In this study, a six-wheeled small mobile robot platform for rough terrain is developed. Speeds, accelerations, and slip ratios of the robot are estimated. We analyzed a vehicle with an articulated suspension (RVAS: robot vehicle with articulated suspension) for actual rough terrain. We then design a small RVAS mobile robot by reducing the scale. The mobile robot is modeled and fabricated by using 3D printing technique. Considering physical limitations of small mobile robots and available sensors, one microcontroller, six hall sensor encoders, and one IMU sensor are used. A Kalman filter-based estimator is also used to remove noise from the acquired data and improve estimation of the robot states. The slip rate of each wheel is experimentally estimated by using the angular velocity of each wheel and the linear velocity of the robot acquired from the IMU sensor.