For the purpose of preventing a free-falling object from damage, this study is devoted to the landing posture control via trajectory planning for a generalized twin-body system by employing the methods of PO and sliding control. The system discussed herein is the simplified model of a free-falling cellular phone with two rotational OOFs. In this paper, the governing equations of the system are first established based on the Lagrange-Euler formulation. Then, PO and sliding controllers are designed to achieve the desired landing posture. In addition, the trajectory planning is adopted to reduce the input energy. The performance of the controller is validated by MATLAB simulations, and the relations between input energy, trajectoryfunction, and falling height are discussed.