FIG. 1 is a top, front, and right side perspective view of a mobile robot showing our new design; FIG. 2 is a left side elevational view of the mobile robot; FIG. 3 is a right side elevational view of the mobile robot; FIG. 4 is a rear side elevational view of the mobile robot; FIG. 5 is a front side elevational view of the mobile robot; FIG. 6 is a top plan view of the mobile robot; and, FIG. 7 is a bottom plan view of the mobile robot.