Additive manufacturing (AM) technologies not only reduce the new product development cycle, but also allow users to design models of their own style. Fused Filament Fabrication is a method that builds a model of rapid prototyping and product in customization fashion. With path generation and planning methods for additive manufacturing, common 3D printers print an object layer by layer. However, when multiple objects are printed at the same time, the nozzle moves among objects and always increases enormous distance of the transition travel. In this paper, a novel trajectory generation and planning algorithm are proposed for printing multi-object structures simultaneously. The algorithm has two parts. In the first part, different textures of different objects are created respectively in the same batch. This process solves the problem that objects must have same texture in conventional processes. For the other process, trajectory planning optimizes motion paths of the printing head to reduce the period of fabrication. We have demonstrated the success of the proposed methods using the development of hybrid 3D printing machine consists of additive and subtractive processes in our NTU robotics and automation lab.
