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Assessment of Options for Extending the Life of the Hubble Space Telescope: Final Report
on the sensors and computers available to the robot. A key requirement for successful teleoperation is that the communication link between the human operator and the robot is sufficient to provide enough information for the remote operator to make decisions and to issue appropriate control commands in a correct and timely manner. Teleoperated robots typically require and exhibit very little autonomy because of the presence of the human operator in the loop.
It is useful to look at some well-known applications of robotics to understand the difference between automated, autonomous, and teleoperated robots.
One of the most visible and successful application of robotics is in factories and on the shop floor. Here, reprogrammable, multilink robotic arms have replaced special-purpose machines to perform precise and quick repetitive operations, such as pick and place tasks, for handling parts and tools and for assembling parts. The advantage of using robots in these applications is that their reconfigurability and flexibility make it possible for one assembly line to be multifunctional and to be adapted for a range of parts or products. However, a production facility or a factory is typically a highly structured environment. Precisely manufactured parts arrive on schedule at predetermined positions and orientations for robotic operation, and all operations are, for the most part, predictable. Once a robot is programmed, very little “intelligence” or autonomy is required of the robot for it to perform its limited set of functions. Very little adaptation to uncertainties is required. In spirit, these robots are closer to machines like programmable looms or dishwashers than to Hollywood’s R2D2.
Another recent, very visible application of robotics is the pair of Mars Exploratory Rovers (MERs), Spirit and Opportunity. These very successful mobile robots exhibit multiple levels of autonomous or semi-autonomous operation. These rovers have sensors that provide information about the environment in which they are operating, about their position in that environment, and about the status of the task they are performing. The sensors provide information to computers, which reason about the state of the robot and the environment and calculate the commands sent to the robot’s actuators to control its motion and activities. Some of this reasoning is done onboard the vehicle. However, much of the high-level reasoning and decision making is done by the remote human users, albeit infrequently because of the time delays associated with communication between the rovers and mission control on Earth. For example, remote human users set the science objectives (e.g., on which rock to place an instrument) and issue high-level commands (e.g., “go to that rock”). The rovers then execute these commands using onboard sensors and computers to determine and follow safe paths through the terrain. Importantly, the onboard autonomy is limited primarily to the specific tasks of navigation and instrumentation placement. The rovers have some limited ability to adapt to operating conditions and the environment. When unexpected situations or failures are encountered, the rovers can stop and wait for the remote human users to issue a new set of commands. Human users can also make the decision to send new software to the rovers or patch software bugs that may be discovered during the mission. Thus, while these robots are not, strictly speaking, teleoperated, there is an element of teleoperation in the functioning of these rovers. At the same time, the rovers exhibit a significantly greater degree of autonomy than the automated factory robots discussed earlier. This combination of autonomy with an element of teleoperation is often called supervised autonomy.
There are many remotely operated vehicles like Spirit and Opportunity that have been deployed on Earth. Rovers have been used for nuclear reactor inspection at Three Mile Island and have been deployed by the military for de-mining in Bosnia and for reconnaissance in caves in Afghanistan. In Iraq teleoperated rovers with manipulators are used for disruption and disposal of improvised explosive devices. Robotic submersibles have been used in the deep sea for exploration tasks by the marine science community, for inspection and maintenance tasks by the oil industry, and for salvage of wrecks like the Titanic. The level of autonomy employed in these devices varies. It is not feasible to teleoperate