Synthesis of Mechanisms

a subdivision of the theory of machines and mechanisms. The synthesis of mechanisms investigates methods for the graphic kinematic design of mechanisms according to specified kinematic and dynamic principles. The most thoroughly developed methods for the synthesis of mechanisms are those based on specified kinematic principles —the kinematic synthesis of mechanisms. This method consists in determining the graphic kinematic design of the mechanism and the design parameters that will provide the required motion. The simplest kinematic synthesis is that of cam mechanisms. For such mechanisms it is possible to specify almost any motion for a known member and, with the aid of simple graphs or calculations, to find a cam profile that will provide the specified motion. A much more complicated synthesis is that of linkage mechanisms; such synthesis can be carried out only approximately. Methods of synthesis for hinged mechanisms are based on the application of the theory of approximation of functions. These methods were first proposed in 1853 by P. L. Chebyshev.

Two common drawbacks of all methods for the synthesis of mechanisms are the lack of choice of design for the mechanism and the structural impracticableness of the dimensions obtained for the members. However, these drawbacks can be virtually eliminated by the use of electronic computers, which are capable of optimizing various criteria and of considering a large number of kinematic, dynamic, and structural limitations.