PROCESS SIMULATION USING DELMIA

RĂCĂŞAN Radu*, GYÖRKE Gyöngyi Timea **, GHINEA Rareş***, POPIŞTER Florin****, NEAMŢU Călin Dan*****

*University of Cluj-Napoca –Romania

Abstract: The simulation of different kind of processes is used more and more in a large spectrum of fields. This paper presents and compares the most often used software packages in the simulation of manufacturing processes and in in-dustrial robot programming. The main part of the paper focuses on a more de-tailed presentation of Delmia V5 software, one of the most complex robot simu-lation software packages. The main advantages of a simulation with this soft-ware are highlighted through a case study on a manufacturing cell which pro-duces parts for the automotive industry.

Key words: robot simulation, delmia, process simulation

1. INTRODUCTION

When talking about simulation we usually refer to designing the virtual model of a product or a system, performing the desired simulations and analyzing the results. Simulation is a process that often appears in our everyday life. Many times we try to imagine dynamical scenes and act out different roles in order to answer the “what-if” questions.

One of the main advantages of simulation is that it offers the possibility of solving creative-ly many upcoming problems, which occur while designing, visualizing and testing a product. Simulation can be used for either a real product or one that doesn’t yet exist.

Simulation has become a powerful tool used in many fields such as academic research, de-sign and manufacturing. It offers the possibility of developing a virtual manufacturing environ-ment in order to design the factory layout, plan the production process, to simulate the processes within the factory as well as to study ergonomics and inspection procedures. The benefits of va-lidating a process in a virtual environment are that it offers support for technological modeling, shortens time to market of the products and reduces costs. Other benefits include the possibility of understanding more easily the effects of a decision without putting personnel or equipment at risk.

The importance of using simulation increases with the complexity of the studied process. Robotics, as a branch of the modern technology, recognizes the role of the simulation in phases such as designing and offline programming the robot, simulating multiple devices for robots, defining robots’ tasks, simulating and validating multi-resource operations and uses it to shorten the overall time of designing and launching new automated manufacturing systems. As robots usually work in a system, in the recent years Computer Aided Robotics Systems (CAR-System) appeared, which facilitate the design of robot cells and platforms and the creation of offline pro-grams.

Complex software systems allow users to define the robots or to import them from different robot builders’ libraries and use them to design a particular manufacturing plant. This paper presents a digital manufacturing environment developed using software solutions from Dassault

Systèmes for optimizing a production system while it is still in the virtual realm. Dassault Systèmes' PLM portfolio includes DelmiaV5 an application which allows manufacturers from any industry to virtually define, plan, create all production processes. Delmia V5 is one of the most complex software systems for simulation that use several types of robots from different manufacturers. It also offers the possibility to program them individually and extract the code for each robot.

Fig. 1 – DELMIA Digital Manufacturing Solution [2]

The results obtained by using simulation are mainly the 3D model of the product and the layout of a flexible manufacturing system. Programming the robots of a work cell provides ma-terial, a work flow plan and facilitates the study of ergonomics of human operators on the manu-facturing plant. From simulation one can obtain relevant reports regarding process improvement opportunities. Based on the acquired data process optimization can be easily made thus obtain-ing reduced costs for manufacturing, shortening the product launch lifecycle and facilitate asset preservation.

2. 3D SIMULATION OF THE MANUFACTURING PROCESS USING ROBOTS

There are two types of software used for simulation of processes within a factory: open source and commercial software. Each one of these two has its own advantages as well as dis-advantages due to the different purposes for which they were created.

Open source software can be downloaded for free but the provided results are mainly of a visual nature and they also have just a few functions developed. All robot manufacturers have their own proprietary software for simulation and offline programming.

Software like Robot Studio (ABB) or KukaSimPro allows offline programming or simula-tion of one or multiple robots in a manufacturing plant. They offer the possibility of instantly vi-sualizing the results within a 3D scenario. In these kinds of software systems usually one can simulate only robots produced by the same manufacturer, the one who provides the software. There are also programs that offer the possibility of programming robots from several manufac-turers. Simulations can be done using either robots from a single manufacturer or by combining robots from different ones using virtual controllers.

