diff --git a/data/urdf/hyq/hyq_trunk_large.urdf b/data/urdf/hyq/hyq_trunk_large.urdf
index 3b11b53c1f49e5c2a5ba24b059d06279f7844f9d..64a7c768d72dd35cd43106ad7229883afc468291 100755
--- a/data/urdf/hyq/hyq_trunk_large.urdf
+++ b/data/urdf/hyq/hyq_trunk_large.urdf
@@ -1,5 +1,8 @@
 <robot name="hyq_trunk_large">
   <link name="base_link">
+  <inertial>
+     <mass value="50.26"/>
+  </inertial>
     <visual>
       <origin xyz="0 0 0" rpy="0 0 0" />
       <geometry>