An autonomous robot lawnmower includes a blade assembly including blades, a drive system to drive the blades through a cutting area having a cutting width, and a lateral blade guard including at least four bars spaced apart from one another by no less than 1 mm and no more than 15 mm. The at least four bars are positioned between the blades and a mowable area when the robot lawnmower is supported on the mowable area. The at least four bars extend across a portion of the cutting width and extending rearward and forward of the cutting area.