The software systems mentioned above (open source and commercial) can be divided in three categories: proprietary (specialized) software, generic software and add-ons for 3D model-ing software.

The role of simulation software is to reduce risk, to shorten change-over and to improve productivity.

The paper presents several simulation software that are available on the market. Kuka-SimPro is a dedicated software system which was developed for offline programming of KUKA manufactured robots. The virtual KUKA controller, OfficeLite, allows the generation of robot program and cycle time analyses. Programming a robot in real time without shutting down the production is the best way to reduce risk, to maximize return on investment in robot systems or to increase productivity.

RobotStudio is the software system developed by ABB robot designer and manufacturer which is also a dedicated system software used in offline programming for ABB robots. ABB provides RobotStudio, which is built on the ABB VirtualController, in order to develop simula-tion, programs and configuration files identical to those used in the production environment.

Roboguide Handlingpro is a robot simulation software package developed by Fanuc. The package consists of HandlingPRO, PiantPRO, PalletPRO and WeldPRO. These allow the simu-lation of manipulation, palletizing, painting and welding activities.

RoboLogix is a robotics simulator designed primarily as an education tool, but has all the features and functionality of professional software packages costing thousands of dollars. Con-sequently, RoboLogix is ideal for students as well as robot designers and engineers. The option to preview the behavior of a robotic system in a “virtual” world allows for a variety of mechan-isms, devices, configurations and controllers to be tried out and tested before being applied to a “real world” system.

There are some other software systems, on the market used for offline programming and simulation of the manufacturing processes using robots. One of these software systems is Ro-botWorks that can be installed like an add-on application for a CAD software that runs with SolidWorks and it uses the graphics and kinematics engine to create a robot path. RobotWorks provides some robot models that can be used in a simulation.

Another software system Delmia offers the possibility to virtually define, plan, create, con-trol and monitor all production processes. Having a 3D visualization of the real world, Delmia technology allows engineers to interact with factory processes from the early design stages to direct implementation of the production commitment. This advantage, among others, helps en-gineers eliminate costly errors, design mistake and optimize the shop floor operations.

DELMIA (Digital Enterprise Lean Manufacturing Interactive Application) is a highly de-veloped software package. Due to its versatility and abundance of modules included in the package DELMIA can be easily used in a wide range of fields. The main applications of this software package are in the fields of: Automotive; Aerospace; Shipbuilding; and others.

Delmia Robotics Simulation is much more than a basic offline programming system. It al-lows companies to automate the repetitive work of robot programming by capturing and reusing best practices as well as leverage programming knowledge. Having a standard library contain-ing over 700 accurate robot models, Delmia Robot Simulation offers support for accurate trajec-tories and cycle time, direct manipulation, cell and robot calibration for accurate downloads. These characteristics define some of the advantages given by Delmia Robotic Simulation to any enterprise in order to obtain higher quality and foster greater innovation.

Unlike other robot simulation software systems Delmia Robotic Simulation offers the pos-sibility of importing and programming robots from different vendors such as KUKA, ABB, etc in order to simulate complex workcell.

The following table presents the main characteristics of software systems used in the simu-lation and programming of robots in the manufacturing processes:

Tab. 1

Features

Kuk

aSim

Pro

Rob

ot S

tudi

o

Rob

ogui

de

Han

dlin

gpro

Rob

o Lo

gix

Rob

ot W

orks

Del

mia

CAD Import X X X X X X Automated Path Calculation X X

X

X

X Path Optimization X X X X X Program Editor X X X X X X Automatically Analyses Reachability X X X Virtual Teach Pad X X X X X X Collision Detection X X X X Event Manager (ex. Gantt) X Online Programming X X X X X Using Macros X 3D Modeling X X X Controllers Configuration X X X X X Workcell Simulation X Equipment Simulation X Human Task Simulation X Library X X X X X Use Robots From Different Producers X

