The present disclosure relates to an articulated self-propelled robotic tool 1 with first and second platforms 3, 7, each comprising a wheel set 5, 9 driven by motors. A link arrangement connects the first platform to the second platform at a turning axis 11. A driving error is determined by recording a driving input to the motors and a resulting movement parameter, comparing the resulting movement with an estimated resulting movement which is based on the driving input. Slip is detected using the driving error.