Improve air brake systems

New variant of EP braking where every vehicle modifies BP pressure
Better handling of dynamic brake blending

Author: cesarBLG

Source/Orts.Simulation/Common/Scripting/BrakeController.cs

@@ -222,11 +222,11 @@ public void SetUpdateValue(float value)
         /// </summary>
         public void SetDynamicBrakeIntervention(float value)
         {
-            // TODO: Set dynamic brake intervention instead of controller position
-            // There are some issues that need to be identified and fixed before setting the intervention directly
-            if (Locomotive.DynamicBrakeController == null) return;
-            Locomotive.DynamicBrakeChangeActiveState(value > 0);
-            Locomotive.DynamicBrakeController.SetValue(value);
+            if (value > 0 && Host.TrainDynamicBrakeIntervention <= 0)
+                Host.TrainDynamicBrakeCommandStartTime = Host.Simulator.ClockTime;
+            if (value <= 0)
+                Host.TrainDynamicBrakeIntervention = -1;
+            else Host.TrainDynamicBrakeIntervention = Math.Min(value, 1);
         }
 
         /// <summary>

Source/Orts.Simulation/Simulation/RollingStocks/MSTSLocomotive.cs

@@ -1808,14 +1808,12 @@ protected void CorrectBrakingParams()
         /// </summary>
         public void DynamicBrakeBlending(float elapsedClockSeconds)
         {
-            if (Math.Abs(SpeedMpS) > DynamicBrakeSpeed1MpS && airPipeSystem != null && ((airPipeSystem is EPBrakeSystem && Train.BrakeLine4 > 0f) || airPipeSystem.BrakeLine1PressurePSI < TrainBrakeController.MaxPressurePSI - 1f)
-                && ThrottleController.CurrentValue == 0f && !(DynamicBrakeController != null && DynamicBrakeBlendingOverride && DynamicBrakeController.CurrentValue > 0f)
-                /* && (!DynamicBrakeBlendingLeverOverride && DynamicBrakeController != null && DynamicBrakeIntervention < DynamicBrakeController.CurrentValue)*/)
+            // Local blending
+            if (Math.Abs(SpeedMpS) > DynamicBrakeSpeed1MpS && airPipeSystem != null && airPipeSystem.AutoCylPressurePSI > 0.1f
+                && ThrottlePercent == 0 && !(DynamicBrakeController != null && DynamicBrakeBlendingOverride && DynamicBrakeController.CurrentValue > 0))
             {
-                float threshold = DynamicBrakeBlendingForceMatch ? 100f : 0.01f;
                 float maxCylPressurePSI = airPipeSystem.GetMaxCylPressurePSI();
-                float targetDynamicBrakePercent = airPipeSystem is EPBrakeSystem ? Train.BrakeLine4 : Math.Min(((TrainBrakeController.MaxPressurePSI - airPipeSystem.BrakeLine1PressurePSI) * airPipeSystem.GetAuxCylVolumeRatio()) / maxCylPressurePSI, 1f);
-                //DynamicBrakeIntervention = Math.Min(((TrainBrakeController.CurrentValue - DynamicBrakeBlendingStart) / (DynamicBrakeBlendingStop - DynamicBrakeBlendingStart)), 1f);
+                float target = airPipeSystem.AutoCylPressurePSI / maxCylPressurePSI;
 
                 if (!DynamicBrakeBlended)
                 {
@@ -1828,11 +1826,19 @@ public void DynamicBrakeBlending(float elapsedClockSeconds)
                 }
                 if (DynamicBrake)
                 {
-                    float diff = DynamicBrakeBlendingForceMatch ? targetDynamicBrakePercent * MaxBrakeForceN - DynamicBrakeForceN : targetDynamicBrakePercent - DynamicBrakeIntervention;
-                    if (diff > threshold && DynamicBrakeIntervention <= 1)
-                        DynamicBrakeIntervention = Math.Min( DynamicBrakeIntervention + elapsedClockSeconds * (airPipeSystem.GetMaxApplicationRatePSIpS() / maxCylPressurePSI), 1.0f);
-                    else if (diff < -threshold)
-                        DynamicBrakeIntervention -= elapsedClockSeconds * (airPipeSystem.GetMaxReleaseRatePSIpS() / maxCylPressurePSI);
+                    if (DynamicBrakeBlendingForceMatch)
+                    {
+                        float diff = target * MaxBrakeForceN - DynamicBrakeForceN;
+                        float threshold = 100;
+                        if (diff > threshold && DynamicBrakeIntervention < 1)
+                            DynamicBrakeIntervention = Math.Min(DynamicBrakeIntervention + elapsedClockSeconds, 1);
+                        else if (diff < -threshold)
+                            DynamicBrakeIntervention -= elapsedClockSeconds;
+                    }
+                    else
+                    {
+                        DynamicBrakeIntervention = target;
+                    }
                 }
                 if (DynamicBrakeController != null)
                     DynamicBrakeIntervention = Math.Max(DynamicBrakeIntervention, DynamicBrakeController.CurrentValue);
@@ -1842,6 +1848,17 @@ public void DynamicBrakeBlending(float elapsedClockSeconds)
                 DynamicBrakeIntervention = -1;
                 DynamicBrakeBlended = false;
             }
+            // Train blending
+            if (IsLeadLocomotive())
+            {
+                if (TrainBrakeController.TrainDynamicBrakeIntervention > DynamicBrakeIntervention)
+                {
+                    DynamicBrakeBlended = true;
+                    DynamicBrakeIntervention = TrainBrakeController.TrainDynamicBrakeIntervention;
+                }
+                if (TrainBrakeController.TrainDynamicBrakeCommandStartTime > DynamicBrakeCommandStartTime)
+                    DynamicBrakeCommandStartTime = TrainBrakeController.TrainDynamicBrakeCommandStartTime;
+            }
         }
 
         /// <summary>
@@ -2243,6 +2260,7 @@ protected virtual void UpdateControllers(float elapsedClockSeconds)
             }
 
             DynamicBrakeBlending(elapsedClockSeconds);
+
             if (DynamicBrakeController != null && DynamicBrakeController.CommandStartTime > DynamicBrakeCommandStartTime) // use the latest command time
                 DynamicBrakeCommandStartTime = DynamicBrakeController.CommandStartTime;