position and repeating the cycle. Two of these linkages coupled together at the crank and one-half cycle out of phase with each other will allow the frame of a vehicle to travel parallel to the ground.

The Klann linkage provides many of the benefits of more advanced walking vehicles without some of their limitations. It can step over curbs, climb stairs, or travel into areas that are currently not accessible with wheels but does not require microprocessor control or multitudes of actuator mechanisms. It fits into the technological space between these walking devices and axle-driven wheels.

Mechanism

Klann linkage work on the basis of kinematics where all links gives relative motion with each other. It converts the rotatory motion to linear motion, and looks like an animal walking.

These figures show a single linkage in the fully extended, mid-stride, retracted, and lifted positions of the walking cycle. These four figures show the crank (rightmost link in the first figure on the left with the extended pin) in the 0, 90, 180, and 270 degree positions.

This animation show the working of klann mechanism.

This is a repeating animation of the legs in motion with the near legs of each set outlined in blue. A reasonable understanding of the functioning of the linkage can be gained by focusing on a specific point and following it through several cycles. Each of the pivot points is displayed in green. The three positions grounded to the frame for each leg are stationary. The upper and lower rockers move back and forth along a fixed arc and the crank traces out a circle.

Movement paths of each point (in blue is the ground link)

Comparison with Jansen's linkage

Jansen Linkage

The Klann mechanism uses six links per leg, whereas the Jansen's linkage developed by Theo Jansen uses eight links per leg, with one degree of freedom.

Example leg

example leg illustrated

In U.S. Patent 6,260,862 there is a set of coordinates for an example leg:

See also

• Wheel
• Linkage (mechanical)
• Leg mechanism
• Mondo Spider
• Jansen's linkage
• Chebyshev linkage and Chebyshev's Lambda Mechanism

External links

Wikimedia Commons has media related to Klann linkages.

Wikibooks has a book on the topic of: Klann linkage

• Klann Linkage In Phun on YouTube Animation of the linkage's climbing ability
• Legs, mk2 on YouTube Clear side-on view of linkage in motion
• Son of Mr Crabby - CamBam made Klann linkage walking crab robot on YouTube
• Mechanicalspider
• Mechanisms101 Archived 2009-02-02 at the Wayback Machine
• Mondo Spider
• Walking Beast
• Crabfu