Rehabilitation robots may help the patient improve their recovery by supporting them to perform repetitive, systematic training sessions. Safety and comfortable feeling of the patients who training with robots is an important issue in not only the steady state but also the transient process. In this research, the trajectory tracking control problems of a two-degrees of freedom (2-DOF) robotic orthosis is discussed. The robotic orthosis is powered by pneumatic artificial muscles (PAMs) in an antagonistic configuration. based on a mathematical model, a modified computed torque control scheme is employed to enhance the tracking performance. The effectiveness of the proposed control strategy is verified by the experiments with the participation of different subjects.