Multi-spot sequential ultrasonic welding is a promising joining technique for thermoplastic composites in an overlap configuration. In the framework of the EU Clean Sky 2 Multi-functional fuselage demonstrator (MFFD) and the lower shell SmarT multifUNctioNal and INteGrated TP fuselage (STUNNING) projects, a robot-based sequential ultrasonic spot welding process has been developed for joining of large thermoplastic structural components, based on process development steps reported in previous work [1]. The technology is being demonstrated on a full-scale thermoplastic composite fuselage section of 8 m length and 4 m shell radius. The fuselage skin is being joined to longitudinal stringers and circumferential frames through welded clips, in the lower shell of the fuselage demonstrator. This paper presents an overview of the robotic sequential welding technology developed at SAM|XL in collaboration with Delft University of Technology and the ongoing sub-assembly process of the fuselage demonstrator, led by GKN Aerospace.