robotics programming
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Robot Programming
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)
Robot programming A robot must be programmed to do useful works and
perform its tasks – a robot is an idiot waiting for you to make it work by the use of programming.
Robot program is defined as a path of movements of its manipulator, combined with peripheral equipment actions to support its work cycle.
The peripheral equipment actions include– Operation of the end-effector.– Making logical decisions.– Communicating with environments.
A robot programmer needs to understand the whole task and interfaces with its environment before he/she starts a 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
Robot programming method
Walk-through method OR Manual (limited-sequence robots)
Lead-through method (teach-by-showing the desired motion ‘ Manual and Powered’ – adequate for shop floor operators)
Computer like robot programming languages (requires computer background, enhanced sensor capabilities, improved control, computation capabilities, communications, compatibility with CIM)
Off-Line programming ( doesn’t interrupt production) Robot Simulation
Walk-through method•A person doing the programming has physical contacts with the robot arm, actually gains control and walks the robot's arm through the desired positions.•Each movement is recorded into the memory for the playback during production, including unintended motions.•The main concern is on achieving the correct positioning sequences. Cycle time and speed can be changed later, when necessary•A dead man’s control should be fitted for the safety reason.•A high precision in generating paths cannot be achieved (Manual operation) - Highly skilled operator required.•Optimum trajectory velocity cannot be achieved•Movements are stored in the sampled time - required large memory.•Mainly used in spray painting, arc welding,grinding, deburring and polishing
Lead-through method (teach-pendant programming)
•Teaching the robot via teach pendants that has toggle switches or contact buttons for controlling the movement of the robot.•Allows a trained operator physically to lead the robot through the desired sequence of events by activating the appropriate pendant buttons or switches.•Position data and functional information are "taught" to the robot, and a new program is written into memory•The speed and termination type of the movement should be specified•Particularly useful in pick-place, arc welding applications.
Lead-through Programming : Powered Each axis is moved under push-button control
using a “teach” pendant to produce a series of desired position of the end point. Typical command keys:
JOG HOME TEACH MOVE
The corresponding series of joint positions or points are stored for playback later during actual operation.
Suitable for PTP control only since paths between two consecutive positions are not predictable.
Lead-through Programming : Manual
The entire path is “taught” by manually moving through the motion sequence. The measured positions of the joints and speeds (how?) are recorded as editable programs for later playback during actual operation.
For large robot, a special programming device replaces the actual robot.
Used for Continuous Path programming . A typical application of this programming method is spray painting where smooth and free flowing movements are required.
Computer like Robot Programming Languages :Basic Elements
Define Constants and Variables Motion commands (coordinate systems) End Effectors Commands Sensor Commands Program Control Commands Communications Commands Monitor Mode Commands
Robot Programming Languages WAVE
– Developed at Standford
– Demonstrated a robot hand-eye coordination in the machine vision robot
– Trajectory calculations through coordination of joint movements, end-effector positions and touch sensing
– Algorithm is too complex and not user friendly AL
– Later developed at Standford
– The language can implement various subroutines, involving activities between the robot and its surroundings.
Robot Programming Languages
VAL
– Popular textual robot language developed by Unimation Inc. for the PUMA series of robots.
– Victor Sheinman developed VAL languages.
– Later VAL II is developed
– It provides arm movement in joint, world and tool coordinates, gripping and speed control.
AML
– Developed by IBM
– It is possible to interface other programming languages.
Robot Programming Languages MCL
– Developed by McDonnel-Douglas at US Air force– Modification of APT (Automatically programmed
Tooling) languages used for CNC RAIL
– Developed by Automatix for robotic assembly, inspection, arc welding and machine vision
– A variety of data types as used in PASCAL can be used
Robot Programming Languages HELP
– Developed by General Electric Company– It has capability to control two robot arms at the
same time JARS
– Developed by NASA’s JPL.– The base language is PASCAL– It can be interfaced with PUMA 6000 robot
RPL– Developed by SRI international.– The basic ideas of LISP language have been
organized into a FORTRAN – like syntax– It can be interfaced with PUMA 500 robot
Classification of Robot Languages First generation language
– It provides an off-line programming in combination with the programming through robot pendant teaching.
