A robotic work tool system, comprising a robotic work tool, said robotic work tool comprising a position determining device for determining a current position and at least one deduced reckoning (also known as dead reckoning) navigation sensor, the robotic work tool being configured to determine that a reliable and accurate current position is possible to determine and in response thereto determine an expected navigation parameter, compare the expected navigation parameter to a current navigation parameter to determine a navigation error, determine if the navigation error is negligible, and if the navigation error is not negligible, cause the robotic work tool to change its trajectory to accommodate for the navigation error. Wherein the robotic work tool (100) is further configured to change the trajectory by aligning the trajectory with an expected trajectory, wherein the expected trajectory is determined as an expected direction originating from an expected position and wherein the robotic work tool (100) is configured to change the trajectory by returning to a position that should have been visited and aligning the trajectory with the expected direction originating from the expected position, said position that should have been visited being aligned with the expected direction originating from the expected position.L'invention concerne un système d'outil de travail robotique, comprenant un outil de travail robotique, ledit outil de travail robotique comprenant un dispositif de détermination de position pour déterminer une position actuelle et au moins un capteur de navigation de point déduit (également connu sous le nom de point estimé), l'outil de travail robotique étant configuré pour déterminer qu'une position actuelle fiable et précise est possible pour déterminer et, en réponse à cela, déterminer un paramètre de navigation attendu, comparer le paramètre de navigation attendu à un paramètre de navigation actuel pour déterminer une erreur de navigation, détermi
