ChristopherRabotin
commented
6 years ago To simplify the handling of states, I might simply have Orbit be an alias for Vector6<f64> with several added functions... although the problem with this approach is that I won't be able to store any computations or add the frames. So this is actually a bad idea. The frame information (cf. comment above) needs to be available in the struct itself in order to provide reference frame transformations and prevent bad math (e.g. adding two vectors defined in different frames). Moreover, in order to do many orbital computations, I need to store the gravity parameter mu. I initially think that the best approach here is to handle that via monomorphism, e.g. Orbit::<Earth>new(). I'm also considering adding the frame as a type parameter but I'm not sure what information from a Frame object would suffice to handle everything: hence it's likely that the frame will need to be passed as a parameter instead of a type parameter. Back to the propagator information, maybe I should simply have a into_state and from_state set of functions, but that would definitely add overhead to propagator calls. In fact let (t, state) = prop.derive(cur_t, &init_state, two_body_dynamics); would become something like let (t, state) = prop.derive(cur_t, orbit.into_state(), two_body_dynamics); orbit = Orbit::from_state(). That's kinda cumbersome. Moreover, the orbital elements should be as simple to get as in GMAT: orbit.inc() or orbit.mean_brower_inc(). Finally, I need consider how I'll handle the concatenation of these different states when I have a position, a velocity, the Cr, ground station positions, etc.
This module should handle all orbit manipulation. The organization of this module isn't necessarily trivial, and I really need to think of a good way of handling this. The constructors in
smdwere not all that useful, especially for the control laws.Another thing to consider is the size of state vector. The propagators handle
VectorN, so it must be possible to provide a VectorN which represents the full state which needs to be propagated, may that be simply a position and velocity vector, or P, V and STM, or equinoctal propagation if that feature is desired. I also need to support frames, as defined in GMAT here.