The precision agriculture has been progressing rapidly to improve the efficiency of operation with the quality and consistency of products. High-tech machines have been developed exploiting information technology and getting widely used. Oil most of farms, however, there still works simple agricultural machines. From cost saving and Sustainable development point Of View, utilization of existing facilities call be significant alternative strategy. In this paper we propose two design methods of an agricultural machine. One is modifying relevant structural parameters by numerical optimization. The other is appending all actuator and a controller to the machine and then employing simultaneous optimization of both controller and machine parameters. We also compared their performance and robustness.