Fig. 1. A prototype of the mobile robot velocity estimation using three optical mice [6].Abstract-This paper presents the optimal placement of optical mice for the velocity estimation of a mobile robot. It is assumed that there can be some structural restriction on the installation of two or more optical mice at the bottom of a mobile robot. First, the velocity kinematics of a mobile robot equipped with an array of optical mice is obtained, which maps the velocity of a mobile robot in the world coordinate frame to the velocities of optical mice in their local frames. Second, the error characteristics of the mobile robot velocity estimation using optical mice is represented by the so-called uncertainty ellipsoid, and then the performance index for the optimal optical mouse placement is defined as the inverse of the volume of the uncertainty ellipsoid. Third, the global optimization strategy is stated in terms of the distance to each optical mouse and the geometrical center of optical mice, and the local optimization strategy is stated as the condition of the positional change of each optical mouse leading to the optimal placement. Fourth, simulation results for the optimal placements of three optical mice within a given elliptical region are given.Index Terms-Optical mice, mobile robot, velocity estimation, uncertainty ellipsoid, optimal placement.