Robot programming

Robot Programming Revisited
• Robot Programming is the defining of
desired motions so that the robot may
perform them without human intervention.
– identifying and specifying the robot configurations
(i.e. the pose of the end-effector, Pe, with respect to
the base-frame)
1.MANUAL METHOD
2.WALKTHROUGH METHOD
3.LEADTHROUGH METHOD
4.OFF-LINE PROGRAMMING

Type of Robot Programming
• Joint level programming
– basic actions are positions (and possibly
movements) of the individual joints of the robot
arm: joint angles in the case of rotational joints
and linear positions in the case of linear or
prismatic joints.
• Robot-level programming
– the basic actions are positions and orientations
(and perhaps trajectories) of Pe and the frame of
reference attached to it.
• High-level programming
– Object-level programming
– Task-level programming

pick-up part-A by side-A1 and side-A3
move part-A to location-2
pick-up part-B by side-B1 and side-B3
put part-B on-top-off part-A
with side-A5 in-plane-with side-B6 and
with side-A1 in-plane-with side-B1 and
with side-A2 in-plane-with side-B2
Object Level Programming
• basic actions are operations to be performed
on the parts, or relationships that must be
established between parts

paint-the car-body red
assemble the gear-box
Task Level Programming
• basic actions specified by the program are
complete tasks or subtasks

ROBOT PROGRAMMING
• Typically performed using one of the
following
– On line
• teach pendant
• lead through programming
– Off line
• robot programming languages
• task level programming

Robot Programming Methods
• Offline:
– write a program using a text-based robot programming
language
– does not need access to the robot until its final testing and
implementation
• On-line:
– Use the robot to generate the program
• Teaching/guiding the robot through a sequence of motions that
can them be executed repeatedly
• Combination Programming:
– Often programming is a combination of on-line and off-line
• on-line to teach locations in space
• off-line to define the task or “sequence of operations"

Use of Teach Pendant
• 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 Programming
• lead 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/Lead Through
• Advantage:
– Easy
– No special programming skills or training
• Disadvantages:
– not practical for large or heavy robots
– High accuracy and straight-line movements are difficult to
achieve, as are any other kind of geometrically defined
trajectory, such as circular arcs, etc.
– difficult to edit out unwanted operator moves
– difficult to incorporate external sensor data
– Synchronization with other machines or equipment in the
work cell is difficult
– A large amount of memory is required

On-Line Programming
• Requires access to the robot
• Programs exist only in the memory of robot
control system – often difficult to transfer,
document, maintain, modify
SUMMARY OF ROBOT APPLICATIONS
• Easy to use, no special programming skills required
• Useful when programming robots for wide range of
repetitive tasks for long production runs
• RAPID

On-Line/Teach Box
• Advantage:
– 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 Programming
• Programs 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
• External sensor data can be incorporated, though this typically makes
the programs more complicated, and so more difficult to modify and
maintain
• 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.

Coordinate Systems
World coordinate system Tool coordinate system

Configuration: Any particular
position and orientation of Pe in
space, and so any particular set of
joint values, is called a configuration
of the robot arm.

Motion Commands
MOVE P1
HERE P1 - used during lead through of manipulator
MOVES P1
DMOVE(4, 125)
APPROACH P1, 40 MM
DEPART 40 MM
DEFINE PATH123 = PATH(P1, P2, P3)
MOVE PATH123
SPEED 75

 Robot motion programming commands

 MOVE P1
 HERE P1 -used during leadthrough of manipulator
 MOVES P1
 DMOVE(4, 125)
 APPROACH P1, 40 MM
 DEPART 40 MM
 DEFINE PATH123 = PATH(P1, P2, P3)
 MOVE PATH123
 SPEED 75

 Input interlock:
 WAIT 20, ON
 Output interlock:
 SIGNAL 10, ON
 SIGNAL 10, 6.0
 Interlock for continuous monitoring:
 REACT 25, SAFESTOP

 Gripper
 OPEN
 CLOSE
 Sensor and servo-controlled hands
 CLOSE 25 MM

Interlock and Sensor Commands
Interlock Commands
WAIT 20, ON
SIGNAL 10, ON
SIGNAL 10, 6.0
REACT 25, SAFESTOP
Gripper Commands
OPEN
CLOSE
CLOSE 25 MM
CLOSE 2.0 N

