Strategy for returning to service a wheel unit declared to have become detached in a motor vehicle tyre pressure monitoring system TPMS

A tire pressure monitoring system (TPMS) for checking tire pressure of an automotive vehicle, the TPMS system comprising:

• a central unit;
• and
• at least one wheel unit,
• each of the at least one wheel unit comprising a pressure sensor and an emitter to allow pressure check transmissions from the at least one wheel unit to the central unit taking place at a first frequency and each comprising pressure measurements of the tire and measurements used to calculate a detachment parameter for the at least one wheel unit,
• a test module configured to determine whether each of the at least one wheel unit is in a detached state or in an operational state, the at least one wheel unit being declared detached if the detachment parameter is greater than or equal to a predetermined nominal threshold of detachment;
• and
• a return-to-service module configured to, when the at least one wheel unit has been detected as being in the detached state, toggle a state of the at least one wheel unit from the detached state to the operational state if and only if the following two conditions are fulfilled:
• a first condition according to which, since the at least one wheel unit was declared detached, a pressure less than or equal to a reference atmospheric pressure has been measured while the vehicle was at rest,
• a second condition according to which, after this rest, at least one of the following two criteria is satisfied:
• the detachment parameter has not attained the nominal detachment threshold in a first movement time;
• an attachment index is detected under specific evaluation conditions, the attachment index being that a measurement signal of the at least one wheel unit exhibits a particular shape representative of an attached state of the wheel unit.