added target valid check in impedance controller

source/RobotAPI/components/units/RobotUnit/NJointControllers/NJointTaskSpaceImpedanceController.cpp

@@ -192,7 +192,12 @@ void NJointTaskSpaceImpedanceController::rtRun(const IceUtil::Time& sensorValues
 
         debugDataInfo.getWriteBuffer().desired_torques[jointNames[i]] = jointDesiredTorques(i);
 
+
         targets.at(i)->torque = desiredTorque;
+        if (!targets.at(i)->isValid())
+        {
+            targets.at(i)->torque = 0;
+        }
     }