1. A method for determining an energy-efficient path of an autonomous device wherein said autonomous device moves over a global grid of cells into which a given operating area has been split, said determination of the energy-efficient path comprises the steps of: processing of a current cell which represents a current position of the autonomous device; taking a measurement σ of the processing; classifying the measurement σ to be of a particular level, taking into account a predefined range of measurement results which is divided into a plurality of distinct levels; storing said classified measurement in a memory of the autonomous device and associating the stored classified measurement with the current cell; selecting a reference probability grid, wherein values in the cells of the reference probability grid express a probability that a measurement σ of the processing in a cell will be the same, respectively, to a cell at the reference probability grid, whereas a center cell in the selected reference probability grid which is associated with the current cell is assigned a maximum probability, while other cells within the reference grid have a probability assigned, which lowers with an increase of a distance of a cell from the current cell; updating the probabilities by applying the reference grid to the global grid at the current position such that each cell on the reference grid corresponds unambiguously to one cell on the global grid; and moving the autonomous device to a next cell of the global grid and setting said next cell as the current cell in order to process the next cell.