• EM L1 Lyapunov
• EM L1 Halo
• SE L1 Lyapunov
• SE L1 Halo

Write a differential corrector to solve a CorrectionsProblem

My previous architecture:

• A ProblemSolver accepts a CorrectionsProblem as an input
• The problem solver has a set of "update generators" that can be used; if the first one cannot be applied, the second is tried, and so forth until either the problem is solved or the list of generators is exhuasted
• Update Generators can include minimum norm, least squares, etc.
• The problem solver has a single "convergence check"
• Convergence Checks can include L2 norm of the constraint vector, infinity norm of the constraint vector, etc.

A line search for a step size in the differential corrector would be a helpful addition for difficult problems. See astrohelion::MultShootEngine 929-954 and astrohleion::MultShootEngine.chooseStep_LineSearch

Add a constraint on the distance between a control point and a body

Add a propagator event that triggers when the angle between a pre-defined vector and a subset of the propagated variable vector matches the desired value. The vectors need not be 2D or 3D; use the dot-product to get the angle in N-dimensions

Create a class that inherits from CorrectionsProblem and but uses the higher level ControlPoint and Segment objects to construct the problem rather than an explicit set of Variables. This class will construct a directed graph of these points and segments and check the graph for illegal paths.

The CR3BP+LT will add non-state parameters to the propagation; test all relevant objects (Segment, constraints, etc.) that use these values to make sure they're bookkept correctly

With static acceleration (fixed magnitude and direction)

• EM L1 Lyapunov
• EM L1 Halo
• SE L1 Lyapunov
• SE L1 Halo

Add a constraint on the RSS of the velocity discontinuities between a propagated segment and the terminal node

Add a class method to Segment that creates a sequence of segments from a propagated arc. The default behavior is a single segment that starts and ends at the propagation time limits, but the user can specify more than two indices at which to "break" the propagation. Origin and terminal control points are automatically created.

Segment.fromProp(propSol)    # --> single segment
Segment.fromProp(propSol, indices=[0, 100, 200, -1])    # --> three segments
Segment.fromProp(propSol, tof=2.3, shareTOFVar=True)    # --> multiple segments that share a single TOF variable

Create a constraint object that accepts another "equality" constraint as an input, adds a slack variable, and then modifies the evaluation and adds the partials for the slack variable. This will utilize the self.importableVariables attribute to add the slack variable to a corrections problem

Add a constraint that forces the unmasked values of one variable to be equal to another

Add a constraint that forces a control point to be an apse with respect to a body, or maybe just a fixed point in space?

Add a constraint on the epochs of two control points linked by a segment such that the delta between the epochs is the segment time of flight