PRESENTED BY-

PAWAN PORWAL

IIMT COLLEGE OF ENGINEERING

PRESENTING

Robots

Robota (Czech) = A worker of forced laborFrom Czech playwright Karel Capek's 1921 play “R.U.R”

(“Rossum's Universal Robots”)Japanese Industrial Robot Association (JIRA) :

“A device with degrees of freedom that can be controlled.”Class 1 : Manual handling device

Class 2 : Fixed sequence robotClass 3 : Variable sequence robot

Class 4 : Playback robotClass 5 : Numerical control robot

Class 6 : Intelligent robot

DEFINITIONROBOT TECHNOLOGY IS AN APPLIED SCIENCE THAT IS REFERRED TO AS A COMBINATION OF

MACHINE TOOLS AND COMPUTER APPLICATIONS.INCLUDES SUCH DIVERSE FIELDS AS MACHINE DESIGN, CONTROL THEORY,

MICROELECTRONICS, COMPUTER PROGRAMMING, ARTIFICIAL INTELLIGENCE, HUMAN FACTORS, AND PRODUCTION THEORY.

GENERAL CHARACTERSTICSA SPECIALIZED MACHINE TOOLS WITH A DEGREEN OF FLEXIBILITY THAT DISTINGUISHES

THEM FROM FIXED-PURPOSE AUTOMATION.

IS ESSENTIALLY A MECHANICAL ARM THAT IS BOLTED TO THE FLOOR, A MACHINE, THE CEILING, OR, IN SOME CASES THE WALL FITTED WITH ITS MECHANICAL HAND, AND TAUGHT

TO DO REPETITIVE TASK IN A CONTROLLED, ORDERED ENVIRONMENT.

ABILITY TO MOVE MECHANICAL ARM TO PERFORM WORK.

ROBOT INTERFACE WITH THEIR WORK ENVIRONMENT ONCE A MECHANICAL HAND HAS BEEN ATTACHED TO THE ROBOT’S TOOL-MOUNTING PLATE.

ROBOT TECHNOLOGY

• Mechanical Automata – Ancient Greece & Egypt

• Water powered for ceremonies

– 14th – 19th century Europe• Clockwork driven for

entertainment

• Motor driven Robots– 1928: First motor driven

automata– 1961: Unimate

• First industrial robot– 1967: Shakey

• Autonomous mobile research robot

– 1969: Stanford Arm• Dextrous, electric motor

driven robot arm

HISTORY OF ROBOTICS

Autonomous Robots• The control of autonomous robots involves a

number of subtasks– Understanding and modeling of the mechanism

• Kinematics, Dynamics, and Odometry– Reliable control of the actuators

• Closed-loop control– Generation of task-specific motions

• Path planning– Integration of sensors

• Selection and interfacing of various types of sensors– Coping with noise and uncertainty

• Filtering of sensor noise and actuator uncertainty– Creation of flexible control policies

• Control has to deal with new situations

Traditional Industrial Robots

• Traditional industrial robot control uses robot arms and largely pre-computed motions Programming using “teach box” Repetitive tasks High speed Few sensing operations High precision movements Pre-planned trajectories and

task policies No interaction with humans

BASIC COMPONENTS• THE BASIC COMPONENTS OF AN INDUSTRIAL ROBOT ARE THE

– MANIPULATOR – THE END EFFECTOR (WHICH IS THE PART OF THE MANIPULATOR).– THE POWER SUPLLY– AND THE CONTROLLER.

• THE MANIPULATOR, WHICH IS THE ROBOT’S ARM, CONSISTS OF SEGMENTS JOINTED TOGETHER WITH AXES CAPABLE OF MOTION IN VARIOUS DIRECTIONS ALLOWING THE ROBOT TO PERFORM WORK.

• THE END EFFECTOR WHICH IS A GRIPPER TOOL, A SPECIAL DEVICE, OR FIXTURE ATTACHED TO THE ROBOT’S ARM, ACTUALLY PERFORMS THE WORK.

• POWER SUPPLY PROVIDES AND REGULATES THE ENERGY THAT IS CONVERTED TO MOTION BY THE ROBOT ACTUATOR, AND IT MAY BE EITHER ELECTRIC, PNEUMATIC, OR HYDRAULIC.

• THE CONTROLLER INITIATES, TERMINATES, AND COORDINATES THE MOTION OF SEQUENCES OF A ROBOT. ALSO IT ACCEPTS THE NECESSARY INPUTS TO THE ROBOT AND PROVIDES THE OUTPUTS TO INTERFACE WITH THE OUTSIDE WORLD.

