Device and method for command and/or control of a particular pressure

The system controls the pressure in variable volume cushions (10,12) in the seat (18) and backrest (22) of the vehicle seat (14). The cushions are connected (28,30) to piston-cylinder units (24,26) with electric motors (40,41) moving the pistons (31,32). A common line (50) connects the working chambers (34,36) to a pump (46) mounted on a module (58) with a computer (56).