public boolean compare(SimulationConstructionSet scs1, SimulationConstructionSet scs2) {
   // compare variables
   YoVariable var0 = getRootJoint(scs1).getQx();
   YoVariable var1 = getRootJoint(scs2).getQx();
   return (MathTools.epsilonEquals(var0.getValueAsDouble(), var1.getValueAsDouble(), epsilon));
 }