lec02 manipulators

8/12/2019 Lec02 Manipulators

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Lecture 02

Industrial Robot Manipulators

Prof. Rohan MunasingheDepartment of Electronic and Telecommunication EngineeringUniversity of Moratuwa 10400

Industrial Applications of Robots

Paletizing / Unitizing in warehouses

Laser cutting

Palletizing.dat

rc we ng po e ng

Assembly lines

List goes on ..Laser Cutting.dat

Arc Welding.dat

Spot Welding.datAssemblyt.dat

.

Industrial Robot Manipulators IFR Def: An automatically

controlled, reprogrammable,multipurpose manipulatorprogrammable in three or moreaxes, w c may e e t er xe n

place or mobile for use in industrialautomation applications

Robot manipulators consists of rigidlinks, which are connected throughoint actuators that create relative

In robotics, constant

motion of neighboring links. Joints

are attached with sensors that readjoin position and speed

mon or ng o pos onsand orientations ofmanipulator links, tools,objects it handles, andother objects in thevicinity is essential

Joint Primitives Describes how adjacent links are connected to each other

Two primitive joint types

Prismatic (sliding) joint : Pair of links makes a.

slides on the other along a straight line Revolute (rotary) joint : Two links rotate about a fixed

axis. This type of joint is often referred to as a hinge,articulated, or rotationaljoint

Man useful mechanisms for robot mani ulation andlocomotion can be designed by combining these primitive

joints.


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Serial Link Manipulators

Most of the industrial robots are serial combinations ofrevolute and prismatic joints.

The most fundamental functional requirements for a robotic

sys em s o e a e o oca e s en -e ec er an , oo , orend-device), in 3D space, with respect to the world co-ordinate frame

Following types of robot mechanisms are available:

Cartesian co-ordinate robot

-

Spherical co-ordinate robot

SCARA robot

Articulated robot

Cartesian Co-ordinate Robot PPP: three prismatic

joints indpendentlyadjust the three co-ordinates (x,y,z) of theend-effector osition

Applicationspick and place applications (where eitherthere are no orientation requirements orthe parts can be pre-oriented before therobot picks them up such as surfacemounted circuit board assembly), position

CrocRobot.dat

a w e var e y o en -e ec ors suc as:

automatic screwdrivers, automatic drills,dispensing heads, welding heads, waterjetcutting heads and grippers, materialhandling applications such as pick andplace, machine loading and unloading,stacking, unitizing, palletizing, and co-ordinate measuring devices

Cylindrical Co-ordinate Robot RPP

R(spans a cylindricalworkspace)

P(adjusts the height)

Sands Technology, R19

CrocRobot.dat

Spherical Co-ordinate Robot RRP: called as polar co-ordinate

robot

R (horizontal swing)

R vertical swin

P (radius).

.


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SCARA Robot SCARA: Selective Compliant

Assembly Robot Arm

No analogy with commoncoordinate systems, however, it

CrocRobot.dat

s use u n ocat ng t e en -effecter in space, and it hassalient features desirable forspecific tasks.

Assembly automation in manufacturingsystems, having a wide workspace in thehorizontal direction and an independentvertical axis appropriate for insertion of parts

Articulated Robot RRR (all rotary) known as Elbow Robot

Great amount of flexibility, manipulatability, and versatality

.

Precision

Robot Type HorizontalPrecision

VerticalPrecision

Cartesian Uniform Uniform

y n r ca ecreaseradially

n orm

Spherical Decreaseradially

Decreaseradially

SCARA Varies Uniform

Articulated Varies Varies

Parallel Linkages Joints are constrained with each other

Possesses active joints as well as passive joints

Complex, mechanisms, yet provide some useful behaviors

be passive joints, which are

free to rotate. Only two jointsshould be active joints, drivenby independent actuators

Closed kinematic chain is formedby five links and, thereby, the twoserial link arms must conform to

a certain geometric constraint.End-effecter position isdetermined if two of the five jointangles are given.

The robot arm can be made lighter by placing both actuators at the base. A largerload at the end-effector can be born with the two serial linkage arms sharing the load


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Stewart Mechanism Consists of a moving platform, a fixed base, six prismatic

joints connecting moving platform to the base

The position and orientation of the moving platform aredetermined by the six independent actuators

The load acting on themoving platform isborn by the six "arms".Therefore, the loadcapacity is generally

CrocRobot.dat

arge, an ynam c

response is fast

Degrees of Freedom

Degrees of Freedom: is the number of independent positionvariables that would have to be specified in order to locateall parts of the mechanism

In open kinematic chains, where each joint contributes a

End-Effector

single joint variable (joint angle or link offset), number ofdegrees of freedom is equal to the number of joints

At the end of the manipulator is the end-e ec or. cou e a gr pper, a we ng

torch, electromagnet, or any othertool/device that is required to perform theintended task

Manipulator Control System

Controller calculates at each loop, the torque commands for joint actuators.loop time is usually 2~10ms

Calculated torque commands are sent to the individual joint servo controllers

Manipulator Control System

JointTrajectory(pos, vel)

Robot ControlRobot Arm

u(k)

ABBI

RB6

640

CTM, PID, etc

Robot Armmotion

(pos, vel)

TrackingPerformanceEvaluation

ynam cModel

ref

ref (k-1)


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Usage of Industrial Mnipulators

Altogether 1million

industrial robots

are in the world

Japan records highest

density (10 times the

average)

Asian

Europe is the regional epicenter of industrial robots

Data: International Federation of Robotics and Intl Labor Organization

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Industrial Robots: Recent Statistics

Data: International Federation of Robotics and Intl Labor Organization

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Growth of Market Worldwide stock of operational industrial robots

at the end of 2011 was in the range of 1,153,000and 1,400,000 units. Value of the market ofrobotsystems (HW/SW+) was up to US$25.5 billion

166,02838%

Distribution Among Industries Usage of industrial robots


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Usage Trend in Regions Factory Roboticization is Demanding

The major reasons for the increasing demand for factoryroboticization are:

Declining cost of robots and increasing cost of humanlabor

Robots continue to getting speed, accuracy, capability,and reprogrammability for a variety of jobs (welding,painting etc.)

Deployability of robots for tasks that might be dangerous,or impossible for human workers to perform (space,undersea, radioactive sites)

Robots and Automatic Machines

Small volumes use human labor volume [v1,v2] use robots volume > v2 hard automation

The distinction between a robot and a factory machine (such

as NC machines) lies in the programmability of the device.Robots can be re-programmable to perform a wide variety oftasks, whereas factory machines, which are generallylimited to one class of tasks (fixed automation)

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