core: add ETCS LOA logic to ETCS braking simulator

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

@@ -1,6 +1,69 @@
 package fr.sncf.osrd.envelope_sim.etcs
 
-/** See Subset referenced in ETCSBrakingSimulator: table in Appendix A.3.1. */
+/**
+ * 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 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 026: §3.13.9.3.2.9.
+ */
+const val aEst2 = 0.4
+
+/** 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
+const val vEbiMax = 210.0 / 3.6 // m/s
+const val tWarning = 2.0 // s
 const val tDriver = 4.0 // s
 const val mRotatingMax = 15.0 // %
 const val mRotatingMin = 2.0 // %
+
+/** 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 interpolateLinearSpeed(speed, vUraMinLimit, vUraMaxLimit, vUraMin, vUraMax)
+}
+
+/** See Subset 026: §3.13.9.3.2.10. */
+fun vDelta0(speed: Double): Double {
+    return if (!qNvinhsmicperm) vUra(speed) else 0.0
+}
+
+/** See Subset 026: §3.13.9.2.3. */
+fun dvEbi(speed: Double): Double {
+    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
+}