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Robotic WeldingSystem Issues
J. Norberto PiresMechanical Engineering Department
University of Coimbra – Portugal
[email protected]/norberto/
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Outline
1. Robot Technology State of the Art
2. Robot environment and Driving Forces to Automation
3. Difficulties in Automation
4. Improvements needed in the near future.
5. Welding Application - Overview
6. Software architecture
7. Remote Services
8. Adding equipment
9. Conclusions
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Brief History
Robotics was part of the thoughts of many of the great thinkers of common history. From all of them we select:
Ctesibius (270 BC) ⇒ the Greeks and the Arabians
Leonardo da Vinci (1452-1519)
Nicola Tesla (1845-1943)
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Ctesibius the Greeks and the Arabians
Briefly, the first works on robotics may be traced back until 270 BC, in the ancient Greece, to the water clocks with mobile figures designed by the Civil EngineerCtesibius. His work was followed by Phyloof Byzantium (author of the marvellousbook “Mechanical Collection”, 200 BC), Hero of Alexandria (85 BC) and MarcusVitruvius (25 BC). Several hundred years later, the Arabians documented (the threeBanu Musa working for the Kalifa of Baghdad, 786-833 AC) and developed (Badías-Zaman Isma’Il bin ar-Razzazal-Jazari in the book “The science of the Ingenious Devices”, 1150-1220 AC) the Greek designs to be used on their own creations.
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Leonardo
Leonardo Da Vinci also spent some time on robotics, when he was working for the Sforza family. By the same time he painted “The last supper”, he was also involved with building the “Salle delle Asse” of theSforza Castle, where he planned to put a human-like robot in the form of a XV century knight. Somehow, the plans and drawings were never found, although some pages of his famous book “Codex Atlanticus” are missing precisely in the point where it seams that he was preparing the robot project.
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Nicola Tesla
Nicola Tesla did another outstanding contribution to robotics, in the turn to our century. He was thinking about automatons and how he could command them or “embody” intelligence on them. At the time, there was a German scientist (Hertz) claiming that an electromagnetic excitation generates radiation of the same type that can be detected far from the excitation. Tesla thought about using this to command an automaton: the term “tele-automatics” appeared. In its own words:
“… But this element I could easily embody in it by conveying to it my own intelligence, my own understanding. So this invention was evolved, and so a new art came into existence, for which the name “teleautomatics” has been suggested, which means the art of controlling movements and operations of distant automatons.”
AcademiaIndustry
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
These
are
the
industria
l robots o
f
our d
ays ...
How
they w
ill
evo
lve?
Technical Mile Stones
• ’74: Electrical Drive Train• ’74: Microprocessor Control• ’82: Cartesian Interpolation• ’82: Computer Communication• ’82: Joy-stick• ’82: Menu Programming• ’84: Vision Guidance• ’86: Digital Control Loops• ’86: AC Drives• ’90: Networking
Source: ABB Robotics
• ’91: Digital Torque Control• ’94: Full Dynamic Model• ’94: Windows Interface• ’94: Virtual Robot• ’94: Fieldbus I/O• ’96: Co-operating Robots• ’98: Collision Detection• ’98: Load Identification• ’98: Fast Pick & Place
Robotics State of Art
1. Position and Motion controllers ⇒ Basically that’s all they can do.
2. PLC capabilities for IO control.3. Ethernet, fieldbuses, serial connections.4. Programming language or script for accessing resources.
Repeatability up to 0.03 mm (0.1 mm is common)
Velocity up to 5 m/s
Acceleration up to around 25 m/s2
Payload from 2-3 kg up to ~350 kg
Weight/payload around 30-40
Axis 6
Communications Profibus, Can, Ethernet and serial channels (RS 232, 485)
IO capabilities PLC like capabilities to handle digital and analog IO.
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Computer Integrated Manufacturing
Router
Switch
InternetEconomic and FinantialManagment
Market Surveys andMarketing
ProjectProduction Managment and Planning
HUB
CL_1 CL_N...
