Solutions

Closed form solutions

Cone intercept and the single frame Schuster method can be used for attitude determination. In the case of Schuster's method it is important to account for delays in the dihedral angle otherwise large errors can be introduced into the results.

The plot on the right shows the use of cone intercept which just uses sun angles and horizon sensor chordwidths. Each cone intercept produces two estimates, the real solution and and a false solution. However over a large number of measurements the real solution will stay consistent and the false one will move. The plot shows the sorting of solutions to find the correct one.

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Attitude Determination

Several numerical algorithms are provided. They are

• Differential Corrector
• Conjugate Gradient/Steepest Descent
• Recursive Least Squares
• Iterated Extended Kalman Filter
• Nonlinear Equation Solver
• Nelder-Meade

The plot below shows the horizon sensor data employed by all of the methods.