Programming Languages
• Motivation
– need to interface robot control system to
external sensors, to provide “real time”
changes based on sensory equipment
– computing based on geometry of environment
– ability to interface with CAD/CAM systems
– meaningful task descriptions
– off-line programming capability

• Large number of robot languages available
– AML, VAL, AL, RAIL, RobotStudio, etc.
(200+)
• Each robot manufacturer has their own
robot programming language
• No standards exist
• Portability of programs virtually non-
existent

ROBOT PROGRAMMING LANGUAGES
 The VALTM Language
 The VAL language was developed for PUMA robot
 Monitor command are set of administrative
instructions that direct the operation of the
 robot system. Some of the functions of Monitor
commands are
 Preparing the system for the user to write programs for
PUMA
 Defining points in space
 Commanding the PUMA to execute a program
 Listing program on the CRT
• Examples for monitor commands are: EDIT,
EXECUTE, SPEED, HERE etc.

THE MCL LANGUAGE
 MCL stands for Machine Control Language developed by Douglas.
 The language is based on the APT and NC language. Designed control complete
 manufacturing cell.
 MCL is enhancement of APT which possesses additional options and features
needed
 to do off-line programming of robotic work cell.
 Additional vocabulary words were developed to provide the supplementary
 capabilities intended to be covered by the MCL. These capability include Vision,
 Inspection and Control of signals
 MCL also permits the user to define MACROS like statement that would be
 convenient to use for specialized applications.
 MCL program is needed to compile to produce CLFILE.
 Some commands of MCL programming languages are DEVICE, SEND, RECEIV,
 WORKPT, ABORT, TASK, REGION, LOCATE etc.

INDUSTRIAL ROBOT APPLICATIONS
 Material-handling applications:
• Involve the movement of material or parts from one location to
another.
• It includes part placement, palletizing and/or de-palletizing,
machine loading and unloading.
 Processing Operations:
• Requires the robot to manipulate a special process tool as the end
effectors.
• The application include spot welding, arc welding, riveting, spray
painting, machining, metal cutting, de-burring, polishing.
 Assembly Applications:
• Involve part-handling manipulations of a special tools and other
automatic tasks and operations.
 Inspection Operations:
• Require the robot to position a work part to an inspection device.
• Involve the robot to manipulate a device or sensor to perform the
inspection.

Industrial Robot Applications
1. Material handling applications
 Material transfer – pick-and-place, palletizing
 Machine loading and/or unloading
2. Processing operations
 Welding
 Spray coating
 Cutting and grinding
3. Assembly and inspection

MATERIAL HANDLING APPLICATIONS
 This category includes the following:
• Part Placement
• Palletizing and/or depalletizing
• Machine loading and/or unloading
• Stacking and insertion operations

THE GENERAL CONSIDERATIONS IN ROBOT
MATERIAL HANDLING
 Part positioning orientation
 Gripper design
 Minimum distance moved
 Robot work volume
 Robot weight capacity
 Accuracy and repeatability
 Robot configuration, Degree of Freedom and Control
 Machine utilization problems

PART PLACEMENT
 The basic operation in this category is the relatively
simple pick-and-place operation.
 This application needs a low-technology robot of
the cylindrical coordinate type.
 Only two, three, or four joints are required for most
of the applications.
 Pneumatically powered robots are often utilized.

PALLETIZING AND/OR DEPALLETIZING
 The applications require robot to stack parts one on
top of the other, that is to palletize them, or to
unstack parts by removing from the top one by one,
that is depalletize them.
 Example: process of taking parts from the assembly
line and stacking them on a pallet or vice versa.

MACHINE LOADING AND/OR UNLOADING
 Robot transfers parts into and/or from a production
machine.
 There are three possible cases:
Machine loading in which the robot loads parts into a
production machine, but the parts are unloaded by some
other means.
 Example: a press working operation, where the robot feeds
sheet blanks into the press, but the finished parts drop out of
the press by gravity.
Machine loading in which the raw materials are fed into the
machine without robot assistance. The robot unloads the
part from the machine assisted by vision or no vision.
 Example: bin picking, die casting, and plastic moulding.
Machine loading and unloading that involves both loading
and unloading of the work parts by the robot. The robot
loads a raw work part into the process ad unloads a finished
part.
 Example: Machine operation difficulties
 Difference in cycle time between the robot and the

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

STACKING AND INSERTION OPERATION
 In the stacking process the robot places flat parts on top of
each other, where the vertical location of the drop-off
position is continuously changing with cycle time.
 In the insertion process robot inserts parts into the
compartments of a divided carton.
 The robot must have following features to facilitate material
handling:
• The manipulator must be able to lift the parts safely.
• The robot must have the reach needed.
• The robot must have cylindrical coordinate type.
• The robot’s controller must have a large enough memory to
store all the programmed points so that the robot can move
from one location to another.
• The robot must have the speed necessary for meeting the
transfer cycle of the operation.

