Vacuum cleaner having adaptive dirt identification and method for operating the vacuum cleaner

A method for operating a vacuum cleaner, the method comprising:

• providing the vacuum cleaner, wherein the vacuum cleaner comprising:
• a dirt sensor configured to determine a dirt value indicating an amount of dirt currently being sucked up;
• a floor sensor configured to determine a degree of hardness indicating the hardness of a currently vacuumed surface;
• a display;
• and a controller configured to operate in at least one automatic mode;
• said controller, upon the degree of the hardness being below a soft-bottom limit value:
• outputting the dirt value on said display, and otherwise determining a reduction value of the dirt value weighted by a weighting value being less than one, and outputting the reduction value on said display;
• said controller configured to be switched at least between said at least one automatic mode and a real mode, and in said real mode said controller configured, upon the degree of the hardness being above the soft-bottom limit value, to output the dirt value in lieu of the reduction value on said display;
• using said dirt sensor to determine the dirt value;
• using said floor sensor to determine the degree of the hardness;
• using said controller in said at least one automatic mode, upon the degree of the hardness being below the soft-bottom limit value:
• to output the dirt value on said display, and
• otherwise to determine the reduction value and output the reduction value on said display and switching said controller at least between said at least one automatic mode and said real mode, and using said controller in said real mode to output the dirt value in lieu of the reduction value on said display, upon the degree of the hardness being above the soft bottom limit value.