Editor's Note: This is the first of a four-part series from Chapter 4 of: The Absolute Beginner's Guide to Building Robots. The chapter offers an overview of robot types, motion, power sources, shells and software, providing enough background to whet your appetite
for the actual step-by-step instructions found in the book that will be necessary to follow to
really build your robotic wonder.
Flesh and Steel
The human body is an unfathomably beautiful creation, and no, we're not talking about supermodels or Natalie Portman (those are freaks of nature). We're talking about the flesh and blood machinery of which we're all so miraculously constructed. Open up an anatomy textbook, or watch one of the many "wonders of the human body" shows on educational cable, and you can't help but be awestruck by our impressive design. Going on such a fantastic voyage, two things are immediately apparent: The human body is elegantly and deeply complex, and it is also extremely fragile. There are literally millions of things that could go wrong at any given moment, but luckily for billions of us, don't. The body has evolved an impressive host of checks and balances and backup systems.
When looking at the human body with an eye toward robots, once again, our old friend, the "fantasy versus reality" dichotomy rears its ugly mug. We can't help but compare the machinery of a robot to our own "machinery" and find the robot's sorely lacking. But the human body has had millions of years to tinker with its hardware and software, while robot anatomy is measured in a few short decades. At the rate technology develops, though, imagine where robots will be in 50, 100, or even 1,000 years.
But all along this evolutionary timetable, robots will likely be comprised of the same subsystems they're comprised of today (only smaller, faster, and better). Ultimately, these subsystems are not entirely unlike our own.
In this chapter, we'll drag out our virtual toolbox ("Geordi, hand me that positronic flux wrench; Lt. Commander Data needs a little...checkup"), deconstruct some robots, and detail their subsystems. As a convenient reference, we'll use the systems of the human body, though we'll try not to belabor that point.
Robot Body Types
Before we start pouring over the parts of your average robot, it might be worthwhile to categorize some basic robot body types. This way, as we go through the various robot subsystems (frame, brain, power source), you can think about how each of these might be applied to different types of bots.
Although robots come in a staggering number of shapes and sizes (just like humans), we can muscle most of them into some general categories:
These are obviously the most prevalent type of robots to date. Not only your car, but also many of the consumer items in your home were probably bot-handled at some point. We tend to think of only the fixed robotic arm in this category, but industrial manipulators come in all sorts of configurations these days. If you ever see a news item about the auto industry, computer chip manufacturing, or other bot-intensive business, all of those ganglia you see snaking around the product as it moves down the assembly line-each with a specialized function and tool on its tip-is an industrial manipulator (see Figure 4.1).
A typical industrial manipulator, this one is an ABB-brand arm with a spot welder as its "end effector." It is also on a movable track base. Photo used with permission of ABB, USA.
Robots of this type need to be strong, extremely durable, and capable of doing the exact same sequence of tasks over and over again without fail. With this species of bot, boring is good, surprises are bad.
Any mobile robot that does work would fit into this category. Bots of this type are often called "field robots" (see Figure 4.2). This area of robotics is coming on strong right now, and within a decade, utility robots will likely be everywhere. Robots in this category include bomb squad bots, emergency response robots (like the ones that searched the rubble of the World Trade Center), military reconnaissance bots, and those in the burgeoning market of domestic robots (robot vacuum cleaners, robo-mowers, and home security robots). Combat robots would also fit into this category. Their job? Kickin' bot!
Because robots of this type are often battery-powered, they need to be lightweight enough to not unnecessarily tax their motors and stored power source. Utility robots designed for harsh environments need to balance power/weight concerns with protection from the elements. Like industrial manipulators, utility robots don't usually look very sexy (think R2-D2), focusing on function over form. For this robot category, reliability under changing real-world conditions is key.
Houdini, one of RedZone's field robots, is designed to fold in half so that it can move through tight spaces on its way to the job (which usually involves bulldozing toxic waste). Photo used with permission of Redzone Robotics.
Looking to nature for inspiration in robot design has led to a fantastic menagerie of mechanical creatures. All sorts of bugs, reptiles, fish, crustaceans, and mammals have provided design ideas (see Figure 4.3). Even how these critters behave-the communalism of ants, the swarming of bees, and the flocking of birds-has inspired designs for clusters of robots that function in a similar manner. Robo-critters often have legs, only basic brainpower (instinct-level), and are frequently autonomous (either solar powered or capable of finding their own power source). Many of today's entertainment robots (AIBO, B.I.O. Bugs, iCybie) fall into this category.
For robots of this type, weight is often critical. As legged mobility is complicated and fragile, this is often a weakness of the design. Legs are power-hungry, too, drinking up precious battery juice. The robots we will build in Projects 1 and 2 would be considered robo-critters.
FIGURE 4.3 JPL's latest robocritter, Spiderbot, is designed for extraplanetary exploration. Let's hope it doesn't get blown away in a stiff Martian wind. Photo used with permission of NASA/JPL/Cal Tech
Hello C-3PO! This fidgety fella from a galaxy far, far away has become the poster bot for our dreams of the humanoid robot (personally, I always get the image of a rampaging Terminator, but then, I'm a perverse sort). Humanoid robots are bipedal, have heads, usually arms, and are often human height (or at least human proportions). These robots tend to be the most complex, have the biggest "brains" (and aspirations of higher intelligence), and spend much of their lives on workbenches with people in white coats cursing over them. These same people in lab coats assure us that this will one day change (see Figure 4.4).
For robots of this type, brainpower is key. Articulated movement and walking is a huge challenge, as is a robotic vision system that allows such robots to interact effectively with people and their environment. Also, getting all of the hardware required to mimic their makers inside of a human-sized/human-shaped body is a real problem.