Chebyshev's Lambda Mechanism

The Chebyshev's Lambda Mechanism[1] is a four-bar mechanism that converts rotational motion to approximate straight-line motion with approximate constant velocity.[2] 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.[3]

Chebyshev's Lambda Mechanism

Tchebyshevs plantigrade machine

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 Chebyshev's Lambda Mechanism is a cognate linkage of the Chebyshev linkage.

The linkage was first shown in Paris on the Exposition Universelle (1878) as "The Plantigrade Machine".[4][5]

The Chebyshev's Lambda Mechanism looks like the Greek letter lambda, therefore the linkage is also known as Lambda Mechanism.[6]

Chebyshev's Lambda Mechanism 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 Mechanism to distribute the force evenly on to ground with providing the straight vertical wheel motion.[7]

Double Lambda Chebyshev Mechanism rover suspension design manufactured and tested in Earth Rover Project of Los Angeles City College Electronics Club[8]