- Curriculum Vitae
- Ph.D. Candidate in Mechanical Engineering – University of Illinois
- M.S. Mechanical Engineering – University of Illinois (August 2017)
- B.S. Mechanical Engineering – University of Notre Dame (May 2015)
- Research Interests: Control Systems, Manufacturing Systems, Biomechanics, Iterative Learning Control
This research is sponsored by the National Science Foundation (NSF) Graduate Research Fellowship Program (GRFP).
Dynamic modeling and control of a Micro Robotic Deposition System, with bone scaffold manufacturing as the target application. In this research, precision motion control techniques will be explored to achieve the high levels of precision and response time demanded by microscale applications. Sensing techniques and control algorithms will be employed to enable printing of bone scaffolds with advanced architecture.
The development of patient-specific bone scaffolds with spatially varying architecture requires precise three-dimensional additive manufacturing capabilities. But, a major limitation in extrusion based additive manufacturing is the lack of direct process control, which limits the resolution and design complexity. Therefore, I am developing in situ process monitoring and control strategies to improve precision in 3D bioprinting to enable precise printing of bone scaffolds with complex geometry.
In addition, my work on the theoretical side involves advancement of control design in iterative learning applications. The speed of convergence to the appropriate input signal for iterative learning control (ILC) is currently limited by the level of knowledge of the plant model. If the plant model is uncertain, caution must be taken in convergence and this can be slow. I am investigating how we can achieve more aggressive rates of learning in cases with little to no plant knowledge.
Relevant Publications (Thesis)
- Armstrong, Ashley, “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. (PDF)
Relevant Publications (Journal)
- A.A. Armstrong, A.G. Alleyne, and A.J. Wagoner Johnson, “1D and 2D error assessment and correction for extrusion-based bioprinting using process sensing and control strategies,” Biofabrication, 2020.
- A.A. Armstrong, and A.G. Alleyne, “A Multi-Input Single-Output Iterative Learning Control for Improved Material Placement in Extrusion-based Additive Manufacturing,” Control Engineering Practice, 2020 (submitted).
- A.A. Armstrong, A.G. Alleyne, and A.J. Wagoner Johnson, “An Improved Approach to Iterative Learning Control for Uncertain Systems,” IEEE Trans. Control System Tech., 2019.
- A.A. Armstrong, J.A. Norato, A.G. Alleyne, and A.J. Wagoner Johnson, “Direct Process Feedback in Extrusion-based 3D Bioprinting,” Biofabrication, 2019.
- A.A. Armstrong, Tisha, A.L., 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. https://doi.org/10.1123/jab.2018-0049
Relevant Publications (Conference)
- Armstrong, A., and A. Alleyne, “An Improved Iterative Learning Control for Uncertain Multi-Axis Systems,” Proceedings of the 2020 American Controls Conference (ACC) July 1-3, 2020.
- 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.
Oral Presentations and Poster Sessions
- “Direct Process Feedback in Extrusion-based Additive Manufacturing Using Learning Control,” Materials Science & Technology Conference, October 2019, Portland, OR.
- “Direct Process Feedback in Extrusion-based Additive Manufacturing Using an ILC-based Approach,” Materials Science & Technology Conference, October 2018, Columbus, OH.
- “Improved Cross-Coupled Iterative Learning Control for Contouring NURBS Curves,” ASME 2018
Dynamic Systems and Control Conference, October 2018, Atlanta, GA.
- “3D ILC for fabrication of advanced architecture bone scaffolds,” Poster Session at the Coordinated Science Laboratory (CSL) Student Conference, February 2018 – won Best Poster Award.
- “Easy-to-use 3D printer for fabrication of biological scaffolds,” ASME 2017 Dynamic Systems and Control Conference, October 2017, Tysons Corner, VA.