CHAPTER 4 Basics of Industial Robots

VocTRA XXI 26-30.09.2011, Warsaw, Poland

Vocational Training in Robotics Automation - XXI Century

VocTRA XXI

26-30.09.2011, Warsaw, Polan

CHAPTER 4

Basics of Industial Robots


Overview

VILAROB – CHAPTER 4 – Basics of Industrial Robots

Introduction to industrial robots

What is an industrial robot?

Present industrial robots in market and their categorisation

Robot system components

Basics of motion in industrial robots

Frame concept


Introduction


A robot the size of a person can easily carry a load over one

hundred pounds

It can move it very quickly with a repeatability of +/-0.006

inches

Robots can do the same motion 24 hours a day for years on

end

And with no failures whatsoever


Introduction


A robot is made up of the very same components like human

being.

■ A typical robot has a movable physical structure

■ A motor of some sort

■ A sensor system

■ A power supply

■ A computer "brain" that controls all of these elements

Essentially, robots are man-made versions of animal life

They are machines that replicate human and animal

behaviour.




Industrial robots are automated machines that work on

assembly lines

With six joints closely resembles a human arm

They are machines that replicate human and animal

behaviour.

They have often six independent joints, also called six

degrees of freedom







Industrial robots are designed to do exactly

the same thing

In a controlled environment

Over and over again




EXAMPLE

A robot should weld two metal

pieces to produce a car door again

and again

To teach a robot how to do its job,

the programmer guides the arm

through the motions using a

handheld controller

The robot stores the exact

sequence of movements in its

memory, and does it again and

again every time a new unit comes

down the assembly line




Robots can do a lot of this work more efficiently than

human beings because ■ They are so precise

■ They always drill in the exactly the same place

■ They always tighten bolts with the same amount of force

■ No matter how many hours they've been working


Industrial robot categorisation


The industrial joint-arm robots are categorized in different

ways

■ “Limit of Payload”

■ “Field of applications”

■ “Kinematic type”


Industrial robots categorisation


Regarding with the application type, it may be possible to

use a more flexible or a less flexible robot

Some applications may need faster motion

Another application may need less speed but more

accurate

An application may need motion in 3 dimension and extra

rotation.

Another application may need motion only in two

directions.




WELDING ROBOTS




PALLETIZING ROBOTS




HANDLING ROBOTS




ASSEMBLING ROBOTS




LASER CUTTING ROBOTS




Limit of payload of an industrial robot is the maximal

weight that the robot can carry during the motion.

Each robot has a maximum limit of payload

The weight of the tool/work-piece, mounted to the TCP of

robot will affect : ■ complete dynamic of the robot

■ motion planning

■ motion execution

“Pay attention in selection of the robot which is suitable

for the application that is automated”




Type Max. Payload Description

Low Payload Category

(5 to 16 kg)

Robots with Low Payloads are particularly suitable for small-scale activities such as component testing, assembly of small parts, or grinding, polishing and bonding.

Medium Payload Category

(30 to 60 kg)

Potential applications for medium payload robots range from simple handling tasks to complex operations such as measuring air currents in the wind tunnel or sewing leather seat covers.

High Payload Category

(80 kg to 270 kg)

Robots from the high payload range are particularly sought after for spot welding, handling and loading/unloading tasks. Their long reach and great flexibility make them indispensable partners.

Heavy Duty (360 kg to 1000 kg)

With payloads of up to 1300 kg, these robots can e.g. handle side panels in automotive body-in-white construction or, in the palletizing variant, carry out tasks in the beverage or building materials industries.

In the following table, the it the payload categorization is done for the KUKA robots:



VILAROB – CHAPTER 4 – Basics of Industrial Robots In the following table, the it the payload categorization is done for the KUKA robots:

KR6 KR16 KR30




KR60 KR100 KR150




KR360L KR500 KUKA

TITAN




Parallel Kinematic: Axis are joined parallel to each

other. One or more Axes can be joined to another axis




Forward Kinematic: Axis are joined with each other

serially, one to another




A robot system consists of the following components: ■ Robot mechanics

■ Robot controller

■ Control panel - Teach pendant

■ Connecting cables

■ Software

■ Accessories




1.Robot 2.Connecting cables 3.Robot controller 4.Teach pendant




Robot Mechanics

■ Majority of ind. robots feature six

axes, also called six degrees of

freedom.

