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AN EFFICIENT METHODOLOGICAL APPROACH IN THE DIDATIC OF AUTOMATION APPLIED TO INTEGRATED MANUFACTURING
AN EFFICIENT METHODOLOGICAL APPROACH IN THE DIDATIC OF AUTOMATION APPLIED TO INTEGRATED MANUFACTURING Galdenoro Botura Junior
Marilza A. de Lemos
Marcio A. Marques
Control and Automation Engineering Department Universidade Estadual Paulista – UNESP – Campus Sorocaba Av. Três de Março, 511- 18087-180 – Sorocaba – SP – Brasil {galdenoro, marilza, marciomq}@sorocaba.unesp.br
Abstract: This work presents challenges and solutions for the teaching and learning of automation applied to integrated manufacturing by means of a methodological approach based on techniques, tools and industrial equipment directly applicable in the industry. The approach was implemented in a control and automation engineering course divided into expositive and laboratory classes. Since the success of the approach is mainly from the practical activities, the article focus more on activities developed in laboratory than theorical classes. Copyright © 2007 IFAC Keywords: factory automation, education, robotic, flexible manufacturing system, programmable logic controllers.
1. INTRODUCTION The processes meant to automation are becoming more and more present in various fields of either industrial or services activities (Rangel, 2006). In industries, obtaining skilled hand labor has been one of their main obstacles, mainly the one carrying out procedures which aim at substituting automated operations for manual ones. As qualified people are demanded to work within such processes, the decision of a system implantation, migration and modernization is, many times, postponed. Damage and loss of competitiveness constitutes a consequence of this. On the other hand, besides experience and computation culture, knowledge of complex electronic systems and sophisticated machines composing an automated system is required what makes such professional rare and thus expensive. Qualifying professional asks for an enormous initial investment in laboratories which need sophisticated mechatronic systems and experienced teachers (Pereira and Lima, 1998). A partnership between the university and the industry is a means to minimize qualification costs in this area (Tilbury. and Khargonekar, 2000). The university has the laboratories required, since it gives courses in
the area of Control and Automation Engineering. On the other hand, in the industry, there are engineers and technicians with knowledge of industrial processes who are apt to receive proper qualification for the implementation, maintenance or operation of automated systems (Tsichritzis, 1999). A course proposing a new approach, intended to deepen the initial qualification in the area of automation, for technicians and engineers holding basic knowledge in this area, has been implemented and taught to students of the seventh term of the Control and Automation Engineering Course of the São Paulo State University (UNESP), Sorocaba campus. Such a course has served as a laboratory to study the possibility of use of this approach to offer human resource qualification and training to the industrial sector in the city of Sorocaba and region which consists of 2,000 industries. The rest of the paper is divided into the following: section 2 presents the methodology proposal, section 3 presents a summary of the work developed in the Milling and Robotics Station, section 4 presents a summary of the work developed at the Robotics Assembly Station and section 5 presents a summary of the work developed at the Storage Station. Finally, the section 6 draws conclusions from this work.
2. METHODOLOGICAL PROPOSAL The course consisted of 75 class/hours, divided into 45 hour expositive classes and 30 hour laboratory classes. Study hours as well as the time dedicated to the development of works and projects are not included in this period. Nevertheless, it has also been considered that, future industry participants engaged with their professional activities will have a limited number of hours available for extra class studies. It has also been considered that participants should have previous knowledge of microprocessors, programmable logical controllers; measure basic instruments and basic concepts of automation common to all engineers or technicians working in this area. The topics tackled in the exposition classes comprised: • Introduction to Mechatronics; • Automation Discreet Processes; • Petri Nets: conception, projects and simulation; • Software for automated system projects; • Introduction to Industrial Networks; • Introduction to Robotics; • Continuous Processes in Automation. As part of the course activities, the students had a total of 30 class/hours to dedicate to the implementation of a discreet automated system. Such hours were spent in the automation laboratory which has a Festo FMS-50 Flexible Manufacturing System integrated to a Siemens PLCs S7-300. The system consists of six cells, interconnected by a conveyor belt (figure 1), enumerated as follows: • Test and Distribution Station • Manipulation and Process Station • Vision and Quality Control Station • Robot-Assembly Station • Storage Station • Sorting Station The laboratory also has a CNC EMCO Milling 105, with a six axle articulated robot that can be integrated to the FMS (Figure 2).
laboratory and in notebooks used to send programs to robots and programmable logical controllers.
