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FlightPathAngle3Energy.cs
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FlightPathAngle3Energy.cs
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/*
* Copyright Lamont Granquist, Sebastien Gaggini and the MechJeb contributors
* SPDX-License-Identifier: LicenseRef-PD-hp OR Unlicense OR CC0-1.0 OR 0BSD OR MIT-0 OR MIT OR LGPL-2.1+
*/
using System;
using MechJebLib.Primitives;
using static MechJebLib.Statics;
#nullable enable
namespace MechJebLib.PVG.Terminal
{
/// <summary>
/// 3 constraint terminal conditions with fixed attachment for the fixed-time, maximum-energy problem.
/// Lu, Ping, Hongsheng Sun, and Bruce Tsai. “Closed-Loop Endoatmospheric Ascent Guidance.”
/// Journal of Guidance, Control, and Dynamics 26, no. 2 (March 2003): 283–94. https://doi.org/10.2514/2.5045.
/// </summary>
public readonly struct FlightPathAngle3Energy : IPVGTerminal
{
private readonly double _gammaT;
private readonly double _rT;
private readonly double _incT;
public FlightPathAngle3Energy(double gammaT, double rT, double incT)
{
_gammaT = gammaT;
_rT = rT;
_incT = Math.Abs(ClampPi(incT));
}
public IPVGTerminal Rescale(Scale scale)
{
return new FlightPathAngle3Energy(_gammaT, _rT / scale.LengthScale, _incT);
}
public (double a, double b, double c, double d, double e, double f) TerminalConstraints(OutputLayout yf)
{
var hf = V3.Cross(yf.R, yf.V);
var n = new V3(0, 0, 1);
var rn = V3.Cross(yf.R, n);
var vn = V3.Cross(yf.V, n);
double con1 = (yf.R.sqrMagnitude - _rT * _rT) * 0.5;
double con2 = V3.Dot(n, hf.normalized) - Math.Cos(_incT);
double con3 = V3.Dot(yf.R.normalized, yf.V.normalized) - Math.Sin(_gammaT);
double tv1 = V3.Dot(yf.V, yf.PR) * yf.R.sqrMagnitude - V3.Dot(yf.R, yf.PV) * yf.V.sqrMagnitude +
V3.Dot(yf.R, yf.V) * (yf.V.sqrMagnitude - V3.Dot(yf.R, yf.PR));
double tv2 = V3.Dot(yf.V, yf.PV) - yf.V.sqrMagnitude;
double tv3 = V3.Dot(hf, yf.PR) * V3.Dot(hf, rn) + V3.Dot(hf, yf.PV) * V3.Dot(hf, vn);
return (con1, con2, con3, tv1, tv2, tv3);
}
}
}