초소형 자율비행 오니솝터(Ornithopter) 생체모방 날갯짓 & 1,000Hz 0-Alloc C# 비정상 와류 양력 제어 엔진

using System;
using System.Runtime.CompilerServices;

namespace ZeliDesk.Stem.BiomimeticRobotics;

/// 

/// 생체모방 오니솝터 플래핑 공기역학 상태 구조체 (100% Stack Allocation)
/// 
public readonly ref struct OrnithopterState
{
    public readonly double FlappingPhaseRad;     // 날갯짓 위상 (0 ~ 2π)
    public readonly double InstantLiftGramForce; // 순간 양력 (gf)
    public readonly double InstantThrustGramForce;// 순간 추력 (gf)
    public readonly double LevVortexStrength;    // 앞전 와류 강도 (Circulation Γ)
    public readonly double PowerConsumptionWatts;// 근골격 액추에이터 전력 (W)
    public readonly double PitchAngleDeg;        // 날개 능동 피치각 (도)

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public OrnithopterState(
        double flappingPhaseRad,
        double instantLiftGramForce,
        double instantThrustGramForce,
        double levVortexStrength,
        double powerConsumptionWatts,
        double pitchAngleDeg)
    {
        FlappingPhaseRad = flappingPhaseRad;
        InstantLiftGramForce = instantLiftGramForce;
        InstantThrustGramForce = instantThrustGramForce;
        LevVortexStrength = levVortexStrength;
        PowerConsumptionWatts = powerConsumptionWatts;
        PitchAngleDeg = pitchAngleDeg;
    }
}

/// 

/// 1,000Hz 0-Alloc C# 초소형 생체모방 오니솝터 날갯짓 공기역학 시뮬레이터
/// 
public static class FlappingWingEngine
{
    private const double AirDensity = 1.225;          // kg/m^3
    private const double WingSpanM = 0.16;            // 스팬 16 cm (벌새 크기)
    private const double MeanChordM = 0.035;          // 평균 시위 3.5 cm
    private const double WingAreaM2 = WingSpanM * MeanChordM * 0.5; // 날개 면적
    private const double FlappingFreqHz = 35.0;       // 날갯짓 주파수 35 Hz
    private const double StrokeAmplitudeRad = 1.2;    // 스트로크 각진폭 (~68도)

    /// 

    /// 1ms 타임스텝 플래핑 비정상 양력 및 추력 연산 (0-Alloc)
    /// 
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static OrnithopterState StepAeroDynamics(
        double simulationTimeSec,
        double commandedPitchOffsetDeg = 0.0)
    {
        double omega = 2.0 * Math.PI * FlappingFreqHz;
        double phase = (omega * simulationTimeSec) % (2.0 * Math.PI);

        // 1. 스트로크 각도 및 각속도: phi(t) = Phi_0 * cos(omega * t)
        double strokeVelRadS = -StrokeAmplitudeRad * omega * Math.Sin(phase);
        double tipSpeedMPerS = Math.Abs(strokeVelRadS) * (WingSpanM * 0.5);

        // 2. 능동 피칭 각도: 파동 형태의 사인파 피칭 + 제어 오프셋
        double pitchRad = 0.45 * Math.Cos(phase) + commandedPitchOffsetDeg * (Math.PI / 180.0);
        double pitchDeg = pitchRad * (180.0 / Math.PI);
        double alphaAttack = Math.Clamp(Math.Abs(pitchRad), 0.1, 1.2);

        // 3. 앞전 와류(LEV) 병진 양력 계산: C_L = 1.8 * sin(2*alpha)
        double clTrans = 1.85 * Math.Sin(2.0 * alphaAttack);
        double qDyn = 0.5 * AirDensity * (tipSpeedMPerS * tipSpeedMPerS);
        double liftNewtons = qDyn * WingAreaM2 * clTrans * 2.0; // 양 날개
        double liftGf = (liftNewtons / 9.80665) * 1000.0;

        // 4. 추력 성분: 날개 뒤틀림에 의한 수평 분력
        double cdTrans = 1.9 * (1.0 - Math.Cos(2.0 * alphaAttack));
        double thrustNewtons = (liftNewtons * Math.Sin(pitchRad)) - (qDyn * WingAreaM2 * cdTrans * Math.Cos(pitchRad) * 0.2);
        double thrustGf = (thrustNewtons / 9.80665) * 1000.0;

        // 5. LEV 순환 강도 및 소비 전력
        double gammaLev = 0.5 * tipSpeedMPerS * MeanChordM * clTrans;
        double aeroPower = Math.Abs(thrustNewtons * tipSpeedMPerS) + Math.Abs(liftNewtons * 1.5);
        double powerWatts = Math.Clamp(aeroPower * 1.4 + 0.35, 0.5, 8.5);

        return new OrnithopterState(
            phase,
            liftGf,
            thrustGf,
            gammaLev,
            powerWatts,
            pitchDeg);
    }
}