Color sorting Robot is one of the useful, costless and fastest systems in Industrial applications to reduce manual working
time and provides less human mistake when manual system is undertaken. The objective of this project is to design an efficient,
microcontroller based system that pick up right color of objects and put it down at right place to optimize the productivity, minimizing
the cost of the products and decreasing human mistakes. The controller used is a PIC Microcontroller (18F452) having high speed
performance, low cost and 32 K bytes program memory. It communicates with color sensor TCS 3200 and various motor modules in real
time to detect the right color object and to control the arm movement. Designed system can pick objects of 1kG weight and arm can
rotate up to 3600
. Also, the use of easily available components reduces the manufacturing and maintenance costs. The design is quite
flexible as the software can be changed according to specific requirements of the user. This makes the proposed system to be an
economical, portable and a low maintenance solution for industrial applications

Ahmad, G.

Ahmed, M.

Amin, Uzma

Liaqat, N.

Zahoor, S.

English

espace@Curtin

International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Impact Factor (2012): 3.358 Volume 3 Issue 6, June 2014 www.ijsr.netLicensed Under Creative Commons Attribution CC BYDetection & Distinction of Colors using ColorSorting Robotic Arm in a Pick & Place MechanismUzma Amin1, Ghulam Ahmad2, Nudrat Liaqat3, Manzar Ahmed4 , Sumbal Zahoor51, 3, 4, 5 University of South Asia, Electrical Engineering Department, 5-KM Raiwind Road Loahore, Pakistan 2 University of Gujrat, Electrical Engineering Department, Hafiz Hayat Road, Jalal Pur Jattan, Gujrat,Pakistan Abstract: Color sorting Robot is one of the useful, costless and fastest systems in Industrial applications to reduce manual working time and provides less human mistake when manual system is undertaken. The objective of this project is to design an efficient,microcontroller based system that pick up right color of objects and put it down at right place to optimize the productivity, minimizing the cost of the products and decreasing human mistakes. The controller used is a PIC Microcontroller (18F452) having high speedperformance, low cost and 32 K bytes program memory. It communicates with color sensor TCS 3200 and various motor modules in real time to detect the right color object and to control the arm movement. Designed system can pick objects of 1kG weight and arm canrotate up to 3600. Also, the use of easily available components reduces the manufacturing and maintenance costs. The design is quite flexible as the software can be changed according to specific requirements of the user. This makes the proposed system to be aneconomical, portable and a low maintenance solution for industrial applications.Keywords: Color Sorting, Robotics, Motors, Color Sensor1. IntroductionThe importance of robotics in 21st century is increasing dayby day to reduce human mistakes in their daily tasks becauseof their ability to do much difficult tasks; the automotiveindustry fully operates with robots completing tasks on timewithout any mistake [1]. The “Rancho Arm” was designedin 1963 to assist handicapped persons. Revolution in therobotics has opened the way to help the handicapped peopleso that they can reclaim the use of lost limbs. By 1969 morerobotics arm were developed and controlled throughcomputer such as Stanford arm was robotics arm this respect[2].The proposed system is an embedded system which willincrease the speed of color sorting procedure, provide theaccurate color sorting process, decrease the cost of colorsorting process and optimize the productivity of an industrialobject. The system comprises of color sensor, stepper &servo motors and microcontroller. Color sensor detects thespecified color of the object and microcontroller reads thisfrom the data at its input ports. The microcontroller conveysits decision to the station that been programmed. Since amicrocontroller is used as a heart of the system, it makes theset up low cost and effective nevertheless. The significanceof a project can be estimated from its current utilization andfuture prospects of advancements. Industry utilization andmanufacturing also defined the significance of this project.2. MethodologyColor sorting robotic arm is a system having a capability toselect the specified color object and placed it at a desiredlocation. Firstly, when object is determined by the robot, thegripper of the robot will pick the object and place it to thespecified color differentiating station. The station consists ofa color sensor named Light Dependent Resistor (LDR)which detects the light reflected by the body. TCS 3200 is anarray arrangement of configurable silicon photodiodes andfrequency converter mounted of the chip in the form of aCMOS integrated circuit on RGB color sensor.There is an8*8 matrix of photodiodes in the sensor i.e. 64filter sensors are used in it. All these filters are collect RGB(red, green, blue) data from the source [3][ 4]. The datacollected from the sensor is converted into a square wave of50% duty cycle by an oscillator integrated in the chip. Thiswave is then