Virtual decommissioning22 November 2017
Virtual reality has now reached the field of remote handling and robotics. Jean-Michel Wagner, Hubert Hafen and Wolfgang Metzger explain how using it for training and interactive feasibility studies can lead to cost and time savings on complex decommissioning projects
Many projects to dismantle nuclear facilities have to be carried out using remote handling. In these high-radiation environments, having a clear vision of decommissioning operations, even underwater, is essential. It is also critical to have a well-defined plan for disassembling active components, as the measure of a project’s success is often based on clean efficient cutting and removing of materials. Remote handling workers, who are responsible for these tasks, should therefore be a key focus of attention. Using virtual reality to help operators to prepare for their tasks can result in significant savings to cost and schedule.
Wälischmiller Engineering has developed a virtual suite to train operators in the use of its Telbot® system. The idea was developed in collaboration with Kerntechnische Entsorgung Karlsruhe GmbH, which is responsible for decommissioning Germany’s Karlsruhe Reprocessing Plant.
The Telbot is a modular robot with selectable drives, arm lengths and joint modules. Its components have been chosen to resist harsh environments such as those in the nuclear or chemical industries, and to be suitable for confined spaces.
The Telbot arms can be operated using the Joyarm and the Master-Arm. The Joyarm is a universal operating device for all kinds of multi-axis robots. It has been ergonomically designed for operators in order to minimise fatigue, independent from the slave-manipulator structure. With the Joyarm, operators can realise precise motion control, like that provided by a joystick, and then switch to the intuitive quick positioning offered by master-slave control systems. Joyarm sends commands with six degrees of freedom for position and rotation, and receives six degrees of freedom force and torque feedback in a cartesian coordinate frame.
The HWM Master-Arm is an operating element for manipulators. It has force feedback on its seven degrees of freedom. The operator can sense feedback on the Master-Arm from what is happening on the manipulator. Using the Master-Arm reduces training time for new operators, because the system has the same configuration as the slave arm, so operators can easily recognise the joint positions. The slave follows the master exactly, as in the case of a mechanical manipulator.
The virtual suite
To support Kerntechnische Entsorgung Karlsruhe GmbH’s project decommission and dismantle the Karlsruhe Reprocessing Plant in Germany, Wälischmiller was involved in developing a virtual test suite, which combines 3D models of the facilities and equipment to be decommissioned (hot cells, components, pipelines, etc.) with a virtual Telbot. It will enable operators to practice decommissioning tasks and familiarise themselves with the project steps. All movements – cuts, and loading vessel segments into transportation and disposal casks – can be taught, scheduled and practiced within the virtual test suite. This reduces the need for costly and complex construction of test rigs, and it allows operators to be trained without the risk of damaging expensive remote- handling equipment.
The virtual reality suite comprises a large screen, control cabinet, simulation computer, a Wälischmiller Joyarm and a Master-Arm. Simulations are based on 3D CAD data collected from the facility. The system runs in real time, so the command on the operating elements is transferred to the simulation almost without delay. This feature is important to improve the haptic and so operators receive a force feedback.
The virtual reality environment has a range of features, including different controlling modes (for moving the tool and camera perspective), a minimum distance checker (automatic stop if minimum distance is reached), collision detection and a path planner with teaching mode.
Benefits of VR
Wälischmiller develops manipulators and systems with the aim of balancing the customer’s needs – better technology, user friendliness and economical constraints, as well as budget, return on investment and life time of the equipment.
User friendliness has always been a driving force behind our design and manufacturing.
There is a large diversity of remote handling equipment on the market today, but it is customer desire for advanced solutions and comfort that encourages manufacturers to develop smarter equipment.
Today’s remote handling technologies allow for operations to be prepared in a virtual environment, which has several advantages over traditional preparation and testing methods.
The virtual reality suite expands the options in planning single dismantling steps, especially those requiring critical handling procedures. The situation and the operations that have been carried out can be analysed from different views and angles – something that is not possible with traditional cameras. This modern technique also opens new possibilities for planning decommissioning tasks. Different scenarios can be conducted to find the best solution for effective and safe dismantling operations.
It also reduces cost. Until now, challenging dismantling steps had to be tested, and operators trained, on complex construction test rigs. Commissioning these rigs is cost- intensive and time consuming. The virtual suite offers a fast and cost-effective test environment, which is close to reality.
The operators can be trained as often as necessary, and the test environment can be rebuilt very quickly using virtual reality, something that is not possible with a traditional test rig.
Operating personnel can be trained on a virtual test rig without the risk of damaging expensive remote handling equipment. Consequently, the remote handling equipment will not be used – which also leads to cost saving.
Safety is improved because operators can practice using the virtual suite and familiarise themselves with the projects. They can also be trained on cutting procedures for dividing objects with special tools. As the training takes place in a virtual environment, operators cannot damage the robotic arm or the in-cell equipment, nor cause injury.
As it is not possible to damage expensive equipment through incorrect handling, this virtual approach to training improves operator self-confidence.
The detailed structure of the manipulator and the operational facilities in the hot cells are modelled and simulated in real time. The optical collision detection during the simulation avoids damage to the manipulator and the facilities. The collision detector sends a signal to stop the arm before any collision occurs.
To date, the virtual suite integrates a Telbot system. In the future, 3D models of the power manipulators A1000 and of the remote-controlled handling vehicle V1000 that are also used at the decommissioning site will be integrated in the virtual suite. The standard control console of the A1000 will be linked with the suite, widening the scope for feasibility studies.
The virtual suite can be used as training environment for future remote handling operators and to qualify workers, for example at job interviews.
About the authors: Jean-Michel Wagner and Hubert Hafen are with Wälischmiller Engineering GmbH; Wolfgang Metzger is with Kerntechnische Entsorgung Karlsruhe GmbH