Fig. 2. Milling and Robot. The tools used in the system modeling, programming, simulation and integration assignments are as follows: (i) HPSIM (Anschuetz 2001) for edition and simulation of Petri nets, (ii) Simatic Step 7 for PLCs programming, (iii) Cosimir PLC and Cosimir Educational for simulations of stations, and (iv) Cosimir Industrial for robot programming and simulation. The approach adopted is based on the idea that using environments for simulation and real environments contributes a great deal to the qualification of professionals who successfully achieve high performance in industries (Upton e Kim, 1996). The participants were split into work groups and each group was responsible for assignments related to one part of the FMS system, according to table 1. Table 1 Distribution of the FMS Group 1
FMS Milling and Robotics Station
2
Distribution and Test
3
Manipulation and Processing
4
Robotics Assembly
5
Storage
6
Sorting
7
AS-i conveyor belt
Fig. 1. Flexible Manufacturing System. Besides such equipment, the students could count on software tools to program PLCs and robots and 3D simulators to simulate the stations operations. The software available consists of a set of didatic and commercial tools installed both in a computational
Software HPSIM COSIMIR INDUSTRIAL HPSIM COSIMIR PLC COSIMIR EDUCATIONAL SIMATIC STEP 7 HIGRAPH HPSIM COSIMIR PLC COSIMIR EDUCATIONAL SIMATIC STEP 7 HIGRAPH HPSIM COSIMIR INDUSTRIAL HPSIM SIMATIC STEP 7 SCL HPSIM COSIMIR PLC COSIMIR EDUCATIONAL SIMATIC STEP 7 HIGRAPH HPSIM SIMATIC STEP 7 HIGRAPH
The following sections describe a summary of the work developed by three work groups.
3. MILLING AND ROBOT CELL The Robot and Milling Cell are part of a class of systems aiming at the increase of speed in production, dimensional accuracy and the use of robots for repetitive or dangerous works. Such a manufacturing cell consists of a robot Mitsubishi RV-1A and a machining center EMCO MILL 105. The robot is free to move in six axles known as J1 to J6, besides the pneumatic gripper drive. Programming can be directly carried out in the robot by the teach pendant or in the Cosimir Industrial environment. Such an environment provides facilities for programming besides simulating desired movements to the robot. The robot is connected with the control unit that can be linked to a computer for direct operation. The machining center consists of a CNC machine controlled by a PC through the WinNC32 software. It has a milling or reduction tool magazine for up to ten tools, an automatic safety door and an interface direct to the robot. The raw material to be machined is manually placed in a small conveyor belt. In the conveyor belt there is a separator of pieces and two sensors allowing the robot to take a piece and transport it to the machining center. After machining, the robot removes the piece from the machining center and places it in the storage module of the next cell of the Flexible Manufacturing System. In such a cell, called Test and Distribution, there is a sensor indicating if the stock is full. In this case, the robot waits until a new piece can be supplied to be machined by the Milling. 3.1 Programming the CNC Cell The students implemented the control program between milling and robot based on the interface inputs and outputs in between. Table 2 illustrates part of this communication interface. Table 2 Cell Inputs and Outputs Input
Comment
Place
1
Operation Panel
6
Start Button Indicates the existence of a piece in the separator
7
Indicates if the magazine is full
9
Indicates if the door is open
11
Indicates if the vise is open
12
Indicates if the vise is closed
Output
Comment
0
Turns on the Start light
4
Turns on the conveyor belt
5
Open separator
8
Turn the program
12
Open the door
15
Close the vise
Robot Station
160 HOPEN 1 'open gripper 170 DLY 0.5 'time to open gripper 180 MVS P0 'position to take a piece in the conveyor belt 190 DLY 0.5 'time to close gripper 200 M_OUT (13)=0 'reset bit close door 210 M_OUT (12)=1 'open the milling door 220 WAIT M_IN (9)=1 'wait to open milling door 230 M_OUT (15)=0 'reset bit close vise 240 M_OUT (14)=1 'open vise 250 WAIT M_IN (11)=1 'wait to open vise 260 HCLOSE 1 'close gripper 270 DLY 0.5 'time the robot leaves the conveyor belt 280 MVS P1 'start way to the vise 350 M_OUT (15)=1 'close vise
