Skip to content

Commit

Permalink
Avoids wheelslip when the precision level is changed.
Browse files Browse the repository at this point in the history 
Also moved IsPrecisionHigh() from Axle class to Axles.
  • Loading branch information
@cjakeman
cjakeman committed Dec 28, 2023
1 parent a325039 commit 4b4afe3
Show file tree
Hide file tree
Showing 2 changed files with 92 additions and 90 deletions.
180 changes: 91 additions & 89 deletions Source/Orts.Simulation/Simulation/RollingStocks/SubSystems/PowerTransmissions/Axle.cs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -281,23 +281,105 @@ public void Restore(BinaryReader inf)
AxleList[i].Restore(inf);
}
}

/// <summary>
/// switch between Polach and Pacha adhesion calculation
/// </summary>
public static bool UsePolachAdhesion = false; // "static" so there's only one value in the program.
public bool PreviousUsePolachAdhesion = false; // Keep a note for each Axles so that we can tell if it changed.

/// <summary>
/// Updates each axle on the list
/// </summary>
/// <param name="elapsedClockSeconds">Time span within the simulation cycle</param>
public void Update(float elapsedClockSeconds)
/// <param name="elapsedSeconds">Time span within the simulation cycle</param>
public void Update(float elapsedSeconds)
{
UsePolachAdhesion = AdhesionPrecision.IsPrecisionHigh(this, elapsedSeconds, Car.Simulator.GameTime);
foreach (var axle in AxleList)
{
axle.Update(elapsedClockSeconds);
if (UsePolachAdhesion != PreviousUsePolachAdhesion) // There's been a transition
{
axle.AxleSpeedMpS = axle.TrainSpeedMpS; // So the transition doesn't cause a wheelslip
}
axle.Update(elapsedSeconds);
}
PreviousUsePolachAdhesion = UsePolachAdhesion;
}
public List<Axle>.Enumerator GetEnumerator()
{
return AxleList.GetEnumerator();
}
}

static class AdhesionPrecision // "static" so all "Axles" share the same level of precision
{
enum AdhesionPrecisionLevel
{
/// <summary>
/// Initial level uses Polach algorithm
/// </summary>
High = 0,
/// <summary>
/// Low-performance PCs use Pacha's algorithm
/// </summary>
Low = 1,
/// <summary>
/// After frequent transitions, low-performance PCs are locked to Pacha's algorithm
/// </summary>
LowLocked = 2
}

// Adjustable limits
const float LowerLimitS = 0.025f; // timespan 0.025 = 40 fps screen rate, low timeSpan and high FPS
const float UpperLimitS = 0.033f; // timespan 0.033 = 30 fps screen rate, high timeSpan and low FPS
const double IntervalBetweenDowngradesLimitS = 5 * 60; // Locks in low precision if < 5 mins between downgrades

static AdhesionPrecisionLevel PrecisionLevel = AdhesionPrecisionLevel.High;
static double TimeOfLatestDowngrade = 0 - IntervalBetweenDowngradesLimitS; // Starts at -5 mins

// Tested by dropping the framerate below 30 fps interactively. Did this by opening and closing the HelpWindow after inserting
// Threading.Thread.Sleep(40);
// into HelpWindow.PrepareFrame() temporarily.
public static bool IsPrecisionHigh(Axles axles, float elapsedSeconds, double gameTime)
{
// Switches between Polach (high precision) adhesion model and Pacha (low precision) adhesion model depending upon the PC performance
switch (PrecisionLevel)
{
case AdhesionPrecisionLevel.High:
if (elapsedSeconds > UpperLimitS)
{
var screenFrameRate = 1 / elapsedSeconds;
var timeSincePreviousDowngradeS = gameTime - TimeOfLatestDowngrade;
if (timeSincePreviousDowngradeS < IntervalBetweenDowngradesLimitS)
{
Trace.TraceInformation($"At {gameTime:F0} secs, advanced adhesion model switched to low precision permanently after {timeSincePreviousDowngradeS:F0} secs since previous switch (less than limit of {IntervalBetweenDowngradesLimitS})");
PrecisionLevel = AdhesionPrecisionLevel.LowLocked;
}
else
{
TimeOfLatestDowngrade = gameTime;
Trace.TraceInformation($"At {gameTime:F0} secs, advanced adhesion model switched to low precision after low frame rate {screenFrameRate:F1} below limit {1 / UpperLimitS:F0}");
PrecisionLevel = AdhesionPrecisionLevel.Low;
}
}
break;

