PhD Candidate in Mechanical Engineering
Co-advised by Dr. Alleyne and Dr. Wagoner Johnson.
My projects build off of my M.S. thesis in which I designed and constructed an additive manufacturing system from scratch, providing me with a unique overlap of expertise in robotics, controls and manufacturing. My current work involves control theory, simulation, and hardware, providing me with a well rounded graduate experience.
Research Interests: Control Systems, Biofabrication, Additive Manufacturing, Control Systems, Iterative Learning Control
BIOFABRICATION OF BONE SCAFFOLDS WITH CURVILINEAR ARCHITECTURE
The target application of my work in additive manufacturing is the fabrication of bone replacement material to repair defects above a critical size. The development of patient-specific bone scaffolds with spatially varying architecture requires precise material placement to ensure in vivo functionality.
DIRECT PROCESS FEEDBACK IN EXTRUSION-BASED ADDITIVE MANUFACTURING
A major limitation in extrusion based additive manufacturing is the lack of direct process control, which limits the resolution and design complexity of printed constructs. But, we can use a combination of improved sensing and improved control methods to improve material placement. Therefore, I am developing in situ process monitoring and control strategies to improve precision of the fabrication of bone scaffolds with complex geometry.
DEVELOPMENT OF NOVEL ITERATIVE LEARNING CONTROL (ILC) DESIGN LAWS
My work on the theoretical side involves the development of novel iterative learning control (ILC) laws. I am investigating how we can achieve more aggressive rates of learning in cases with little to no plant knowledge. An example scenario is extrusion based bioprinting, where the material behavior is nonlinear and uncertain.
DEVELOPMENT AND CONTROL OF A DIRECT-WRITE PRINTER
One feature of my project is the dynamic modeling and control of a Micro Robotic Deposition System. This work builds off y M.S. thesis in which I designed and constructed an additive manufacturing robot from scratch. The image on the left is the second additive manufacturing system I designed and built, which is being used to fabricate patient-specific bone scaffolds. The machine is equipped with a Keyence Laser Displacement Sensor for processing monitoring during fabrication.
A.A. Armstrong, J.A. Norato, A.G. Alleyne, and A.J. Wagoner Johnson, "Direct Process Feedback in Extrusion-based 3D Bioprinting," Biofabrication, 2019 (accepted).
Tisha, A.L., A.A. Armstrong, C. Lopez-Ortiz, and A.J. Wagoner Johnson, "A Review of Skeletal Muscle Adaptations and Passive Muscle Stiffness in Cerebral Palsy," Journal of Applied Biomechanics, 35, 1, 2019.
Journal Publications Under Review
A.A. Armstrong, A.J. Wagoner Johnson, and A.G. Alleyne, "An Improved Approach to Iterative Learning Control for Uncertain Systems," submitted to Trans. Control System Tech. May 2019.
Armstrong, A., A. Wagoner Johnson, and A. Alleyne, "Improved Cross-Coupled Iterative Learning Control for Contouring NURBS Curves," Proceedings of the ASME 2018 Dynamic Systems and Control Conference (DSCC2018) September 30-October 3, 2018, Atlanta, Georgia, USA, DSCC2018-9145, 2018. doi:10.1115/DSCC2018-9145
Armstrong, A., A. Alleyne, and A. J. Wagoner Johnson, "Easy-to-use 3D printer for fabrication of biological scaffolds," Proceedings of the ASME 2017 Dynamic Systems and Controls Conference, October 11-13, 2017, Tysons Corner, Virginia DSCC2017-5147. doi:10.1115/DSCC2017-5147
Dobelin, N.; Armstrong, A.; Wagoner Johnson, A.; Bohner, M.; "Phosphate Evaporation by Thermal Treatment of CaP Ceramics," Proc. of the 28th Annual Meeting of the International Society for Ceramics in Medicine (Bioceramics 28), November 2016.
"Modeling and Control of an Easy-to-Use Direct Write Printing System for Fabrication of Bone Scaffolds,” M.S. Thesis, Dept. Mech. Eng., Univ. Illinois Urbana-Champaign, Urbana, IL., July 2017. Link
A LITTLE MORE ABOUT ME...
I am passionate about STEM outreach, and started a graduate student outreach organization called ENVISION (ENgineers Volunteering in STEM educatION).
I played competitive golf for 12 years, and was the captain of the Notre Dame women's golf team. Need a
If I am not at the lab, you will likely find me cooking, at the gym (I love powerlifting!), or hanging out with my dog named Marshmallow.
Two of my favorite things are Taylor Swift and Holidays. Like Taylor Swift and Holidays as much as I do? Check out my first attempt at a Halloween Light show.
WHERE TO FIND ME
1206 W Green Street
University of Illinois at Urbana-Champaign
Urbana, IL 61801