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Adjustments to derail algorithim
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@peternewell
peternewell committed Oct 18, 2021
1 parent 8a7c2af commit 780b0e8
Showing 1 changed file with 23 additions and 15 deletions.
38 changes: 23 additions & 15 deletions Source/Orts.Simulation/Simulation/RollingStocks/TrainCar.cs
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Expand Up @@ -1420,6 +1420,7 @@ public void UpdateTrainDerailmentRisk(float elapsedClockSeconds)

// Calculate the vertical force on the wheel of the car, to determine whether wagon derails or not
// To calculate vertical force on outer wheel = (WagMass / NumWheels) * gravity + WagMass / NumAxles * ( (Speed^2 / CurveRadius) - (gravity * superelevation angle)) * (height * track width)
// Equation 5

if (IsPlayerTrain)
{
Expand All @@ -1435,7 +1436,7 @@ public void UpdateTrainDerailmentRisk(float elapsedClockSeconds)
// Prevent NaN if numWheels = 0
if (numWheels != 0)
{
A = MassKG * GravitationalAccelerationMpS2 / numWheels;
A = (MassKG / numWheels) * GravitationalAccelerationMpS2;
}
else
{
Expand All @@ -1445,16 +1446,17 @@ public void UpdateTrainDerailmentRisk(float elapsedClockSeconds)
// Prevent NaN if numAxles = 0
if (numAxles != 0)
{
B1 = (MassKG / numAxles) * (float)Math.Pow(Math.Abs(SpeedMpS), 2) / CurrentCurveRadius;
B1 = (MassKG / numAxles);
}
else
{
B1 = MassKG * (float)Math.Pow(Math.Abs(SpeedMpS), 2) / CurrentCurveRadius;
B1 = MassKG;
}
var B2 = GravitationalAccelerationMpS2 * (float)Math.Cos(SuperElevationAngleRad);
var B3 = CentreOfGravityM.Y / TrackGaugeM;
var B2 = GravitationalAccelerationMpS2 * (float)Math.Sin(SuperElevationAngleRad);
var B3 = (float)Math.Pow(Math.Abs(SpeedMpS), 2) / CurrentCurveRadius;
var B4 = CentreOfGravityM.Y / TrackGaugeM;

TotalWagonVerticalDerailForceN = A + (B1 - B2) * B3;
TotalWagonVerticalDerailForceN = A + B1 * (B3 - B2) * B4;

// Calculate lateral force per wheelset on the first bogie
// Lateral Force = (Coupler force x Sin (Coupler Angle) / NumBogies) + WagMass / NumAxles * ( (Speed^2 / CurveRadius) - (gravity * superelevation angle))
Expand All @@ -1467,11 +1469,13 @@ public void UpdateTrainDerailmentRisk(float elapsedClockSeconds)
// Prevent NaN if WagonNumBogies = 0
if ( WagonNumBogies != 0)
{
AA1 = CarAhead.CouplerForceU * (float)Math.Sin(WagonCouplerAngleDerailRad) / WagonNumBogies;
// AA1 = CarAhead.CouplerForceU * (float)Math.Sin(WagonCouplerAngleDerailRad) / WagonNumBogies;
AA1 = Math.Abs(CarAhead.CouplerForceUSmoothed.SmoothedValue) * (float)Math.Sin(WagonCouplerAngleDerailRad) / WagonNumBogies;
}
else
{
AA1 = CarAhead.CouplerForceU * (float)Math.Sin(WagonCouplerAngleDerailRad);
// AA1 = CarAhead.CouplerForceU * (float)Math.Sin(WagonCouplerAngleDerailRad);
AA1 = Math.Abs(CarAhead.CouplerForceUSmoothed.SmoothedValue) * (float)Math.Sin(WagonCouplerAngleDerailRad);
}

// Prevent NaN if numAxles = 0
Expand All @@ -1486,19 +1490,21 @@ public void UpdateTrainDerailmentRisk(float elapsedClockSeconds)
var BB2 = (float)Math.Pow(Math.Abs(SpeedMpS), 2) / CurrentCurveRadius;
var BB3 = GravitationalAccelerationMpS2 * (float)Math.Sin(SuperElevationAngleRad);