3. SIMULATION USING DELMIA V5

DELMIA allows manufacturers in any industry to virtually define, plan, create and monitor all production processes. It provides an array of dedicated applications for industries, combined with an environment for knowledge-sharing, process and resource management, as to capture and implement best practices for manufacturing. DELMIA technology allows manufacturers to interact with factory processes early in the design stage months before actual production com-mitment. Engineers, management, and stakeholders can have a 3D visualization of the real world with the ability to evaluate “what-if scenarios,” make changes, optimize shop floor opera-tions, and identify and eliminate costly errors and design mistakes.

DELMIA’s Robotics Simulation offers a scalable, flexible, easy to use solution for tooling definition, workcell layout, robot programming, and workcell simulation. DELMIA Robotics Simulation is ideally suited for work in the Automotive Body in White industry, specifically spot welding robots and material handling operations. It can be extended so it can be used in other domains.

DELMIA Robotics Simulation is much more than a basic offline programming system. It can capture the underlying philosophy and intent of the robot programmer allowing the company to acquire and reuse best practices, leverage programming knowledge, and automate the repetitive work of robot programming.

DELMIA Robotics Simulation has an easy-to-learn and easy-to-use graphical programming interface to teach and sequence robots and associated tooling. This interface allows programmers to visualize and edit many aspects of the robot program directly in the 3D

view. For example, users can change the robot pose by directly moving the robot joints by dragging them with the mouse, or they can modify the TCP position orientation directly by using a 6 degree of freedom "compass" widget in the 3D model. Robot target points, the sequence of points, I/O signals, and even tooling actions performed at the pointes can also be displayed and modified in the 3D window without having to use text or dialog boxes. This novel use of 3D-direct manipulation in a Windows standard user interface dramatically shortens the learning curve and improves the user's efficiency.

3.1 Steps in creating the simulation For simulating a process in Delmia V5 beside the robots there are several other components

which need to be modeled. This can be easily done with the help of a few modules grouped un-der the name of Mechanical Design module. These components are modeled separately and as-sembled in the Assembly Design module.

Fig. 2 – CNC lathe assembled in Assembly Design module (left) and the kinematic model (right)

In the next phase kinematic relations are assigned to the 3D models according to the oper-ating diagram. After the kinematic modeling is done the points in wich the gripper will be fixed on the robot (tool base) have to be specified for the end-effectors as well as the reference point (tool point) used for the manipulation of the objects.

Fig. 3 – Tool point (a) and the layout of a workcell (b )modeled in Plant Layout

The equipments will be arranged in the Plant Layout module on a vitrtual floor in order to provide a functional model of the project. After setting up the equpiment there will be intro-duced the robots from the Robotlib robot library of the program. The next step has to realize the

attaching of en-effectors to the robots and their positioning so that the work area remains in the robots work area.

After the layout is completed the next step will be the programming of the robots and the equipment in order to obtain the desired work cycle. In this step the programmer has three dif-ferent ways of programming the robots in order to ease his job: defining each point the robot will go through, using coordinates, and using the drag and drop method.

Fig. 4 Delmia library (left), robot work space (left with yelow)

In this stage the module called Human Task Definition is used in order to define and pro-

gram models representing the operators who interact with the equipments and the robots. After the simulation is complete, the next step will be analyzing and optimizing the process using a tool called Gant Chart where each activity can be synchronized so the linear diagram of the sys-tem will be optimized.

Fig. 5 Steps for simulation in Delmia (left), human integration (right)

3.2 Case study The manufacturing cell presented in this paper is used to manufacture parts for the automo-

tive industry. The cell is made up of nine computer numerical control machine tools, fourteen industrial robots, the equipment necessary for transporting the components from one machine tool to another and three forklifts that transport the deposited components outside the cell.

There are two main components that are manufactured in the cell. One of them is made of sheet metal and the other is made of raw material which passes through lathe machines, milling centers and then it is heat treated.

