Designing Control Algorithms with Gebhardt FlexConveyor Kit
- 1. TECHNICAL UNIVERSITY OF APPLIED SCIENCES WILDAU FACULTY OF ENGINEERING AND NATURAL SCIENCES Material Handling Control Systems Lab Session: Designing Control Algorithms with GEBHARDT FlexConveyor Modular Conveyor Kit Academic Master Study programme “Logistics and Supply Chain Management” Merve Nur Tas Supervisor of the Module Course: Prof. Dr. -Ing. Gaby Neumann
- 2. i Contents 1 Section 1............................................................................................................................. 1 1.1 Task Definition............................................................................................................ 1 2 Section 2............................................................................................................................. 1 2.1 Initial Control Algorithm and System Layout............................................................. 1 2.2 Formalized Representation.......................................................................................... 2 2.3 Objectives .................................................................................................................... 2 2.4 Working Principle........................................................................................................ 2 3 Section 2: Experiment ........................................................................................................ 3 3.1 Objective(s) ................................................................................................................. 3 3.2 Setting / Working Principle ......................................................................................... 3 3.3 Experimentation Plan / Input....................................................................................... 4 3.4 Observations / Output.................................................................................................. 4 3.5 Results ......................................................................................................................... 5 3.6 Conclusions ................................................................................................................. 5 Figures List: Figure 1: System Layout ............................................................................................................ 1 Figure 2: Routes ......................................................................................................................... 2 Figure 3: Conveyor System........................................................................................................ 3 Figure 4: FlexControl Monitor................................................................................................... 4 Figure 5: Conveyor System and Boxes used in the Experiment................................................ 5
- 3. 1 1 Section 1 1.1 Task Definition i ) Develop alternative control algorithms (and system layout) for enabling effective, flexible object flows in a conveyor system between 2 sources (ratio of flow intensities 2:1) and 3 sinks (ratio of demand 1:2:1) ii ) Plan and run experiments for implementing, testing and evaluating control algorithms (and system layout) – either or both of the aspects might be adjusted if problems or malfunctions occur 2 Section 2 2.1 Initial Control Algorithm and System Layout 112 116115 133 111 Figure 1: System Layout 118 129 119 113 128 114 127
- 4. 2 The system layout used for the experiment is portrayed above in Figure 1. The system consists of short and long basic conveyors along with multi directional conveyors. The sources are numerically represented by 112, 111 and are colored orange. The sinks are represented by the numbers 133, 115, 116 and are colored green. The length of the single elements is not crucial but the numerical representation in the diagram is imperative for route depicting purposes. Finally, all these elements can be adjusted according to the availability in the laboratory. The available conveyor modules are showed below. Conveyor Modules: 1. Long Basic Conveyor Used Pieces: 4 2. Short Basic Conveyor Used Pieces: 5 3. Twisting Basic Conveyor Used Pieces: None 4. Multi-directional Conveyor Used Pieces: 3 Conveyor Routes: Figure 2: Routes 113 128 114 112 118 129 133 115 116 127 119 111
- 5. 2 Route 1: 112-118-129-133 --- 6 of every 8 boxes fed from 112 will be sent to 133 Route 2: 112-118-119-113-128-115 --- 2 of every 8 boxes fed from 112 will be sent to 115 Route 3: 111-119-127-114-128-115 --- 1 of every 4 boxes fed from 111 will be sent to 115 Route 4: 111-119-127-116 --- 3 of every 4 boxes fed from 111 will be sent to 116 2.2 Formalized Representation A decision table is the method selected to represent the working algorithm. The main advantage of this method is that they help you detect every possible combination of conditions and reduce the risk of having missing requirements that have not been detected and therefore not tested or developed. Each column in the table corresponds to a rule in the working logic that describes the unique combination of circumstances that will result in the actions. The decision table with the complete rules is given below (Table 1). To give an example, one of the rules is “Send the box to sink 116 if the box is fed from the source 111 and Route 3 is already used.” Table 1: Decision Table Rules Conditions Box is fed from source 112 T T T T F F F F Box is fed from source 111 F F F F T T T T Route 1 is used 6 times. F T F T Route 2 is used 2 times. F F T T Route 3 is already used. F T F T Route 4 is used 3 times. F F T T Actions Send the box to Sink 115 X X X Send the box to Sink 133 X X Send to Sink 116 X Finish Counting and Start from 0. X X 2.3 Objectives Enabling effective and flexible object flows in a conveyor system between 2 sources (ratio of flow intensities 2:1) and 3 sinks (ratio of demand 1:2:1). 