Path Generation, Control, and Monitoring

Abstract

A critical issue in additive manufacturing (AM) is the control of the printer actuators such that the deposition of material (or a few different materials) takes place in an organized way. Typically, the actuators are connected with a low-level controller that can receive computer numerical control (CNC) instruction. A 3D printer controller is, usually, expected to receive a set of CNC instructions in a format called G-Code, where a set of control instructions is provided. These instructions include the necessary settings for the printer to work (e.g., a temperature setup) and printer head movement instructions (e.g., the x-, y-, and z-positions in reference axes). The set of the printer actuators positions, where some operations take place, is called the printer path. Path planning or generation corresponds to the computation of the printer head trajectory during a period of time where the object is to be built. A five-degree of freedom/5-axis 3D printer that considers a hybrid process based on additive manufacturing of composites with long or short fibers reinforced thermoplastic matrix is being addressed in this book. The 5-axis printer considers the three usual degrees of freedom plus two additional degrees of freedom, located at the printer table. While software for 3D printing is still possible to be used, full advantage of the printer potential demands for new path generation strategies. We start in Sect. 6.1 by introducing the reader to the optimal orientation of objects, where object orientation is optimal w.r.t. some objective functions that measure the printing performance. Since we are majorly interested in a 5-axis printer control, we present a printer emulator in Sect. 6.2, which allows us to monitor the printing process. Path generation is addressed in Sect. 6.3. We aim to provide flat and curved path planning to take advantage on the 5-axis printer, and in Sect. 6.4, we provide a strategy to print complex objects. The proposed approach for path planning can also be used for inspecting the printed objects by a non-destructive test, and we introduce this topic in Sect. 6.5.