4. ROBOTIC ASSEMBLING CELL The assembling cell consists of a Mitsubishi RV-2AJ Robot and two pneumatic cylinders (actuators); three optical sensors and a torque sensor; places for pieces under processing, pallet for pistons and reservoir for discarded pieces. Within the scope of the activities defined in the project, this cell is responsible for the assembling of a pneumatic valve. The integration with the FMS is done through the conveyor belt which transports the base of the valve in a pallet and sends a signal so that the assembling can start. The base of the valve arrives through the conveyor belt, already made and tested by the previous cells. The remaining components (piston, spring and cover) are in the own robot station. After assemblage, the valve is given back to the pallet in the conveyor belt. The robotic cell sends a signal to the conveyor belt indicating the product is ready to be sent to the next station. Figure 3 shows the main parts of the Robotic Assembling cell. 4.1 Description of the Sequence of the Robot Operations The robot identifies the right position where it has got to put the piece in the assembling place. In this place there is a pin that provides the reaction torque when the cover is being assembled. After, it places the piston and the spring inside the piece in this order, respectively. At last, the robot assembles the cover which has two fixation rims to guarantee the perfect assembling.
Machine CNC
Place Operation Panel Robot Station
Machine CNC
Part of the program developed by group 1 can be seen as follow:
Fig. 3. General view of the Assembling cell.
The process starts form the signal sent by the conveyor belt to assemble the product. The robot takes the valve base (the piece), transports it from the conveyor belt to a shallow cradle (Figure 4) and checks the color of the piece. If it is black, the valve is assembled with a silver piston, if it is silver or pink, the valve is assembled with a black piston. After that, the robot takes the piece again and places it on a sensor. The robot, with a revolving movement of the gripper, finds the hole in the piece and fits it into a deeper cradle (Figure 4).
Fig. 5. Robot Positions
Fig. 4. Places for pieces under processing. The assembly starts from this point on: the robot goes to the piston deposit, takes one of them, returns and puts it in the base of the valve. In the case of the spring and the cover, the robot controller sends a signal so that the pneumatic actuators make such components available. The robot takes the spring and places it in the base of the valve. After that, it takes the cover and places it in a kind of thimble (Figure 4). With the help of such thimble, the robot takes the cover, places it in a sensor for detection of the fitting rim. Finally, it returns to the valve and taps the cover. As the assembly finishes, the robot transports the product to the conveyor belt. 4.2 Programming the Assembling Cell The programming of the assembling cell was implemented in the Cosimir Industrial environment. The first step was the configuration of the origin of the robot so that it can be seen virtually in the Cosimir. This is possible through a kind of procedure in which all the axles of the handler are placed in their negative extremes. Such data is informed to the robot controller as being the origin points of the robot RV-2AJ. A serial connection allows communication with the development environment in the PC and the robot. This way it is possible to obtain and send parameters, as well as discharge and interrupt programs allocated in the robot. Figure 5 shows part of the positions defined for robot actions which are used in the program. Figure 6 illustrates the edition window of programs with part of the developed application which is responsible for taking the assembled valve and giving it back to the pallet in the conveyor belt.
Fig. 6. Program that controls the Assembling Cell. 5. STORAGE CELL ASRS20 ASRS20 is a recovering and storage system of components manufactured (products) in the Flexible Manufacturing System. The ASRS20 operation can be manually or automatically carried out. In the manual way, it is possible to control the movements of the actuators and of the Cartesian axles (the gripper, for example) from a group of keys. In the automatic way, the control is done through a PLC. The station is composed of: (i) a PLC, (ii) five shelves with four spaces in each one to storage manufactured products, (iii) a mechanic arm which has a pneumatic gripper, two motorized Cartesian axles and ten sensors. 5.1 Description of the storage operation The transport system (conveyor belt and pallet) transports the ready product until the Storage cell. The pallet stops in front of the station and the mechanic arm places itself on the pallet towards the product. The pneumatic gripper opens, moves forward to the product and closes holding it and retreats. The mechanic arm transports the product to the first free space. The pneumatic gripper goes forward to the desired position and opens.