2.4 Working Principle For this experiment, the Gebhardt flexible conveyor technology is being used to design the material handling control system. This technology is composed out of several elements (conveyors, sensors, actuators) which can be connected and disconnected through cables to each other. Each conveying segment has female and male input ports. The cables have a female and male outputs, thus connecting the conveying segments respectively. When properly connecting cables between components the flow of electricity is ensured along with
- 6. 3 correct identification of system control algorithm by the main computer. After connecting to power and proper assembly of the elements there is no further set up needed for the system to be controlled from the Gebhardt software and represent the system structure and layout on the screen. Gebhardt FlexConveyor Kit, uses a HTML5-based multifunctional configurator. The configurator named FlexControl, displays the system layout including each individual conveyor module and the route definitions. After selecting the Flex Basic mode, system allows the operator to draw and define the transport route manually with a drag and drop technique on the screen. The route can be easily redefined, deleted or an existing route definition can be selected. 3 Section 2: Experiment 3.1 Objective(s) The objective of this experiment is assembling a conveyor system that allows the flow of objects between 2 sources (ratio of flow intensities 2: 1) and 3 sinks (ratio of demand 1: 2: 1). Further, verify if the control algorithm developed in Section 1 achieves the specified ratio of flow and demand between sources and sinks. 3.2 Setting / Working Principle To assemble the conveyor system, 9 sections of (long and short) conveyors and 3 multidirectional conveyors were used. They were connected to each other by means of two cables, one of them is the data cable and the other is to pass power to the system. Each conveyor section has an arrow that indicates the direction in which it must be connected, in some of these components the direction also determines if they are sources or sinks. The Figure 3: Conveyor System
- 7. 4 data cable must be connected in the lateral part located ports because the ports below the conveyor section are used to add other components such as RFID and Data Matrix readers, and then each cable is secured by a special lock that keeps the cables in place and safe. The power cable is used to pass electricity from one of the sources that is plugged directly into the electrical outlet to the entire system through the connection of cables between the components. Once the entire system is connected, the available conveyors are displayed on the FlexControl’s screen for system configuration. 3.3 Experimentation Plan / Input The algorithm was implemented using FlexBasic mode of FlexControl. Through this controller different routes can be drawn to link a source and a sink. To perform and test the ratio of flow intensities (2: 1), 12 boxes were used, feeding the system with 8 boxes from source 112 and with 4 boxes from source 111. The routes determined before (Route 1, 2, 3 and 4) were drawn by the FlexBasic mode on the FlexContol monitor. FlexBasic requires the user to draw all the necessary routes and number them. Then the system applies the drawn routes according to order and when the last route is used it starts from the route number 1 again and so on. Thus the routes were drawn: route 1- six times, route 2 - twice, route 3 - once and route 4 - 3 times. This was done taking into consideration the decision table. 3.4 Observations / Output The demand rate of each sink was achieved, thus it resulted in receiving sink 1 - six boxes, sink 2 - three boxes and sink 3 - three boxes out of every 12 boxes have been sent from two sources. If the data cables are not properly connected between the conveyors, then the system does not recognize them. There were no bottlenecks during any of the experimentation rounds. Figure 4: FlexControl Monitor
- 8. 5 3.5 Results It was proved that the algorithm written in section 1 could be implemented and complied with the statement. All boxes were sent and received according to the experimentation plan. The experiment was run twice continuously, obtaining the same results. The conveyors must be fitted together and then the safety locks must be placed. Thanks to the design of the conveyor system there were no bottlenecks or long waiting times. 3.6 Conclusions The objective of the developed laboratory session was to design a control algorithm for enabling an effective and flexible object flow in a conveyor system between 2 sources and 3 sinks. This was done first by describing a structured concept of the technical system to be automated including the functional components found in the system, and making a formal representation of the flows and the control strategies to use the conveying technology from Gebhardt FlexBasic mode. As a conclusion from the laboratory experiments carried, it can be stated that the control mode performed in a successful and efficient way as it always reached the objective of having correct ratios per both, source and sink. Figure 5: Conveyor System and Boxes used in the Experiment