diff --git a/include/OpenSoT/constraints/velocity/CollisionAvoidance.h b/include/OpenSoT/constraints/velocity/CollisionAvoidance.h
index 96694b18..e884bd8b 100644
--- a/include/OpenSoT/constraints/velocity/CollisionAvoidance.h
+++ b/include/OpenSoT/constraints/velocity/CollisionAvoidance.h
@@ -68,6 +68,12 @@ class CollisionAvoidance: public Constraint<Eigen::MatrixXd, Eigen::VectorXd>
      */
     double getLinkPairThreshold();
 
+    /**
+     * @brief getError
+     * @param e
+     */
+    void getError(Eigen::VectorXd& e);
+
     /**
      * @brief getDetectionThreshold
      * @return _Detection_threshold the maximum distance which we use to look for link pairs