The pneumatic gripper retreats and the mechanic arm stands back, not moving until another product arrives. The recovering operation of the product is analogically done. 5.2 Programming ASRS20 Cell SCL (Structured Control Language), the programming language used in this application, is a higher-level programming language oriented on PASCAL. It is based on a standard for programming PLCs. It was chosen due to the easiness to implement the procedural programming and mainly, to the need of use of data structures such as arrays. The programming was based on the mapping of the PLC inputs and outputs with the other components of the cell and of the conveyor belt. Table 3 gives an example of such mapping. Table 3 Input and Output of the ASRS20 Cell Input and Output of the ASRS20 Cell Address I126.7 Q124.0
Symbol Gri_open Xleft
ID B17 M1
Comment Open gripper Move axle X to the left
Table 4 presents part of the program developed in Structured Control Language responsible for the removing procedure of the products from the stock to be sent to the Sorting Station. Table 4 Product Recovering Procedure // handler opens gripper 200 :
OpenGrp:=true; IF (Grpopened=true) THEN Task:=Task+1; END_IF;
// handler finds piece position 201:
MANAGEMENT. MANAGEMENT_DATA (Instruction:=3); Task:=Task+1;
// handler goes forward to the piece position 202 : IF (PosXatual < PosXarmaz) THEN MvXleft:=true; IF PosXatual<(PosXarmaz-1000) THEN Xfast:=true; ELSE Xfast:=false; END_IF; ELSE Xfast:=false; MvXleft:=false; END_IF;
CONCLUSION One of the biggest problems to reach reduction of costs, quality and productivity through automation of
an industrial plant lies on the acquisition of qualified staff to carry out the automation itself and its future operation and maintenance. This work presents challenges and solutions for the teaching and learning of automation applied to integrated manufacturing by means of a methodology approach under techniques, tools and industrial equipment directly applicable in the industry. The set of tools, the diversity of components manipulated by the students and the interaction between them allowed a fast and homogeneous evolution in the knowledge of the students. The existence of an only and challenging goal for all (the functioning of the FMS) from the initially individual effort and later of the necessary interaction between groups of students, revealed a very efficient approach to learning about integrated manufacturing. The teaching methodology made the students aware that the system, primarily consisting of isolated and static parts, was integrated by them and became a complex manufacturing system. Moreover, the students proved the functioning of the system in accordance with the idealized one together with all the overcome obstacles. In the end of the course, the students showed to be confident of the experience acquired and motivated to continue developing in the area. ACKNOWLEDGEMENTS This publication is sponsored by the FESTO German, Mexico and Brazil. REFERENCES Anschuetz, H (2001). HPSim Version: 1.1. Petri Nets World. Obtained: http://www.informatik.unihamburg.de/TGI/PetriNets/ Moraes, C. C. and Castrucci, P.L. (2001) Engenharia de Automação Industrial. Editora LTC, pag. 295. FESTO (2002). FMS50 Manual Brasil. Festo Didatic. pag. 201. Denkendorf, German. Pereira, L. F. A. and Lima, J. C. M. (1998) Reestruturing of the teaching of automation and control through the implementation of laboratories. In: Proceedings of ICEE’98. Rio de Janeiro, Brazil. Rangel, F.; Lemos, M. A.; Botura, Galdenoro (2006). “Implementation of a Didatic Plant in Automated Industrial Processes”. Global Congress on Manufacturing and Management, GCMM 2006, November19-22, Santos, Brazil. Tilbury, D. and Khargonekar, P. (2000). Challenges and Opportunities in Logic Control for Manufacturing Systems. Report of the NSF Workshop held at the University of Michigan, An Arbor, MI, June 26-27. Tsichritzis, D. (1999) Reengineering the university. Communications of ACM, 1999. volume 42, no 6, pags. 93–100. Upton, D. M. and Kim, B. (1996). An Empirical Study of Alternative Methods of Learning and Process Improvement in Manufacturing. Report 96-006 Re. 12/96, Harvard Business School.
