A telemanipulator (or teleoperator) is a device that is controlled remotely by a human operator. In simple cases the controlling operator's command actions correspond directly to actions in the device controlled, as for example in a radio-controlled model aircraft or a tethered deep submergence vehicle. Where communications delays make direct control impractical (such as a remote planetary rover), or it is desired to reduce operator workload (as in a remotely controlled spy or attack aircraft), the device will not be controlled directly, instead being commanded to follow a specified path. At increasing levels of sophistication the device may operate somewhat independently in matters such as obstacle avoidance, also commonly employed in planetary rovers.