Use of teleoperators and transporters in JET

The teleoperator for dexterous tasks is the Mascot IV force-feedback servomanipulator, consisting of a two-armed master unit and a kinematically similar slave. A load capacity of 20 kg, a sensitivity of 150 g, low inertia and good stiffness are among the main features. A microprocessor-based digital control system allows serial link and computer-aided teleoperation, teach-repeat, weight compensation and trajectory constraints. Typical tasks for the manipulator are leak detection, repair welding, bolting, insertion of connectors, positioning of mating parts, heating jackets and special tools, such as the lip cutting/welding trolleys and the orbital pipe welders and cutters. The manipulator can be positioned in the vessel by an articulated boom with five vertical hinges and a pan/tilt/roll end fixture. The boom enters the vessel through a port with small clearances situated on the equatorial plane and reaches round to the opposite side of the torus. To handle heavy components (antennae and limiters), the manipulator is replaced by special end-effectors. By controlling the accelerations to limit oscillations, it is possible to position a 350 kg payload at 10 m from the first hinge with 1 mm accuracy. The control modes, using a microprocessor-based system, are teach-repeat, joint-by-joint or resolved motion. Viewing is provided by two mono TV cameras mounted on articulated arms pre-programmed and in future, self-tracking to obtain direct and side views for depth perception. Outside the vessel, the main transporter will be a bridge-mounted telescopic boom at present being built by Noell to JET specifications, supplemented by the roving turret truck and low-level transporter. (author). 1 ref., 14 figs