ROBOT ANATOMY• ROBOT ANATOMY IS CONCERNED WITH THE PHYSICAL CONSTRUCTION AND

CHARACTERISTICS OF THE BODY, ARM, AND WRIST, WHICH ARE COMPONENTS OF ROBOT MANIPULATOR.

• MOVEMENTS BETWEEN THE VARIOUS COMPONENTS OF THE BODY, ARM, AND WRIST ARE PROVIDED BY A SERIES OF JOINTS.

• ATTACHED TO THE ROBOT WRIST IS THE END EFFECTOR (OR END-OF-ARM TOOLING) THAT PERFORMS THE WORK.

• THE END EFFECTOR IS NOT CONSIDERED A PART OF THE ROBOT’S ANATOMY.

ROBOT CONFIGURATIONS:1. INDUSTRIAL ROBOTS ARE AVAILABLE IN A WIDE RANGE OF SHAPES, SIZES,

SPEEDS, LOAD CAPACITIES, AND OTHER CAPABILITIES.2. THE VAST MAJORITY OF TODY’S COMMERCIALLY AVAILABLE ROBOTS POSSESS

FIVE DISTINCT DESIGN CONFIGURATIONS:A. RECTANGULAR (OR CARTESIAN)B. CYLINDIRICAL (OR POST-TYPE)C. SPHERICAL (OR POLAR)D. JOINTED ARM (ARTICULATED OR REVOLUTE)E. SCARA (SELECTIVE COMPLAINCE ASSEMBLY ROBOT ARM)

Autonomous Robot Control

• To control robots to perform tasks autonomously a number of tasks have to be addressed:– Modeling of robot mechanisms

• Kinematics, Dynamics– Robot sensor selection

• Active and passive proximity sensors– Low-level control of actuators

• Closed-loop control– Control architectures

• Traditional planning architectures• Behavior-based control architectures• Hybrid architectures

• Forward kinematics describes how the robots joint angle configurations translate to locations in the world

• Inverse kinematics computes the joint angle configuration necessary to reach a particular point in space.

• Jacobians calculate how the speed and configuration of the actuators translate into velocity of the robot

Modeling the Robot Mechanism

(x, y, z)1

2

(x, y, )

Actuator Control

• To get a particular robot actuator to a particular location it is important to apply the correct amount of force or torque to it.– Requires knowledge of the dynamics of the robot

• Mass, inertia, friction• For a simplistic mobile robot: F = m a + B v

– Frequently actuators are treated as if they were independent (i.e. as if moving one joint would not affect any of the other joints).

– The most common control approach is PD-control (proportional, differential control)• For the simplistic mobile robot moving in the x direction:

actualdesiredDactualdesiredP vvKxxKF

Sensor-Driven Robot Control

• To accurately achieve a task in an intelligent environment, a robot has to be able to react dynamically to changes ion its surrounding– Robots need sensors to perceive the

environment– Most robots use a set of different sensors

• Different sensors serve different purposes– Information from sensors has to be

integrated into the control of the robot

Robot Sensors

• Proximity sensors are used to measure the distance or location of objects in the environment. This can then be used to determine the location of the robot.– Infrared sensors determine the distance to an object by measuring

the amount of infrared light the object reflects back to the robot

– Ultrasonic sensors (sonars) measure the time that an ultrasonic signal takes until it returns to the robot

– Laser range finders determine distance by measuring either the time it takes for a laser beam to be reflected back to the robot or by measuring where the laser hits the object

Uncertainty in Robot Systems

Robot systems in intelligent environments have to deal with sensor noise and uncertainty Sensor uncertainty

Sensor readings are imprecise and unreliable Non-observability

Various aspects of the environment can not be observed

The environment is initially unknown Action uncertainty

Actions can fail Actions have nondeterministic outcomes

Deliberative Robot Control Architectures• In a deliberative control architecture the robot first

plans a solution for the task by reasoning about the outcome of its actions and then executes it

– Control process goes through a sequence of sencing, model update, and planning steps

Behavior-BasedRobot Control Architectures

• In a behavior-based control architecture the robot’s actions are determined by a set of parallel, reactive behaviors which map sensory input and state to actions.

