A process control system and a method for process control of a solid-state additive manufacturing system capable of performing various additive processes, such as joining, additive manufacturing, coating, repair and others, are disclosed. The process control system is capable of simultaneous measuring, monitoring and controlling multiple process variables, viz. material temperature, actuator down force, tool force (or torque), tool position, tool angular and transverse velocity, spindle torque (angular velocity), filler flow rate, filler composition, track width, inert gas flow rate and others. A feeding system for continuous supply of filler material to the solid-state additive manufacturing system is also disclosed. The filler material can be in a form of a powder, granules, briquettes, beads, flakes, wires, rods, films, scrap pieces, sheets, blocks or their combinations. Methods for generation of different periodic and non-periodic structures and joints using the process-controlled solid-state additive manufacturing system are also disclosed.