From 17be3653ae67defad72b4afea012737f2e2fc8b8 Mon Sep 17 00:00:00 2001
From: Arndt Brenschede <Arndt.Brenschede@web.de>
Date: Sun, 25 Nov 2018 20:11:50 +0100
Subject: [PATCH] bike ETA: more ele-filter, energy-correction

---
 .../java/btools/router/RoutingContext.java    | 22 ++++++-------
 .../src/main/java/btools/router/StdPath.java  | 33 +++++++++++++++----
 2 files changed, 37 insertions(+), 18 deletions(-)

diff --git a/brouter-core/src/main/java/btools/router/RoutingContext.java b/brouter-core/src/main/java/btools/router/RoutingContext.java
index 7489425..8db475f 100644
--- a/brouter-core/src/main/java/btools/router/RoutingContext.java
+++ b/brouter-core/src/main/java/btools/router/RoutingContext.java
@@ -174,18 +174,16 @@ public final class RoutingContext
     turnInstructionRoundabouts = expctxGlobal.getVariableValue( "turnInstructionRoundabouts", 1.f ) != 0.f;
 
     // Speed computation model (for bikes)
-    if (bikeMode) {
-      // Mass of the biker + bike + luggages, in kg
-      bikeMass = expctxGlobal.getVariableValue( "bikeMass", 90.f );
-      // Max speed (before braking), in km/h in profile and m/s in code
-      maxSpeed = expctxGlobal.getVariableValue( "maxSpeed", 45.f ) / 3.6;
-      // Equivalent surface for wind, S * C_x, F = -1/2 * S * C_x * v^2 = - S_C_x * v^2
-      S_C_x = expctxGlobal.getVariableValue( "S_C_x", 0.5f * 0.45f );
-      // Default resistance of the road, F = - m * g * C_r (for good quality road)
-      defaultC_r = expctxGlobal.getVariableValue( "C_r", 0.01f );
-      // Constant power of the biker (in W)
-      bikerPower = expctxGlobal.getVariableValue( "bikerPower", 100.f );
-    }
+    // Mass of the biker + bike + luggages, in kg
+    bikeMass = expctxGlobal.getVariableValue( "bikeMass", 90.f );
+    // Max speed (before braking), in km/h in profile and m/s in code
+    maxSpeed = expctxGlobal.getVariableValue( "maxSpeed", 45.f ) / 3.6;
+    // Equivalent surface for wind, S * C_x, F = -1/2 * S * C_x * v^2 = - S_C_x * v^2
+    S_C_x = expctxGlobal.getVariableValue( "S_C_x", 0.5f * 0.45f );
+    // Default resistance of the road, F = - m * g * C_r (for good quality road)
+    defaultC_r = expctxGlobal.getVariableValue( "C_r", 0.01f );
+    // Constant power of the biker (in W)
+    bikerPower = expctxGlobal.getVariableValue( "bikerPower", 100.f );
   }
 
   public List<OsmNodeNamed> nogopoints = null;
diff --git a/brouter-core/src/main/java/btools/router/StdPath.java b/brouter-core/src/main/java/btools/router/StdPath.java
index d0e607e..a89a349 100644
--- a/brouter-core/src/main/java/btools/router/StdPath.java
+++ b/brouter-core/src/main/java/btools/router/StdPath.java
@@ -606,6 +606,29 @@ final class StdPath extends OsmPath
 	  return cost > c;
   }
 
+  private double calcIncline( double dist )
+  {
+    double min_delta = 3.;
+    double shift;
+    if ( elevation_buffer > min_delta )
+    {
+      shift = -min_delta;
+    }
+    else if ( elevation_buffer < min_delta )
+    {
+      shift = -min_delta;
+    }
+    else
+    {
+      return 0.;
+    }
+    double decayFactor = exp( - dist / 100. );
+    float new_elevation_buffer = (float)( (elevation_buffer+shift) * decayFactor - shift);
+    double incline = ( elevation_buffer - new_elevation_buffer ) / dist;
+    elevation_buffer = new_elevation_buffer;
+    return incline;
+  }
+
   @Override
   protected void computeKinematic( RoutingContext rc, double dist, double delta_h, boolean detailMode )
   {
@@ -615,13 +638,11 @@ final class StdPath extends OsmPath
     }
 
     // compute incline
-    double decayFactor = exp( - dist / 100. );
     elevation_buffer += delta_h;
-    float new_elevation_buffer = (float)( elevation_buffer * decayFactor );
-    double incline = ( elevation_buffer - new_elevation_buffer ) / dist;
-    elevation_buffer = new_elevation_buffer;
+    double incline = calcIncline( dist );
 
     double speed; // Travel speed
+    double f_roll = rc.bikeMass * GRAVITY * ( rc.defaultC_r + incline );
     if (rc.footMode )
     {
       // Use Tobler's hiking function for walking sections
@@ -629,7 +650,7 @@ final class StdPath extends OsmPath
     }
     else if (rc.bikeMode)
     {
-      speed = solveCubic( rc.S_C_x, rc.bikeMass * GRAVITY * ( rc.defaultC_r + incline ), rc.bikerPower );
+      speed = solveCubic( f_air, f_roll, rc.bikerPower );
       speed = Math.min(speed, rc.maxSpeed);
     }
     else
@@ -638,7 +659,7 @@ final class StdPath extends OsmPath
     }
     float dt = (float) ( dist / speed );
     totalTime += dt;
-    totalEnergy += dt*rc.bikerPower;
+    totalEnergy += dist*(rc.S_C_x*speed*speed + f_roll);
   }
 
   private static double solveCubic( double a, double c, double d )