Thomas B. Sheridan, a pioneer of robotics and remote control technology, defined a robot as “a machine that senses and acts upon its environment autonomously, and . . . behaves with what appears to be human intelligence”. This explanation, which likely bears strong resemblance to most common descriptions of the autonomous machines, implies a certain level of individualistic performance of the robot in carrying out tasks; its purpose is to substitute a human for completing his or her duties. However, many robots work in conjunction with humans.
Take, for example, collaborative robots (or cobots), which, according to ISO/TS 15066:2016 – Robots and robotic devices – Collaborative robots, are intended to combine the repetitive performance of robots with the individual skills and ability of people. These human-robot workspaces benefit from enhanced precision and power over those composed solely of human workers.
In space missions, telerobots accomplish this same feat, and they are used for improving the efficiency of different types of work through advanced practices in robotics and ergonomics.
A telerobot is closely tied with a teleoperator, which Sheridan refers to as “a machine enabling a human operator to move about, sense, and mechanically manipulate objects at a distance”. He distinctly calls a telerobot a “subclass of teleoperator in which the machine acts as a robot for short periods, but is monitored by a human supervisor and reprogrammed from time to time”. Telerobotics is concerned with the operator control of a robot at a distance, not the commands coded into a self-controlled machine.
Telerobotics is not limited to space, as the machines have long been utilized for military purposes, as well as being optimized for different industries. Just to name a few, telerobots have been used for ensuring precision in surgery, intensifying recreational activities (remote controlled cars and helicopters), and even the control of battlebots.
The Human Factors and Ergonomics Society (HFES) has defined a space telerobot as “a remotely operated robot that works in a space rich environment”, meaning that it can function on an unstructured surface, such as a planet or asteroid, or a complex operational setting, such as the on-orbit servicing of a satellite. In space, despite the fact that astronauts, due to their rigorous training and selection process, possess cognitive capabilities that are virtually unmatched, their time is always limited and there exists much work that would be impractical or unfeasible for humans to perform. This is where space telerobots come into play.
Space telerobots can perform a slew of intravehicular activity (IVA) and extravehicular activity (EVA) work for missions in orbit, in deep space, or on surface environments. The label of space telerobot encompasses remotely operated planetary rovers, manipulator arms, and highly-maneuverable free-flying systems. It does not include deep-space probes, orbiters, landers, and automated spacecraft.
There are two primary methods of telerobot control: manual control (or direct teleoperation), involving the complete control of the actuators on the robot by the operator, and supervisory control, in which the operator sends intermittent commands and intervenes only when necessary. Both of these may be utilized by the same telerobot, as evidenced by the popular Mars Curiosity Rover.
Telerobotics has been utilized in space missions for 50 years now, and they have a proven record of benefitting the space work environment. These robots can be and have been successful in performing relatively dangerous, tedious, repetitive, or long-lasting tasks, such as scouting, site preparation, and habitat construction. Telerobots, in addition to operating with robotic precision, are reliable due to their graceful degradation. For example, the MER Spirit successfully operated for 4 additional years following the failure of its right-front wheel drive motor.
Telerobots can also be useful in assisting humans side by side, a practice that is not as common as their operation by humans on the ground. Despite being remarkably helpful, these human-robot workspaces in space environments are hindered by the telerobots’ current limitations.
Telerobots possess the best of both worlds; they make use of the decision making skills of humans with the efficiency, power, and precision of robots. However, in a space workspace with active humans and telerobots, any space-related constraints placed on the human sending commands to or controlling the machine, such as disorientation, mental slowing, poor concentration, and confusion, are transferred to the telerobot’s performance, as the efficiency of the two are one.
The space environment can also be harsh for equipment, even telerobots themselves. Out of the Earth’s atmosphere, these machines may cross paths with the extremes of space, including radiation, high temperatures, illumination variations, micrometeoroids, and other environmental factors. Furthermore, the latency in data communications between the operator and telerobot can negatively impact activities.
It is anticipated that future exploration missions will require human-robot collaboration across multiple spatial ranges, from shoulder-to-shoulder (e.g., human and robot in a shared space) to line-of-sight (human in habitat, robot outside) to over-the-horizon (human in habitat, robot far away) to interplanetary (human at ground control, robot on planetary surface) interaction. Many telerobotic systems have been designed so far, yet all of them are optimized for application-specific spatial ranges and cannot be used for all of these purposes.
To address some of these issues, HFES proposes that humans and telerobots must be able to:
- Communicate clearly about their goals, abilities, plans, and achievements.
- Collaborate to solve problems, especially when situations exceed autonomous capabilities.
- Interact via multiple modalities (dialogue, gestures, etc.), both locally and remotely.
However, there currently few guidelines for the design of space telerobots, and further efforts are needed in related ergonomic concerns.