The rigidization capability of the torque/force sensor is necessary to provide the required stiffness when  the end effector acts as the shoulder and if "hand" stiffness is required during transportation operations. The End Effector Subsystem (EES) consists of:  1. Structure housing.2. Actuation and Sensing Unit  a) Actuator Unit b) Torque/Force Sensor (TFS) c) TFS Rigidization Mechanism 3. Moving Platform4. Grapple Mechanisms5. System Harness Connectors6. Integrated Servicing Tool (IST)7. Base points (BP) The EES is also equipped with specific mechanical elements for EVA manual override.  /g20/g17/g3/g54/g87/g85/g88/g70/g87/g88/g85/g72/g3/g75/g82/g88/g86/g76/g81/g74   The main load-carrying structure of the end effector consists of the lower housing  structure and the housing that contains the Electronics Unit. The lower housing structure is built up by the  three stiffeners; the cover sheets, which are attached to the stiffeners; interface ring; and the guidance.  The Electronics Unit housing provides the interface to the roll joint of the ERA Manipulator Joint System (MJS) and to the Camera and Lighting Unit (CLU). All parts of the housing structures are manufactured from high-strength aluminum alloy, the interfacing ring and the guidance from titanium, the spindles and the hooks from steel. /g21/g17/g3/g36/g70/g87/g88/g68/g87/g76/g82/g81/g3/g68/g81/g71/g3/g54/g72/g81/g86/g76/g81/g74/g3/g56/g81/g76/g87 /g3The Actuation and Sensing Unit consists of the Actuator Unit, the Torque  Force Sensor, and the TFS Rigidization Mechanism. a)Actuator Unit : The actuator unit drives with its electromotor and mechanisms the moving platform.  The actuator unit consists of an internally redundant brushless-type electromotor, a redundant set of  Hall sensors mounted to the motor shaft, a gear train, and three roller screws with nuts that are  mounted to the moving platform. The gear/motor assembly rotates the synchronized roller screws. Three roller screw nuts are mounted with a restricted floating capability to a platform, which will move  upwards/downwards by the rotating roller screws. b)/g55/g82/g85/g84/g88/g72/g18/g41/g82/g85/g70/g72/g3/g54/g72/g81/g86/g82/g85/g3/g11/g55/g41/g54 /g12/g29  The TFS is an electro-mechanical unit equipped with strain gauges,  which measures torques and forces in 6 degrees of freedom. The analog TFS signals will be acquired  and processed by the TFS electronics and will be sent via the Electronic Unit to the ERA OBC. The TFS is temperature compensated and is protected against mechanical overloading by rigid end stops.In case the measured function of the TFS is not needed and an increased stiffness for the TFS is required, the TFS will be blocked by the Torque Force Sensor Rigidization Mechanism. c)/g55/g41/g54/g3/g53/g76/g74/g76/g71/g76/g93/g68/g87/g76/g82/g81/g3/g48/g72/g70/g75/g68/g81/g76/g86/g80 : The TFS rigidization mechanism (TRM) will block the TFS when its  function is not needed. It will automatically form a stiff structure when not in operation and a flexible  structure to protect the arm from overloading when disengaged. The TRM consists of the following items: /g120one electrically redundant brushless motor, which is the same as being used for the Actuator Unit  and the Integrated Servicing Tool; the motor control is included within the Electronics Unit; /g120one worm gear, to provide the required gear ratio (N= 105); /g120three conical shaped blocking elements; each of it consisting of a solid inner cone and a flexible,  slotted outer cone; /g120 a cam wheel, which is driven via the worm gear by the motor; the cam wheel includes three  tracks that transform the rotation of the cam wheel into a translational motion of 3 mm; /g120three rods, which transfer the translational motion of 3 mm from the wheel to the inner cones. The  rods are connected to t he tracks of the cam wheel via deep groove bearings; 322