Marilza A. de Lemos
Marcio A. Marques
Control and Automation Engineering Department Universidade Estadual Paulista – UNESP – Campus Sorocaba Av. Três de Março, 511- 18087-180 – Sorocaba – SP – Brasil {galdenoro, marilza, marciomq}@sorocaba.unesp.br
Abstract: This work presents challenges and solutions for the teaching and learning of automation applied to integrated manufacturing by means of a methodological approach based on techniques, tools and industrial equipment directly applicable in the industry. The approach was implemented in a control and automation engineering course divided into expositive and laboratory classes. Since the success of the approach is mainly from the practical activities, the article focus more on activities developed in laboratory than theorical classes. Copyright © 2007 IFAC Keywords: factory automation, education, robotic, flexible manufacturing system, programmable logic controllers.
1. INTRODUCTION The processes meant to automation are becoming more and more present in various fields of either industrial or services activities (Rangel, 2006). In industries, obtaining skilled hand labor has been one of their main obstacles, mainly the one carrying out procedures which aim at substituting automated operations for manual ones. As qualified people are demanded to work within such processes, the decision of a system implantation, migration and modernization is, many times, postponed. Damage and loss of competitiveness constitutes a consequence of this. On the other hand, besides experience and computation culture, knowledge of complex electronic systems and sophisticated machines composing an automated system is required what makes such professional rare and thus expensive. Qualifying professional asks for an enormous initial investment in laboratories which need sophisticated mechatronic systems and experienced teachers (Pereira and Lima, 1998). A partnership between the university and the industry is a means to minimize qualification costs in this area (Tilbury. and Khargonekar, 2000). The university has the laboratories required, since it gives courses in
the area of Control and Automation Engineering. On the other hand, in the industry, there are engineers and technicians with knowledge of industrial processes who are apt to receive proper qualification for the implementation, maintenance or operation of automated systems (Tsichritzis, 1999). A course proposing a new approach, intended to deepen the initial qualification in the area of automation, for technicians and engineers holding basic knowledge in this area, has been implemented and taught to students of the seventh term of the Control and Automation Engineering Course of the São Paulo State University (UNESP), Sorocaba campus. Such a course has served as a laboratory to study the possibility of use of this approach to offer human resource qualification and training to the industrial sector in the city of Sorocaba and region which consists of 2,000 industries. The rest of the paper is divided into the following: section 2 presents the methodology proposal, section 3 presents a summary of the work developed in the Milling and Robotics Station, section 4 presents a summary of the work developed at the Robotics Assembly Station and section 5 presents a summary of the work developed at the Storage Station. Finally, the section 6 draws conclusions from this work.
2. METHODOLOGICAL PROPOSAL The course consisted of 75 class/hours, divided into 45 hour expositive classes and 30 hour laboratory classes. Study hours as well as the time dedicated to the development of works and projects are not included in this period. Nevertheless, it has also been considered that, future industry participants engaged with their professional activities will have a limited number of hours available for extra class studies. It has also been considered that participants should have previous knowledge of microprocessors, programmable logical controllers; measure basic instruments and basic concepts of automation common to all engineers or technicians working in this area. The topics tackled in the exposition classes comprised: • Introduction to Mechatronics; • Automation Discreet Processes; • Petri Nets: conception, projects and simulation; • Software for automated system projects; • Introduction to Industrial Networks; • Introduction to Robotics; • Continuous Processes in Automation. As part of the course activities, the students had a total of 30 class/hours to dedicate to the implementation of a discreet automated system. Such hours were spent in the automation laboratory which has a Festo FMS-50 Flexible Manufacturing System integrated to a Siemens PLCs S7-300. The system consists of six cells, interconnected by a conveyor belt (figure 1), enumerated as follows: • Test and Distribution Station • Manipulation and Process Station • Vision and Quality Control Station • Robot-Assembly Station • Storage Station • Sorting Station The laboratory also has a CNC EMCO Milling 105, with a six axle articulated robot that can be integrated to the FMS (Figure 2).
laboratory and in notebooks used to send programs to robots and programmable logical controllers.
