In order to reduce synthesis error, a new approach is reported to select precision points for function synthesis of spherical 4R linkages. Based on a closed-form symbolic solution of the set of function synthesis equations of spherical 4R linkages, the structure error equation has been derived by introducing a scaling factor. After this, an optimization model was constructed to search for the precision points. The initial solution of the optimization model was chosen using a numerical interpolation method. The global optimal solution was obtained using the fractal algorithm. To illustrate this, an example is presented and discussed before finally deriving conclusions.
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