Higher-order kinematic error sensitivity analysis and optimum dimensional tolerancing of dyad and non-dyad mechanisms

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Ho, John Rong Ming
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A higher-order kinematic error sensitivity analysis and the synthesis of dimensional tolerance bands for complex planar mechanisms are investigated in this thesis. The initial phase of the research involves developing a novel approach for a computer-aided kinematic analysis of dyad and non-dyad mechanisms. The approach includes transforming the original non-dyad mechanism into a series of dyad mechanisms whose solutions are readily computable. This is achieved by disconnecting appropriate link and/or joints, and prescribing dyad drivers for the transformed linkage. An iterative technique is then employed to recover the disconnected links by restoring the affected geometric conditions to their original values. All these steps do not require human intervention as they are generated automatically by the program, aptly entitled as NDPLAn (Non-Dyad Planar Linkage Analysis). Two non-dyad mechanisms are solved to demonstrate the procedure, and the programs' accuracies, capabilities and versatilities. Having developed a method for performing a kinematic analysis of dyad and non-dyad mechanisms, attention is then turned to developing a procedure for synthesizing optimum dimensional tolerances in these complex mechanisms. The method which is based on a mechanical error sensitivity analysis involving displacements, velocities and accelerations, then proceeds to choose the smallest of the maximum input errors associated with these kinematical quantities without exceeding the specified allowable output limits. (Abstract shortened by UMI.)