A Robot is man-made mechanical device that can move itself, whose motion must be modeled, 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.
12.2 Three Laws of Robotics –
Science-fiction author Isaac Asimov is often given credit for being the first person to use the term robotics in a short story composed in the 1940s. He suggested three principles to guide the behavior of robots and smart machines.-
A robot may not injure a human being or, through inaction, allow a human being to come to harm.
A robot must obey orders given it by human beings except where such orders would conflict with the First Law.
A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.
12.3 Components of robotic systems –
This figure depicts the components that are part of all robotic systems. 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.
Robotics as an integrated system of control interacting with the
Figure : components of robotic system
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”. Sensing and actuation are the physical ports through which the “Controller” of the robot determines the interaction of its mechanical body with the physical world. As mentioned already before, the controller can, in one extreme, consist of software only, but in the other extreme everything can also be implemented in hardware. Within the Controller component, several sub-activities are often identified:
Modelling- The input-output relationships of all control components can (but need not) be derived from information that is stored in a model. This model can have many forms: analytical formulas, empirical look-up tables, fuzzy rules, neural networks, etc.
The other components discussed below can all have models inside. A “System model” can be used to tie multiple components together, but it is clear that not all robots use a System model. The “Sensing model” and “Actuation model” contain the information with which to transform raw physical data into task-dependent information for the controller, and vice versa.
Planning- This is the activity that predicts the outcome of potential actions, and selects the “best” one. Almost by definition, planning can only be done on the basis of some sort of model.
Regulation- This component processes the outputs of the sensing and planning components, to generate an actuation setpoint. Again, this regulation activity could or could not rely on some sort of (system) model. The term “control” is often used instead of “regulation”, but it is impossible to clearly identify the domains that use one term or the other.
12.4 Parts & Concept required for Robot – Generally robots have at least the below mentioned parts and concepts:
Sensors – Most robots of today are nearly deaf and blind. Sensors can provide some limited feedback to the robot so it can do its job. Compared to the senses and abilities of even the simplest living things, robots have a very long way to go. The sensor sends information, in the form of electronic signals back to the controller. A sensor also gives the robot controller information about its surroundings and lets it know the exact position of the arm, or the state of the world around it. Sight, sound, touch, taste, and smell are the kinds of information we get from our world. Robots can be designed and programmed to get specific information that is beyond what our 5 senses can tell us. For instance, a robot sensor might “see” in the dark, detect tiny amounts of invisible radiation or measure movement that is too small or fast for the human eye to see –
Switch Sensors
Light Sensors
Polarized light
Resistive Position Sensors
Effectors – An effector is any device that affects the environment. Robots control their effectors, which are also known as end effectors. Effectors include legs, wheels, arms, fingers, wings and fins. Controllers cause the effectors to produce desired effects on the environment. Two basic ways of using effectors:
to move the robot around =>locomotion
to move other object around =>manipulation
Actuators – Actuators, also known as drives, are mechanisms for getting robots to move. Most actuators are powered by pneumatics (air pressure), hydraulics (fluid pressure), or motors (electric current). Most actuation uses electromagnetic motors and gears but there have been frequent uses of other forms of actuation including “muscle-wires” and inexpensive Radio Control servos. To get a motor under computer control, different motor types and actuator types are used. Some of the motor types are Synchronous, Stepper, AC servo, Brushless DC servo, and Brushed DC servo. Radio Control servos for model airplanes, cars and other vehicles are light, rugged, cheap and fairly easy to interface. Some of the units can provide very high torque speed. A Radio Control servo can be controlled from a parallel port.
Controllers – The robot connects to a computer, which keeps the pieces of the arm working together. This computer is the controller. The controller functions as the “brain” of the robot. The controller can also network to other systems, so that the robot may work together with other machines, processes, or robots
Arms – common effectors known as Arms. The robot arm comes in all shapes and sizes and is the single most important part in robotic architecture. The arm is the part of the robot that positions the End Effector and Sensors to do their pre-programmed business. Many (but not all) resemble human arms, and have shoulders, elbows, wrists, even fingers. This gives the robot a lot of ways to position itself in its environment.
