A system for autonomous welding of two chamfered panels (191, 192), in particular along a seam joint, according to a welding sequence comprising a plurality of passes and comprising a. a carriage comprising motorized means for moving along a welded joint; b. a platform carried by the carriage comprising actuators and guide means, called movement axes, capable of supporting and moving an effector relative to the carriage according to a movement comprising two axes (y,z) perpendicular to the direction (x) in which the carriage advances along the welded joint; c. a welding torch supported as an effector by said platform; d. a profilometer carried by the carriage and adapted to acquire a signal depending on the profile of the welded joint in front of the welding torch in the direction in which the carriage advances along said weld joint; e. a control computer (160, 161) capable of: ei. acquiring the signal from the profilometer to measure the profile of an open section of the welded joint over all or part of the length of the welded joint, the open section of the welded joint being the part not filled with material of a section of the space delimited, at the welded joint, by the edges of the panels to be assembled; eii. performing profile calculations of the welded joint; eiii. controlling the movement axes of the platform and the motorized means of the carriage as a function of the calculation carried out in eii); characterized in that: - the computer calculates, from the profilometer acquisition, the successive positions of the barycenter in the y-z plane of the open sections of the profile measured in ei) along the welded joint; the successive positions of the barycenter in the x-y plane define the trajectory in x of the welding torch along the welded joint; - the controlling of the motorized means of the carriage is carried out by tracking successive positions of the barycenter of the open section of the profile measured in ei) along the welded joint; - the controlling of the axes of movement of the platform is carried out so that the effector is moved between two average slopes of the chamfered edges of the weld, calculated during the first measurement of said welded joint, carried out before the welding of the panels. a. a carriage comprising motorized means for moving along a welded joint; b. a platform carried by the carriage comprising actuators and guide means, called movement axes, capable of supporting and moving an effector relative to the carriage according to a movement comprising two axes (y,z) perpendicular to the direction (x) in which the carriage advances along the welded joint; c. a welding torch supported as an effector by said platform; d. a profilometer carried by the carriage and adapted to acquire a signal depending on the profile of the welded joint in front of the welding torch in the direction in which the carriage advances along said weld joint; e. a control computer (160, 161) capable of: ei. acquiring the signal from the profilometer to measure the profile of an open section of the welded joint over all or part of the length of the welded joint, the open section of the welded joint being the part not filled with material of a section of the space delimited, at the welded joint, by the edges of the panels to be assembled; eii. performing profile calculations of the welded joint; eiii. controlling the movement axes of the platform and the motorized means of the carriage as a function of the calculation carried out in eii); ei. acquiring the signal from the profilometer to measure the profile of an open section of the welded joint over all or part of the length of the welded joint, the open section of the welded joint being the part not filled with material of a section of the space delimited, at the welded joint, by the edges of the panels to be assembled; eii. performing profile calculations of the welded joint; eiii. controlling the movement axes of the platform and the motorized means of the carriage as a function of the calculation carried out in eii); - the computer calculates, from the profilometer acquisition, the successive positions of the barycenter in the y-z plane of the open sections of the profile measured in ei) along the welded joint; the successive positions of the barycenter in the x-y plane define the trajectory in x of the welding torch along the welded joint; - the controlling of the motorized means of the carriage is carried out by tracking successive positions of the barycenter of the open section of the profile measured in ei) along the welded joint; - the controlling of the axes of movement of the platform is carried out so that the effector is moved between two average slopes of the chamfered edges of the weld, calculated during the first measurement of said welded joint, carried out before the welding of the panels.