Economic Design of Joint X(bar) and R Control ChartsUsing Differential Evolution

Benefits of economic designs can be realized to the full extent only by employing appropriate optimization techniques for minimizing the so called loss-cost functions or the total cost functions. Approximate methods employed to find the best control chart parameters may not be effective in obtaining the intended cost benefits. In the present work, differential evolution (DE), a population based evolutionary optimization technique has been employed to design joint X(bar) and R control charts. The optimum costs obtained are compared with the earlier designs which are based on conventional optimization techniques. It has been observed that the designs obtained using DE are very effective and in majority of the cases remarkable improvements are obtained in cost reductions.