sent directly to the microcontroller.Microcontroller transfers signal to the motor drivers toactivate the arm to pick the object and drop it to the placedefined by programming of controller. The arm rotates to thespecific angle (may be 900, 1200, 2700 or 3600). Theselection of frequency and color is shown in followingTables # 1 & 2. The selection of output frequency is done byterminals S0 and S1, while the color selection task isaccomplished by the photodiode output terminals S2 and S3[5] [6]. Table 1: Frequency SelectionS0 S1 Output Frequency Scaling (f0)L H 2% L L Power DownH H 100% H L 20% Table 2: Color Selection (photodiode Type) S2 S3 Photodiode Type L H BLUE L L RED H H Green H L Clear (no filter) 3. Flow ChartThe function of robotic arm in the form of flow chart isshown in figure 1. In start robot will take its home positionthen color sensor detects the object’s color with the help ofPaper ID: 020131882 1164International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Impact Factor (2012): 3.358 Volume 3 Issue 6, June 2014 www.ijsr.netLicensed Under Creative Commons Attribution CC BYPIC microcontroller. If detected color is true means nospecified color object then robotic arm will remain itsposition. When color is false means desired color is detectedthen robot will rotate from its position towards objectlocation, drop it to specified place and returns to its originalposition until other color is detected.Figure 1: Flow Chart 4. Mechanical Design of Robotic Arm Mechanical structure of the robot is constructed on a CNCmachine for proper working. The material used in thisproject is aluminum sheet due to its flexibility andreliability. The design of the robot arm includes four majorparts: base, elbow, shoulder and wrist. Different parts ofrobotic arm with description shown in Figure 2. The roboticarm can be used to achieve the concept of degrees offreedom. Using the robot arm in straight position, rotating itfrom shoulder side, the robot can move in three differentways. The movement of the robot to up-and-down positionis called pitch. The right and left movement is called yaw.Whole movement of the robot arm as a screwdriver is calledroll [7].Figure 2: Parts of Robotic Arm [6] The wrist and shoulder has three degrees of freedom andthey are pitch, yaw and roll but elbow has only pitch.Moving the robot arm from the elbow side only, holding theshoulder keeping in same position constantly, the elbowjoint has equivalent pitch in the shoulder joint, giving theelbow with one degree of freedom. Now rotating the wrist tostraight position and motion less, we can easily bend thewrist to up and down position, side to side and it can easilytwist. The mechanical design of robotic arm is shown inFigure 3 below. Figure 3: Mechanical Design of Robotic Arm The lower arm has also three degrees of freedom. Thus therobot arm has seven degrees of freedom. These three degreesof freedom are enough to bring the end of an arm to anypoint at the workplace [8]. 5. Design and Working 5.1 Main Control Unit (MCU) The main unit contains a microcontroller (PIC18F452), 4modules of stepper driver, a servo (for grip) and some othercomponents. To provide 5 volts, LM7805 (regulator) is usedin the power supply circuit board. Pin number 1 is pulled upby using 1K ohm resistor and also pulled down by using0.1uF capacitor. Pin number 11 and 32 are connected toVCC (positive potential) and pin number 12 and 31 to theground (negative potential). The 20MHz crystal oscillator isconnected with the pin number 13 of the controller. Itproduces Clock pulses for the execution of microcontrollerinstructions. Microcontroller is operated under 5 MHzfrequencies. Figure 4 shows the PCB design of Main Controlcircuit.Figure 4: PCB Design of Main Control Board Paper ID: 020131882 1165International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Impact Factor (2012): 3.358 Volume 3 Issue 6, June 2014 www.ijsr.netLicensed Under Creative Commons Attribution CC BYFour stepper motors were used for controlling robotic armmovements. Each stepper motor is controlled by the stepperdriver having L297, 74HC08, four 75NF75 and some othercomponents. Every stepper motor driver has three inputs tocontrol motor with microcontroller. The three inputs ofstepper driver which are connected to microcontroller aresteps input pin, mode selection pin and direction selectionpin. Steps input pin is for rotating of motor. Low to highpluses are given at that pin to rotate the motor rotor. Mode selection is for selection of mode of motor half stepor full step mode. Direction selection is for controlling thedirection of the motor in clock wise direction or anti-clockwise direction. Servo motor is used for grip motion. Theservo motor has 3 pins (i.e. 5V, Signal, Ground). The servomotor is controlled by the timing signal at the frequency of50Hz signal. If duty cycle of input is 25% then servo willmaintain its position in center. If duty cycle is reduced theservo will move 180 degree. Center position of servo willclose the grip jaw and when moves 180 degree then, gripjaw will open.5.2 Motor Driver Motor driver consists of L297, 74HC08 and four FieldEffect Transistors which are used for switching as well asamplifying and also provides isolation between