Fig. 2. Milling and Robot. The tools used in the system modeling, programming, simulation and integration assignments are as follows: (i) HPSIM (Anschuetz 2001) for edition and simulation of Petri nets, (ii) Simatic Step 7 for PLCs programming, (iii) Cosimir PLC and Cosimir Educational for simulations of stations, and (iv) Cosimir Industrial for robot programming and simulation. The approach adopted is based on the idea that using environments for simulation and real environments contributes a great deal to the qualification of professionals who successfully achieve high performance in industries (Upton e Kim, 1996). The participants were split into work groups and each group was responsible for assignments related to one part of the FMS system, according to table 1. Table 1 Distribution of the FMS Group 1
FMS Milling and Robotics Station
2
Distribution and Test
3
Manipulation and Processing
4
Robotics Assembly
5
Storage
6
Sorting
7
AS-i conveyor belt
Fig. 1. Flexible Manufacturing System. Besides such equipment, the students could count on software tools to program PLCs and robots and 3D simulators to simulate the stations operations. The software available consists of a set of didatic and commercial tools installed both in a computational
Software HPSIM COSIMIR INDUSTRIAL HPSIM COSIMIR PLC COSIMIR EDUCATIONAL SIMATIC STEP 7 HIGRAPH HPSIM COSIMIR PLC COSIMIR EDUCATIONAL SIMATIC STEP 7 HIGRAPH HPSIM COSIMIR INDUSTRIAL HPSIM SIMATIC STEP 7 SCL HPSIM COSIMIR PLC COSIMIR EDUCATIONAL SIMATIC STEP 7 HIGRAPH HPSIM SIMATIC STEP 7 HIGRAPH
The following sections describe a summary of the work developed by three work groups.
3. MILLING AND ROBOT CELL The Robot and Milling Cell are part of a class of systems aiming at the increase of speed in production, dimensional accuracy and the use of robots for repetitive or dangerous works. Such a manufacturing cell consists of a robot Mitsubishi RV-1A and a machining center EMCO MILL 105. The robot is free to move in six axles known as J1 to J6, besides the pneumatic gripper drive. Programming can be directly carried out in the robot by the teach pendant or in the Cosimir Industrial environment. Such an environment provides facilities for programming besides simulating desired movements to the robot. The robot is connected with the control unit that can be linked to a computer for direct operation. The machining center consists of a CNC machine controlled by a PC through the WinNC32 software. It has a milling or reduction tool magazine for up to ten tools, an automatic safety door and an interface direct to the robot. The raw material to be machined is manually placed in a small conveyor belt. In the conveyor belt there is a separator of pieces and two sensors allowing the robot to take a piece and transport it to the machining center. After machining, the robot removes the piece from the machining center and places it in the storage module of the next cell of the Flexible Manufacturing System. In such a cell, called Test and Distribution, there is a sensor indicating if the stock is full. In this case, the robot waits until a new piece can be supplied to be machined by the Milling. 3.1 Programming the CNC Cell The students implemented the control program between milling and robot based on the interface inputs and outputs in between. Table 2 illustrates part of this communication interface. Table 2 Cell Inputs and Outputs Input
Comment
Place
1
Operation Panel
6
Start Button Indicates the existence of a piece in the separator
7
Indicates if the magazine is full
9
Indicates if the door is open
11
Indicates if the vise is open
12
Indicates if the vise is closed
Output
Comment
0
Turns on the Start light
4
Turns on the conveyor belt
5
Open separator
8
Turn the program
12
Open the door
15
Close the vise
Robot Station
160 HOPEN 1 'open gripper 170 DLY 0.5 'time to open gripper 180 MVS P0 'position to take a piece in the conveyor belt 190 DLY 0.5 'time to close gripper 200 M_OUT (13)=0 'reset bit close door 210 M_OUT (12)=1 'open the milling door 220 WAIT M_IN (9)=1 'wait to open milling door 230 M_OUT (15)=0 'reset bit close vise 240 M_OUT (14)=1 'open vise 250 WAIT M_IN (11)=1 'wait to open vise 260 HCLOSE 1 'close gripper 270 DLY 0.5 'time the robot leaves the conveyor belt 280 MVS P1 'start way to the vise 350 M_OUT (15)=1 'close vise
