The invention relates to heterocyclic derivatives of formula, or pharmaceutically-acceptable salts thereof, which possess antithrombotic and anticoagulant properties and are accordingly useful in methods of treatment of humans or animals. The first and second fingers 14 and 11 are shaped such that when the large plate 4 rotates in a first direction a, the first finger 14 drives the second 11 which moves around a first side 20 of said first finger to release the locking pallet-stone. A pitch frequency converter determines an inverse of a pitch period to calculate a pitch frequency. The second power storage device is connected to the PCU through SMR3 and SMR4.