In this paper, the posture stabilization and longitudinal motion control of a unicycle robot is presented. This unicycle robot has two gyroscopes acting as an actuator for the lateral stabilization and a wheel as an actuator for the longitudinal stabilization. The system is modeled based on Lagrangian Dynamics and system identification method. A gain-scheduled robust control method is applied to enhance its disturbance attenuation ability so as to achieve better performance in posture stabilization and longitudinal motion control. Satisfactory experimental results are obtained.