A tracking system is provided for tracking an objects. A first and a second trackable member each have an inertial sensor unit producing at least orientation-based data. A processing unit receives the orientation-based data from the trackable members. The processing unit has an orientation calculator calculating an orientation of the second trackable member with respect to the first trackable member from the orientation-based data of both said trackable members, whereby the processing unit calculates an orientation of the objects. A method is also provided.