circuits [9].PCB design of motor driver circuit is shown in Figure 5. Figure 5: Motor Driver Board 5.3 Color Sensing Board This unit consists of a Microcontroller (PIC18F452), ColorSensor TCS 3200, a Push Button (named GO Button) andsome other components [17]. When GO Button is pressed,microcontroller will enable the color sensor to detect thecolor of placed object on it. Color Sensor TCS 3200 willdetect the intensity of Red, Green and Blue in color of theplaced object and send it to microcontroller for furtherprocess. PCB design of color sensor is shown in Figure 6.Figure 6: Color Sensing Board The microcontroller will compare intensity values of red,green and blue to detect the color of placed object. Ifintensity value of red is greater than green and blue thenobject’s color is red. If intensity value of green is greaterthan red and blue then object’s color is green. If intensityvalue of blue is greater than green and red then objects coloris blue [10]. After detecting color of the object, themicrocontroller will give signal from low to high of timeinterval of 500 ms and then, low its pin of correspondingcolor.6. Hardware Description Different components were used in this project. List of thecomponents used in this project are:6.1 Stepper MotorsA brushless, synchronous motor that exchanges digitalpulses into mechanical rotation of shaft is called steppermotor. The stepper motor’s revolution is divided into adiscrete number of steps, almost 200 steps in each revolutionand sent a separate pulse for each step. At a time one stepcan be taken by stepper motor and each step includes thesame size. Since each pulse of the step causes the motor torotate at an angle of 1.8°, the position of the motor can becontrolled without any providing feedback mechanism asshown in Figure 7. As the frequency of the digital pulsesincreases, the movement of the steps also increases causingcontinuous rotation with the speed of rotation proportional tothe frequency of pulses. Due to their low price, highpotential torque at low speeds, high reliability and a simple,rugged construction, Stepper motors are used daily in bothindustrial and commercial applications [11][12]. Paper ID: 020131882 1166International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Impact Factor (2012): 3.358 Volume 3 Issue 6, June 2014 www.ijsr.netLicensed Under Creative Commons Attribution CC BYFigure 7: Stepper Motor [11]. 6.2 Servo MotorServo means to an error sensing feedback control that isused for correcting the performance of any type of system.Basically servo motors are DC motors as shown in Figure 8that are equipped with a servo mechanism for the purpose ofcontrolling precise angular position. These motors usuallyhave a rotation limit ranging from 90° to 180°. But thedrawback is that servos do not rotate continually to performcertain tasks. The rotation of these motors is restricted inbetween the fixed angles. So the Servos are also used forprecision positioning. There are most applications whereservos are used such as in robotic arms and legs, sensorscanners, RC airplanes etc. [13].Figure 8: Servo Motor [13] 6.3 PIC MicrocontrollerIn the present day, PIC Microcontrollers are quicklyreplacing computers when programming robotic devices areconsidered. PIC micro controller is developed by microtechnology in 1975. 18F452 microcontroller has dominatedfeatures over the other PIC microcontrollers. It has operatingfrequency is 40 MHZ at DC, Program memory is 32 K bytesand data EEPROM memory is 256 bytes [14].6.4 Color Sensor The Color sensor is a programmable light-to-frequencyconverter, it can filter RGB (Red, Green, and Blue) dataobtained from source light and convert it to a square waveform having 50% duty cycle with frequency proportional tolight intensity. The full-scale output frequency can bemeasured by one of available three preset values with thehelp of two control input pins SO, S1 and pins S2, S3 areused to control the RGB filter. Digital inputs and digitaloutputs allow interfacing with a microcontroller directly. Socolor of the object’s light is calculated by RGB values. Theschematic diagram of color sensor is shown in figure 9.TCS 3200 color sensor is chosen for this project due toconversion of light intensity into frequency, programmablecolor ability and giving full-scale output frequency, directcommunication with a PIC microcontroller, power supplycan be 2.7 V to 5.5 V, minimum error capability [5][15].Figure 9: TCS 3200 [16]. 7. Software’s Following are the software’s used in the project. 7.1 MPLAB IDEMPLAB Integrated Development Environment (IDE) is atool which is used for development of embeddedapplications for PIC microcontroller series. MPLAB can beused in XP windows; it provides the option for editingprogram in its editor and to drags the code. It can also beused for single unified graphical user interface for moremicrochip and 3rd party software and hardware. It has thesame user interface for all tools such as flash programmingtools and upgrading from the free software simulator tohardware debug is done. [17]. 7.2 Motor DriversThere are four motor drivers for each stepper motor tocontrol the speed of these motors. Stepper driver includesL297 IC with H Bridge built-in (automatically generatingduty cycle) which is used to control the motor according toinstructions giving by Microcontroller [18]. 