A crawler system provides much larger ground contact, leading to excellent terrain adaptability. Due to its structural characteristics, high-frequency vibration proportional to the vehicle speed is generated during the driving process. This is a result of the polygon and rolling effects between the track and the wheels. A field test of a tracked vehicle is performed to monitor movement signals of the chassis and a rocker arm. Their corresponding power spectral density distributions confirm the correctness of the frequency-calculation equation. Then, a novel elastic track tensioning device with a damper is designed as a cushion between the idler and the chassis. Depending on its geometry, the equivalent damping coefficient for a dynamic model is evaluated.Subsequently, the damping is altered in response to different operating conditions by a hybrid damping fuzzy semiactive control system. The controller accounts for both chassis and track vibration. Based on the transfer matrix method for multibody systems, a dynamical model of the track system is developed. Control performances are evaluated using two numerical simulations of obstacle crossing and off-road driving operations. Results indicate that the proposed semiactive tensioner is substantially better than the conventional one. This paper provides a novel feasible scheme for vibration reduction of tracked vehicles.