The workcell is divided into three zones: sheet metal manufacturing, heat treatment and mechanical processing. In the right zone the focus is on operations regarding sheet metal opera-tions. On a euro pallet the sheet metal parts are stored. A suspended robot takes one sheet metal part at a time and places it on the laser cutting machine. After cutting the part is picked by another robot and is placed on a hydraulic press which bends the sheet metal. From there the component is taken by a robot to a new bending machine. The robot then takes the component to another laser cutting machine and after that the component is put on a new euro pallet from where the forklift will transport it outside the work cell.

The center zone consists of two ovens used for heat treating components. The components are stored on a conveyor belt which takes them through the ovens. The ovens heat the compo-nents up to a programmed temperature in order to improve the component’s mechanical charac-teristics. From the ovens the components arrive near an index table on which the robots will as-semble the components into sub assemblies. These will be stored and then transported using the forklifts.

The right zone consists mainly of machine tools that manufacture components using the splintering process. A robot inserts the raw material into a lathe machine. After the process is fi-nished the robot takes the component and depending on its diameter inserts it into one of the two milling centers. The closest one to the lathe machine is used for components with a large diameter and small length and the other one is used for components with smaller diameters and higher length. After this process is ended the robots will take the components to the center zone for heat treating.

Fig.6 – Workcell described in case study

Besides the workcell described above within the case study additional workcells have been de-signed in order to illustrate other felxible cells presented, which are presented in Fig. 3, Fig.4, Fig.5 and Fig. 7.

3. SOFTWARE EVALUATION

The following criteria have been considered to objectivaly evaluate the manufacturing process simulation possibilities offered by Delmia V5. For each criteria a mark from 1 to 10 has been assigned. 3D Modeling and visualization. The 3-D solid representation of the robot cell layout, tooling, and robot reach has become an indispensable tool for communicating design issues among the design team and customers. Simultaneous engineering of product, tooling, and robot process is more practical because of this ability for team members see the conditions affecting design. Delmia provides 18 modules grouped under the label of Mechanical Design which can be used for solid parts modeling and 8 modules grouped under the label of Shape for surface modeling Mark: 10 Collision detection. The ability of the simulation software to calculate where collisions will oc-cur in the simulated process is essential for making the process suitable for use in the real world. It also enables the engineer to detect design problems early and test more alternative solutions. Mark: 8 Reachability checks. Checking reach in a virtual environment is far quicker than working with a real robot. Early design reach checks can be performed without regard to the path the robot uses to get to key locations like pick or drop points. The operator simply “jumps” the robot to the location to be checked. The virtual environment where there is no risk of damaging equip-ment also enables the operator to check reach conditions with small clearances to collisions. Mark: 9.50 Path creation. Robot paths can be created more quickly in the simulation environment since the operator has no worry about safety issues like damaging equipment or moving the robot fast enough to hurt someone. Simulation software often contains tools to generate portions of paths automatically. For example, a sealant application path could be generated based on CAD data for the part the sealant is applied to. Mark: 10 Process helpers & guidance. The software contain features that simplify the programming of complex processes. Specialized software tools automate or simplify the most complex tasks for creating designs or paths for an application. For example, a painting process helper may set paint flow parameters or adjust path-to-path spacing by asking the operator simple questions about the desired result. Mark: 9 Accurate motion & cycle time estimation. Early simulation systems attempted to create gen-eral robot control algorithms within the simulation software but actual robot control designs of-ten had specialized technology that the general algorithms could not handle. The simulation al-gorithms could never predict cycle time & motion very accurately. In response, the simulation software vendors and robot manufacturers combined efforts to create the Realistic Robot Simu-lation (RRS) specification (see http://www.realistic-robot-simulation.org). More recently, a next generation specification was created, called RRS2, which is much more comprehensive. RRS2 adds to the motion predictions to include input/output and full language support for the robot. RRS & RRS2 typically create motion time and path predictions that are 97% accurate or better. Mark: 9 Representation of other equipment. Robots never work alone. They must utilize and interface with other pieces of equipment. Even simple applications require an end-effector of some sort. Other tools or machines that are part of the automation process must also be simulated. Representing the motion of these other machines can be important for collision detection and cycle time prediction. Simulating the communication interface to these other pieces of equip-ment is also necessary for creating a properly working process. Mark: 10