4. ROBOTIC ASSEMBLING CELL The assembling cell consists of a Mitsubishi RV-2AJ Robot and two pneumatic cylinders (actuators); three optical sensors and a torque sensor; places for pieces under processing, pallet for pistons and reservoir for discarded pieces. Within the scope of the activities defined in the project, this cell is responsible for the assembling of a pneumatic valve. The integration with the FMS is done through the conveyor belt which transports the base of the valve in a pallet and sends a signal so that the assembling can start. The base of the valve arrives through the conveyor belt, already made and tested by the previous cells. The remaining components (piston, spring and cover) are in the own robot station. After assemblage, the valve is given back to the pallet in the conveyor belt. The robotic cell sends a signal to the conveyor belt indicating the product is ready to be sent to the next station. Figure 3 shows the main parts of the Robotic Assembling cell. 4.1 Description of the Sequence of the Robot Operations The robot identifies the right position where it has got to put the piece in the assembling place. In this place there is a pin that provides the reaction torque when the cover is being assembled. After, it places the piston and the spring inside the piece in this order, respectively. At last, the robot assembles the cover which has two fixation rims to guarantee the perfect assembling.
Machine CNC
Place Operation Panel Robot Station
Machine CNC
Part of the program developed by group 1 can be seen as follow:
Fig. 3. General view of the Assembling cell.
The process starts form the signal sent by the conveyor belt to assemble the product. The robot takes the valve base (the piece), transports it from the conveyor belt to a shallow cradle (Figure 4) and checks the color of the piece. If it is black, the valve is assembled with a silver piston, if it is silver or pink, the valve is assembled with a black piston. After that, the robot takes the piece again and places it on a sensor. The robot, with a revolving movement of the gripper, finds the hole in the piece and fits it into a deeper cradle (Figure 4).
Fig. 5. Robot Positions
Fig. 4. Places for pieces under processing. The assembly starts from this point on: the robot goes to the piston deposit, takes one of them, returns and puts it in the base of the valve. In the case of the spring and the cover, the robot controller sends a signal so that the pneumatic actuators make such components available. The robot takes the spring and places it in the base of the valve. After that, it takes the cover and places it in a kind of thimble (Figure 4). With the help of such thimble, the robot takes the cover, places it in a sensor for detection of the fitting rim. Finally, it returns to the valve and taps the cover. As the assembly finishes, the robot transports the product to the conveyor belt. 4.2 Programming the Assembling Cell The programming of the assembling cell was implemented in the Cosimir Industrial environment. The first step was the configuration of the origin of the robot so that it can be seen virtually in the Cosimir. This is possible through a kind of procedure in which all the axles of the handler are placed in their negative extremes. Such data is informed to the robot controller as being the origin points of the robot RV-2AJ. A serial connection allows communication with the development environment in the PC and the robot. This way it is possible to obtain and send parameters, as well as discharge and interrupt programs allocated in the robot. Figure 5 shows part of the positions defined for robot actions which are used in the program. Figure 6 illustrates the edition window of programs with part of the developed application which is responsible for taking the assembled valve and giving it back to the pallet in the conveyor belt.
Fig. 6. Program that controls the Assembling Cell. 5. STORAGE CELL ASRS20 ASRS20 is a recovering and storage system of components manufactured (products) in the Flexible Manufacturing System. The ASRS20 operation can be manually or automatically carried out. In the manual way, it is possible to control the movements of the actuators and of the Cartesian axles (the gripper, for example) from a group of keys. In the automatic way, the control is done through a PLC. The station is composed of: (i) a PLC, (ii) five shelves with four spaces in each one to storage manufactured products, (iii) a mechanic arm which has a pneumatic gripper, two motorized Cartesian axles and ten sensors. 5.1 Description of the storage operation The transport system (conveyor belt and pallet) transports the ready product until the Storage cell. The pallet stops in front of the station and the mechanic arm places itself on the pallet towards the product. The pneumatic gripper opens, moves forward to the product and closes holding it and retreats. The mechanic arm transports the product to the first free space. The pneumatic gripper goes forward to the desired position and opens.
