Fix zero-crossing detection in CS FMUs

fixes #233
modelica · Apr 8, 2022 · 55a94b6 · 55a94b6
1 parent 2ddad46
commit 55a94b6
Show file tree

Hide file tree

Showing 2 changed files with 6 additions and 7 deletions.
diff --git a/BouncingBall/model.c b/BouncingBall/model.c
@@ -1,4 +1,5 @@
 #include <math.h>  // for fabs()
+#include <float.h> // for DBL_MIN
 #include "config.h"
 #include "model.h"
 
@@ -115,7 +116,7 @@ void eventUpdate(ModelInstance *comp) {
 
     if (M(h) <= 0 && M(v) < 0) {
 
-        M(h) = 0;
+        M(h) = DBL_MIN;  // slightly above 0 to avoid zero-crossing
         M(v) = -M(v) * M(e);
 
         if (M(v) < V_MIN) {
@@ -124,12 +125,10 @@ void eventUpdate(ModelInstance *comp) {
             M(g) = 0;
         }
 
-        comp->valuesOfContinuousStatesChanged = true;
-    }
+        // reset previous event indicators
+        getEventIndicators(comp, comp->z, NZ);
 
-    // reset the previous event indicators
-    for (int i = 0; i < NZ; i++) {
-        comp->z[i] = 0;
+        comp->valuesOfContinuousStatesChanged = true;
     }
 
     comp->nominalsOfContinuousStatesChanged = false;

diff --git a/src/cosimulation.c b/src/cosimulation.c
@@ -548,7 +548,7 @@ void doFixedStep(ModelInstance *comp, bool* stateEvent, bool* timeEvent) {
 
     // check for zero-crossings
     for (int i = 0; i < NZ; i++) {
-        *stateEvent |= comp->z[i] * z[i] < 0;
+        *stateEvent |= (comp->z[i] <= 0 && z[i] > 0) || (comp->z[i] > 0 && z[i] <= 0);
     }
 
     // remember the current event indicators