TotalWagonLateralDerailForceN = AA1 + BB1 * (BB2 - BB3);
TotalWagonLateralDerailForceN = Math.Abs(AA1 + BB1 * (BB2 - BB3));
}

DerailmentCoefficient = Math.Abs(TotalWagonLateralDerailForceN / TotalWagonVerticalDerailForceN);
DerailmentCoefficient = TotalWagonLateralDerailForceN / TotalWagonVerticalDerailForceN;

// use the dynamic multiplication coefficient to calculate final derailment coefficient
// use the dynamic multiplication coefficient to calculate final derailment coefficient, the above method calculated using quasi-static factors.
// The quasi-static do not include allowance for wheel unloading due to static carbody pitch. Hence the following factors have been used to adjust to dynamic effects.
// They have been adjusted slightly based upon derailment accident reports. Original figures quoted were 2 x for standard curves, and 3.1 x for turnouts.
if (IsOverJunction())
{
DerailmentCoefficient *= 3.1f;
DerailmentCoefficient *= 2.17f;
}
else
{
DerailmentCoefficient *= 2.0f;
DerailmentCoefficient *= 1.4f;
}

var wagonAdhesion = Train.WagonCoefficientFriction;
Expand Down Expand Up @@ -1543,11 +1549,13 @@ public void UpdateTrainDerailmentRisk(float elapsedClockSeconds)
{
DerailExpected = true;
Simulator.Confirmer.Message(ConfirmLevel.Warning, Simulator.Catalog.GetStringFmt("Car {0} has derailed on the curve.", CarID));

// Trace.TraceInformation("Car Derail - CarID: {0}, Coupler: {1}, CouplerSmoothed {2}, Lateral {3}, Vertical {4}, Angle {5} Nadal {6} Coeff {7}", CarID, CouplerForceU, CouplerForceUSmoothed.SmoothedValue, TotalWagonLateralDerailForceN, TotalWagonVerticalDerailForceN, WagonCouplerAngleDerailRad, NadalDerailmentCoefficient, DerailmentCoefficient);
// Trace.TraceInformation("Car Ahead Derail - CarID: {0}, Coupler: {1}, CouplerSmoothed {2}, Lateral {3}, Vertical {4}, Angle {5}", CarAhead.CarID, CarAhead.CouplerForceU, CarAhead.CouplerForceUSmoothed.SmoothedValue, CarAhead.TotalWagonLateralDerailForceN, CarAhead.TotalWagonVerticalDerailForceN, CarAhead.WagonCouplerAngleDerailRad);
}
else if (DerailPossible)
{
DerailElapsedTimeS += elapsedClockSeconds;
// Trace.TraceInformation("Car Derail Time - CarID: {0}, Coupler: {1}, CouplerSmoothed {2}, Lateral {3}, Vertical {4}, Angle {5}, Elapsed {6}, DeratilTime {7}, Distance {8} Nadal {9} Coeff {10}", CarID, CouplerForceU, CouplerForceUSmoothed.SmoothedValue, TotalWagonLateralDerailForceN, TotalWagonVerticalDerailForceN, WagonCouplerAngleDerailRad, DerailElapsedTimeS, derailTimeS, DerailClimbDistanceM, NadalDerailmentCoefficient, DerailmentCoefficient);
}
else
{
Expand Down Expand Up @@ -1767,7 +1775,7 @@ public virtual void UpdateCurveSpeedLimit()

SuperelevationM = MathHelper.Clamp(SuperelevationM, 0.0001f, 0.150f); // If superelevation is greater then 6" (150mm) then limit to this value, having a value of zero causes problems with calculations

SuperElevationAngleRad = (float)Math.Sinh(SuperelevationM); // Total superelevation includes both balanced and unbalanced superelevation
SuperElevationAngleRad = (float)Math.Sinh(SuperelevationM); // Balanced superelevation only angle

MaxCurveEqualLoadSpeedMps = (float)Math.Sqrt((SuperelevationM * GravitationalAccelerationMpS2 * CurrentCurveRadius) / TrackGaugeM); // Used for calculating curve resistance

Expand Down

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