add iiwa_torque_external

Author: RussTedrake

manipulation_station.ipynb

@@ -128,6 +128,9 @@
         "    #builder.ExportOutput(adder.get_output_port(), \"iiwa_torque_commanded\")\n",
         "    #builder.ExportOutput(adder.get_output_port(), \"iiwa_torque_measured\")\n",
         "\n",
+        "    builder.ExportOutput(plant.get_generalized_contact_forces_output_port(iiwa),\n",
+        "                         \"iiwa_torque_external\")\n",
+        "\n",
         "    # Wsg controller.\n",
         "    wsg_controller = builder.AddSystem(SchunkWsgPositionController())\n",
         "    wsg_controller.set_name(\"wsg_controller\")\n",
@@ -160,8 +163,7 @@
         "                         \"plant_continuous_state\")\n",
         "\n",
         "    diagram = builder.Build()\n",
-        "    return diagram\n",
-        "\n"
+        "    return diagram\n"
       ]
     },
     {