An R/C servo motor is a compact package of DC
geared-motor associated with position servo controller. They are widely used in small-sized robotics and mechatronics by virtue of their compactness, easiness-to-use and high power/weight ratio. However, in order to improve control performance of mechatronic systems using R/C servo motors, such as biped robots or under-actuated systems, it is crucial to clarify their mathematical model. This paper describes the development and modeling of motor using system identification methodology. The development of controllers is considered the most crucial issue. An experimental test was carried out to record and analyze the motor input/output signals in open loop system. The experiments showed that it was feasible to represent the dynamic characteristics of the motor using the system identification technique.