Proceeding of NCRIET-2015 & Indian J.Sci.Res. 12(1):186-191, 2015 ISSN: 0976-2876 (Print) ISSN: 2250-0138 (Online) PLC BASED ELEVATOR SYSTEM WITH COLOR SENSING CAPABILITIES IN INDUSTRIAL APPLICATIONS ZEBA BHAKTIYAR MANGALORE a1 AND VEENA V. NAIK b ab Department of Electronics and Communication, Basaveshwar Engineering College, Bagalkot, India ABSTRACT This paper presents an application to sort colored objects with color sensors and an industrial control of elevator for material handling in industrial plant with color capabilities. The ladder diagram for PLC based elevator control system incorporating color sensing features is implemented. This scheme is useful for industrial applications where box of different colors are to be downloaded at different floors. Here the ladder diagram simulated is for the sorting of boxes with color, blue, red and green, and to be downloaded to 3 rd, 2 nd and 1 st floor respectively. KEYWORDS: Elevator, PLC, Color Sensors, Ladder diagram Industries now a day s use color sensor for sorting purpose to fulfill their requirements for higher production and precise quality. Color sensors were considered as expensive and required precision support circuitry, hence this limited their application in many industries. However, rapid developments in technology lead to color sensors with higher levels of integration. This in turn reduced the cost of color sensors and hence increased the number of application using color sensors. Color sensors play a significant role in many process industries, cosmetics manufacture and medical applications. In process industries sorting of materials based on their color is considered as fast and efficient way of sorting. Example in the lumber industry, different lumber types is sorted by color sensors because the grade, quality and intended purpose of the lumber is indicated by color. Use of color sensors for color based sorting operation is highly complex and needs interacting at both input and output levels. The first and foremost step in any industrial automation is identifying number of inputs, outputs, appropriate sensors and actuators which has to be designed and selected [Dharmannagari, 2014]. An Indralogic series PLC is selected as it offers excellent machine control capabilities. The operational sequence of the complete elevator control system is studied. An advantage of using PLC in controlling a mechanical system is much easier as compared to relay control. PLC allows easily interfacing of variety of sensors and analog inputs. Hence PLC becomes the obvious choice for industrial processes [Darshil, 2008]. The PLC is programmed using one of the PLC programming languages that is the ladder diagram for the sorting of boxes with color blue, red and green, and to be downloaded to 3 rd, 2 nd and 1 st floor respectively. PROPOSED SYSTEM The proposed system consists of PLC interfaced with input devices and output devices as shown in figure 1. Figure 1: Proposed System Block Diagram The input devices consist of sensors, switches and push buttons are used to design the proposed system. Output devices consist of motor to drive elevator and conveyor, buzzer and led are used for indication of system performance [Lei Jun, 2013]. Here we are using optical proximity sensors and inductive sensors. The optical proximity sensors have a good sensitivity as compared to the other sensors and can be used for any type object except black color. The inductive proximity switches are preferred when the sensing object is of metallic body. The infrared sensor has the capability to sense colors of the body based on its reflectivity. The amount of reflection by specific color is recorded and this data is used to separate objects based on the surface color. Initially, size of prototype system is finalized and then the various possible 1 Corresponding author
sensors are evaluated for sensing and the actuators needed for the effective operation of system [Maher Assaad, 2014] [Pankaj Agarwal, 2014]. REXROTH PLC The Rexroth PLC is a modular and scalable control. It combines the benefits of a compact small control with a standardized I/O system on the basis of terminal technology. It is a hardware platform that can be used for PLC applications. It provides communication interfaces. Examples include Ethernet as well as on board interfaces with 8 fast inputs and 4 fast outputs. The locally available I/O units can be extended by the Rexroth Inline I/O system, just by simply mounting the components side by side. All application programs, including runtime, are stored on an easily accessible standardized compact flash medium. Here IndraWorks ML * 12V12 software is used for simulation. SEQUENCE OF OPERATION The sequence of operation and control of conveyer cum elevator system is as follows: The system is started using the push button provided. Conveyor starts as object is sensed on it by the object sensor placed on the conveyor belt and one more condition is that the elevator should be in the ground position. Color sensor identifies the color of the object. The color sensors used will detect blue, green and red color. This result will be sent to the PLC. Object is placed on elevator base by the conveyer belt. Elevator lifts the object to the level as per indication