– Example : VAL language– The capability of a first generation language is limited to the
handling of sensory data (except ON/OFF binary signals) and combination with other computer
Second generation language– AML, RAIL, MCL, VAL II languages– They are structured programming languages performing complex
tasks– Force, torque, slip and other sensor can be incorporated in joints
World modelling and task-oriented object level languages– A task is defined through a command, say TIGHTEN THE NUT.– The robot should be capable of performing step by step functions
to accomplish the objective of tightening the nut.
Off-Line programming
The programming for the required sequence of functions and positions is written on a remote computer console. Then transfer to the robot controller (floppy disk or downloading).
The robot programming language is to make it easy for this purpose (ADA, RAPID, ...).
Robot Simulation
Off-line programming can provide a means of programming without interruption of actual production
However, it would cause unintended movement and in turn serious problems – collision, or injuries
Simulation enables to test new or modified programs in virtual environment or even test a new manufacturing cell before the construction.
VAL programming language Defining and Determining Locations
– HERE : current location• HERE PART• HERE P1
– POINT : previously defined location• POINT PART = P1
– WHERE : the current location can be displayed
– TEACH : records a series of location values• TEACH P1
Editing programs– EDIT : permits to create or modify (edit) a
user program• EDIT SRD
.
.
.
E - exit of the editing mode
VAL programming language
VAL programming language Storing and Retrieving Program and
Location-data– LISTF : displays the file directory of the diskette– STOREP : storing program– STOREL : storing location– STORE : storing program and location– LOADP : loading program– LOADL : loading location– LOAD : loading program and location– COPY : copying the program– RENAME : renaming the files– DELETE : deleting the files– In VAL II language
• FLIST – listing the file names kept on a disk
VAL programming language
Program Control– SPEED : specifies the speed for all subsequent robot motions
under program control– EXECUTE : execute a specified user program for once– EXECUTE , 5: execute 5 times– EXECUTE, -1 : execute indefinitely– ABORT : terminates program execution after completion of the
current step
– In VAL II language
• DRIVE 2, 60, 30 : joint number 2 may be changed by driving it say 600 at a speed of 30 percent of the monitor speed
• DO : allows a robot to execute a program instruction
DO ALIGN
DO MOVE PART
VAL programming language
Program instructions– Robot configuration control– Motion control– Hand control– Location assignment and modification– Program control, interlock commands and
I/O controls
VAL programming language
• Robot configuration control– Any robot configuration change is accomplished
during the execution of the next motion instruction other than a straight line motion.
– RIGHTY : change the robot configuration to resemble a right human arm
– LEFTY : change the robot configuration to resemble a left human arm
– ABOVE : make the elbow of the robot to point up– BELOW : make the elbow of the robot to point down
VAL programming language Motion Control
– MOVE : moves the robot to specified location– MOVES : moves the robot to straight line path– DRAW : moves the robot to straight line through specified
distance in X, Y and Z directions– APPRO : moves the robot to location which is at an offset
( along tool z-axis) from a specified point– DEPART : moves the tool along the current tool Z-axis– APPROS : moves the robot to location which is at an offset (
along tool z-axis) from a specified point in straight line path– DEPARTS : moves the tool along the current tool Z-axis in
straight line path– CIRCLE : moves the robot through circular interpolation via
three specified point locations
VAL programming language
Hand Control– OPEN : the opening of the gripper during the next instruction– CLOSE : the closing of the gripper during the next instruction– OPENI : the opening of the gripper during the next instruction
immediately– CLOSEI: the closing of the gripper during the next instruction
immediately– MOVEST PART, 30 : the servo-controlled end-effector causes a
straight line motion to a point defined by PART and the gripper opening is changed to 30 mm.
– MOVET PART, 30 : the gripper to move to position. PART with an opening of 30 mm by joint-interpolated motion.
– In VAL II language• CLOSEI 75 : if servo-controlled gripper is used, then this command
causes the gripper to close immediately to 75 mm.• GRASP 20, 15 : the gripper to close immediately and checks
whether the opening is less than the amount of 20 mm. If the opening is less than 20 mm, the program, branches to the statement 15.