PROCESSING OPERATIONS
 Robot performs a processing procedure on the part.
 The robot is equipped with some type of process tooling as its
end effector.
 Manipulates the tooling relative to the working part during the
cycle.
 Industrial robot applications in the processing operations
include:
Spot welding
Continuous arc welding
Spray painting
Metal cutting and deburring operations
Various machining operations like drilling, grinding, laser and
water jet cutting, and riveting.
Rotating and spindle operations
Adhesives and sealant dispensing

ASSEMBLY OPERATIONS
 The applications involve both material-handling and the
manipulation of a tool.
 They typically include components to build the product and
to perform material handling operations.
 Are traditionally labor-intensive activities in industry and
are highly repetitive and boring. Hence are logical candidates
for robotic applications.
 These are classified as:
Batch assembly: As many as one million products might be
assembled.
The assembly operation has long production runs.
Low-volume: In this a sample run of ten thousand or less
products might be made.
The assembly robot cell should be a modular cell.
One of the well suited areas for robotics assembly is the
insertion of odd electronic components.

INSPECTION OPERATION
 Some inspection operation requires parts to be manipulated, and other
applications require that an inspection tool be manipulated.
 Inspection work requires high precision and patience, and human judgment is
often needed to determine whether a product is within quality specifications
or not.
 Inspection tasks that are performed by industrial robots can usually be
divided into the following three techniques:
By using a feeler gauge or a linear displacement transducer known as a linear
variable differential transformer (LVDT), the part being measured will come
in physical contact with the instrument or by means of air pressure, which will
cause it to ride above the surface being measured.
By utilizing robotic vision, matrix video cameras are used to obtain an image of
the area of interest, which is digitized and compared to a similar image with
specified tolerance.
By involving the use of optics and light, usually a laser or infrared source is used
to illustrate the area of interest.
 The robot may be in active or passive role.
In active role robot is responsible for determining whether the part is good or
bad.
In the passive role the robot feeds a gauging station with the part. While the
gauging station is determining whether the part meets the specification, the
robot waits for the process to finish.

ADVANTAGES OF ROBOTS
 Robotics and automation can, in many situation,
increase productivity, safety, efficiency, quality, and
consistency of Products
 Robots can work in hazardous environments
 Robots need no environmental comfort
 Robots work continuously without any humanity needs
and illnesses
 Robots have repeatable precision at all times
 Robots can be much more accurate than humans, they
may have milli or micro inch accuracy.
 Robots and their sensors can have capabilities beyond
that of humans.
 Robots can process multiple stimuli or tasks
simultaneously, humans can only one.
 Robots replace human workers who can create
economic problems.

ROBOT APPLICATIONS
 Work environment hazardous for human beings
 Repetitive tasks
 Boring and unpleasant tasks
 Multi shift operations
 Infrequent changeovers
 Performing at a steady pace
 Operating for long hours without rest
 Responding in automated operations
 Minimizing variation

DISADVANTAGES OF ROBOTS
 Robots lack capability to respond in emergencies, this can cause:
Inappropriate and wrong responses
A lack of decision-making power
A loss of power
Damage to the robot and other devices
Human injuries
 Robots may have limited capabilities in
Degrees of Freedom
Dexterity
Sensors
Vision systems
Real-time Response
 Robots are costly, due to
Initial cost of equipment
Installation Costs
Need for peripherals
Need for training
Need for Programming

SUMMARY OF ROBOT APPLICATIONS
 1. Hazardous work environment for humans
 2. Repetitive work cycle
 3. Difficult handling task for humans
 4. Multi shift operations
 5. Infrequent changeovers
 6. Part position and orientation are established in the
work cell

Robot programming

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Robot programming