Definitions of Robot

"A reprogrammable, multifunctional manipulator designed to move

material, parts, tools, or specialized devices through various

programmed motions or the performance of a variety of task."

- Robot Institute of America, 1979

"An automatic device that performs functions normally

ascribed to humans or a machine in the form of a human."

Webster's Dictionary

"Robotics is that field concerned with the intelligent connection

of perception to action." - Mike Brady

Alternate definition:

An automatic device that performs functions normally

ascribed to humans or a machine in the form of a human. 1

Automation vs. Robots

• Automation –Machinery designed to carry out a specific task

• Bottling machine

• Dishwasher

• Paint sprayer

• Robots – machinery designed

to carry out a variety of tasks

• Pick and place arms

• Mobile robots

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How Robots Work

Human Robot

A body structure.

A muscle system.

A sensory system.

A power source.

A brain system.

A movable physical structure

A motor of some sort

A sensor system

A power supply

A computer "brain"

As human beings are made up of five major components , Robots are also

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Figure 1.1. An illustration of a humanlike robot and its ‘‘internal organs.’’

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All Have 5 Common Components

• Mobility: legs, arms, neck, wrists

• Platform, also called “effectors”

• Perception: eyes, ears, nose, smell, touch

• Sensors and sensing

• Control: central nervous system

• Inner loop and outer loop; layers of the brain

• Power: food and digestive system

• Communications: voice, gestures, hearing

• How does it communicate (I/O, wireless, expressions)

• What does it say?

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SPECIFICATIONS OF A ROBOT SYSTEM

1. Pay load / Load carrying Capacity

2. Repeatability – it is the ability of a manipulator to return to its position in

space where it has been previously.

3. Maximum tip speed – how fast the manipulator can move.

4. Coordinate system

5. Maximum movements

6. Type of Drive system

7. Control system – Servo /no-servo and PTP or CP motion

8. Memory Devices – internal memory types and mass storage capacity.

9. Programming Method – via keyboard, teach pendant, walk-through etc.

10.Memory Capacity – It gives an indication of the no. of program steps or

points that the robot controller can handle.

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Work Space Vs. Configuration Space

• Work space

• The space in which the object exists

• Dimensionality

• R3 for most things, R2 for planar arms

• Configuration space

• The space that defines the possible object configurations

• Degrees of Freedom

• The number of parameters that necessary and sufficient to define position in configuration

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Degrees of freedom

So, a simple robot arm with 3 degrees

of freedom could move in 3 ways: up

and down, left and right, forward and

backward. Most working robots today

have 6 degrees of freedom.

Humans have many more and some robots have 8, 12, or even 20

degrees of freedom, but these 6 are enough for most basic tasks.

As a result, most jointed-arm robots in use today have 6 degrees of

freedom

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ROBOT CONFIGURATIONS Ro

bot C

onfig

uratio

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• Rectangular / Cartesian / X, Y, Z Robot

• Cylindrical /Post-type Robot

• Spherical / Polar Robot

• Articulated / Joined-arm Robot

• SCARA Robot (Horizontal or Vertical)

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ROBOT CONGIOGURATIONS

Classification By Mechanical Structure

Cartesian Robot

Cartesian robot is form by 3 prismatic joints, whose axes are coincident with the X, Y and Z planes.

Application Areas

This structure is most often seen in machine tools and co-ordinate measuring because of its rigidity.

This robot is suited for pick and place applications where either there are no orientation requirements or the parts can be pre-oriented before the robot picks them up (such as surface mounted circuit board assembly).

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Gantry Robot

Cartesian coordinate robots with the horizontal member supported at both ends are sometimes called Gantry robots.

Application Areas:

It is used primarily to position a wide varietyof end-effectors such as: Automatic screwdrivers, Automatic drills, Dispensing heads, Welding heads, Water jet cutting heads and Grippers.

Gantry robots provide flexible and efficient solutions for a wide range of material handling applications such as pick and place, machine loading and unloading, stacking, unitizing, and palletizing

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Cylindrical RobotCylindrical robot is able to rotate along his main axes forming a cylindrical shape.