• Complex behavior can be achieved using very simple control mechanisms– Braitenberg vehicles: differential drive mobile

robots with two light sensors

• Complex external behavior does not necessarily require a complex reasoning mechanism

Complex Behavior from Simple Elements: Braitenberg Vehicles

+ +

“Coward” “Aggressive”+ + - -

“Love” “Explore”- -

ROBOT GENERATIONS• THE FIVE GENERATIONS OF ROBOT CONTROLLERS AFTER THE

HIGH-TECH INCEPTION IN 1960 ARE AS FOLLOWS:

– FIRST GENERATION: REPEATING ROBOTS. THESE WERE GENRALLY PICK AND PLACE ROBOTS, WITH MECHANICAL SEQUENCES DEFINING STOP POINTS.

– SECOND GENERATION: HARDWIRED CONTROLLERS PROVIDED THE FIRST PROGRAMMABLE UNITS.

– THIRD GENERATION: PROGRAMMABLE LOGIC CONTROLLERS (PLC), INTRODUCED IN THE INDUSTRY OVER THIRTEEN YEARS AGO, PROVIDED A MICROPROCESSOR-BASED ROBOTIC CONTROLLER THAT IS EASY TO PROGRAM.

– FOURTH GENERATION: WHEN CONTROL BEYOND THE PLC IS REQUIRED, A MICROCOMPUTER MAY CONTROL THE ENTIRE SYSTEM, INCLUDING OTHER PROGRAMMABLE MACHINERY IN A ROBOT WORKCELL.

– FIFTH GENERATION: ROBOT CONTROLLER WILL INVOLVE COMPLETE ARTIFICAIL INTELLIGENCE (AI), MINIATURED SENSORS, AD DECISION MAKING CAPABILITIES.

• AN ARTIFICIAL BIOLOGICAL ROBOT MIGHT PROVIDE THE IMPETUS FOR SIXTH AND HIGHER GENERATION ROBOTS.

ROBOT SELECTION• ROBOT MUST BE MATCHED PROPERLY BY CAPABILITIES TO TASK REQUIREMENTS.

• AN OBJECTIVE APPROACH TO ROBOT SELECTION PROVIDES FEWER RESTRICTIONS IN SYSTEM DESIGN BY ALLOWING FOR THE OPTIMUM SYSTEM DESIGN TO BE ACHIEVED REGARDLESS OF THE SPECIFIC ROBOT NEED.

• CRITERIA FOR ROBOT SELECTION:– TECHINICAL ISSUES:

• TYPE: NONSERVO, SERVO, SERVO-CONTROLLED• WORK ENVELOPE: RECTANGULAR, CYLINDIRCAL, SPHERICAL, JOINTED ARM, SCARA• PAYLOAD• CYCLE TIME• REPEATABILITY• DRIVE: ELECTRIC, PNEUMATIC, HYDRAULIC, ANY COMBINATION• UNIQUE CAPABILITIES

– NON-TECHNICAL ISSUES:• COST AND BENEFIT CONSIDERATION• COMMONALITY OF EQUIPMENT• TRAINING AND MAINTENANCE REQUIREMENTS• RELIABILITY• SERVICE• “SYSTEMS” HELP• SAFETY

Robots in the Real World• Welding• Painting• Assembly• Laboratory• Manufacturers

SUMMARY• ROBOT TECHNOLOGY IS AN APPLIED SCIENCE THAT IS REFERRED TO AS

COMBINATION OF MACHINE TOOL FUNDAMENTALS AND COMPUTER APPLICATIONS.

• THE BASIC COMPONENTS OF AN INDUSTRIAL ROBOT ARE, MANIPULATOR, END EFFECTOR, POWER SUPPLY AND CONTROL SYSTEM.

• ROBOT ANATOMY IS CONCERNED WITH THE PHYSICAL CONSTRUCTION AND OPERATION OF THE MANIPULATOR AND HAS FIVE BASIC CONFIGURATIONS:

RECTANGULAR, CYLINDRICAL, SPHERICAL, JOINTED-ARM, AND SCARA.

• ROBOTS WITH INCREASING INTELLIGENCE, SENSORY CAPABILITY, DEXTERITY & SOPHISTICATED CONTROL SYSTEMS HAVE BECOME DOMINANT

FACTOR IN MODERN MANUFACTURING.

• THE THREE FACTORS THAT INFLUENCE THE SELECTION OF ROBOTS IN MANUFACTURING ARE: DYNAMIC PROPERTIES AND PERFORMANCE,

ECONOMICS AND SAFETY.