In this work, we solve the pose estimation problem for robot motion by placing multiple cameras on the robot. In particular, we use four cameras arranged as two back-to-back stereo pairs combined with the Extended Kalman Filter (EKF). The reason for using multiple cameras is that the pose estimation problem is more constrained for multiple cameras than for a single camera. Back-to-back cameras are used since they provide more information. Stereo information is used in self initialization and outlier rejection. Different approaches to solve the long-sequence-drift have been suggested. Both the simulations and the real experiments show that our approach is fast, robust, and accurate.