Offline Programming. This is the process of transferring the simulated paths to real world ro-bot programs. Proving a process in simulation has huge value alone, but the ability to take a ro-bot program from simulation to the real world increases the value of simulation even more. Mark: 8 Customization. Robots are very flexible tools. Operators often need to solve complex or repeti-tive problems. The ability to integrate custom software into the simulation environment to address these problems is a commonly provided feature. Mark: 6 Human integration. Integrating human operators into the simulation is a seldom seen feature in simulation software, but it offers a complete view of the interactions and functions of a flexible manufacturing system (cell). Mark: 10

Fig.7 – Example of Workcell developed in Delmia

Library. Simulation software systems usually have robot libraries with models from only one robot manufacturer. An increase in the number of robots means the user has more solutions for his simulation. There are a few simulation software which have robot libraries from various manufacturers.

4. CONCLUSIONS

Delmia V5 is an excellent simulation software package for robotized manufacturing sys-tems It is a “key delivered” simulation solution that allows the geometrical modeling of a system’s components (Mechanical Design – Part Design), to assembly them using geometrical constraints (Mechanical Design – Assembly Design) and allows the simulation of the entire process.

The creation of a robot’s working sequence can be done easily by defining tags which the robot will reach if they are in its workspace. The tags can be reached in any order the user establishes. The software also allows the identification and removal of collisions between the robot and any component that reaches its workspace. The software also allows the user to gen-

erate the robot’s workspace in order to avoid collisions with other robots if they are pro-grammed to work at the same task

It also allows simulating at the same time robots, operators and equipments. The soft-ware allows the simulation of a considerable number of robots and operators.

Delmia also has functions that allow the user to obtain the robot’s program. After the simulation is made and all the movements and points are defined the program can generate the program that can be uploaded in a real robot’s controller. The results form the simulation can be used to optimize the processes and to train the people who work with that process. Other Advantages of DELMIA

• Open architecture for customization/extension • Resource kinematics and logic modeling • Editing in context for tooling resources • Automatic interference zone computation • Automatic weld feasibility analysis at the workcell level • Drag and drop, direct manipulation and table based task editing • Standard library containing over 700 accurate robot models • Realistic Robot Simulation (optional RRS I and RRS II) support for accurate

trajectories and cycle times • Cell and robot calibration for accurate downloads • Comprehensive Multi-CAD Interfaces.

5. REFERENCES [1] Gene Bellinger – “Modeling & Simulation: An Introduction” (http://www.systems-

thinking.org/modsim/modsim.htm) [2] http://www.appliedgroup.com/pdfs/delmia_factory_simulation.pdf [3] Andrea Emilio Rizzoli – “A Collection of Modelling and Simulation Resources on the Internet” (http://www.idsia.ch/~andrea/simtools.html) [4] Sagar Shinde – “Introduction to Modeling and Simulation Systems”

(http://www.uh.edu/~lcr3600/simulation/historical.html) [5] Peter Ball – “Introduction to Discrete Event Simulation”

(http://www.dmem.strath.ac.uk/~pball/simulation/simulate.html) [6] Kenneth J. Goldman – “Distributed Discrete Event Simulation”

(http://www.cs.wustl.edu/~kjg/cs333/devs.html) [7] Prof. Gabriel A. Wainer – “Cell Based Discreet – Event Simulation” [8] Prof. Hossein Arsham – “System Simulation: The Shortest Route to Applications”

(http://home.ubalt.edu/ntsbarsh/simulation/sim.htm). [9] http://www.3ds.com/