removed a deadlock

source/RobotAPI/components/units/HeadIKUnit.cpp

@@ -170,10 +170,16 @@ namespace armarx
         bool doCalculation = false;
 
         {
-            ScopedLock lock(accessMutex);
-
-            doCalculation = requested && newTargetSet;
-            newTargetSet = false;
+            ScopedTryLock lock(accessMutex);
+            if (lock.owns_lock())
+            {
+                doCalculation = requested && newTargetSet;
+                newTargetSet = false;
+            }
+            else
+            {
+                return;
+            }
         }