7.3 CCS C CompilerLevelheaded and efficient CCS C compilers comprisetouchstone C operators and built-in function libraries that areparticular to PIC registers, allow developers with a right toolfor accessing device hardware features from the C languagelevel. The CCS code optimizes C compiler supports up to56K instructions and 4K RAM for these new 14-bit devices.The compiler runs under Windows 95, 98, 2000, XP, Vista,Windows 7 and Linux. It outputs debug and hex files thatare selectable and compatible with popular emulators andPaper ID: 020131882 1167International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Impact Factor (2012): 3.358 Volume 3 Issue 6, June 2014 www.ijsr.netLicensed Under Creative Commons Attribution CC BYprogrammers including the MPLAB® IDE for source leveldebugging [19]. 8. ConclusionThe system has been successfully designed and it has thecapability to rotate 3600 and handle the required task. It cantake specific colored object, hold it and put it to a particularstation even to some height using RGB color sensor. Colorsensing section performed two main tasks; object’s detectionand color recognition. System is fully remote controlled andcan pick objects of 1kg weight approximately. The costeffective system was designed to perform the continuous andreliable tasks without human errors using the simplestconcepts. The robotic sorting systems are useful in industriesand different household activities. Since this system ismainly controlled by the PIC Microcontroller, the resultsobtained are more reliable and faster.9. Recommendations The color sorting robotic arm is used to perform the sortingof objects with the help of color sensor. The system can beadvanced by increasing the efficiency of color sensor whichis the key component of the project used for distinguishingthe objects. Selecting the right material for selection of rightcolor sensor to accurately distinguish between differentcolors. Another area of improvement in this project is adesign for using Digital Image Processing (DIP). Theultrasonic imaging, remote sensing, astronomy, medicine,automated industry inspection and space exploration. Imageprocessing can be done by using some image classificationalgorithms using different spectral features, the brightness,and color information presented in each pixel. References[1] Yeow Khang Yung, ‘’Color Sorting System with RobotArm’’ Faculty of Electronic and Computer EngineeringUniversity Technical Malaysia Melaka, (2011). [2] http://robotics.megagiant.com/history.html [3] www.colourtherapyhealing.com/colour [4] Alexander Getman, Jinhak Kim, Tae-Chan Kim; Imaging system having White-RGB color filter array’ in Proceedings of 2010 IEEE 17th International Conference on Image Processing September 26-29, 2010, Hong Kong. [5] http://www.mouser.com/catalog/specsheets/TCS3200- E11.pdf [6] M. C. Mulder, S. R. Malladi, “A minimum effort control application for Cooperating sensor driven intelligent multi-jointed robotic arm,” Proceedings of the 30th  IEEE Conference on Decision and Control, vol. 2, pp. 1573–1578, 1991. [7] E. Oyama, T. Maeda, J.Q. Gan, E.M. Rosales, K.F. MacDorman, S. Tachi, A. Agah, “Inverse kinematics learning for robotic arms with fewer degrees of freedom  by modular neural network systems,” International Conference on Intelligent Robots and Systems (IROS), 2005, pp. 1791–1798. [8] Malvin Nkomo, Member of SAIEE and Michael Collier ‘’A Color-Sorting SCARA Robotic Arm’’ College of Information and Electrical Engineering Shandong University of Science and Technology Qingdao, (2010), China [9] http://www.lsicsi.com/pdfs/Data_Sheets/LS8397.pdf [10] http://www.dfrobot.com/wiki/index.php/TCS3200\ Color_Sensor_(SKU:SEN0101) [11] sM.H. Liyanage, N. Krouglicof, R. Gosine, “Design and control of a high Performance SCARA type robotic arm  with rotary hydraulic actuators,” Canadian Conference on Electrical and Computer Engineering (CCECE),  2009, pp. 827–832. [12] M. H. Liyanage, N. Krouglicof, R. Gosine, “High speed electro-hydraulic Actuator for a scara type robotic arm,” International Conference on Intelligent Robots and Systems (IROS), 2010, pp. 470–476. [13] http://www.stepperworld.com/Tutorials/pgUni polarTutorial.html [14] Mike J. Johnson and Guru Subramanian "A Parallel Port Interface Circuit for Computer Control Applications Involving Multiple Stepper Motors" University of Northern Iowa, IEEE, Circuits and Systems, Vol 2, pp 889- 892, 1997.  [15] Kapil Shivatare, Prashant Jadhav, Amit Shelke “Three way controlled Robotic Arm. Siddhant College of Engineering Sudumbare (May 2011), India [16] http://highered.mcgrawhill.com/sites/0070669007/information_center_view0/ [17] http://www.microchip.com/pagehandler/enus/family/mplabx/ [18] http://www.technologicalarts.com/myfiles/data/AN470.pdf [19] http://www.ccsinfo.com/content.php?page=compilers Paper ID: 020131882 1168

Detection & Distinction of Colors using Color Sorting Robotic Arm in a Pick & Place Mechanism

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Detection & Distinction of Colors using Color Sorting Robotic Arm in a Pick & Place Mechanism

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