The front end of the vehicle is almost always the "business end." It is fitted with manipulators for performing work, and TV cameras, lights and sonars so operators can see to navigate and conduct the work operations assigned. Because the underwater environment is intrinsically inhospitable to humans, using remotely manipulated mechanical arms is a natural way to perform subsea work. Remote manipulation (also called teleoperation) allows human operators working from the surface to manipulate underwater objects. A teleoperated manipulator is not the same as a factory robot that repetitively performs a single assigned task or set of tasks under controlled conditions in a structured environment. Instead, a telerobotic manipulator is the mechanical equivalent of human arms and hands. It manipulates objects under direct human control in real time (that is, while the task is being performed) and can therefore function in an unstructured environment. The most basic remote manipulator systems contain only an operator-input device and a jointed manipulator arm. More sophisticated systems also contain control electronics. The tip of the manipulator arm is attached to a tool (such as a pair of jaws, a drill, or a pair of snips) used to perform the required task (see photo).

A wide variety of manipulator types have evolved to cover a very broad range of subsea applications. These applications range from simple tasks, such as grasping a lift line, to more complex ones, such as plugging and unplugging electrical and hydraulic connectors. When selecting a manipulator, it is important to choose the simplest possible type that can accomplish the task in a reasonable time. In the offshore environment, complexity can generate problems with reliability, operation, and maintenance. A simple grabber, Schilling’s RigMaster, is shown in the photo to the right.

The choice and integration of a manipulator system is complex, and the vehicle designer should consider the following: number and types required, their location, required control type (rate, spatially correspondent, force feedback), lift, maximum (and minimum) reach, and camera locations. Remember, if you can’t see it, you can’t manipulate it.

Manipulator arms can provide multiple degree of freedom, as shown if the following figure of the advanced Kraft TeleRobotics Predator-7 manipulator.

Manipulator designs have improved dramatically over the years, integrating effective ergonomics along with power, dexterity and control. They have become easier to operate and maintain and have incorporated space-age technologies that have increased their reliability. Various configurations, degrees of freedom, and end uses are available in manipulators that are on the market today such as the Orion 7-function manipulator (see photo), developed by Schilling Robotics of Alstom Automation.

The future will see computer-aided teleoperation that will allow automatically detect potential collisions, move the slave arm directly to an object or along a pre-defined curve, and record manipulator movement paths for later review or playback.

Computer aided control will allow the operator to work with "virtual cameras" that display multiple views of an object from any camera location or angle, along with the ability to pan around the object, or zoom in and out. By creating a viewing site at the end of the arm, the operator will even get a "tool’s-eye view" of the task being performed.