Interplanetary optical navigation - Voyager Uranus encounter

AutoNav Mark3: Engineering the Next Generation of Autonomous Onboard Navigation and Guidance

“…Data partial derivatives of such observations are purely geometrical (Refs. 5,6), and are easily and reliably computed onboard a spacecraft. Calibrations for such observables are readily made by taking images of star fields and calibrating the distortion in the camera.…”

Image Processing for Planetary Limb/Terminator Extraction

“…The boundaries of celestial objects can be extracted using an edge-based histogramrning method similar to the typical segmentation of a computer vision system to separate objects from the background [2]- [3] (note the dark background with few stars in our applications). Although many segmentation techniques have been proposed, the methodology to extract limb and terminator features of celestial objects has never been fully addressed, and current solutions based on some a priori topographic/photometric models [4] are not reliable because of terrain variations which are extremely difficult to automate. Hence, constrained by onboard computing power, robustness requirements, and the lack of a priori knowledge about the planetary Wrains, we seek a germane limb/terminator extraction solution for planetary images.…”

“…1; Figure 4 shows the result of a histogram-based segmentation technique [5], [ 16]- [ 17] used in detecting the object region; and Figure 5 demonstrates the tracing of boundary points [18]- [ 19] which completes the preprocessing steps required prior to the limb/terminator bifurcation. However, step 4…”

“…x(t) = R cos(2@t + @ ) + Px ; y(t) = R sin(2@l +-~ ) + Py ; (4) whcref is the frequency and will be less than 1 because of less than one complete sinusoidal cycle…”

Analysis of Orbital Dynamic Equation in Navigation for a Mars Gravity-Assist Mission

“…The original data from the image are the line number (l) and the pixel number (p) of the optical centre of a planet image. Therefore, the measurement model using the pixel number and the line number is given via the lens equation (Synnott and Donegan, 1986) in Equation (3):…”