■ Six axis robots allow for greater

flexibility and can perform a wider

variety of applications than robots

with fewer axes.


Robot Mechanics

■ The axis ranges of main axes A 1 to

A 3 and wrist axis A 5 are limited.

▪ Mechanical limits

▪ Software limits






Robot Controller

The robot controller is the hardware component of the

robot system

Responsible from the controlling of the complete system

like: ■ motion planning

■ communication with other components

■ execution of robot program




Teach Pendant

Pendants are used to control and to program the

industrial robots.

A Pendant is a hand-held unit linked to the control system

with which a robot can be programmed or moved.

It is also referred as ■ Teach Pendant.

■ Control Panel (by KUKA),

■ iPendant (by FANUC)




Teach Pendant

Teach pendants are used as human robot interface in the

robot controller.

Most of the robot processes are achieved by the teach

pendant.




Teach Pendant – Important Input Buttons

The following buttons are placed on most teach pendant as

standard:

Name Functionality

Mode selector switch Selects operation mode

Drives on / off Switches the robot drives on/off

EMERGENCY STOP Stops the robot in hazardous situations.

Start key The Start key is used to start a program.

STOP key The STOP key is used to stop a program that is running.

Softkeys For diferent purposes




Teach Pendant- Emergancy Stop

In case of emergency, robots are required to halt immediately.

EN ISO 13850

This button provides a rapid means to disconnect the energy

source of the device to protect workers.




Teach Pendant- Deadman Switch

The deadman switch stops the robot,

and is a form of fail-safe

automatically operated in case the

human operator becomes

incapacitated

There are up to three deadman

switch are place on the control panel




Teach Pendant – Mode Selector

There are different operation modes

of robots

Each mode has different motion and

reaction specifications

Mode can be change by a switch

which is place on the control panel

• Test Mode

• Automatic Mode

• Extern Mode




Teach Pendant – Drive On/Off

This button is used to close the loop

to give power to the motors

When the robot program is started

the joint motors should have power

in order to move the joint.

This button is places on the control

panel to control the motor powers.


Basics of industrial robot motion


The axis of the robot can be moved

in two different ways

■ move the robot manually axis specific

■ Motion with respect to a definite

Cartesian coordinate system




Axis Specific

Each robot axis can be

individually moved in

positive or negative

axis direction

The axis positions would change

independent of each other.




Cartesian

The robot can move with respect to a

definite coordinate system

Different coordinate system to be

used

Cartesian manual jogging is mostly

used. Since reaching a target point is

easier in a coordinate system rather

than moving the axis of the robot

specifically.




Cartesian

BASE coordinate system: Rectangular

coordinate system, whose origin is located

in the work piece.

WORLD coordinate system: A fixed,

rectangular coordinate system which has

its origin at the base of the robot.




Cartesian

TOOL coordinate system: Rectangular coordinate system, whose origin is

located in the tool.


Frame Concept


The three dimension (x,y,z) modeling is enough for

representing a point(particle) in the space

but it is not enough for the representation of any rigid body

which has a volume.


Frame Concept


Therefore a position is represented with a FRAME

A frame of reference in physics, may refer to a coordinate

system or set of axes within which to measure the position and

orientation. A frame has the following components.

Component Meaning

X distance to the origin in X-Axis

Y distance to the origin in Y-Axis

Z distance to the origin in Z-Axis

A rotation angel over Z-Axis

B rotation angel over Y-Axis

C rotation angel over X-Axis

Eu

ler-Z

XY

no

tatio

n


Frame Concept


Position representation in 6D with Frames

The frames are widely used in industrial robots where all points

are represented as frames in robot programs

Linear motion with changes in orientation during linear motion


Frame Concept: Robots with 3 Axes


Industrial robots which move only in three dimension called

Cartesian robots

Cartesian robots allow only x-y-z positioning

Three linear joints provide the three axes of motion


Basics of Industrial Robots


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CHAPTER 4 Basics of Industial Robots