industrial robots

Industrial robots

Outlines :

Manipulator components

Robot control systems

End Effectors

Industrial robot applications

Robot programming language

Industrial Robot Defined

A general-purpose, programmable machine possessing certain anthropomorphic characteristics

Hazardous work environments

Repetitive work cycle

Consistency and accuracy

Difficult handling task for humans

Multishift operations

Re-programmable, flexible

Interfaced to other computer systems

Manipulator components

Manipulator consists of joints and links

Joints provide relative motion

Links are rigid members between joints

Various joint types: linear and rotary

Each joint provides a degree-of-freedom

Most robots possess five or six degrees-of-freedom

Robot manipulator consists of two sections:

Body-and-arm for positioning of objects in the robot's work volume

Wrist assembly for orientation of objects

Manipulator Joints

Translational motion

Linear joint (type L)

Orthogonal joint (type O)

Rotary motion

Rotational joint (type R)

Twisting joint (type T)

Revolving joint (type V)

Polar Coordinate Body-and-Arm Assembly

Notation scheme (TRL):

Cylindrical Body-and-Arm Assembly

Notation scheme (TLO) :

Cartesian Coordinate
Body-and-Arm Assembly

Notation scheme (LOO):

Jointed-Arm Robot

Notation scheme (TRR) :

SCARA Robot

Notation scheme (VRO):

Stands for Selectivity Compliant Assembly Robot Arm

Wrist Configurations

Wrist assembly is attached to end-of-arm

End effector is attached to wrist assembly

Function of wrist assembly is to orient end effector

Body-and-arm determines global position of end effector

Two or three degrees of freedom:

Roll

Pitch

Yaw

Notation : (RRT)

Grippers and Tools

Joint Drive Systems

Electric

Uses electric motors to actuate individual joints

Preferred drive system in today's robots

Hydraulic

Uses hydraulic pistons and rotary vane actuators Noted for their high power and lift capacity

Pneumatic

Typically limited to smaller robots and simple material transfer applications

Industrial Robot Control System

Limited sequence control

Playback with point-to-point control

Playback with continuous path control

Intelligent control


Limited sequence control

pick-and-place operations using mechanical stops to set positions.

These robots do not require any sort of programming, and just uses the manipulator to perform the operation.

every joint can only travel to the intense limits .


Playback Robots with Point to Point ControlThey can be programmed (taught) to move from a point within the work envelope to another point within the work envelope.

Application: machine loading and unloading applications as well as more-complex applications, such as spot welding and assembly .


Playback Robots with Continuous Path Control

This type of robots can control the path, and can end on any specified position.

These robots commonly move in the straight line. The initial and final point is first described by the programmer.

it can also move in a curved path by moving its arm at the desired points.

Applications :

are arc welding,

spray painting,

and gluing operations.


Intelligent controlThe intelligent control robot is capable of performing some of the functions and tasks carried out by human beings.

It can detect changes in the work environment by means of sensory perception.

It is equipped with a variety of sensors providing visual (computer vision) and tactile (touching) capabilities to respond instantly to variable situations.

Industrial Robot Applications

Material handling applicationsMaterial transfer pick-and-place, palletizing

Machine loading and/or unloading

Processing operationsWelding

Spray coating

Cutting and grinding

Assembly and inspection

Robotic Arc-Welding Cell

Robot performs flux-cored arc welding (FCAW) operation at one workstation while fitter changes parts at the other workstation

Robot programming

Type of Robot ProgrammingJoint level programmingbasic actions are positions (and possibly movements)

joint angles in the case of rotational joints .

linear positions in the case of linear or prismatic joints.

Robot-level programmingthe basic actions are positions and orientations (and perhaps trajectories) of Pe and the frame of reference attached to it.

High-level programmingObject-level programming

Task-level programming

Robot programming methods

Typically performed using one of the following

On lineteach pendant

lead through programming

Off linerobot programming languages

task level programming


Online teach pendant programming

hand held device with switches used to control the robot motions

End points are recorded in controller memory

sequentially played back to execute robot actions

trajectory determined by robot controller

suited for point to point control applications


Lead Through Programminglead the robot physically through the required sequence of motions

trajectory and endpoints are recorded, using a sampling routine which records points at 60-80 times a second

when played back results in a smooth continuous motion

large memory requirements


On-Line/Teach BoxAdvantage:Easy

No special programming skills or training

Can specify other conditions on robot movements (type of trajectory to use line, arc)

Disadvantages:Potential dangerous (motors are on)

Off-line ProgrammingPrograms can be developed without needing to use the robot

The sequence of operations and robot movements can be optimized or easily improved

Previously developed and tested procedures and subroutines can be used

Existing CAD data can be incorporated-the dimensions of parts and the geometric relationships between them, for example.

Programs can be tested and evaluated using simulation techniques, though this can never remove the need to do final testing of the program using the real robot

Programs can more easily be maintained and modified

Programs can more be easily properly documented and commented.

industrial robots

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