signal u2225 a u2225 and the norm of the gyroscope signal i e angular velocity u2225 q u2225 where the euclidian norm of a vector x x 1 x 2 x 3 is defined as u2225 x u2225 u221a x 1 2 x 2 2 x 3 2 regarding the period between ts and ho events it is characterized by a lower amount of movement since the ground applies a mechanical constraint to the foot and it is so called foot flat period consequently ts and ho features are detected using a threshold on derivative of angular velocity norm u2225 q u2225 u2032 on pitch angular velocity u03c9 p and the absolute value of the jerk indicated by the derivative of accelerometer signal 39 s norm u2225 a u2225 u2032 for all inertial signals the use of the norm of 3d signals allows being independent of sensor placement on the foot making it more repeatable and no specific calibration to align them with anatomical frames cappozzo 1995 is required whereas the use of only pitch signal allow to use a single sensor configuration those entire hypotheses for detecting temporal events are illustrated in fig3 during running gait foot kinematics can be slightly modified other robust features and.