High Altitude Balloon with Stabilized Camera System
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High Altitude Balloon with Stabilized Camera System Lee Wasilenko APSC 479 Engineering Physics University of British Columbia January 10, 2011 2 Executive Summary This report describes the design and testing of a camera stabilization system intended for use with on a high altitude balloon. The objective is to be able to control and stabilize a camera with enough precision to obtain clear photos of the stars and other celestial bodies. This report describes several possible mechanical designs but no clearly superior mechanical design emerged during the time allotted to the project. Tests were performed to determine an acceptable level of relative displacement between the camera and its subject. This was determined to be <0.5deg overall and can also be characterized as a rate <0.05/E(t) where E(t) is the shutter speed of the camera. The team constructed and tested a simple stabilization system with a gyroscopic rate sensor, an Arduino microcontroller, and a servo. The system behaviour was determined by PI code written by the team. The team found that this system was not sufficient to provide the stringent level of control required for a stable image. The displacement measured by the team was 5.7deg, which is 10 times higher than that required. Further optimization and design research must be performed before the stability requirements can be met. 3 Table of Contents Executive Summary ....................................................................................................................................... 3 List of Figures ................................................................................................................................................ 5 1. Background and Motivation ................................................................................................................. 6 2 Project Objectives ................................................................................................................................. 9 2.1 Specific Objectives for APSC 479................................................................................................... 9 2.2 Objectives for future HAB Launch ............................................................................................... 10 2.3 Scope and Limitations ................................................................................................................. 11 2.4 Organization ................................................................................................................................ 11 3.0 HAB Launch Research ..................................................................................................................... 12 3.1 Balloon Selection......................................................................................................................... 12 3.2 HAB Flight Trajectory Prediction ................................................................................................. 12 3.3 Communications and Recovery .................................................................................................. 15 3.4 Camera Selection ........................................................................................................................ 15 3.5 Star and Region of Space Recognition ........................................................................................ 16 4.0 Camera Stabilization ....................................................................................................................... 17 4.1 Stability Theory and Requirements............................................................................................. 17 4.2 Mechanical Design ...................................................................................................................... 24 4.3 Control Algorithm ....................................................................................................................... 29 4.4 Description of Experimental Testing ........................................................................................... 30 4.5 Results ......................................................................................................................................... 32 4.6 Discussion of Results ................................................................................................................... 32 5.0 Conclusions ..................................................................................................................................... 34 6.0 Project Deliverables and Financial Summary .................................................................................. 35 6.1 Deliverables ................................................................................................................................. 35 6.2 Financial Summary ...................................................................................................................... 35 6.3 Ongoing Commitments ............................................................................................................... 35 7.0 Recommendations .......................................................................................................................... 37 References .................................................................................................................................................. 38 4 List of Figures Figure 1: Payload Axis Definition. Positive Z-axis points in the direction of latex balloon ........................... 7 Figure 2: Curvature of the Earth from 33km. Photo credit: David Stillman (4) ............................................ 9 Figure 3: CU Spaceflight Trajectory Prediction ........................................................................................... 13 Figure 4: University of Wyoming Balloon Trajectory Prediction ................................................................ 14 Figure 5: 1.5deg of camera displacement, large view ................................................................................ 19 Figure 6: 1.5deg of camera displacement, close up view ........................................................................... 19 Figure 7: 1.0deg of camera displacement, large view ................................................................................ 20 Figure 8: 1.0deg of camera displacement, close up view ........................................................................... 20 Figure 9: 0.5deg of camera displacement, large view ................................................................................ 21 Figure 10: 0.5deg of camera displacement, close up view ......................................................................... 21 Figure 11: Shaky camera, large view ........................................................................................................... 22 Figure 12: Shaky camera, close up view ..................................................................................................... 22 Figure 13: Shaky camera with VR off, large view ........................................................................................ 23 Figure 14: Shaky camera with VR off, close up view .................................................................................. 23 Figure 15: First draft stabilization design .................................................................................................... 25 Figure 16: Second iteration design ............................................................................................................. 26 Figure 17: Full and close up view of iteration three mechanical design. Mockup courtesy of Bernhard Zender, UBC Engineering Physics Project Lab ............................................................................................. 27 Figure 18: Alternate design with gyroscopic stabilizer. Mockup courtesy of Bernhard Zender, UBC Engineering Physics Project Lab .................................................................................................................. 27 Figure 19: Stabilizer design using gyroscopic stabilizer and inherent stiffness. Mockup courtesy of Bernhard Zender, UBC Engineering Physics Project Lab ............................................................................. 28 Figure 20: Control program flow diagram .................................................................................................. 30 Figure 21: Components of experimental performance tests...................................................................... 31 5 1. Background and Motivation The low cost and ready availability of a plethora of electronic components and semi-conductor devices has made it possible for the amateur, hobbyist and student to construct devices and perform experiments which in the past would have been prohibitively expensive and complex. Two endeavours which are benefitting from the semi-conductor revolution are the fields of amateur photography and high altitude balloon (HAB) projects. Photography has benefitted from the development of the CMOS and CCD technologies which make it possible to capture high quality images, view the result instantaneously, edit as desired, and store the image in a variety of digital formats. At the cutting edge the current state of the art in digital photography rivals that of film photography with much less expense and greater ease in editing. At the low and mid-range, digital cameras are inexpensive, light weight, easy to operate, and have a very