Remote-control system

Remote-control system

A control system in which the issuing of the control command and its execution are separated by a relatively significant distance. The system normally includes a command device where the control command is entered, and an actuator that executes it. These are connected by a transmission medium that transmits the command, usually in a coded format.

The transmission medium may be a mechanical link, where the command is transmitted as force; a pneumatic or hydraulic line, where pressure represents the command; an electrical line with a voltage or current signal; or radio or infrared waves that are modulated according to the command.

The simplest remote-control systems are limited to switching-type functions. These systems operate basically in an open loop, that is, without relying on feedback. Some typical examples are a ceiling lamp turned on and off by a light switch via an electrical wire; the on/off function of a television receiver with an infrared remote controller; and railway switches operated from a remote-control room.

The most characteristic remote-control systems involve feedback that is provided by the human operator. The person issuing the control command senses the result of the control action and guides the system accordingly. This kind of operation can be found, for example, in remote control of toy cars and airplanes by wire or radio, remote operation of large construction cranes, and cockpit control of an airplane's engines and control surfaces. See Flight controls

Teleoperation represents an important class within remote-control systems with human feedback. Teleoperators (or remote manipulators) act as extensions of the human hand. They are employed in situations where access is difficult or impossible or where the environment is hazardous for humans, such as in underwater and space operations, or in the presence of radiation, chemical, or biological contamination. See Remote manipulators

Many automatic control systems may also be considered as remote controllers. This is the case whenever the sensing of the controlled variable and the automatic formation of the control command are removed from the actuator. A typical example is the heating and air-conditioning system of a building, where room thermostats operate remotely located furnaces, compressors, and fans. See Control systems