Minimum Error Synthesis of Multiloop Plane Mechanisms for Rigid Body Guidance

A variational method of synthesizing single-degree of freedom, single or multiloop plane mechanisms to guide rigid bodies through specified planar positions is presented. The optimum set of dimensions of a mechanism is determined by minimizing an objective function, which is the sum of the squared errors in the generated coordinates of two body points. The design equations are solved either by matrix iteration or Gaussian relaxation methods. By introducing constraints necessary to coincide the two body points, the problem is reduced to that of optimizing a plane mechanism to generate a planar path. Stephenson six-bar mechanism of Type I and the 4R plane mechanism are synthesized for rigid body guidance and path generation. Numerical examples are given, where all the geometric inversions of a mechanism are synthesized as distinct mechanisms, thereby eliminating the mixing of the geometric inversions at the design positions, thus assuring the mobility of the resulting mechanisms within the design interval.