HUB HUB
CC_1 CC_N... ...
CFM_1Equipments
CFM_NEquipments
...
Equi
pmen
tLe
vel
Cel
lLe
vel
Proc
ess
Leve
lPr
oduc
tion
Leve
lM
anag
men
tLe
vel
Driving Forces
• Global Market
• Products defined in part by the costumers.
• Products are technological complex and dense.
• Small batch manufacturing.
• More quality at lower prices.
Flexible and agile production
• Organization.
• Standards
• Programmable equipments.
• Decision support and information systems.
• Programmable Automation.
• Robotics.
• Industrial computation.
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Near Future
• Lower price• Higher performance• More sophisticated sensor control• Better on-line control from prod. control systems• Better simulation and off-line programming tools• Better remote services• Better quality• Better diagnostics• Lower energy consumption• Support for new production processes• Force control ⇒ As a regular feature• Evolve to lighter structures
Better SOFTWARE ...
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Near future
Capacity: better performance, lighter structures ⇒ better accelerations and velocities, better position control, force control ... Actually dynamical models used by robots have 7-10% of error.
Usability: Programming environments, easier to use, some ways to access the original system and change its standard way of working ⇒ object oriented software and programming.
Connectivity: Standard links and protocols: nets, protocols, net services (telnet, ftp, disk mounting), RPC, RMI (Java), OPC.
We need robots very easy to command, in a way that they can follow complex requests done with “high level” interfaces.
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
We could summarize the main difficulties has follows, considering a researcherpoint of view and also a system integrator point of view:
End-user programming: It is still to complex, too platform dependent, non standard and consequently only for specialists;
System programming: APIs are very limited or non-existing, making a simple job of adding a new resource (a board, a sensor, a new feature, etc) almost impossible;
Human Machine Interface (HMI): It is really not working. Systems require too many training and customization. There is some need for other approaches like skill learning so that robots could be easily customized and get into efficient production;
Connectivity: lacking of inter-connectable the facto standards;
What are the problems or difficulties of current robot control units?
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Open Source ??
Industrial Manipulators
Industrial Mobile Robots
Human Robots
Space Robots
Medical Robots (Tele-Operated)
Op
en
So
urc
e
APIsInterfaces
Software architecture
User InterfaceDialogs
Object_A
Object_B
Object_C
Sensor A
Sensor B
Server
CommercialApplication
Executor Services
Equipment
PortmaperServer
FMC Controller
LAIN
- Local Area Industrial N
etwork
Application
Remote call to service_iof equipment_j
Synchronous answer from equipment_j to the remote call to service_i
Asynchronous answer"spontaneous message"
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Software architecture
The implementation of this requires the use of three programming models:
Client/server: We require to have server code running on the equipment that deals with receiving calls from remote computers (clients), execute them and return the results.
Remote Procedure Calls (RPC): This is the usual way to implement communications between the client and the server of a distributed application. The client makes what looks like a procedure call, although the resource is not local. The RPC mechanism in use translates that into network communications. The server receives the request, executes accordingly and returns the results.
Data Sharing: We want to have services that share files, programs, databases, etc. The data sharing services will be built on top of RPC, which provides the means for transferring data.
Object Technology: OMG CORBA, COM/OLE/ActiveX, Java beans ...
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
ActiveXRobot
CommunicationObject
ActiveXForce/TorqueSensor Object
DDE CallbackFunction
DDE Services
DDE ClientApplications
DDE
OLE
OLE
DDE Server
RPC CallsSync. Answers
ActiveXRobot
CommunicationObject
ActiveXForce/TorqueSensor Object
OLE
OLE
WindowsDialog
Win32 Application
RPC Calls
Sync. Answers
RPCServer
Async. Msg.Portm
aperMessages
BoardNT Kernel
Driver
Forc
e/To
rque
Sens
or B
oard
RPCServer
Programs RAPIDAplication
Robot Control System
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Software architecture
Joystick Application
Robot
Request
Answer
Event = async. answer
Broadcast MSG
RPC server
Master/Slave
Tele-robotics
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Matlab exampleIndustrial Robot Example
RobotRPC Server
DDE
RPC Assync. Call
RPC Sync. Call
RPC Sync. Answer
ABB IRB1400S4 Controller
Matlab 5.3
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
EmailWareA tool for e-Manufacturing.
