Is your robot lawnmower or regular lawnmower too noisy? Here are some things you can check.
1) Try cleaning the blades. Grass can build up between the blades, the screw and the platform they are screwed in to. On my model I unscrew the blades, clean the blades themselves with a flat screwdriver, clean the area they are attached to, and clean the screw.
2) Try loosening, cleaning (if required) and re-attaching the platform that connects the blades to the body of the lawnmower. It could be that the platform has become loose and is set at an angle to the body.
3) Try increasing the distance between the cutting platform and the ground. On the lawnmowers that I know, we can set the grass height from 5 to 1. 1 will result in the shortest grass and 5 will result in the longest grass. I need to set my lawnmower to 4. If I set my lawnmower to three or less it will result in a loud rattling noise. This is because the blades are digging in to the ground at that height. The platform can also be dragging on the ground.