Doctoral Dissertations

Keywords and Phrases

Additive manufacturing; Contour control; Force control


"The need for changing the control objective during the process has been reported in many systems in manufacturing, robotics, etc. However, not many works have been devoted to systematically investigating the proper strategies for these types of problems. In this dissertation, two approaches to such problems have been suggested for fast varying systems. The first approach, addresses problems where some of the objectives are statically related to the states of the systems. Hierarchical Optimal Control was proposed to simplify the nonlinearity caused by adding the statically related objectives into control problem. The proposed method was implemented for contour-position control of motion systems as well as force-position control of end milling processes. It was shown for a motion control system, when contour tracking is important, the controller can reduce the contour error even when the axial control signals are saturating. Also, for end milling processes it was shown that during machining sharp edges where, excessive cutting forces can cause tool breakage, by using the proposed controller, force can be bounded without sacrificing the position tracking performance. The second approach that was proposed (Hierarchical Model Predictive Control), addressed the problems where all the objectives are dynamically related. In this method neural network approximation methods were used to convert a nonlinear optimization problem into an explicit form which is feasible for real time implementation. This method was implemented for force-velocity control of ram based freeform extrusion fabrication of ceramics. Excellent extrusion results were achieved with the proposed method showing excellent performance for different changes in control objective during the process"--Abstract, page iv.


Landers, Robert G.

Committee Member(s)

Balakrishnan, S. N.
Bristow, Douglas A.
Leu, M. C. (Ming-Chuan)
Sarangapani, Jagannathan, 1965-


Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Mechanical Engineering


Missouri University of Science and Technology. Intelligent Systems Center

Research Center/Lab(s)

Intelligent Systems Center


Missouri University of Science and Technology

Publication Date

Spring 2016

Journal article titles appearing in thesis/dissertation

  • Hierarchical optimal contour control of motion systems
  • Hierarchical optimal force-position control of complex manufacturing processes
  • Hierarchical explicit model predictive control for extrusion fabrication processes


x, 118 pages

Note about bibliography

Includes bibliographic references.


© 2016 Hesam Zomorodi Moghadam, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Subject Headings

Manufacturing processes -- Automation
Rapid prototyping
Solid freeform fabrication
Ceramics -- Extrusion

Thesis Number

T 10931

Electronic OCLC #