Control of Screw Extruder Delay/Partial Differential Equation (PDE) Dynamics for 3D Printing

由于增材制造在技术、经济和社会方面的潜在影响，该项目致力于控制器的设计，以消除实现3D打印高速和产品质量的一些关键瓶颈。该项目将建立既具有高研究价值又适合工业使用的控制和建模方法，在构建速度和零件质量方面进行改进。与标准的熔融沉积成型和基于注射器的挤出工艺相比，我们所解决的螺杆挤出工艺的新配置可以允许连续进料，加快生产，升级混合能力，同时有效地减少熔体的热降解和此类工艺的成本。在过去的项目中，PI监督了20多名来自弱势群体的学生，如女性、西班牙裔和非洲裔美国人，而目前的项目将邀请来自弱势群体的特定个人作为顾问和合作者。螺杆挤出机质量和热流的偏微分方程（PDE）模型将用于设计精确和鲁棒的控制器，以取代现有的3D打印控制方法，这些方法通常使用保守的黑盒或集总模型构建，这降低了它们对大范围材料的性能。此外，还将讨论影响粘度演变和凝固过程的熔体热行为的控制。控制设计将基于螺杆挤出机的无限维模型，包括由pde组成的双区模型，该模型通过常微分方程描述的移动界面耦合。新颖的控制设计技术，从PI的无限维反演工具包将开发用于此目的。设计的控制器的实现将在PI组开发的实验平台上进行。该项目将为通过移动界面耦合的偏微分方程的一般控制领域提供进展，除了挤出机外，还出现在多相流，晶体生长，冷冻干燥和蒸馏过程中。

Motivated by both the potential for a technological, economic, and social impact of additive manufacturing, the project is dedicated to the design of controllers to remove some of the key bottlenecks to achieving high speed and product quality in 3D printing. The project will build control and modeling methodologies that are both of high research value and are suitable for industrial use, going after improvements in the build speed and part quality. Compared to the standard Fused Deposition Modeling and Syringe Based extrusion processes, the novel configuration of the Screw Extruder process that we address may allow continuous feeding, speed up production, and upgrade the mixing capabilities, while efficiently reducing the thermal degradation of the melt and the cost for such processes. The PI has supervised two dozen students from underrepresented groups on past projects, such as women, Hispanics, and African-Americans, and the present project will involve specific individuals from underserved communities as advisees and collaborators. Partial Differential Equation (PDE) models of mass and thermal flows in the Screw Extruder will be used to design accurate and robust controllers, to replace the existing control methods for 3D printing, which are typically constructed using conservative black-box or lumped models, which reduces their performance for a large range of materials. Moreover, control of the melt thermal behavior that impacts viscosity evolution and the solidification process will be addressed. The control design will be based on infinite-dimensional models of screw extruders, including a bi-zone model consisting of PDEs coupled through a moving interface described by an ordinary differential equation. Novel control design techniques from the PI's infinite-dimensional backstepping toolkit will be developed for this purpose. Implementation of the designed controller will be performed on an experimental platform developed in the PI's group. The project will provide advancements to the general area of control of PDEs that are coupled through a moving interface, which, besides extruders, arise in multi-phase flows, crystal growth, freeze-drying, and distillation processes.