An impact motion tracking system for tracking an object in a three-dimensional space, whereby: - a motion tracking sensor comprises a housing , a magnetic measurement module and an inertial measurement module ; - a transmitter module generates magnetic fields; - said magnetic measurement module measures magnetic fields generated by said transmitter module , said magnetic measurement modules has a fixed positional relationship with at least one object portion of said object ; - said inertial measurement module measures at least one of a linear acceleration and an angular acceleration, said inertial measurement module has a fixed positional relationship with said at least one object portion ; - an electronic processor receives measured signals from said motion tracking sensor ; - said electronic processor derives an impact motion information for said object portion based on received measured signals from said inertial measurement module ; - said electronic processor derives a magnetic motion information for said object portion based on received measured signals from said magnetic measurement module ; - said electronic processor periodically calibrates impact motion information with magnetic motion information; characterized in that - said object being at least one of a crash test dummy and a vehicle to be crashed ; - one magnetic measurement module serves as reference magnetic measurement module for said object portion ; and said electronic processor periodically calibrates magnetic motion information from other magnetic measurement modules with referential magnetic motion information from said reference magnetic measurement module . - a motion tracking sensor comprises a housing , a magnetic measurement module and an inertial measurement module ; - a transmitter module generates magnetic fields; - said magnetic measurement module measures magnetic fields generated by said transmitter module , said magnetic measurement modules has a fixed positional relationship with at least one object portion of said object ; - said inertial measurement module measures at least one of a linear acceleration and an angular acceleration, said inertial measurement module has a fixed positional relationship with said at least one object portion ; - an electronic processor receives measured signals from said motion tracking sensor ; - said electronic processor derives an impact motion information for said object portion based on received measured signals from said inertial measurement module ; - said electronic processor derives a magnetic motion information for said object portion based on received measured signals from said magnetic measurement module ; - said electronic processor periodically calibrates impact motion information with magnetic motion information; characterized in that - said object being at least one of a crash test dummy and a vehicle to be crashed ; - one magnetic measurement module serves as reference magnetic measurement module for said object portion ; and said electronic processor periodically calibrates magnetic motion information from other magnetic measurement modules with referential magnetic motion information from said reference magnetic measurement module . <EOS>