A robotic work tool system (200) comprising a robotic work tool (100) comprising a collision detection sensor (190), said collision detection sensor (190) comprising a first sensor element (191) and a plurality of second sensor elements (192), wherein said first sensor element (191) is movably arranged with respect to said plurality of second sensor elements (192), wherein said robotic work tool (100) is configured to detect that said first sensor element (191) is proximate a peripheral second sensor element (192) and in response thereto determine that a collision has been detected, and detect that said first sensor element (191) is not proximate any peripheral second sensor element (192) and in response thereto determine that a lift has been detected.