case AdhesionPrecisionLevel.Low:
if (elapsedSeconds > 0 // When debugging step by step, elapsedSeconds == 0, so test for that
&& elapsedSeconds < LowerLimitS)
{
PrecisionLevel = AdhesionPrecisionLevel.High;
var ScreenFrameRate = 1 / elapsedSeconds;
Trace.TraceInformation($"At {gameTime:F0} secs, advanced adhesion model switched to high precision after high frame rate {ScreenFrameRate:F1} above limit {1 / LowerLimitS:F0}");
}
break;

case AdhesionPrecisionLevel.LowLocked:
break;
}
return (PrecisionLevel == AdhesionPrecisionLevel.High);
}
}
}


/// <summary>
Expand Down Expand Up @@ -428,12 +510,6 @@ public float InertiaKgm2
/// </summary>
float forceToAccelerationFactor;

/// <summary>
/// switch between Polach and Pacha adhesion calculation
/// </summary>
public static bool UsePolachAdhesion = false; // "static" so it's shared by all axles of the Player's loco
public double GameTime; // Set by MSTSLocomotive and used by AdhesionPrecision.IsPrecisionHigh

/// <summary>
/// Pre-calculation of slip characteristics at 0 slip speed
/// </summary>
Expand Down Expand Up @@ -546,7 +622,7 @@ public float TransmissionEfficiency
/// <summary>
/// Axle speed value, in metric meters per second
/// </summary>
public double AxleSpeedMpS { get; private set; }
public double AxleSpeedMpS { get; set; }

/// <summary>
/// Axle angular position in radians
Expand Down Expand Up @@ -824,7 +900,7 @@ public void Save(BinaryWriter outf)
double slipSpeedMpS = axleSpeedMpS - TrainSpeedMpS;
double axleOutForceN = 0;

if (UsePolachAdhesion)
if (Axles.UsePolachAdhesion)
{
axleOutForceN = Math.Sign(slipSpeedMpS) * AxleWeightN * SlipCharacteristicsPolach(slipSpeedMpS);
}
Expand Down Expand Up @@ -870,7 +946,7 @@ void Integrate(float elapsedClockSeconds)
if (elapsedClockSeconds <= 0) return;
double prevSpeedMpS = AxleSpeedMpS;

if (UsePolachAdhesion)
if (Axles.UsePolachAdhesion)
{

float upperSubStepLimit = 100;
Expand Down Expand Up @@ -959,7 +1035,7 @@ void Integrate(float elapsedClockSeconds)
{
var k1 = GetAxleMotionVariation(AxleSpeedMpS, dt);

if (i == 0 && !UsePolachAdhesion)
if (i == 0 && !Axles.UsePolachAdhesion)
{
if (k1.Item1 * dt > Math.Max((Math.Abs(SlipSpeedMpS) - 1) * 10, 1) / 100)
{
Expand Down Expand Up @@ -1002,8 +1078,7 @@ void Integrate(float elapsedClockSeconds)
/// <param name="elapsedSeconds"></param>
public virtual void Update(float elapsedSeconds)
{
UsePolachAdhesion = AdhesionPrecision.IsPrecisionHigh(elapsedSeconds, GameTime);
if (UsePolachAdhesion)
if (Axles.UsePolachAdhesion)
{
forceToAccelerationFactor = WheelRadiusM * WheelRadiusM / totalInertiaKgm2;

