Remote manipulators

Remote manipulators

Mechanical, electromechanical, or hydromechanical devices which enable a person to perform manual operations while separated from the site of the work. Remote manipulators are designed for situations where direct contact would be dangerous to the human (working with radioactive material), where direct human contact is ill-advised or impossible (certain medical procedures), and where human force-producing capabilities are absent (the disabled) or need to be amplified to complete some task (industrial assembly or construction).

Basic defining elements are common to almost all remote manipulators. An input device or control handle allows the operator to command the remote manipulator. The movement of the input device is received by a control station that translates the inputs into a form that can be transmitted over the distance separating the human and remote manipulator. This translation can be mechanical, using cables and linkages, or electrical/electromagnetic, using the movement of the input device to generate an electrical or electromagnetic signal that is easily transmitted to the remote manipulator. Since vision is an important cue that humans use in direct manipulation, visual feedback of a remote manipulator's actions typically must be provided. In some remote manipulation systems, tactile feedback to the human operator is provided; that is, forces proportional to those being exerted by the remote manipulator on the object are fed back to the human through the input device. Such force feedback is important in certain tasks where the possibility of damage to the manipulator or object can occur.

The growth in the number and variety of remote manipulator applications has been aided by enabling technologies such as digital computers, lightweight materials, and video communication links. Space applications include the space shuttle remote manipulator arm, which has been used to retrieve and launch large satellites. The arm is operated by astronauts in the shuttle orbiter cabin, and employs graphic displays of the forces and torques being applied by the manipulator arm to the satellite. Other applications include use in crewless underwater vehicles and surgical procedures.

Aiding the disabled is an important use of remote manipulators. One example is devices that allow individuals with little or no control of their upper extremities to feed themselves. Such devices have been referred to as teletheses (alluding to the extrasensory perception of distant objects).

Devices that augment the strength of the human have been proposed for industrial applications. For example, a load-sharing manipulator has been envisioned in which human arm-manipulator coordination effectively allows the human to work with a “partner” that has considerably more strength. See Control systems, Human-machine systems, Robotics