MOSFET transistors having localized stressors for improving carrier mobility are provided. The upper piston part has a cooling oil annular channel that is open towards the piston skirt, into which channel the cooling oil is introduced, and discharged. The setting the moving path also includes calculating respective total costs required for the AGVs to perform a corresponding task or corresponding tasks for all of the cases, determining a smallest and largest value out of the respective total costs for each of the cases, and setting the moving path of the AGVs according to the case having the smallest value.