Rail deployment and storage procedure and test for ITER blanket remote maintenance

A concept of rail-mounted vehicle manipulator system has been developed to apply to the maintenance of the ITER blanket composed of ≈400 modules in the vacuum vessel. The most critical issue of the vehicle manipulator system is the feasibility of the deployment and storage of the articulated rail, composed of eight rail links without any driving mechanism in the joints. To solve this issue, a new driving mechanism and procedure for the rail deployment and storage has been proposed, taking account of the repeated operation of the multi-rail links deployed and stored in the same kinematical manner. The new driving mechanism, which is different from those of a usual articulated manipulator or ‘articulated boom’ equipped with actuators in every joint for movement, is composed of three external mechanisms installed outside the articulated rail, i.e. a vehicle traveling mechanism as main driver and two auxiliary driving mechanisms. A simplified synchronized control of three driving mechanisms has also been proposed, including ‘torque-limit control’ for suppression of the overload of the mechanisms. These proposals have been tested using a full-scale vehicle manipulator system, in order to demonstrate the proof of principle for rail deployment and storage. As a result, the articulated rail has been successfully deployed and stored within 6 h each, less than the target of 8 h, by means of the three external driving mechanisms and the proposed synchronized control. In addition, the overload caused by an unexpected mismatch of the synchronized control of three driving mechanisms has also been successfully suppressed less than the rated torque by the proposed ‘torque-limit control’. It is therefore concluded that the feasibility of the rail deployment and storage of the vehicle manipulator system has been demonstrated.