From 81fbd617f79465dcf780a0f3ee26e5464de21d5f Mon Sep 17 00:00:00 2001
From: Luc Maisonobe <luc@orekit.org>
Date: Wed, 25 Feb 2015 15:50:16 +0100
Subject: [PATCH] Attempt to find an escape solution in some inverse location
cases.
---
.../rugged/linesensor/SensorMeanPlaneCrossing.java | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/src/main/java/org/orekit/rugged/linesensor/SensorMeanPlaneCrossing.java b/src/main/java/org/orekit/rugged/linesensor/SensorMeanPlaneCrossing.java
index ce2d0659..7357b189 100644
--- a/src/main/java/org/orekit/rugged/linesensor/SensorMeanPlaneCrossing.java
+++ b/src/main/java/org/orekit/rugged/linesensor/SensorMeanPlaneCrossing.java
@@ -308,17 +308,24 @@ public class SensorMeanPlaneCrossing {
Transform scToInert = midScToInert;
boolean atMin = false;
boolean atMax = false;
+ double deltaL = Double.NaN;
for (int i = 0; i < maxEval; ++i) {
final FieldVector3D<DerivativeStructure> targetDirection =
evaluateLine(crossingLine, targetPV, bodyToInert, scToInert);
final DerivativeStructure beta = FieldVector3D.angle(targetDirection, meanPlaneNormal);
- final double deltaL = (0.5 * FastMath.PI - beta.getValue()) / beta.getPartialDerivative(1);
+ final double previousDeltaL = deltaL;
+ deltaL = (0.5 * FastMath.PI - beta.getValue()) / beta.getPartialDerivative(1);
if (FastMath.abs(deltaL) <= accuracy) {
// return immediately, without doing any additional evaluation!
return new CrossingResult(sensor.getDate(crossingLine), crossingLine, targetDirection);
}
+ if (FastMath.abs(deltaL + previousDeltaL) <= 0.01 * FastMath.abs(deltaL)) {
+ // we are stuck in a loop between two values!
+ // try to escape from the loop by targeting the middle point
+ deltaL = 0.5 * deltaL;
+ }
crossingLine += deltaL;
if (crossingLine < minLine) {
--
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