IF poll_nowPoll_Robots
Check for
emails
Processcommands
MessageQueue
Processmessage
(poll_now = 1)
SMTPservice
POP3service
E-mailServer
Log file
RPCServer
RPCMessage
Message to send
Retrieve commands
Send
Retrieve
EMAILWARE
E-mail alerts
Logs and errors
System Status
Information
CCD
Profibus
Ethernet
Pentium IIIWindows NTMatlab
PC
CCDDialog
ActiveXCCD
ActiveXRobô
RPCServer
DDE
Robô
MEXFiles
Matlab
Win32 Application
Laser 3D
ActiveX Laser
Laser 3DCamara
Welding ...
Joystick
1. Setup phase - where the user sets up all the parameters and trajectories.
2. Welding phase - the system should monitor the welding process and correct on-line.
3. Analysis phase - detail the welding seam and quality analysis.
Welding 2001, International Workshop on Robotic Welding Systems and Process Monitoring, Portugal
Conclusions
• State of the art of robotics technology was presented.• Brief analysis of driving forces, difficulties and near to come
innovations.• Software needs.• Our way of developing FMS solutions: software architecture.• Several examples: academic & industrial & research.• Application to welding was discussed.
Software presented can be downloaded from:http://robotics.dem.uc.pt/norberto/
Publications also on the site.
Pires JN. and Sá da Costa JMG., "Ferramentas de Software para Controlar, Programar eMonitorizar um Robô Manipulador Industrial usando Computadores Pessoais", Ibero-American Mechanical Engineering Association Magazine, 1998;2(1):43-67.
Bloomer J., "Power Programming with RPC", O'Reilly & Associates, Inc., 1992.
Pires JN, Sá da Costa JMG, “Object Oriented and Distributed Approach forProgramming Robotic Manufacturing Cells”, IFAC Journal on Robotics and Computer Integrated Manufacturing, to appear 1999.
Pires JN, “Controlo de Força em Robôs Manipuladores Industriais”, Ph.D. Thesis,University of Coimbra, June, 1999.
Kusiak A., "Modelling and Design of Flexible Manufacturing Systems", Elsevier Science Publishers, 1986.
Pires JN, “Interfacing Robotic and Automation Equipment with Matlab”, IEEE Roboticsand Automation Magazine, September 2000.
Pires JN, “Emailware: A tool for e-Manufacturing”, Assembly Automation Journal, MCBUniversity Press (to appear, expected February 2001).
Pires JN, “Using Actual Robot Manipulators with Construction Tasks”, Proceedings of the ISARC’17, International Conference on Automation and Robotics in Construction, Taipei,Taiwan, September 2000.
Some References
Final message:
Robotics as a technology will evolve enormously with the cooperation between academia & industry. In that point o view, it is very important to have many fields of application, like robotic welding.
In Europe there is a network that addresses Robotics research and development called EURON. Within EURON there is the interest in “industrial or applied thinking” ...
Check EURON in:
http://www.cas.kth.se/euron/
EURON is coordinated by Dr. Henrik Christensen (KTH, Sweden)
Check EURON “Industrial Robotics & Manufacturing Interest Group” in:
http://www.control.lth.se/~robot/euron/mig.html
This Group is coordinated by Dr. Klas Nilsson (Lund, Sweden), Dr. Gordon Petersen (Odense, Denamrk) & Dr. J. Norberto Pires (Coimbra, Portugal)