Expand Down Expand Up @@ -1098,79 +1173,6 @@ public virtual void Update(float elapsedSeconds)
}
}

static class AdhesionPrecision // "static" so all "Axle"s share the same level of precision
{
enum AdhesionPrecisionLevel
{
/// <summary>
/// Initial level uses Polach algorithm
/// </summary>
High = 0,
/// <summary>
/// Low-performance PCs use Pacha's algorithm
/// </summary>
Low = 1,
/// <summary>
/// After frequent transitions, low-performance PCs are locked to Pacha's algorithm
/// </summary>
LowLocked = 2
}

// Adjustable limits
const float LowerLimitS = 0.025f; // timespan 0.025 = 40 fps screen rate, low timeSpan and high FPS
const float UpperLimitS = 0.033f; // timespan 0.033 = 30 fps screen rate, high timeSpan and low FPS
const double IntervalBetweenDowngradesLimitS = 5 * 60; // Locks in low precision if < 5 mins between downgrades

static AdhesionPrecisionLevel PrecisionLevel = AdhesionPrecisionLevel.High;
static double TimeOfLatestDowngrade = 0 - IntervalBetweenDowngradesLimitS; // Starts at -5 mins

// Tested by varying the framerate interactively. Did this by opening and closing the HelpWindow after inserting
// Threading.Thread.Sleep(40);
// into HelpWindow.PrepareFrame() temporarily.
public static bool IsPrecisionHigh(float elapsedSeconds, double gameTime)
{
// Switches between Polach (high precision) adhesion model and Pacha (low precision) adhesion model depending upon the PC performance
switch (PrecisionLevel)
{
case AdhesionPrecisionLevel.High:
if (elapsedSeconds > UpperLimitS)
{
var screenFrameRate = 1 / elapsedSeconds;
var timeSincePreviousDowngradeS = gameTime - TimeOfLatestDowngrade;
if (timeSincePreviousDowngradeS < IntervalBetweenDowngradesLimitS)
{
Trace.TraceInformation($"At {gameTime:F0} secs, advanced adhesion model switched to low precision permanently after {timeSincePreviousDowngradeS:F0} secs since previous switch (less than limit of {IntervalBetweenDowngradesLimitS})");
PrecisionLevel = AdhesionPrecisionLevel.LowLocked;
}
else
{
TimeOfLatestDowngrade = gameTime;

Trace.TraceInformation($"At {gameTime:F0} secs, advanced adhesion model switched to low precision after low frame rate {screenFrameRate:F1} below limit {1 / UpperLimitS:F0}");
PrecisionLevel = AdhesionPrecisionLevel.Low;

}
}
break;

case AdhesionPrecisionLevel.Low:
if (elapsedSeconds > 0 // When debugging step by step, elapsedSeconds == 0, so test for that
&& elapsedSeconds < LowerLimitS)
{
PrecisionLevel = AdhesionPrecisionLevel.High;
var ScreenFrameRate = 1 / elapsedSeconds;
Trace.TraceInformation($"At {gameTime:F0} secs, advanced adhesion model switched to high precision after high frame rate {ScreenFrameRate:F1} above limit {1 / LowerLimitS:F0}");
}
break;

case AdhesionPrecisionLevel.LowLocked:
break;

}
return (PrecisionLevel == AdhesionPrecisionLevel.High);
}
}

class PolachCalculator
{
Axle Axle;
Expand Down
2 changes: 1 addition & 1 deletion Source/RunActivity/Viewer3D/Popups/HUDWindow.cs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1080,7 +1080,7 @@ void TextPageForceInfo(TableData table)
if (mstsLocomotive.AdvancedAdhesionModel)
{
var text = Viewer.Catalog.GetString("(Advanced adhesion model)");
if (Axle.UsePolachAdhesion == false) text += "???";
if (Axles.UsePolachAdhesion == false) text += "???";
TableAddLine(table, text);
int row0 = table.CurrentRow;
TableSetCell(table, table.CurrentRow++, table.CurrentLabelColumn, Viewer.Catalog.GetString("Wheel slip (Thres)"));
Expand Down

0 comments on commit 4b4afe3

Please sign in to comment.