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, the method being characterized in that determination of said energy-efficient path comprises the steps of: processing of the current cell ( 201 ); taking a measurement σ of the processing ( 202 ); classifying the measurement σ to be of a particular level Σ ( 203 ), taking into account a predefined division, of the measurements results range, into a plurality of measurements levels; storing said classified measurement in a memory of the autonomous device ( 204 ) and associating it with the current cell; selecting a reference probability grid ( 205 ) wherein values in the cells of the reference grid express a probability that the measurement of the processing ( 202 ) will be the same in its respective cell as it is in the current cell ( 103 ), which represents the current position of the autonomous device, whereas a centre cell, associated with the current cell ( 103 ), is assigned a maximum probability while other cells within the reference grid ( 100 ) have a probability assigned, which lowers with an increase of a distance of a cell from the current cell ( 103 ); updating ( 207 ) the probabilities by applying the reference grid ( 100 ) to the global grid at its current position such that every cell on the reference grid ( 100 ) corresponds unambiguously to one cell on the global grid; and moving the autonomous device to a next cell of the global grid ( 208 ) and setting said next cell as the current cell ( 201 ) in order to process the next cell.