update README, change variables to match writeup

Author: itchono

README.md

@@ -8,12 +8,12 @@ My thesis is about trajectory guidance for solar sail spacecraft in orbits aroun
 
 * [See my one-pager description of the academic significance](https://github.com/itchono/SLyGA/files/12779364/Thesis_Proposal.pdf)
 
-* [See my WIP notes for thesis here (late September 2023)](https://github.com/itchono/SLyGA/files/12779359/thesis_notes_sep_2023.pdf)
+* [See my interim writeup (late January 2024)](https://github.com/itchono/SLyGA/files/14046375/Thesis_Interim_Report_Shareable.pdf)
 
 Below is an example of a trajectory I propagated which performs a three-dimensional orbital transfer using a Lyapunov steering law developed by me.
 
-![trajectory plot](https://github.com/itchono/SLyGA/assets/54449457/661a9786-f4a2-41a4-b6e9-d3d812143e94)
-![trajectory_animation](https://github.com/itchono/SLyGA/assets/54449457/103718fc-53da-43e3-b131-8695ff5a3cca)
+![trajectory plot](https://github.com/itchono/SLyGA/assets/54449457/9bc673e4-95c4-481e-a812-39a11eaad1b4)
+![trajectory_animation](https://github.com/itchono/SLyGA/assets/54449457/ccc4bfdc-72cc-4612-a566-3d8ceb14f91c)
 
 
 
@@ -29,27 +29,25 @@ Below is an example of a trajectory I propagated which performs a three-dimensio
 ## Code Structure
 ### `steering` - Steering Algorithms
 This code computes the LVLH steering angle in which to point the sail. There are currently two components to the steering algorithm:
-1. Lyapunov steering law - computes an optimal steering angle which decreases the control-Lyapunov potential function as quickly as possible
-2. NDF Heuristic - accounts for the position of the Sun, and adapts the steering angle proposed by the Lyapunov steering law to something a solar sail can achieve. e.g. Feathering the sail if the desired pointing direction is directly toward the Sun.
+1. Modified Q Law - computes an optimal steering angle which decreases the control-Lyapunov potential function as quickly as possible
+2. Steering Angle Regularization - accounts for the position of the Sun, and adapts the steering angle proposed by the Lyapunov steering law to something a solar sail can achieve. e.g. Feathering the sail if the desired pointing direction is directly toward the Sun.
 
 ### `sim` - Simulator
-This folder includes equations of motion, ephemerides, and propulsion models.
-
-Currently, there are two propulsion models implemented:
-1. Constant thrust - thrusts in the direction of the sail normal vector with a constant magnitude
-2. Solar sail - thrusts in the direction of the sail normal vector with a magnitude dependent on cone angle
-
-`run_mission.m` connects all of the low-level ODEs and guidance stack together.
+This folder includes equations of motion, ephemerides, and propulsion models used to "operate" the guidance law.
 
 ### `postprocess` - Postprocessing Functions
 Used to interpolate, plot, and summarize the results of the simulations.
 
 ### `utils` - Utility Functions
 This folder includes functions for converting between coordinate frames, computing orbital elements, and other miscellaneous functions.
 
+### `scripts` - Case Files
+Various simulation cases to run.
+
 ## Usage
 1. Run one of the mission cases inside `scripts`.
 2. Wait for the sim to finish. Then, run `postprocess` to show plots.
+3. Data will be saved to the `outputs` folder.
 
 ## Code Formatting
 Code is formatted using [MBeautifier](https://github.com/davidvarga/MBeautifier).

steering/q_law/lyapunov_steering.m

@@ -20,23 +20,16 @@
 
 % Calculate penalty and "classic" components separately
 [P, dPdoe] = penalty(y, cfg.penalty_param, cfg.min_pe);
-Xi_penalty = dPdoe .* ((oe - oe_hat) ./ d_oe_max).^2;
-Xi_classic = 2 .* (oe - oe_hat) ./ d_oe_max;
+Xi_P = dPdoe .* ((oe - oe_hat) ./ d_oe_max).^2;
+Xi_E = 2 .* (oe - oe_hat) ./ d_oe_max;
 w_p = cfg.penalty_weight;
 
 % Bring together the components
-d_oe_d_F = A(1:5, :);
-Xi = cfg.guidance_weights .* S .* (w_p * Xi_penalty + (1 + w_p * P) .* Xi_classic);
-
-d_Gamma_d_F = d_oe_d_F.' * Xi;
-
-% Be careful on ordering; GVEs are in r,t,n, but D1, D2, D3 are in t,r,n
-D1 = d_Gamma_d_F(2);
-D2 = d_Gamma_d_F(1);
-D3 = d_Gamma_d_F(3);
+A = A(1:5, :);
+D = A.' * (cfg.guidance_weights .* S .* (w_p * Xi_P + (1 + w_p * P) .* Xi_E));
 
 % Optimal steering angles)
-alpha = atan2(-D2, -D1);
-beta = atan2(-D3, sqrt(D1.^2+D2.^2)); % atan2 for stability (0/0 case)
+alpha = atan2(-D(1), -D(2));
+beta = atan2(-D(3), norm(D(1:2))); % atan2 for stability (0/0 case)
 
 end