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REMOTE HANDLING SYSTEMS

In general terms, performing remote operations requires a manipulator to be transported into and around the remote environment able to deploy tooling for the proposed tasks.

Manipulators
Crude manipulation can be performed using a joystick controlled robotic device. However, sensitive manipulation and handling is most reliably and safely done with a force-reflecting master-slave device such as Dexter.

Transporters
The primary function of the transporter is to position the manipulator, or other more specialised end-effectors, in the remote environment. It may also provide some camera arms for additional viewing.The transporter can be a large fixed robotic system, vehicular, or crane mounted.

Tools
Special tools are often required for remote handling operations. These can be either modified proprietary hand tools such as spanners, or specially designed tools for particular tasks. Careful design of the tools can greatly ease the remote handling, and help ensure components are not damaged.
- Handling Tools : These tools provide lifting features to aid the manipulation of heavy or delicate components. They may incorporate assembly alignment features.
- Cutting Tools : Cutting processes can be automated by the use of tools utilising sawing, punching, or single point cutting. These processes are used for pipe and flange opening. Operation without coolant allows the collection of the dry cutting debris.
- Welding Tools : The automation of the TIG welding process, with and without filler material, provides a reliable means of remotely joining pipework and flanges. These tools may be modified proprietary units or specialised tools to accommodate unusual access difficulties.
- Cleaning Tools : Vacuum cleaner systems used in conjunction with specialised tool heads have been developed to clean up after maintenance. Cyclone devices are capable of collecting dust samples.
- Winches : Assists the manipulation of heavier components allowing the manipulator to be used for the more delicate tactile functions of handling.

Controllers
For medium to large systems we favour solutions which are based on an industry standard VME bus architecture. Single powerful processors such as the PowerPC 750 or Motorola 68xxx series are used as bus masters. Programmable Multi-Axis Controllers (PMAC) from Delta Tau are used as high-performance servo motion controllers capable of commanding up to eight axes of motion simultaneously with a high level of sophistication. These motion controllers have proven to be extremely resourceful, reliable and adaptable.
Using multiple PMAC’s, analogue and digital I/O, and high-resolution resolver to digital converters complex controllers can be configured to control equipment with up to 32 degree of freedom.
For smaller or less demanding equipment programmable logic controllers (PLC’s) can be used as a cost-effective solution.
Safety is a primary concern of any remote handling system design as required by PUWER. For that reason the controllers must incorporate features such as interlocking operation, fail safe condition components, watch-dog timers and hard wired emergency stop systems as well as intelligent diagnostics and condition monitoring.

Software
Software needs to be developed at a number of levels throughout a remote handling system, from control systems, to Human-Machine Interfaces (HMI), to virtual reality modeling, to procedure control. It is important to provide a uniform look-and-feel at the operator level across the multiple sub-systems.
Computer Assisted Software Engineering (CASE) tools can be used throughout the software development cycle, for design, documentation, and version control. Indeed tools based on the Unified Modeling Language (UML) such as I-Logix Rhapsody support the whole development cycle.
Developing software within a modeling package ensures design, documentation and code are synchronised, and greatly facilitates quality control. Version control software such as MS SourceSafe can be applied to the models.
Control systems require hard real-time execution processes. They typically have dedicated processors embedded in a controller, are interrupt driven, and require multiple input/output (I/O) interfaces. Resources at this level are usually scarce. Optimum performance was often found using operating system-less Digital Signal Processors (DSP) programmed in assembler. With the advent of more powerful processors, it is more usual to opt for the convenience of a real-time operating system programmed in a high-level language.
OS-9 is a real-time, multiuser, multitasking operating system developed by Microware Systems Corporation. It supports the Motorola 68XXX family of processors. It is relatively inexpensive and easy to use, and we have developed a number of embedded control systems on top of it. The development and debugging tools are less sophisticated than Wind Rivers VxWorks. VxWorks is the premier development and execution environment for complex real-time and embedded applications on a wide variety of target processors. Three highly integrated components are included with VxWorks: a high performance scalable real-time operating system which executes on a target processor; a set of powerful cross-development tools which are used on a host development system; and a full range of communications software options such as Ethernet or serial line for the target connection to the host.
The computing language used is chosen for its suitability to a particular task: C or C++ for control applications, Java or Basic for fast development of desktop applications. Sometimes legacy code forces the continued use of a particular language when another might be preferred. Oxford Technologies software staff have extensive experience in working with and supporting externally developed code (C, Assembler, Forth, Ladder Logic), and in developing new applications (C, C++, Java, Basic).