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Introduction to Robotics
In the name of AllahIn the name of Allah
Introduction to Robotics
Introduction to RoboticsIntroduction to Robotics
Leila Sharif l_sharif@sharif.edu
Lecture #2: The Big Picture & History
Introduction to Robotics
Last time we saw: Last time we saw:
Grading, projects and .. in this courseHumanoid and Industrial RobotsDifference of Robot & Simple ManipulatorClassification of RobotsDefining “robot”Why “Robot”?Robots may be used in ….Robotics and RobotRobotics is an interdisciplinary subject of …
Introduction to Robotics
Lecture Outline Lecture Outline
What makes a robot Sensors, sensor space State, state space Action/behavior, effectors, action
space The spectrum of control Reactive systems
Introduction to Robotics
Advantages of Robots IAdvantages of Robots I
Increase productivity, safety, efficiency, quality and consistency of products
Without the need for life support, comfort or safety
No need lighting, air conditioning and noise protection
Work continuously without fatigue or boredom. Do not get mad, need no medical insurance and vacation
Introduction to Robotics
Advantages of Robots IIAdvantages of Robots II
More accurate than humanRobots and their accessories and
sensors are beyond that of humanRobots can process multiple task
simultaneously
Introduction to Robotics
Disadvantages of RobotsDisadvantages of Robots
Robots replace human worker create economic problem
Lack capability in response in emergencies, unless the situation is predicted and the response is included in the system
Have limited capabilities in (DOF, Dexterity, Sensors, Vision System, Real time response and ..)
Are costly (Initial cost of equipment, Installation cost, Peripherals, Training, Programming)
Introduction to Robotics
What Makes a Robot?What Makes a Robot?
A robot consists of: Manipulator End effectors Actuators Sensors Controller Processor Software
A robot is capable of: acting autonomously achieving goals
Introduction to Robotics
ManipulatorManipulator
Is the main body of the robotConsist of the links, the joints and other
structural elements
Introduction to Robotics
End effectorsEnd effectors
The part that is connected to the last joint (hand) of the robot to handle objects, make connections to other machines, or perform required task
They are specifically designed for a purpose:
Welding torch Paint spray gun Glue-laying device ….
Introduction to Robotics
ActuatorsActuators
Are muscles of the manipulator Common type of actuators:
1. Servomotors
2. Stepper motors
3. Pneumatic cylinders
4. Hydraulic cylinders
5. …
Introduction to Robotics
Action/Actuation I Action/Actuation I
A robot acts through its actuators (e.g., motors), which typically drive effectors (e.g., wheels)
Robotic actuators are very different from biological ones, both are used for: locomotion (moving around, going places)
manipulation (handling objects)
Introduction to Robotics
Action/Actuation II Action/Actuation II
This divides robotics into two areas mobile robotics manipulator robotics
Introduction to Robotics
Actuators and DOF Actuators and DOF
Mobile robots move around using wheels, tracks, or legs
Mobile robots typically move in 2D (but note that swimming and flying is 3D)
Manipulators are various robot arms They can move from 1 to many D Think of the dimensions as the robot’s
degrees of freedom (DOF)
Introduction to Robotics
Action v. Behavior Action v. Behavior
Behavior is what an external observer sees a robot doing.
Robots are programmed to display desired behavior.
Behavior is a result of a sequence of robot actions.
Observing behavior may not tell us much about the internal control of a robot. Control can be a black box.
Introduction to Robotics
Autonomy Autonomy
Autonomy is the ability to make one’s own decisions and act on them.
For robots, autonomy means the ability to sense and act on a given situation appropriately.
Autonomy can be: complete (e.g., R2D2) partial (e.g., tele-operated robots)
Introduction to Robotics
Sensors: what can be sensed?
Sensors: what can be sensed?
Depends on the sensors on the robot The robot exists in its sensor space:
all possible values of sensory readings
Also called perceptual space Robot sensors are very different from
biological ones A roboticist has to try to imagine the
world in the robot’s sensor space
Introduction to Robotics
State: what can be known? State: what can be known?
A sufficient description of the system Can be:
Observable: robot always knows its stateHidden/inaccessible/unobservable: robot
never knows its statePartially observable: the robot knows a
part of its stateDiscrete (e.g., up, down, blue, red)Continuous (e.g., 3.765 mph)
Introduction to Robotics
Types of State Types of State
External state: state of the worldSensed using the robot’s sensors E.g.: night, day, at-home, sleeping, sunny
Internal state: state of the robot Sensed using internal sensors Stored/remembered E.g.: velocity, mood
The robot’s state is a combination of its external and internal state.
Introduction to Robotics
State and IntelligenceState and Intelligence
State space: all possible states the system can be in
A challenge: sensors do not provide state!
How intelligent a robot appears is strongly dependent on how much it can sense about its environment and about itself.
Introduction to Robotics
Internal Models Internal Models
Internal state can be used to remember information about the world (e.g., remember paths to the goal, remember maps, remember friends v. enemies, etc.)
This is called a representation or an internal model.
Representations/models have a lot to do with how complex a controller is!
Introduction to Robotics
Controller Controller
Is similar to human’s cerebellum Robot control refers to the way in which
the sensing and action of a robot are coordinated.
The controller receives its data from the computer, controls the motions of the actuators and coordinates the motions with the sensory feedback information.
Introduction to Robotics
Processor Processor
Is the brain of robotIs generally a computerCalculates the motions of robot’s jointsDetermines how much and how fast
each joint must move to achieve the desired location and speed
Introduction to Robotics
SoftwareSoftware
Operating systemRobotic software
Calculate the necessary motions of each joint based on the kinematic equations of robot.
Collection of routines and application programs for peripheral devices like vision or to perform the specific task
Introduction to Robotics
Food for Thought Food for Thought
Are exo-skeletons robots? Is HAL a robot? Some intelligent Web agents are
called “softbots”. Are they robots? Most, if not all, of the robots you
build in this class will use reactive control. What more is there?
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