HOME > REMOTE HANDLING > PHILOSOPHY

REMOTE HANDLING METHODOLOGIES

The use of remote handling equipment is demanded by the need to maintain people at a safe distance from a hazardous situation. The remote handling philosophy adopted will depend on the risks associated with that hazard and the complexity of the tasks.

The simplest form of remote handling is the use of long reach tools. This approach extends the length of standard tools to provide an adequate safe distance between the hazard and the operator.

When it is necessary to provide additional shielding for the operator, and the task can be brought to a work cell, it may be appropriate to use “through-the-wall” manipulator arms. This equipment provides a mechanical linkage between the operator on the outside of the cell and the hazardous task inside. The mechanical “hands” of the slave arms are guided by the operator’s control of the geometrically similar master arms. The operator is able to view the task through a window in the cell and he benefits from a high degree of tactile feedback.

Where the task cannot be confined to a cell then a multi-degree of freedom robotic device may be appropriate. They may be similar to industrial robots and can be used to apply high forces. These function under the control of an operator using an analogue joystick or a similar input device. Viewing of the task is provided by closed circuit video cameras mounted on the robotic device. Generally, these devices do not provide tactile feedback for the operator.

Similarly controlled are remotely operated vehicles (ROVs). They range from tracked vehicles capable of operating in a level environment to submersible devices capable of operation on the ocean floor. Tasks are performed using robotic arms. The control communication may be achieved using an umbilical cable or by wireless means.

If a task is of a structured nature then a bespoke automatic or semi-automatic mechanical handling system can be used. Generally, this equipment is not versatile but it does relieve operators of highly repetitive tasks.

The force reflecting master-slave manipulator combines tactile feedback with the ability to operate at great distance from the hazard. The mechanical linkage between master and slave arms of the “through the wall” manipulator is replaced by electric motors and a computer control system. This provision of bi-lateral force reflection is known as the “man-in-the-loop” system enables the operator to perform highly dextrous tasks. As with the other physically distant remote systems, viewing of the task is provided by closed circuit video cameras.

In the future it is anticipated that remote devices will be capable of more autonomous operation. This will enable automated operation in less structured environments and will relieve the operators from the more mundane tasks and reducing the need for video feedback. Many issues influence the selection of suitable remote handling equipment for a task. The size and shape of the task environment is a key factor. Obstacles within the work envelope and will determine the degree of versatility needed from the remote handling system. A poor level of confidence regarding the plant status and condition will necessitate a more sophisticated remote handling approach.

The degree to which the hazard prevents manned access to task area is fundamental. It may be possible for personnel to make brief visits to maintain remote equipment. If not, then a comprehensive study of the possible equipment failure modes must be made and recovery techniques established.

Project budget and timescale constraints will also play an important part in the selection process. A need to provide a high rate of working may determine that a more automated system is appropriate.