Equilibrators for Planar Linkages

Abstract

This manuscript provides a mathematical basis for comparing the complexity of equilibrator methodologies, extends the applications of those methodologies, and develops new methodologies. Two methodologies exist for spring equilibration of two degree of freedom revolute joint planar linkages. Extensions of both methodologies are now demonstrated for equilibration of all rigid body planar linkages having lower and/or higher order kinematic pairs. Reduction in complexity of these general methodologies is demonstrated when kinematic chains include only revolute joints. A mathematical description of the complexity of each of three equilibration methodologies is introduced to provide a means of comparing the effectiveness of each approach. Examples demonstrate the appropriate equilibrator design choice for particular applications, based on the mathematical description of system complexity. A new approach for equilibration of linkages having higher order planar kinematic pairs (1R1T) is introduced. A solution to the problem of spring mass in equilibrator design is presented. Examples are included to demonstrate the effectiveness of both the 1R1T equilibrator design scheme, and the spring mass equilibration scheme. The 1R1T design represents a first equilibration of pantograph type mechanisms.