Modeling and control of an easy-to-use direct write printing system for fabrication of bone scaffolds

3D printing is a diverse field, in particular for biological or bioengineering applications. As a result, research teams working in this area are often multidisciplinary. A (bio) 3D printer in this research environment should balance performance with ease of use to enable system adjustments and operation for all machine users from a wide range of disciplines. This work presented results in the development of an easy-to-use direct-write (DW) printing system for fabrication of rectilinear bone scaffolds. Common motion control problems, which are barriers to ease of use, were addressed and implemented in a way that researchers outside of the controls field could easily understand. The main goal of this work was to ensure that this system could be easily operated and adjusted by future users to enable a wide range of projects. In addition, we hope the design and development steps presented can be extended to other systems to lower the technical hurdle of motion control for any laboratory or researcher with an interest in using DW printing in his or her field. The design aspects and control parameters included a dynamic model of a 3-stage positioning system for bone scaffold fabrication, a feedforward plus feedback controller design, active pressure regulation, and a user-friendly iterative learning control (ILC) compensator. The ability of the (bio) 3D printer to print rectilinear bone scaffolds is presented. Further, prelimineary work in precise start/stop of ink flow and curved scaffold rods was presented to enable printing of multi-material and curvilinear bone scaffolds in future projects