Design and simulation of modular robot work cells.

Hauer, Stefan ; Malisa, Viktorio ; Hieger, Christof 等

1. INTRODUCTION

In business world, smaller and intermediate manufacturer's deals with problem and significant pressure to maintain business and to win market share. This problem of the open Market is recognized in form of high development and research costs. In order to overcome these misconceptions and to meet market demands, a suitable tool(s) and standard solutions are necessary. This paper gives a solution for design based on simulation for large spectrum for Arc Welding.

The concept of flexible manufacturing for rotational parts (Katalinic, 1990) was briefly described. The development of computer hardware and software enables the simulation of this concept (Katalinic et al., 2000 and Stopper & Stuja 2004). The concept of virtual factory including a designing of robot cell was by Kuehn (Kuehn, 2006) presented.

Actually this paper includes the analysis of existing robot cells and the development of possible new modules. Finally the designing process is shown in a practical example by using the developed modules with the simulation environment Delmia Version 5, and the main conclusions of this project are presented.

2. INTRODUCTION OF SIMULATION SUITE DELMIA

Delmia is simulation software, which offers different possibilities to simulate processes. It contains different capable production planning tools to develop and optimize production processes. Delmia offers different solutions for industrial fields like automotive industry, aviation industry, ship building industry, automation industry, etc.

2.1 Delmia Workbench's

Resource planning workbench provides a full 3D graphical environment for building robot workcell. Delmia offers a special software module called "Robot Management--Device Task Definition" which facilitates different possibilities e.g. design robot cells, create robot task, check a collision detection etc. It is necessary to import a robot model from the library, create the environment of the robot cell and import or create parts e.g. tools which are necessary for the simulation.

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The next step is to create a task for the robot and check if every tag is reachable.

A Robotics Workbench provides an environment for teaching and simulating robotic tasks as well to measure workcell cycle. Finally it is necessary to start the simulation and after that, it is required to analyse the simulation in order to be able to optimize the robot movements etc. The design process of a robot cell with Delmia is shown in Fig. 1.

By validating of robotic movements companies will significantly cut costs by eliminating production interruptions and rework costs.

Ergonomics delivers the ability to build 3D human models to simulate different human tasks such as vision, reachability and biomechanics conform to ergonomic standards.

Assembly Planning supports an assembly planner during design stage. With simulation tools will be able to support a simulation engineer during validation of the manufacturing and assemblies' process.

3. FUNDAMENTALS OF MODULAR ROBOTICS CELL

There are different industrial modules for several different industrial fields. In order to get an overview it is possible to define three different main groups of industrial modules:

* Production, like Robotic deburring cell, Welding, Spot welding, etc.

* Manipulating, like Palletizing robotic cell, machine load and unload, etc.

* Quality, like Robotic cell for quality control

3.1 Existing norms and design rules for industrial engineering

During the design process of a robot cell it is required to consider of some important norms and relevant rules regarding the safety of a work cell with special focus on the interaction between robot and human.

The norm ISO 10218 is about "Robots for industrial environments -Safety requirements" and it describes in detail all relevant rules and specification for industrial robots. Lists of examples are shown below for the most important rules, which should be considered during the design process of modular robotics solutions:

Safeguarding are safety measures consisting of the use of safeguards to protect persons from hazards which cannot reasonably be removed or sufficiently eliminated by design. A safeguard prevents hazardous situations by stopping the robot in a controlled manner when a certain safeguarding mechanism such as a light curtain is activated. A safeguarding mechanism consists of a number of guards connected in series like safety fences, emergency stop buttons etc. (The ABB Group 2009b, p. 23).

Reduction of workspace of the main axis: for some applications it is required to reduce the movements of the robot main axis in order to get a safety area. This reduces the risk of damages of the robot by possible collision between the robot and external safety equipment

4. DESIGNING A SUB MODULES

A roughly sub module analysis of a typical palletizing and welding application precipitates to following results:

* Sub module safety which consists of a safety fence, photoelectric barriers, emergency stop buttons

* Sub module incoming and outgoing station of goods. Every cell, regardless of if it is a production cell or a quality control cell, has an incoming and outgoing station, which is essential for the material-flow.

* Sub module controlling and signalling. Every robot or robot group needs at least one controlling station. In addition, robot and manufacturing cells have some signal elements in order to show workers or operators the current state of the cell. Controls offer Smart Device Builder capabilities for the engineer to create the mechanical, kinematical and logical behaviour of devices.

* Sub module robot. The type of the robots can vary depending on the application e.g. 6-axis-joint robots, gantry robots, scara robots etc.

* Sub module end effectors. Depending on the tasks, the end effectors can vary from application to application. An example is shown in Fig. 2.

These sub modules are basically the main sub modules of an industrial robot cell and they are required to design a complete cell. Of course it is possible to have additionally sub modules e.g. end effectors change station, defined place for interaction between robot and operator, additional manufacturing machines but the number of sub module is depending on the application and the robot tasks.

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5. CONCLUSION

The main objective of this paper is introducing of standardization of robot cell design based on simulation. Particularly was given a solution for arc welding process. In order to reduce the cost and to increase the efficiency of the arc welding sophisticated software tools Delmia is used. The simulation has represented the easiest methodology for researching all critical aspects of the manufacturing cell. Using this tool the manufacturers are able to bridge the design of tasks and their execution, virtual world and real world. The key to the success of the simulation technology is its ability to seamlessly work with a complex model. This concept was practically implemented on a case study, which gave valuable results on reducing e design costs. As was described, different Modules and Sub Modules were built. That means, if is not possible to use a complete Module for a manufacturing application as study case, then is possible to use the sub Modules to build very quickly a user defined unique manufacturing application. A drawback of this solution is that, that is applicable just on locally marketplace, where the customers deals with a locally component suppliers.

6. REFERENCES

Katalinic, B. (1990). Industrieroboter und flexible Fertigungssysteme fur Drehteile. VDI-Verl., ISBN 3-18401027-9, Dusseldorf

Katalinic, B.; Stuja, K. & Pllana, S. (2000). Arena: Enterprise Wide Modeling and Simulation. Proceedings of the 11th International DAAAM Symposium, Katalinic, B. (Ed), pp 217-218, ISBN 3-901509-13-5, Opatija, Croatia, October 2000, DAAAM International Vienna, Vienna

Stopper, M. & Stuja, K. (2004). "Optimizing cycle time of flexible manufacturing cell using simulation software", Proceedings of the 4th International DAAAM Symposium, pp. 159-160, ISBN 9985-894-59-6, J. Papstel/B. Katalinic (Ed.), April 2004, Tallin, Estonia

Kuhn, W.K., 2006. Digitale Fabrik--Fabriksimlation fur Produktionsplaner. Munchen: Carl Hanser Verlag

*** (2009) THE ABB GROUP, ABB., 2009b. Operating Manuel IRC5 FlexPendant [online]. ABB Group. Available from:http://library.abb.com/global/scot/scot241.nsf/veritydi splay/50507395393aa913c12571ea00317790/$File/IRC5Fl expai nter.pdfAccesed on:2009-06-10

*** (2009) DELMIA PLM Express, http://www.3ds.com Accesed on:2009-08-13

*** (2009) DELFOI, http://www.delfoi.com/web/solutions/ production/en_GB/robotics/Accesed on:2009-08-13