Robot control system consists of a feedback controller and reference motion pattern. They are designed based on the robot dynamics and coupled with each other, and it requires lots of calculation to obtain them. A new controller design method based on the existing controller will lead useful way to overcome this problem. So far, we have proposed attractor design method of nonlinear dynamics. This method is based on the vector field in state-space and it enables the new controller design based on existing controllers. In this paper, we propose a modified controller design method using definition of "realizable" vector field and a new controller design method based on the superposition of vector field and state-space mapping.