VAL programming language
Location Assignment and Modification– SET : set the value in the monitor– HERE : position displayed on the screen
Program Control, Interlock Commands and Input / Output Control– SETI : set the value of an integer variable
to the result of an expression.– TYPEI : displays the name and values of
an integer variable
VAL programming language
Program Control, Interlock Commands and Input / Output Control– In VAL II language
• PROMPT : the operator respond by typing the value requested and pressing the return key.
– PROMPT “Enter the value” , Y1
– GOTO 20 : an unconditional branch to the program step identified by a given level, 20
– GOSUB : transfer the control to the subroutine– RETURN : Transfer the control from the subroutine– IF … THEN : transfer control to a program step depending on
a relationship (conditions) being true or falseIF ROW LT 3 THEN
(A number of instruction steps)
ELSE
(A number of instruction steps)
END
VAL programming language
Program Control, Interlock Commands and Input / Output Control– PAUSE : terminates the execution of a user program– PROCEED : To terminate PAUSE command– SIGNAL : turns the signal ON or OFF at the specified output
signals• SIGNAL 2, -3
– Output signal 2 (positive) is to be turned ON and output signal 3 (negative) is to be turned OFF
– IFSIG and WAIT: test the status of one or more external signals
• WAIT SIG (-1, 2)– It will prevent the program execution until external
input signal 1 is turned OFF (negative) and external input signal 2 is turned ON (positve)
– RESET : turns OFF all the external signals
Depalletizing
.PROGRAM DEPALLET 1
REMARK PROGRAM TO PICK OBJECTS FROM A PALLET
REMARK CORNER AND CHUTE LOCATIONS ARE TAUGHT
SETI MAXCOL = 4
SETI MAXROW = 3
SETI ROW = 1
SETI COLUMN = 1
SET PICK = CORNER
SHIFT PICK BY 20.00, -20.00, 60.00
OPENI
10MOVE PICK
DRAW 0, 0, -25.00
COLSEI
DRAW 0, 0, 25.00
MOVE CHUTE
OPENI
GOSUB PALLET
IF ROW LE MAXROW THEN 10
.END
.PROGRAM PALLET
REMARK SUBROUTINE FOR LOCATIONS
SETI COLOUM = COLUMN +1
IF COUMN GT MAXCOL THEN 20
SHIFT PICK BY 50.00, 0.00, 0.00
GO TO 10
20 SETI ROW = ROW +1
IF ROW GT MAXROW THEN 30
SHIFT PICK BY -150.00, -30.00,0.00
SETI COLUMN =1
30 RETURN
.END
WELDING INSTRUCTIONS
WVSET 1 = 10, 7, 2, 0, 1, 3, 0
– 10 : cycle distance
– 7 : amplitude
– 2 : right end stop distance
– 0 : right end stop time
– 1 : center stop distance
– 3 : left end stop distance
– 0 : left end stop time
• WSET 1 = 13, 54.3, 63
– A welding speed of 13 mm/s, welding voltage of 54.3% and welding current of 63 % for welding condition 1
WSTART : starts the welding under present welding conditions and weaving conditions (set by WSET and WVSET)
WEND : inactivates a welding start signal
CRATERFILL : It is used when a crater filler is required at a welding end
An Arc Welding Program
.PROGRAM WELD CURVE
1 WSET 1 = 10, 40, 50
2 WSET 2 = 8, 35, 60
3 WSET 3 = 12, 40, 55
4 WVSET 1 = 5, 5
5 WVSET 2 = 10, 7, 2, 0, 1, 2, 0
6 MOVE X1
7 MOVE X2
8 WSTART 1, 1
9 MOVES X3
10 WEND 0.5
11 WSTART 2
12 MOVES X4
13 CIRCLE X4, X5, X6
14 MOVES X7
15 CIRCLE X7, X8, X9
16 MOVES X10
17 WEND 0.5
18 WSTART 3, 2
19 MOVES X11
20 CRATERFILL 0.8, 3
21 WEND 0.5
22 MOVE X12
.END
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