Control Software for Automatic Storage and Retrieval System, Integrated with Mobile Robot in the Part Supply Chain.

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1 Control Software for Automatic Storage and Retrieval System, Integrated with Mobile Robot in the Part Supply Chain. Abstract: Vladimir Todorov Drujba -2 bl. 270 app.19 Sofia 1582, BULGARIA Mentor Sergei Gamer Department of Industrial Engineering and Management, Technion Israel Institute of Technology In the beginning a command prompt based C++ application was created to control a Rotary ASRS using a RS232 serial interface. Later by implementing the logic and the functions of the program a new one was created. Using Microsoft Visual C and Microsoft Foundation Classes (MFC) a Graphical User Interface (GUI) program was developed to control the robot and to manage its database. The MFC application was designed to control the ASRS in automatic mode using commands from a mobile robot, however due to problems with the designing of TCP/IP communication the commands were taken from local file. Introduction: Our daily lives are filled with different technologies. What would we do without our personal computers, television sets, stereo systems, cars, and ovens? Nothing, we need these technologies to keep up our life standards. But to keep up these standards we also need production large enough to satisfy our demands. For the prehistoric person it was satisfying to manufacture a stone hammer or a stone weapon using his hands. The usage of manpower as the center of manufacturing processes continued up to the middle of the 20 th Century. However, for example, to build billions of television sets by hand takes a lot of time. Therefore, for the modern man this Man Integrated Manufacturing does not provide the expected results, and thus in the 1960 s the old productions system was challenged by the Computer Integrated Manufacturing (CIM). Computer Integrated Manufacturing is a management philosophy in which the functions of design and manufacturing are rationalized and coordinated using computer, communication, and information technologies 1.Since 1960 CIM has developed and changed: 1960: The first Robot implementation in a factory. The first Unimate was introduced at the Ford Motor Company to tend a die-casting machine. 1965: International Business Machines introduced a computer controlled production line for manufacturing of circuit boards. The line was designed to use a computer control to supply numerical data for inserters and testers. 1970: The Japanese National Railways placed seven lathes under the simultaneous control of one computer. This brought up the concepts of Direct Numerical Control (DNC) and Computer Numerical Control (CNC).

1975-80: The Distributed Numerical Control was developed. This allowed programs from the mainframe computer to be downloaded to the desired machine tool.

2 : The Distributed Numerical Control was developed. This allowed programs from the mainframe computer to be downloaded to the desired machine tool. 1980s: A concept called Group Technology (GT) was developed to group the different parts into families and thus organizing the production line in so called Manufacturing Cells. 1980s: The Flexible Manufacturing Systems (FMS) were developed. The idea is to use set of machines to create a relatively wide variety of products. This was achieved by movement of products through any sequence of machines which included also testing of the products. Both the combination of the Manufacturing Cells and the Flexible Manufacturing System lead to the Computer Integrated Manufacturing. The main hardware components of the modern CIM are Computer Numerical Control (CNC) Machines, Quality Control (QC) Machines, Material Transporting systems: Conveyors, and Automatic Guided Vehicles (AGVs), Robots, and Automatic Storage and Retrieval Systems (ASRS). Important role of the ASRS in modern CIM is the fast and flexible retrieval of parts. Because the ASRS is guided by computer it can keep information about its contents. The computer guidance also provides various methods of control and in that way making the ASRS easy to integrate in different complex systems. Methods: The Rotary Automatic Storage and Retrieval System in the CIM and Robotics Lab is composed of two main structural elements. The system contains a robot hand, and a Rotary Part Storage (Magazine), which are both controlled by the same Hardware (HW) Controller. The controller, programmed in Advanced Control Language (ACL), executes the desired low level tasks manipulating both the Rotary Part Storage and the robot hand. It has two buffers on which it puts the retrieved parts or from which it takes parts to store. There is also one intermediate buffer on which the gripper changes its grip. Structure of the ASRS The Mobile Robot The Rotary ASRS in the Technion CIM and Robotics Lab The Mobile Robot with which the ASRS had to be integrated is produced by Denning Mobile Robotics, Inc. The model of the robot is MRV-4. Equipped with Navigation Laser (LaserNav2), Manipulator, and SICK LMI 400 scanning laser this robot navigates freely around different obstacles. Using TCP/IP communication the Mobile Robot sends request to the ASRS asking for specific part, takes the part and moves it to some specified location.

