Synthesis of Four-bar Motion Generation Considering Worst Case Joint Tolerances
Abstract— Four-bar motion generation is used to synthesize a mechanism which passes through or approximate prescribed rigid-body positions. This work will discuss the motion generation of four-bar mechanism with position tolerance variations due to joint running clearance. The tolerance variations study will be based on the standards of American National Standard Institute (ANSI). The new design constraint introduced in this paper will consider the joint tolerances and incorporate it into the displacement position matrix of coupler points described in the conventional planar four-bar motion generation models. The synthesized planar four-bar mechanism will produce tolerance limits for moving pivots and link length from which any mechanism can be synthesized to satisfy the prescribed coupler points with their prescribed tolerances. The included example demonstrates the synthesis of a four-bar mechanism with joint tolerances. 1
MULTI-PHASE MOTION GENERATION OF FIVE-BAR MECHANISMS WITH PRESCRIBED RIGID-BODY TOLERANCES
This work presents a technique for synthesizing adjustable planar, five-bar motion generators to approximate prescribed rigid-body positions and satisfy rigid-body positions with prescribed tolerances. This method is an extension of the adjustable planar five-bar motion generation method introduced by the authors (1). By incorporating rigid-body point tolerances in the rigid­ body displacement matrices, the calculated circle and center point curves of the five-bar mechanism become circle and/or center point regions. From these regions, fixed and moving pivots for the five-bar mechanism can be selected that approximate the prescribed rigid-body positions and satisfy rigid-body positions with prescribed tolerances. The example in this work considers two-phase moving pivot adjustments in the planar five-bar motion generator..
Kinematic synthesis of geared linkages
Abstract Planar geared linkages readily lend themselves to function, path and motion generation. Function generation includes any problems in which rotations or sliding motion of input and output elements (either links or gears) must be correlated. In some cases, the designer may want to produce a formal functional relationship between the input and output. In these cases, the input and output rotations can be used as the linear analogs of the independent and dependent variables. In other cases, the designer has no particular functional relationship in mind, but merely wants to produce specific relationships between the input and output at certain “precision points”. Path generation involves moving a tracer point along a specified path. A point attached to any “floating” link (such as a coupler) may be used as the tracer point. Motion generation requires that an entire body be guided through a prescribed motion sequence. The body to be guided can be attached to any floating link.