Think-Sense-Act: What does it mean to be a robot?
As with any evolving technology or idea, the notion of what a robot really is has changed a lot. As you can find in the countless resources describing the evolution of robotics, civilizations ancient and modern have stories about clay golems, automata, mechanical assistants created in forges, steam-powered or other manufactured agents doing tasks normally reserved for living things. In 1920, the term ‘robot’ was first published in the Czech science fiction play, Rossum’s Universal Robots; robots began to inundate print media over the next decades (although somehow nobody used the word robotics until Asimov in 1941)1.
Unimate, the world's first factory robot. It worked in the General Motors assembly line.
Robots began to hit factory floors in the 1960s as computer technology developed, but they looked less like androids and more like automatically controlled versions of factory tools that had previously been controlled by people. Since then, the robot population of the world has exploded. While some research and consumer robots look like the androids and automata of stories, most robots today are more like the factory robots in that they don’t resemble humans. While it's compelling to only allow the status of "true robots" to androids (literally "man-shaped" or "man-like") or machines we can easily personify or imagine are animals, many household appliances parallel these obvious robots in crucial aspects of design and construction. At the core, all of these systems are robots - pieces of technology capable of making actions based on measurements they take.
Left to right, the iconic Honeywell round thermostat and the ATLAS robot by Boston Dynamics.
This definition of a robot could describe something as simple as your thermostat to a complex humanoid like ATLAS. Each "robot" senses its environment -- the thermostat evaluates temperature using a number of different possible methods; ATLAS uses a whole suite of sensors to record visuals, distances, orientation, its own power consumption, and many other states of itself and the world around it. Each "robot" also acts -- the thermostat sends signals to power a furnace or other HVAC system; ATLAS drives motors and hydraulic systems to walk, pick things up, and otherwise be a humanoid robot.
It's what happens in between -- Thinking -- that causes some disagreements about what a robot is. Some thermostats only allow users to set a single setpoint temperature, and the thermostat tries its best to maintain that exact temperature. Other thermostats are full of electronics that allow users to set temperature windows, instruct the thermostat to vary the temperature with the time of day, control settings from anywhere via the internet, or even use algorithms to predict values users might want to set. The first can be accomplished using only mechanical parts; the latter begins to use simple electronic components or even microcontrollers. ATLAS very clearly relies on computer processing to turn information from its sensors into instructions for its actuators, and ATLAS is also conveniently human-shaped, so it's easy for us to imagine ATLAS "thinking." But where should the line be drawn for less complicated systems?
At left, a system with all the attributes of a robot except coolness. At right, the extremely cool Derek SLAMboni.
An Olin Professor famously states that the difference is that "robots are sexy - a project has to be cool to count as a robot." And hey -- that seems like a good enough distinguishment to me. So, at Aerospace Robotics, we use the paradigm of Sense - Think - Act to think about how robots work, design them, and present many of our lessons. Even if a robot is ultimately designed a different way, S-T-A is usually still a useful way to start. While there may be some technical or philosophical arguments about what “Thinking” is required for a system to count as a robot, for our purposes here, we’ll consider anything that’s really cool, capable of sensing something about itself or its environment, processing or otherwise reshaping that information, and then acting (especially with physical parts!) based on its processing (or thinking) to be a robot.