fixup! core: add etcs loa logic to etcs braking simulator

Signed-off-by: Erashin <alwenn.charpentier@gmail.com>

Author: Erashin

core/envelope-sim/src/main/kotlin/fr/sncf/osrd/envelope_sim/etcs/Constants.kt

@@ -1,18 +1,25 @@
 package fr.sncf.osrd.envelope_sim.etcs
 
+/**
+ * Formulas are found in `SUBSET-026-3v400.pdf` from the file at
+ * https://www.era.europa.eu/system/files/2023-09/index004_-_SUBSET-026_v400.zip and in
+ * `SUBSET-041_v400.pdf` from the file at
+ * https://www.era.europa.eu/system/files/2023-09/index014_-_SUBSET-041_v400.pdf
+ */
+
 /**
  * National Default Value: permission to inhibit the compensation of the speed measurement accuracy.
- * See Subset referenced in ETCSBrakingSimulator: table in Appendix A.3.2.
+ * See Subset 026: table in Appendix A.3.2.
  */
 const val qNvinhsmicperm = false
 
 /**
  * Estimated acceleration during tBerem, worst case scenario (aEst2 is between 0 and 0.4), expressed
- * in m/s². See Subset referenced in ETCSBrakingSimulator: §3.13.9.3.2.9.
+ * in m/s². See Subset 026: §3.13.9.3.2.9.
  */
 const val aEst2 = 0.4
 
-/** See Subset referenced in ETCSBrakingSimulator: table in Appendix A.3.1. */
+/** See Subset 026: table in Appendix A.3.1. */
 const val dvEbiMin = 7.5 / 3.6 // m/s
 const val dvEbiMax = 15.0 / 3.6 // m/s
 const val vEbiMin = 110.0 / 3.6 // m/s
@@ -22,23 +29,41 @@ const val tDriver = 4.0 // s
 const val mRotatingMax = 15.0 // %
 const val mRotatingMin = 2.0 // %
 
-/** See https://www.era.europa.eu/system/files/2023-09/index014_-_SUBSET-041_v400.pdf: §5.3.1.2. */
+/** See Subset 041: §5.3.1.2. */
+const val vUraMinLimit = 30 / 3.6 // m/s
+const val vUraMaxLimit = 500 / 3.6 // m/s
+const val vUraMin = 2 / 3.6 // m/s
+const val vUraMax = 12 / 3.6 // m/s
+
+/** See Subset 041: §5.3.1.2. */
 fun vUra(speed: Double): Double {
-    return if (speed <= 30 / 3.6) 2 / 3.6
-    // vUra(30km/h) = 2km/h & vUra(500km/h) = 12km/h with a linear interpolation in between
-    // this gives the following equation : y = (x + 64) / 47, still in km/h
-    else ((speed + 64) / 47) / 3.6
+    return interpolateLinearSpeed(speed, vUraMinLimit, vUraMaxLimit, vUraMin, vUraMax)
 }
 
-/** See Subset referenced in ETCSBrakingSimulator: §3.13.9.3.2.10. */
+/** See Subset 026: §3.13.9.3.2.10. */
 fun vDelta0(speed: Double): Double {
     return if (!qNvinhsmicperm) vUra(speed) else 0.0
 }
 
-/** See Subset referenced in ETCSBrakingSimulator: §3.13.9.2.3. */
+/** See Subset 026: §3.13.9.2.3. */
 fun dvEbi(speed: Double): Double {
-    return if (speed <= vEbiMin) dvEbiMin
-    else if (speed < vEbiMax)
-        (dvEbiMax - dvEbiMin) / (vEbiMax - vEbiMin) * (speed - vEbiMin) + dvEbiMin
-    else dvEbiMax
+    return interpolateLinearSpeed(speed, vEbiMin, vEbiMax, dvEbiMin, dvEbiMax)
+}
+
+/**
+ * The linear curve is the following: below minSpeedLimit = minSpeed, above maxSpeedLimit =
+ * maxSpeed, in between is a linear curve. This method takes a speed input and converts it
+ * accordingly.
+ */
+private fun interpolateLinearSpeed(
+    speed: Double,
+    minSpeedLimit: Double,
+    maxSpeedLimit: Double,
+    minSpeed: Double,
+    maxSpeed: Double
+): Double {
+    return if (speed <= minSpeedLimit) minSpeed
+    else if (speed < maxSpeedLimit)
+        (maxSpeed - minSpeed) / (maxSpeedLimit - minSpeedLimit) * (speed - minSpeedLimit) + minSpeed
+    else maxSpeed
 }