91 lines
3.7 KiB
Plaintext
91 lines
3.7 KiB
Plaintext
@LAZYGLOBAL off.
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run once "lib/node".
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run once "lib/target".
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run once "lib/vectors".
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function rcs_isp_sum {
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//
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// Return the sum of ISP for RCS thrusters.
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//
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local sum is 0.
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for thruster in SHIP:modulesnamed("ModuleRCSFX") {
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set sum to sum + thruster:getfield("rcs isp").
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}
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return sum.
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}
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function rcs_maxthrust {
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// There's no way to get thrust of RCS dynamically in kOS; gonna have to hard-code it :/
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// Source: https://wiki.kerbalspaceprogram.com/wiki/Reaction_Control_System#Thrusters
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local rcs_thrusts is LEXICON( // in kN
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"RCSBlock", 1.0, // RV-105 RCS Thruster Block
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"linearRcs", 2.0, // Place-Anywhere 7 Linear RCS Port
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"vernierEngine", 12.0 // Vernor Engine
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).
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local thrust_sum is 0.
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for module in SHIP:modulesnamed("ModuleRCSFX") {
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local part_name is module:part:name.
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if rcs_thrusts:haskey(part_name) {
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set thrust_sum to thrust_sum + rcs_thrusts[part_name].
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} else { // if non-stock part
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print "WARNING: Unknown RCS Thruster '" + part_name + "'; using default thrust of 1.0 kN".
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set thrust_sum to thrust_sum + 1.0.
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}
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}
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return thrust_sum.
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}
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function rcs_estimated_burn_duration {
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//
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// Calculate estimated burn duration of a vector or node using RCS thrusters instead of main engines.
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//
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parameter burn.
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return estimated_burn_duration(burn, rcs_isp_sum(), rcs_maxthrust()).
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}
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function rcs_translate {
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//
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// Translate the ship's position by the given vector using RCS thrusters.
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//
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parameter translation_vector_delegate.
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parameter max_speed.
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local lock translation_vector to translation_vector_delegate().
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// Find available RCS acceleration by Newton's second law: (F=mg). Note that the acceleration is conservatively divided
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// by 6 since thrusters might not be aligned with thrust vector (but assumed evenly distributed on the 6 axes).
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// Furthermore, acceleration is limited to 0.05m/s^2 since small ships with low mass are uncontrollable if allowed to accelerate wildly.
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local acceleration is min(0.05, (rcs_maxthrust() / SHIP:MASS) / 6).
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// Time t to travel distance d under constant acceleration a is t = sqrt(2d/a) (https://en.wikipedia.org/wiki/Equations_for_a_falling_body).
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// Multiply this by the available acceleration to get speed (s * m/s^2 = m/s) required to decelerate to 0 by the time d=0.
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local lock desired_speed to min(max_speed, sqrt(2*translation_vector:mag / acceleration) * acceleration).
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local lock desired_velocity to translation_vector:normalized * desired_speed.
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// The proportional gain factor is set to the square root of the ship's mass. Why? It was empirically shown to work.
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// The idea is that small ships are more sensitive to adjustments, and so small error corrections will do more harm than good.
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local pid_x is PIDLOOP(sqrt(SHIP:MASS), 0.01, 0.001, -1, 1). // kp, ki, kd, minoutput, maxoutput
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local pid_y is PIDLOOP(sqrt(SHIP:MASS), 0.01, 0.001, -1, 1).
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local pid_z is PIDLOOP(sqrt(SHIP:MASS), 0.01, 0.001, -1, 1).
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//vdraw(SHIP:controlpart:position, translation_vector@, WHITE).
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//vdraw(SHIP:controlpart:position, relative_velocity@, GREEN).
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RCS on.
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until translation_vector:mag < 0.05 and relative_velocity():mag < 0.01 {
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set pid_x:setpoint to desired_velocity:x.
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set pid_y:setpoint to desired_velocity:y.
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set pid_z:setpoint to desired_velocity:z.
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local x is pid_x:update(TIME:seconds, relative_velocity():x).
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local y is pid_y:update(TIME:seconds, relative_velocity():y).
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local z is pid_z:update(TIME:seconds, relative_velocity():z).
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set SHIP:CONTROL:TRANSLATION to ship_raw_to_ship_control(V(x,y,z)).
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}
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}
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