Robotics - What is Robotics?

Roboticists develop man-made mechanical devices that can move by themselves, whose motion must be modelled, planned, sensed, actuated and controlled, and whose motion behaviour can be influenced by “programming”. Robots are called “intelligent” if they succeed in moving in safe interaction with an unstructured environment, while autonomously achieving their specified tasks.

This definition implies that a device can only be called a “robot” if it contains a movable mechanism, influenced by sensing, planning, actuation and control components. It does not imply that a minimum number of these components must be implemented in software, or be changeable by the “consumer” who uses the device; for example, the motion behaviour can have been hard-wired into the device by the manufacturer.

So, the presented definition, as well as the rest of the material in this part of the WEBook, covers not just “pure” robotics or only “intelligent” robots, but rather the somewhat broader domain of robotics and automation. This includes “dumb” robots such as: metal and woodworking machines, “intelligent” washing machines, dish washers and pool cleaning robots, etc. These examples all have sensing, planning and control, but often not in individually separated components. For example, the sensing and planning behaviour of the pool cleaning robot have been integrated into the mechanical design of the device, by the intelligence of the human developer.

Robotics is, to a very large extent, all about system integration, achieving a task by an actuated mechanical device, via an “intelligent” integration of components, many of which it shares with other domains, such as systems and control, computer science, character animation, machine design, computer vision, artificial intelligence, cognitive science, biomechanics, etc. In addition, the boundaries of robotics cannot be clearly defined, since also its “core” ideas, concepts and algorithms are being applied in an ever increasing number of “external” applications, and, vice versa, core technology from other domains (vision, biology, cognitive science or biomechanics, for example) are becoming crucial components in more and more modern robotic systems.

This part of the WEBook makes an effort to define what exactly is that above-mentioned core material of the robotics domain, and to describe it in a consistent and motivated structure. Nevertheless, this chosen structure is only one of the many possible “views” that one can want to have on the robotics domain.

In the same vein, the above-mentioned “definition” of robotics is not meant to be definitive or final, and it is only used as a rough framework to structure the various chapters of the WEBook. (A later phase in the WEBook development will allow different “semantic views” on the WEBook material.)

Components of robotic systems

This figure depicts the components that are part of all robotic systems. The purpose of this Section is to describe the semantics of the terminology used to classify the chapters in the WEBook: “sensing”, “planning”, “modelling”, “control”, etc.

The real robot is some mechanical device (“mechanism”) that moves around in the environment, and, in doing so, physically interacts with this environment. This interaction involves the exchange of physical energy, in some form or another. Both the robot mechanism and the environment can be the “cause” of the physical interaction through “Actuation”, or experience the “effect” of the interaction, which can be measured through “Sensing”. 

Motion Control [Build A Robot]

Do you want to build a robot? A good place to start is with the servo control systems - the robot's muscles!

"What is servo control?" Imagine a simple motor. If you connect it to a battery, it will start spinning. If you connect two batteries, it will spin faster. Now imagine you tell the motor to turn precisely 180 degrees (1/2 revolution) and stay there no matter how many batteries there are. That's servo control.

Central to the task of servo control is the concept of negative feedback. As an example of negative feedback, consider what happens when you are hungry. Hopefully, you will be able to get something to eat. As you eat, you become less and less hungry until you eventually stop eating. This is the idea of negative feedback. Imagine if the opposite were true and eating made you hungrier. You would eat until you exploded - out of control! Please don't build a robot that acts like that.

Negative feedback in a servo control system proceeds in a similar fashion. There is a desired position for the motor and a feedback sensor that tells the motor it is not at the correct position. In effect, it is "hungry" to get to that position and begins turning towards it. As the motor gets closer to the desired position, the feedback device tells the motor that it is becoming "less hungry" and the motor responds by turning more slowly. In a perfect control system, the motor will get to exactly the right position and then will turn no more until it is commanded to a new desired position.

Motion Control includes much more than servo control. Machine setup, for example, involves a very important set of motion control operations. Machine setup includes operations such as setting feed rates, setting offsets, setting limits and writing files. Similarly querying for feed rates, querying for offsets, querying for limits and reading files are important motion control operations. Sending motion start and motion stop commands are further examples of motion control operations. Querying for machine state is another example of an important motion control operation.

Robots In Space

Airborne Robots

The little device at the left is a mock-up of an ambitious project at UC Berkeley to develop an artificial fly. If you ask me, they don't have a chance of succeeding. The challenges are just too great. They need to get the tiny wings flapping at 150 times per second, there needs to be some means of keeping the system stable in the air and somehow it has to navigate. And all this on something the size of a dime. They have gotten one wing to flap fast enough that, if they mount it on a little wire boom, it will generate some thrust. In other words they are nowhere close after years of work. This may be the type of system that can only be developed via evolution.

Robots in the Military

Pretty much by definition, the military is a dangerous place for humans. This makes it a logical application for robotics, but I definitely have mixed feelings about that. I can live with robots assisting soldiers, but automated killing is taking it too far. At left we see the Smart Crane Ammunition Transfer System being developed by the Robotics Research Corporation. The goal is for one soldier to be able to unload the entire truck without ever leaving the cab. The system includes cameras, video screens, force sensors and special grippers.

Industrial Robots

Modern industrial robots are true marvels of engineering. A robot the size of a person can easily carry a load over one hundred pounds and move it very quickly with a repeatability of +/-0.006 inches. Furthermore these robots can do that 24 hours a day for years on end with no failures whatsoever. Though they are reprogrammable, in many applications (particularly those in the auto industry) they are programmed once and then repeat that exact same task for years.

A six-axis robot like the yellow one below costs about $60,000. What I find interesting is that deploying the robot costs another $200,000. Thus, the cost of the robot itself is just a fraction of the cost of the total system. The tools the robot uses combined with the cost of programming the robot form the major percentage of the cost. That's why robots in the auto industry are rarely reprogrammed. If they are going to go to the expense of deploying a robot for another task, then they may as well use a new robot.