In the deterministic optimization design of planar linkage

the optimal solution which meets various constraints is generally close to constraint boundary.With random fluctuation of variables

the optimal solution tends to become infeasible solution against constraints

which results in design failure.Based on the theory of six sigma robust optimization design

a mathematical model of robust optimization design for rendition of link lever mechanism based on the tolerance was established.Robust optimization design is then performed by using six sigma robust optimization design module integrated in the software iSIGHT.The results show that robust optimization design not only reduces the fluctuation of objective functions with design variables

which guaranteed the robustness of mechanism accuracy

but also makes constraint functions away from constraint boundary

thus reaching the level of six sigma.