Remote Operated Vehicles (ROVs) are of great utility in conducting underwater surveillance, data collection, sonar mapping, and searches for underwater objects. However, information gathering is only one of the things these versatile underwater craft can accomplish. With the addition of manipulator and grabber arms, ROVs can perform a wide array of useful tasks. ROVs have used manipulator arms since the first ROVs were deployed by the US Navy in the 1960s to recover objects on the sea bottom (including, famously, a hydrogen bomb that sank to the bottom of the western Mediterranean following a B-52 crash in 1966). Today’s manipulator arms are considerably more advanced than those early grippers.
Generally, modern ROVs use a master-slave manipulation model, where a human operator based on a surface vessel controls the ROV’s arm(s) either with a control panel or with an actual miniature manipulator matching the manipulator on the ROV. Remote control techniques originally developed in the space program allow any operator to work the arm easily, without the need for specialized ‘crane operator’-type skills. This allows the operator to be a mission specialist or a scientist skilled in what the manipulator needs to be doing, rather than a specialist who can control the arm well but needs to be told what to do with it.
Manipulator arms can be deployed to use a wide variety of tools. These tools are often simple or complex grippers, but can also be power tools like drills, saws, cutters, wrenches, or others. The earliest ROVs were limited to very simple grippers, and it was a major step forward when ROVs became capable of doing simple jobs like opening or closing a valve handle on an underwater platform.
There are three broad general categories of manipulator use for ROVs: industrial, military/law enforcement, and scientific. Industrial ROVs can use manipulators to cut and lay pipe, make and break hydraulic connections, lay and retrieving cable, lubricate underwater machinery, carry heavy tools for human divers, conduct trenching operations, and operate machinery like valves and levers. Military/law enforcement ROVs can use manipulator arms to retrieve or tag items, to place charges (for example, to neutralize underwater mines), and to cut cables. Scientific ROVs can use manipulator arms to select samples, to gather materials for analysis, to drill into the sea bottom, to sieve lighter materials, to take core samples, and to deploy and retrieve sensors.
ROVs equipped with manipulating arms have successfully assisted in exploring sunken vessels, raising ships and objects from the ocean floor, finding victims of crimes and criminal evidence, operating oil and gas platforms, and conducting pure scientific research. The use of manipulators makes these useful tools even more effective.