A flexible crank-slider mechanism is considered to investigate the variations of Coupler Point (C.P.) position. The assembly specifications, i.e. C.P. position, have variations in x and y directions. The correlation between these variations also impresses the limits of variation. The bivariate distribution of the assembly specification is determined using the Direct Linearization Method (DLM). The Monte Carlo simulation is implemented to find the valid range of DLM solutions. Then, the percent contribution of each input variable to assembly specifications is computed by DLM. Critical variables, which have the highest contribution to the variations of the assembly specification, are recognized. By improving the tolerance limits of these critical variables and increasing area section r2, the maximum error of mechanism can be decreased significantly. According to Figure 15, tolerance improvements result in 19% reduction of the maximum normal error at θ2=3°. In addition, the curve which represents the minimum cost versus the maximum is derived based on the cost function and the regression equation. It has been observed that external loading will remarkably increase the amount of max error.

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