Simulating and visualizing deflections of a remote handling mechanism

► An infinitesimal transformation represents elastic deflections. ► Equivalent spring factor is used to combine several deformations. ► Initial VR model accuracy improved from 80 to 5mm. ► The deflection model is capable of adapting to changes in load at the end-effector. ► The algorithms and approach described are generic and can be adopted for other mechanisms. Continuing ITER divertor second cassette (SC) remote handling (RH) test campaign has been carried out at divertor test platform (DTP2) in Finland. One of the goals has been to develop and implement efficient algorithms and software tools for simulating and visualizing for the operator the non-instrumented deflections of the RH mechanisms under loading conditions. Based on assumptions of the classical beam theory, the presented solution suggests utilization of an infinitesimal transformation to represent elastic deflections in a mechanical structure. Both structural analysis and measurements of the real structure are utilised during the process. The solution suggests one possible implementation strategy of a software component called structural simulator (SS), which is a software component of the remote handling control system (RHCS) architectural model specified by ITER organisation. Utilisation of the proposed SS necessitates modification of the initial virtual reality (VR) model of RH equipment to a format, which can visually represent the structural deflections. In practise this means adding virtual joints into the model. This will improve the accuracy of the VR visualization and will ensure that the virtual representation of the RH equipment closely aligns with the actual RH equipment. Cassette multifunctional mover (CMM) and second cassette end effector (SCEE) carrying SC were selected to be the initial target system for developing the approach. Demonstrations proved that the approach used can give high levels of accuracy even in complex structures such as the CMM/SCEE: initial VR model accuracy of the CMM/SCEE carrying 9ton cassette improved from 80 to 5mm. Also, the deflection model is capable of adapting to changes in load at the end-effector: during the release/lift of the divertor 2nd cassette to/from the divertor rails the accuracy remains within 5mm. The algorithms and approach described are generic and can be adopted for other mechanisms.