MINIMIZING STRUCTURAL JITTER IN OPTICAL SENSOR SYSTEMS USING PARAMETRIC DYNAMIC RESPONSE OPTIMIZATION by RICHARD L. SCOTT DISSERTATION Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at The University of Texas at Arlington December 2018 Arlington, Texas Supervising Committee: B. P. Wang, Committee Chair Ashfaq Adnan Brian Dennis Kent Lawrence Seiichi Nomura ABSTRACT MINIMIZING STRUCTURAL JITTER IN OPTICAL SENSOR SYSTEMS USING PARAMETRIC DYNAMIC RESPONSE OPTIMIZATION Richard L. Scott, PhD The University of Texas at Arlington, 2018 Supervising Professor: B. P. Wang Deployed in manned and unmanned aircraft, military and commercial ground vehicles, and security and monitoring systems, optical sensor systems are ubiquitous. Developing an optical sensor system includes calculating image motion due to structural dynamics—hereafter, “structural jitter”—and adjusting system design to reduce structural jitter and meet requirements. The current process for adjusting the structural design to reduce structural jitter is manual, labor intensive, and driven mostly by engineering judgment. This paper proposes a well-defined optimization process that provides a more explicit approach to the structural design and likely will reduce labor as the process matures. This project focuses on employing dynamic response optimization to minimize structural jitter caused by random vibration. Investigation of the literature has also shown that performing this optimization during the design ii phase of an optical path-supporting structure has not been documented previously. This dissertation details the optimization process so that researchers and designers may implement it in their efforts to improve image quality in sensor systems. iii Copyright by Richard L. Scott 2018 LIST OF FIGURES Figure 1. Multispectral Targeting System on the General Atomics MQ-1 Predator © 2018 Raytheon Company ....................................................... 11 Figure 2. Venn diagram of researcher’s areas of interest relative to structural jitter ........................................................................................... 12 Figure 3. Examples of Raytheon electro-optic / infrared sensor systems. © 2017 Raytheon Company ......................................................................... 13 Figure 4. Image blur due to sensor motion ............................................... 18 Figure 5. Example two-axis optical sensor system used for structural jitter calculations and optimization .................................................................... 19 Figure 6. Differences between Doyle (2007) work and research in this dissertation ............................................................................................... 27 Figure 7. Jitter Minimization Calculation Process ..................................... 31 Figure 8. Jitter Minimization User Process ............................................... 43 Figure 9. Three-beam design………………………………………………...52 Figure 10. Finite element model of the three-beam design ...................... 55 Figure 11. Plots of the final design variables and convergence of the objective function for Example 1 ............................................................... 58 Figure 12. Stepped shell design ............................................................... 60 Figure 13. Plots of the final design variables and convergence of the objective function for Example 2 ............................................................... 62 Figure 14. Two-axis, optical imaging system ............................................ 63 Figure 15. The six design variables for the imaging system optimization .. ................................................................................................................. 65 v Figure 16. Plots of the final design variables and convergence of the objective function for the optical imaging system design .......................... 71 vi LIST OF TABLES Table 1. References that discuss the minimization of image motion due to dynamic loads or image shift due to static loads ...................................... 25 vii Table of Contents ABSTRACT ............................................................................................... ii List of Figures .......................................................................................... v List of Tables ......................................................................................... vii CHAPTER 1: INTRODUCTION ............................................................... 11 Motivation for research ........................................................................ 11 Research methodology ........................................................................ 14 Research objective .............................................................................. 14 Scope of work ...................................................................................... 15 CHAPTER 2: LITERATURE SURVEY .................................................... 17 Areas of interest and gaps in the literature .......................................... 17 Investigation of structural jitter .......................................................... 18 Investigation of dynamic response optimization ................................... 20 Search for use of dynamic response optimization to minimize structural jitter ...................................................................................................... 24 CHAPTER 3: RESEARCH AND RESULTS............................................ 28 Investigation summary ......................................................................... 28 Calculation Process ............................................................................. 31 Matlab user parameters module ....................................................... 32 Matlab Main module ......................................................................... 32 Matlab objFun module ...................................................................... 37 viii Matlab Read Optics Data module ..................................................... 38 Matlab Modify FEM Input module ..................................................... 39 Matlab Read Modal Data module ..................................................... 39 Matlab Calculate Dynamics module ................................................. 40 Matlab conFun Module ........................................................................ 42 User Process .................................................................................... 42 CHAPTER 4: EXAMPLES ...................................................................... 51 Three beam design .............................................................................. 51 Stepped shell design ............................................................................ 59 Optical imaging system design ............................................................ 63 CHAPTER 5: SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS ................................................................................................................ 72 References ............................................................................................. 75 Appendix A............................................................................................. 79 An Investigation of Methods Used to Calculate Image Motion Due to Structural Flexure in Optical Systems .................................................. 79 Appendix B........................................................................................... 141 Code for Example 1 ........................................................................... 141 Appendix C........................................................................................... 189 Code for Example 2 ........................................................................... 189 Appendix D........................................................................................... 231 ix Code for Example 3 ........................................................................... 231 Biographical Information .................................................................... 280 x CHAPTER 1: INTRODUCTION Motivation for research As a structural analyst at Raytheon Company, I perform structural design, analysis, and testing of electro-optic/infrared imaging systems. An example of these systems is the Multi-Spectral Targeting System on the General Atomics MQ-1 Predator shown in Figure 1: Figure 1. Multispectral Targeting System on the General Atomics MQ-1 Predator © 2018 Raytheon Company. Images taken from https://www.raytheon.com. License per https://www.raytheon.com/legal/ A key task of the structural analyst on this type of program is to calculate image motion due to structural dynamics, hereafter referred to as structural jitter, and to guide the mechanical design to meet the structural jitter requirements. I questioned whether an optimization process existed to aid in these tasks, and I further considered whether research in my areas of interest might support the task of structural jitter analysis. Three major areas of interest are structural dynamics, opto-mechanical analysis, 11 and structural optimization. Figure 2 shows a Venn diagram of these subject areas. The structural jitter work task and the overlapping region of these subject areas of interest suggested that research in structural optimization to minimize structural