Klann linkage

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.[2] It is categorized as a modified Stephenson type III kinematic chain.[3][4][5][6]

Underwater walking robot, using Klann leg linkages in laser-cut and anodised aluminium.[1]

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.[7]

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 US Patent 6,260,862 there is a set of coordinates for an example leg:[4]

PointXYDescription
Fixpoints
91.3661.366first rocker arm axle
111.0090.574second rocker arm axle
151.5990.750crank shaft
fully extended ground stride position
27X0.7410.750elbow joint
29x1.3310.750crank
33x0.0000.000foot
35x0.2320.866knee joint/axle
37x0.8661.500hip joint
grounded gait position
27Y1.2770.750elbow joint
29y1.8670.750crank
33y1.0000.000foot
35y0.7680.866knee joint/axle
37y1.0001.732hip joint


See also

References
  1. Rooney, T., Pearson, M., Welsby, J., Horsfield, I., Sewell, R. and Dogramadzi, S. (6–8 September 2011), Artificial active whiskers for guiding underwater autonomous walking robots (PDF), CLAWAR 2011, Paris, FranceCS1 maint: uses authors parameter (link)
  2. "Mechanical Spider". Klann Research And Development, LLC. Archived from the original on 14 April 2004. Retrieved 22 November 2016.
  3. U.S. Provisional Application Ser. No. 60/074,425, was filed on Feb. 11, 1998
  4. U.S. Patent 6,260,862
  5. U.S. Patent 6,364,040
  6. U.S. Patent 6,478,314
  7. Ganapati, Priya. "Robotic Spider Melds Legos and 3-D Printing". Wired. Retrieved 22 November 2016.
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