The pneumatic gripper retreats and the mechanic arm stands back, not moving until another product arrives. The recovering operation of the product is analogically done. 5.2 Programming ASRS20 Cell SCL (Structured Control Language), the programming language used in this application, is a higher-level programming language oriented on PASCAL. It is based on a standard for programming PLCs. It was chosen due to the easiness to implement the procedural programming and mainly, to the need of use of data structures such as arrays. The programming was based on the mapping of the PLC inputs and outputs with the other components of the cell and of the conveyor belt. Table 3 gives an example of such mapping. Table 3 Input and Output of the ASRS20 Cell Input and Output of the ASRS20 Cell Address I126.7 Q124.0
Symbol Gri_open Xleft
ID B17 M1
Comment Open gripper Move axle X to the left
Table 4 presents part of the program developed in Structured Control Language responsible for the removing procedure of the products from the stock to be sent to the Sorting Station. Table 4 Product Recovering Procedure // handler opens gripper 200 :
OpenGrp:=true; IF (Grpopened=true) THEN Task:=Task+1; END_IF;
// handler finds piece position 201:
MANAGEMENT. MANAGEMENT_DATA (Instruction:=3); Task:=Task+1;
// handler goes forward to the piece position 202 : IF (PosXatual < PosXarmaz) THEN MvXleft:=true; IF PosXatual<(PosXarmaz-1000) THEN Xfast:=true; ELSE Xfast:=false; END_IF; ELSE Xfast:=false; MvXleft:=false; END_IF;
CONCLUSION One of the biggest problems to reach reduction of costs, quality and productivity through automation of
an industrial plant lies on the acquisition of qualified staff to carry out the automation itself and its future operation and maintenance. This work presents challenges and solutions for the teaching and learning of automation applied to integrated manufacturing by means of a methodology approach under techniques, tools and industrial equipment directly applicable in the industry. The set of tools, the diversity of components manipulated by the students and the interaction between them allowed a fast and homogeneous evolution in the knowledge of the students. The existence of an only and challenging goal for all (the functioning of the FMS) from the initially individual effort and later of the necessary interaction between groups of students, revealed a very efficient approach to learning about integrated manufacturing. The teaching methodology made the students aware that the system, primarily consisting of isolated and static parts, was integrated by them and became a complex manufacturing system. Moreover, the students proved the functioning of the system in accordance with the idealized one together with all the overcome obstacles. In the end of the course, the students showed to be confident of the experience acquired and motivated to continue developing in the area. ACKNOWLEDGEMENTS This publication is sponsored by the FESTO German, Mexico and Brazil. REFERENCES Anschuetz, H (2001). HPSim Version: 1.1. Petri Nets World. Obtained: http://www.informatik.unihamburg.de/TGI/PetriNets/ Moraes, C. C. and Castrucci, P.L. (2001) Engenharia de Automação Industrial. Editora LTC, pag. 295. FESTO (2002). FMS50 Manual Brasil. Festo Didatic. pag. 201. Denkendorf, German. Pereira, L. F. A. and Lima, J. C. M. (1998) Reestruturing of the teaching of automation and control through the implementation of laboratories. In: Proceedings of ICEE’98. Rio de Janeiro, Brazil. Rangel, F.; Lemos, M. A.; Botura, Galdenoro (2006). “Implementation of a Didatic Plant in Automated Industrial Processes”. Global Congress on Manufacturing and Management, GCMM 2006, November19-22, Santos, Brazil. Tilbury, D. and Khargonekar, P. (2000). Challenges and Opportunities in Logic Control for Manufacturing Systems. Report of the NSF Workshop held at the University of Michigan, An Arbor, MI, June 26-27. Tsichritzis, D. (1999) Reengineering the university. Communications of ACM, 1999. volume 42, no 6, pags. 93–100. Upton, D. M. and Kim, B. (1996). An Empirical Study of Alternative Methods of Learning and Process Improvement in Manufacturing. Report 96-006 Re. 12/96, Harvard Business School.