Method for activating a vehicle function and associated activation device

A method for activating a vehicle function, by way of an activation device that is intended to be installed in a vehicle and comprises at least one transceiver capable of using ultra-high frequency to communicate with “hands-free” access equipment carried by a user, said equipment being equipped with a magnetometer and a gyroscope, the activation of the function being triggered by detection of the presence of the user in a predetermined zone around the vehicle and on the basis of a result of authentication of the “hands-free” access equipment by the vehicle, wherein the at least one transceiver is first equipped with a gyroscope and a magnetometer and two receiving antennas that have a coefficient of electromagnetic coupling between them that is below a threshold, and wherein said method comprises the following steps with each footstep of the user and for at least two consecutive footsteps:

• a) ultra-high frequency transmission of a signal comprising representative data of the gyroscope and the magnetometer of the “hands-free” access equipment to the vehicle,
• b) comparison of received data with representative values of the gyroscope and the magnetometer of the at least one transceiver,
• c) determination of a first direction of the user between the two footsteps towards the at least one transceiver on the basis of said comparison,
• d) determination of a second direction of the user between the two footsteps, based on an estimation of a first angle of arrival of said signal towards the at least one transceiver through calculation of a phase shift of the received signal between the two antennas, and of a distance between the “hands-free” access equipment and the at least one transceiver,
• e) comparison of the first direction and the second direction,
• f) activation of the vehicle function on the basis of the result of said comparison.