This study is dedicated to achieve landing posture control of a generalized 5-Rotational-DOF (5-RDOF) twin-body system using methods of PD control and input-output linearization. The 5-RDOF twin-body system considered is in fact a simplified model of a cellular phone. A successfully designed landing posture control scheme is expected to prevent structural damage of the cellular phone. To this end, dynamic equations of motion for the 5-RDOF twin-body system are built based on the Lagrange-Euler formulation. To simplify the modeling, the input torques associated with 2-RDOF joint have been decoupled by defining relative rotational angles of the joint as state variables. There are two controllers applied to achieve the final landing posture control: (1) PD controller and (2) input-output linearization with computed torques. Finally, the controller performance is validated by MATLAB simulations. The results show that the design controller is capable of performing landing control, and the relations between dynamics responses and control variables are discussed.