There is provided a mobile robot that performs the obstacle avoidance and visual simultaneous localization and mapping (VSLAM) according to image frames captured by the same optical sensor. The mobile robot includes a pixel array and a processor. An upper part of the pixel array is not coated with any filter and a lower part of the pixel array is coated with an IR filter. The processor performs range estimation using pixel data corresponding to the lower part of the pixel array, and perform the VSLAM using pixel data corresponding to the upper part of the pixel array.