Artificial Intelligence – The term “artificial intelligence” is defined as systems that combine sophisticated hardware and software with elaborate databases and knowledge-based processing models to demonstrate characteristics of effective human decision making. The criteria for artificial systems include the following:
functional: the system must be capable of performing the function for which it has been designed;
able to manufacture: the system must be capable of being manufactured by existing manufacturing processes;
designable: the design of the system must be imaginable by designers working in their cultural context
marketable: the system must be perceived to serve some purpose well enough,
Mobility – Industrial robots are rarely mobile. Work is generally brought to the robot. A few industrial robots are mounted on tracks and are mobile within their workstation. Service robots are virtually the only kind of robots that travel autonomously. Research on robot mobility is extensive. The goal of the research is usually to have the robot navigate in unstructured environments while encountering unforeseen obstacles. Some projects raise the technical barriers by insisting that the locomotion involve walking, either on two appendages, like humans, or on many, like insects. Most projects, however, use wheels or tractor mechanisms. Many kinds of effectors and actuators can be used to move a robot around. Some categories are:
legs (for walking/crawling/climbing/jumping/hopping)
wheels (for rolling)
arms (for swinging/crawling/climbing)
flippers (for swimming)
Types of robot –
12.5.1 Mobile Robot- Mobile robots are able to move, usually they perform task such as search areas. A prime example is the Mars Explorer, specifically designed to roam the mars surface. Mobile robots are a great help to such collapsed building for survivors Mobile robots are used for task where people cannot go. Mobile robots can be divided in two categories –
1.1 Rolling Robots: Rolling robots have wheels to move around. These are the type of robots that can quickly and easily search move around. However they are only useful in flat areas, rocky terrains give them a hard time. Flat terrains are their territory
1.2 Walking Robots: Robots on legs are usually brought in when the terrain is rocky and difficult to enter with wheels. Robots have a hard time shifting balance and keep them from tumbling. That’s why most robots with have at least 4 of them, usually they have 6 legs or more. Even when they lift one or more legs they still keep their balance. Development of legged robots is often modeled after insects or crawfish.
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Stationary Robots
Robots are not only used to explore areas or imitate a human being. Most robots perform repeating tasks without ever moving an inch. Most robots are ‘working’ in industry settings. Especially dull and repeating tasks are suitable for robots. A robot never grows tired; it will perform its duty day and night without ever complaining. In case the tasks at hand are done, the robots will be reprogrammed to perform other tasks
Autonomous Robots
Autonomous robots are self supporting or in other words self contained. In a way they rely on their own ‘brains’. Autonomous robots run a program that gives them the opportunity to decide on the action to perform depending on their surroundings. At times these robots even learn new behavior. They start out with a short routine and adapt this routine to be more successful at the task they perform. The most successful routine will be repeated as such their behavior is shaped. Autonomous robots can learn to walk or avoid obstacles they find in their way. Think about a six legged robot, at first the legs move ad random, after a little while the robot adjust its program and performs a pattern which enables it to move in a direction
Remote-control Robots
An autonomous robot is despite its autonomous not a very clever or intelligent unit. The memory and brain capacity is usually limited; an autonomous robot can be compared to an insect in that respect. In case a robot needs to perform more complicated yet undetermined tasks an autonomous robot is not the right choice.
Complicated tasks are still best performed by human beings with real brainpower. A person can guide a robot by remote control. A person can perform difficult and usually dangerous tasks without being at the spot where the tasks are performed. To detonate a bomb it is safer to send the robot to the danger area
Virtual Robots
Virtual robots don’t exist in real life. Virtual robots are just programs, building blocks of software inside a computer. A virtual robot can simulate a real robot or just perform a repeating task. A special kind of robot is a robot that searches the World Wide Web. The internet has countless robots crawling from site to site. These WebCrawler’s collect information on websites and send this information to the search engines.
BEAM Robots
BEAM is short for Biology, Electronics, Aesthetics and Mechanics. BEAM robots are made by hobbyists. BEAM robots can be simple and very suitable for starters.
Key Points——————————————————————————————————
Robotics is a branch of engineering that involves the conception, design, manufacture, and operation of robots.
Field of robotics overlaps with electronics, computer science, artificial intelligence , mechatronics, nanotechnology , and bioengineering.
MIT’s Kismet: an expressive robotic creature with perceptual and motor modalities tailored to natural human communication channels.
In the future, robots will have a high level of intelligence, such as feeling and emotions, or the ability to make a rational decision on their own.
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Exercise –
Q.1 – Discuss the Laws of Robotic system?
Q.2 – What are main components of any robotic system?
Q.3 – What kind of tasks a robot can perform?
Q.4 – What is the difference between Automation and Robots?
Q.5 – How can we measure performance of any robot?
Q.6- What is degree of freedom? How much degree of freedom is required for 2D and 3D motion?
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