3 Control Architecture While running the ASRS Control software receives instructions either from user input or from TCP/IP interface connected to the Mobile Robot. These instructions are then processed and passed through the logic of the control software. If accepted, they are translated into ASRS low level programs written in Advanced Control Language and then dispatched to the controller as messages through the RS232 Serial Interface. After the ACL low level tasks finish, reply is sent back from the ASRS controller to the control software. ASRS Control Software RS232 Interface TCP/IP Interface ASRS Controller Mobile Robot User Input Figure 1 Although the Rotary ASRS has its own terminal and it is able to be controlled also by the commercial terminals like Hyper Terminal and TTY, it was unable to perform complicated actions and to keep track of the its storage. Therefore, a new Rotary ASRS Control application had to be introduced. Unlike the old interfaces like ATS (Advanced Terminal Software) and the other terminals, the application is graphically oriented, providing better vision, understanding and control of the processes that the ASRS executes. The program simply called Rotary ASRS Control was created to work in two different modes: Manual Mode, in which the user manually manages the control of the Rotary ASRS. Using the MFC classes the mode does not require knowledge of the ACL language and understanding of the Hardware Controller. However, the mode also provides Command line and Console which act in the same way as the other terminals. Automatic Mode, created to listen to the mobile robot s requests using TCP/IP connection. Program Structure and Description The first step of the creation of the control application was to establish RS232 serial communication between a small Win32 Console application and the Hardware Controller of the

4 ASRS. By using RS232 Communication Library implemented in the file called Serial.DLL a simple program was created. This program was the initial state of first of the four layers of the Rotary ASRS Control (Figure 2). Layer 4: TCP/IP Layer 3: MFC Layer 2: Parts Recognition Layer 1: Operational Layer Figure 2 The First Layer actually contains the operation functions and the logic of the application concerning the RS232 communication. This is the most important part of the application, or its engine. When managing the Rotary ASRS all the processes are filtered and formatted there. Using the function SendSerial(),which takes one parameter, the message is then dispatched to the Hardware Controller. Reading the reply of the controller is done by the function read_serial(). However, it needs to be looped since it only returns one character of the reply per call. All the other functions in the first layer deal with initialization of the serial communication and the logic. Layer number Two concerns with the parts recognition. Using a small class called storage the program defines the various types of parts. However, parts cannot be handled by the robot itself. The gripper of the robot is not interchangeable and thus it cannot fit different shapes. Therefore each part has its own template on which it is positioned. All the templates in the ASRS are made such that the gripper is able to pick them. The storage class supports 24 various parts and 24 templates. Each part can have its own template, and also each template can be placed empty. The Third Layer deals with the Graphical User Interface of the program. Although the layer does not lack of logical decisions and functions, their importance to the program is little. Most of them are created for safety and protection. Some of them, however, are important to the program as they implement and add to the logic of the first layer. The visualization of the program is made by using MFC. By means of various Microsoft common controls this layer visualizes and makes the control of the ASRS easier and more organized (Screenshot 1). The Fourth Layer is the TCP/IP communication with the Mobile Robot. The communication establishing source was borrowed from the controlling console of the mobile robot. After implementation and adaptation of the source files to the project the logic of the robot-asrs communication was written. Although the files were successfully implemented, and the functions correctly used there was a failure in establishing the connection. An error in initializing the connection appeared and due to its unknown origin and the lack of time it could not have been traced. Therefore a simulation of the TCP/IP was run to test the logical part.

5 Basic Program Structure (Figure 3) ROBOT TCP/IP Automatic/Manual USER I/O I/O (FILE*) Mode Check delivery buffer if free Assembly of the sequence of actions Manual mode command line RS232 Check for Part ASRS Controller Waiting for final signal Input Data Output Data Console Input Program Modes and Logic Manual Mode Manual mode is the mode with which the user can freely communicate and manage the ASRS. The functions implemented in the manual mode are from the first layer of the program. The first version of this mode was created using C++ but it was made in Win32 Console application. Although all the functions were intact and the mode was working, the application had to be changed to MFC; otherwise it would have represented very much the usual terminals. The mode has an easy and accessible interface (Screenshot 1). The dialog of the application has four list box controls providing information for the parts and the templates on the ASRS, two groups of buttons: Edit buttons and Action buttons, divided by the RUN button, a Legend of the parts and a Command line for direct communication with the controller. The parts that are contained in the four list boxes are kept in four different arrays with 21 cells. Each part has an index from 1 to 24, and the empty templates have indexes from 25 to 48, empty cells have index of 204 and cells with unknown content have the index of 604. There are 18 elements per tier in the ASRS and so the arrays contain the storage data up to the 18 th element. The 19 th element of the array is used as an identifier, keeping a number between 0 and 3. This identifier is used by the function FromCellTo()(The function that moves the parts) to recognize which array it is using. The recognition of the indexes in the arrays is done by the storage class. This class uses two functions GetMaterial() and GetColor() as tables to return both the part type and the part template. The arrays containing the indexes pass in a loop through the class constructor constantly constructing and destructing classes (Figure 4). Thus the information is passed once to

