Chebyshev lambda linkage

The Chebyshev's Lambda Linkage[1] is a four-bar linkage that converts rotational motion to approximate straight-line motion with approximate constant velocity. [2] It is so-named because it looks like a lowercase Greek letter lambda.[3] The precise design trades off straightness, lack of acceleration, and the proportion of the driving rotation that is spent in the linear portion of the full curve.[4]

Animation of the Chebyshev Lambda Linkage

Dimensions:
Cyan Link = a
Green Link = 2.5a
Yellow Link = 2.5a + 2.5a
Horizontal Distance between Ground Joints = 2a

Chebyshev's plantigrade machine

Chebyshev's Translating Table Linkage, which combines together two cognate linkages: Chebyshev's Linkage and Chebyshev's Lambda Linkage

Lambda Mechanism

The example to the right spends over half of the cycle in the near straight portion. Coupler point stays within 1% positional tolerance with intersecting the ideal straight line 6 times.

The linkage was first shown in Paris on the Exposition Universelle (1878) as "The Plantigrade Machine".[5][3] The Chebyshev Lambda Linkage is a cognate linkage of the Chebyshev linkage.

The Chebyshev Lambda Linkage used in vehicle suspension mechanisms, walking robots and rover wheel mechanisms. In 2004, a study completed as a Master of Science Thesis at Izmir Institute of Technology, a new mechanism design introduced by combining two symmetrical Lambda linkages to distribute the force evenly on to ground with providing the straight vertical wheel motion.[6] It was then designed, manufactured and tested in the Earth Rover Project of Los Angeles City College Electronics Club.[7]