Application Areas

With different payload capability, reach and design, articulate robots are designed to employ in the following applications: Arc welding Spot welding Assembly cleaning/spraying Cutting Deburring Die casting

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Polar Robot

Polar robot is able torotate in two different

directions along it’smain axes and the third

joint moves in translation forming a hemisphere or polar coordinate system.

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Parallel RobotParallel robot constitutes two or more kinematics chains between the base and the platform where the end-effectors are located. Parallel robot is a complex mechanism which is constituted by two or more kinematics chains between, the base and the platform where the end-effectors are located. Good examples are the flying simulator and 4-D attractions at Univ. Studios.

Application Areas

Parallel robots are used to assemble automobiles, food products, surgical and many other applications. For instance, the Delta robot is mostly used as a pick-and-place robot. And, almost all flight simulators are based on the hexapod design. They are also used for machining operations where machine tool level tolerances are not required but greater flexibility is

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SCARA Robot

SCARA(Selective Compliance Articulated Robot

Arm) robot is built with 2 parallel rotary joints to provide

compliance in a plane.

Application Areas

The selective compliant feature of the SCARA robot which

provides substantial rigidity for the robot in the vertical

direction, but flexibility in the horizontal plane, makes it very

suitable for many types of assembly operations, e.g., inserting a

round pin in a round hole without binding.

SCARA robots reportedly offer the best price/performance ratio

as regarding speed. They are faster because they move less

mass due to its configuration. Their single pedestal mount

requires a small footprint and provides an easy, unhindered

form of mounting. Thus, besides assembly, Scara is ideal for a

variety of general-purpose applications requiring fast,

repeatable and articulate point to point movements such as

palletizing, de-palletizing, machine loading/unloading, pick-

and-place and packaging applications. The electronic printed

circuit board industry, in particular, use large numbers of

SCARAs for placing semiconductor IC.

Due to their ''elbow'' motions, SCARA robots are also used for

applications requiring constant acceleration through

circular motions like dispensing and in-place gasket

forming.15

It is still in the research laboratory, the Spherical robot is actually a spherical shape robot, which has an internal driving source.

Spherical Robot

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Articulated RobotArticulated robots are mechanic manipulator that looks like

an arm

with at least three rotary joints.

Application Areas

With different payload capability, reach and design, articulate

robots

are designed to employ in the following applications:

Arc welding,

Spot welding ,Assembly

,cleaning/spraying ,Cutting ,

Deburring

Die casting ,

Gluing/sealing

Grinding/polishing ,

Injection molding

Machine tending ,

Material handling ,

Packing

Palletizing ,

Picking ,

Pre-machining

Press brake tending17

Configuration Advantages Disadvantages

Cartesian / XYZ Robot /

Rectilinear Robot

3 linear axes, easy to

visualize, rigid

structure,easy to program

Can only reach front of

itself, requires large floor

space, axes hard to seal

Cylindrical Coordinates 2 linear axes +1 rotating,

can reach all around itself,

reach and height axes

rigid, rotational axis easy to

seal

Can’t reach above itself,

base rotation axis as less

rigid, linear axes is hard to

seal, won’t reach around

obstacles

SCARA Coordinates 1 linear + 2 rotating axes,

height axis is rigid, large

work area for floor space

2 ways to reach point,

difficult to program off-line,

highly complex arm

Spherical Coordinates 1 linear + 2 rotating axes,

long horizontal reach

Can’t reach around

obstacles, short vertical

reach

Revolute Coordinates 3 rotating axes can reach

above or below obstacles,

largest work area for least

floor space

Difficult to program off-line,

2 or 4 ways to reach a

point, most complex

manipulator

Comparison of various Configurations

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Comparison of various Configurations with their work volumes

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Ap

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Basic robot motions

Point to point control

Continuous path control.a. Straight line interpolation

b. Circular interpolation

c. Curvilinear interpolation

d. Parabolic interpolation

Basic

Rob

ot Mo

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PONIT TO POINT CONTROL

• Moves items from one point to

another

• Does not need to follow a specific

path between points

• Uses include loading and

unloading machines, placing

components on circuit boards, and

moving parts off conveyor belts.

Basic

Rob

ot Mo

tions

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CONTINUOUS PATH CONTROL

• Moves along a specific

path

• Uses include welding,

cutting, machining parts.

Basic

Rob

ot Mo

tions

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