6 the list boxes and deleted from the memory. Therefore when saving the data only the indexes need to be kept. a r r a y GetMaterial() storage GetColor() Figure 4 Although the HW Controller has its own internal memory, these arrays are kept in the program s folder. Four files plate1.txt, plate2.txt, plate3.txt and baseplates.txt contain the data from the arrays. The reason for this is that at first the data from the Hardware Controller was unreadable. Therefore the program was made to save the storage of the ASRS in its folder. One important part of the manual mode is the Command line. The Command line is a terminal which can send any kind of string that the user inputs to the hardware controller of the ASRS. In the interface of the program the Command line is the Edit control where the user enters the desired command. The Console is the place where both the user input and the ASRS replies are displayed. The command line faced the same problem as the reading of the arrays. The reply of the ASRS seemed unreadable. However, after converting the ASCII codes sent by the controller to characters it became clear that the controller is returning both user s input and output at once. The resolution of the problem came out of the ACL command noecho, which made the hardware controller return only the output. The Automatic Mode When turned on, the Automatic mode disables all the controls on the dialog of the application. This is of great importance because otherwise the user might interfere and disturb the operation that was set. (Screenshot 2) This mode is designed to communicate with the mobile robot. However, because of the lack of time and complications during initialization of the TCP/IP connection no communication was established between the robot and the ASRS. Although, the code implemented was working at the end the application did not succeed in listening to the specified port. Because of this major problem the communication was abandoned and instead a file was used to simulate a command sent by the robot. A Timer is set reads the file on every 100 milliseconds to check for command. The algorithm for decoding of the command worked and the ASRS was acting as expected. The command is a simple string which consists of four characters. For example, a command can be C205. When it is received by the algorithm of the control program the string is divided and transformed into action. The first character of the string C is identifier that shows that the string is actually a command. Otherwise it would be rejected. The second character 2 is identifier for the program to make the ASRS move the desired part to buffer number 2. The last two characters 05 of the command string are the index of the desired part. Using two of its functions SearchArray() and ChooseArray() the program finds the closest element to turn the magazine to. If the element is not found on any of the three tiers message notfound is dispatched to the robot, otherwise the message sent is ok.

7 The 20 th and the 21 st elements of the arrays are constantly used in the finding of the closest part. The 20 th element keeps the number of the cell in which the desired part is found. The 21 st element keeps information about the distance between the current cell and the cell the element is found. The calculation of the distance and the searching of the array is done by the function SearchArray(). Because the tiers on the ASRS are circles the function is a bit complicated. When it searches particular array for the closes element available it first creates two times bigger array containing twice the elements of the array the function is searching in. This is done in order to calculate the distance between the cells. At the end the function saves the closes distance and the cell on which the part is situated. When this function checks all the three tiers the function ChooseArray() is called. ChooseArray() is a simple function which finds out which of the three arrays has the shortest distance to the desired part. Then the identifier of the array with the shortest distance is returned and FromCellTo() is executed. Results/Discussion ASRS Control Software was created, which provides wide range of possibilities of the user to control Rotary ASRS. The MFC based interface supplies easier and accessible control. The TCP/IP communication failed to be initialized in automatic mode preventing the application from communicating with the mobile robot. The design of the application gives full control over the ASRS. Knowledge of the ACL language is not needed, and the user can operate the ASRS without any problems using the available buttons. The Command line of the Manual mode gives full range manipulation of the Hardware Controller, but it requires knowledge of the ACL. Through it the user may access everything that is situated within the controller. The automatic mode, however, could not have been finished and debugged because of the lack of time. Although, there was no communication set between the robot and the ASRS, the interpretation of commands was tested and it gave positive results. Therefore the only thing that is left for the application is to change the methods by which it tries to use the TCP/IP interface. The Rotary ASRS Control also offers great flexibility in setting the part types it stores. By manipulating the storage class the Rotary ASRS Control can be changed for variety of purposes. Currently the program is set to store drinks. Conclusion The application Rotary ASRS Control provides new way of controlling the ASRS with much better interface than the old terminal software and with error-proof logic implemented in the code. Rotary ASRS Control is effective, efficient and gives easy and complete control over the ASRS. It almost reached its goals, but due to the lack of time and the unknown complications with the TCP/IP communications only the command-understanding algorithm was tested. Acknowledgements I would like to thank my mentor Sergei Gamer for all his help teaching me the principles of the Automatic Storage and Retrieval Systems and the basics of the Advanced Control Language of

8 the Hardware Controller. Also I would like to thank Igal Loevsky and Miron Roznob for their help with the Mobile Robot integration, and SciTech for accepting me into their summer program. References 1. D. Bedworth, M. Henderson, P. Wolfe. Computer Integrated Design Manufacturing. pp. 7-9, p.600. McGraw-Hill Book Co Singapore James Morrison. Computer Integrated Manufacturing. 7/1/ /8/ Computer Integrated Manufacturing. 22/8/

9 Screenshots: Screenshot 1 Screenshot 2

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