by the color sensors. In this system the blue color box is sent to the 3 rd floor, red box to the 2 nd floor and green box to 1 st floor. Elevator reaches the pre-defined level by the sensing the floor sensors on each floor and these are probably will be the proximity sensors. PLC initiates the conveyor inside the elevator cabin. Conveyor places the object on the platform at that level. The object moves away on the roller platform. The elevator comes to the ground level. The next cycle begins. The whole system is halted by emergency stop button provided. The process diagram of the proposed system can be shown in figure 2. Object is placed on the conveyer belt Color sensor senses the color of the box Next Cycle Figure 2: Process Flow Diagram Based on color sensor output elevator lifts the boxes to respective floors The boxes are picked from the respective floors The mechanical structure of the conveyor cum elevator system considered represent four floors. There should be enough space between these floors so that various sensors mountings should be accommodated. Hence the height and width of the floors plays an important role while considering the design of the elevator. The whole mechanical frame considered should be made of mild steel L-sections. The box with rollers will be moved up-down inside the frame. It has rollers at its base to take the object inside the elevator cabin. Motor specification in the present elevator system used to study has single-phase synchronous to pull the elevator cabin. The general mechanical structure of elevator system is as shown in figure 3 Figure 3: Mechanical structure of Elevator system
LADDER DIAGRAM system as based on ladder diagram are specified as in table 2. Based on the inputs and outputs to the system considered the The inputs from the system as based on ladder constructed ladder diagram is as shown in figure 4. diagram are specified as in table 1. The outputs from the Table 1: List of inputs of the ladder diagram Input Definition Type Location X0 To start the system Push button On the conveyor Structure X1 To stop the system Push button On the conveyor Structure X2 To sense the box on the conveyor Diffused beam Sensors On the conveyor Structure X3 To sense the box on the conveyor of lift Diffused beam sensors On the cabin structure X4 Color sensor 1 to sense blue color Color mark sensor On the conveyor structure X5 Color sensor 2 to sense red color Color mark Sensor On the conveyor structure X6 Color sensor 3 to sense green color Color mark sensor On the conveyor structure X7 To sense the presence of box on 3rd floor 3rd floor platform X8 To sense the presence of box on 2nd floor 2nd floor platform X9 To sense the presence of box on 1st floor latform 1st floor platform X10 Ground floor proximity sensor On the elevator Frame X11 3rd floor proximity Sensor Inductive Proximity sensor On the 3rd floor X12 2nd floor proximity sensor Inductive Proximity sensor On the 2nd floor X13 1st floor proximity sensor Inductive proximity sensor On the 1st floor Table 2: List of outputs of the ladder diagram Output Function Definition Y0 To turn conveyor motor ON Relay to turn on motor 1 Y1 To turn on the elevator conveyor in Relay to turn on motor 2 Y2 To turn the roller platform of 1 st floor in Relay to turn on motor Y3 To turn the roller platform of 2 nd floor in Relay to turn on motor Y4 To turn the roller platform of 3 rd floor in Relay to turn on motor Y5 To turn on the lift motor in up direction Relay to turn on motor 3 in up direction Y6 To turn on the lift motor in down direction Relay to turn on motor 3 in down direction
Figure 4: Ladder diagram of proposed system CONCLUSIONS The ladder diagram for the elevator system developed has been found to be working effectively for sensing the blue, green, and red color box. The ladder diagram is such that different color boxes should be automatically downloaded at different levels that is green on 1 st, red on 2 nd and blue on 3 rd floor. ACKNOWLEDGEMENT The authors are thankful to the Principal, Dr. R. N. Herkal, Basaveshwar Engineering College, Bagalkot, for
providing necessary lab facilities. And Dr. A.V,Sutagundar, Prof. Manjula A S and Prof. A H Unnibhavi, Basaveshwar Engineering College, Bagalkot, for guiding us. REFERENCES Darshil, Sagar, Rajiv, Satyajit A. Pangaokar, and V.K. Sharma, Development Of A Plc Based Elevator System With Color Sensing Capabilities For Material Handling In Industrial Plant, IEEE, 2008. Dharmannagari Vinay Kumar Reddy, Sorting Of Objects Based On Colour By Pick And Place Robotic Arm And With Conveyor Belt Arrangement, in IJMERR, Vol. 3, January 2014. Lei Jun, Luo Min, Development of Elevator Intelligent Safety Control System Based on PLC, Internal conference on computational and information sciences, 2013 Maher Assaad, Israel Yohannes, Amine Bermak, Dominique Ginhac, Fabrice Meriaudeau, Design And Characterization Of Automated Color Sensors System, in the International Journal on Smart Sensing and Intelligent Systems, 2014, pp. 1-12. Pankaj Agarwal, Ratnesh Kumar tiwari, Samardeep Banyal, Santosh Kanigicherla, Shivang Chaudhary, Color/Metal Sensing Sorting System, International Journal Of Engineering Research & Management Technology, Volume1, Issue 2, March 2014, pp. 168-178.