Proceedings of 2011 The 3rd International Conference on Machine Vision Design and Development of LED Based Irregular Leather Area Measuring Machine Jamal.A.Khan 1 1 College of Engineering, National University of science and Technology, Karachi, Pakistan. Karachi, Pakistan. Abstract. Using optical sensor array, a precision motion control system in a conveyer follows the irregular shaped leather sheet to measure its surface area. In operation, irregular shaped leather sheet passes on conveyer belt and optical sensor array detects the leather sheet edge. In this way outside curvature of the leather sheet is detected and is then feed to the controller to measure its approximate area. Such system can measure irregular shapes, by neglecting rounded corners, ellipses etc. To minimize the error in calculating surface area of irregular curve to the above mentioned system, the motion control system only requires the footprint of the optical sensor to be small and the distance between the sensors is to be minimized. In the proposed technique surface area measurement of irregular shaped leather sheet is done by defining velocity and detecting position of the move. The motion controller takes the information and creates the necessary edge profile on point-to-point bases. As a result irregular shape of leather sheet is mapped and is then feed to the controller to calculate surface area. Keywords: leather sheet, Pinwheel, Irregular shape, Measuring Systems, surface area, Planimeters, Optical Sensor, image processing1. Introduction Earlier industrial solutions to the surface area measuring problem were based on manual or less accuratetechniques. Now days due high production and quality demands systems need to be automated and senseddata to be storage for calculating the tolerance to get the accuracy, for this electronic machinery is the onlycompetent solution. Human placement on leather measurement machinery can cause serious health problemsand it adds to the labor cost. Moreover, the calculations done manually depend on the experience of theoperator and the quality of the solution is not even consistent for a single given instance of the problem as italso vary from time to time. The proposed system aims to develop an automated signalling system and provide accuracy. Theproposed system has the following features. It is quick, while having negligible errors in calculation. It approximates the curves as polygons. This problem type is defined as a problem category where a two-dimensional irregular shaped item hasto be completely accommodated by a two-dimensional polygon object. This paper mainly addresses the two-dimensional area measuring of irregular shape problem .2. RELEATED STUDY2.1. Pinwheel Mechanism: The international standard for Turner machine is Pinwheel mechanism . In which a driven feedroller coupled with rows of friction driven wheels having pins in their rim. Leather presses the pins in the
pinwheel up down to show the presence or absence of the leather at the desired position thus creating themap of the leather on a paper sheet or on a dial. The area of leather is then calculated from the pin pressrecord as showed in Fig. 1 . Fig. 1: Pinwheel Mechanism: International standard for measuring leather sheet.2.2. Roller Planimeter: Roller Planimeters are commonly used for computing the area of leather sheet in the leather industry.Roller planimeters are attached to wheels that allow unlimited horizontal travel and vertical travel within thelimits of the arm movement. Unlike Pinwheel Mechanism it is not "pinned" down to work area. Rollerplanimeters can roll all over the place without the restriction of an attached base.  The Popular Mechanical planimeters are more economical for leather measurement. These systems areusually of maximum counting capacity of 4 digits (9999). Electronic Planimeters are more accurate and arebased on memory and signaling system and they offer more speed and calculate scale factor automatically . In case of Mechanical planimeter scale factor need to be calculated manually. The scale factor is themultiple of x and y scale parameters. Its accuracy is 0.2% of the measured area.2.3. Vision Based Leather Area Measuring Systems Vision Based leather area measuring systems take images between different points marked on the leathersheet and then extract the area of interest which in the case is leather of out the complete image and at lastarea is measured through pixels to area conversion softwares such as Bersoft image measurement software.Both specialized hardware and Softwares are used in these systems. 3. ANALYSIS Pinwheel, Roller Planimeters and Vision Based leather area measuring machines are all internationallyused machines for measuring surface area of leather. Each of the discussed methods lack to fulfill recentindustrial requirements such as Pinwheel mechanism is international standard but is very slow and is notbased on signaling system . Secondly Roller Planimeters are based on memory and signaling system butthey slow . The last discussed system are based on Vision which are very expensive, slow and needcalibration of individual parts such as camera, variable speed linear rail actuator and others  . In short none off the presently available system fulfills every current industrial requirement which requirea system to be fast, accurate and self calibrated which results as production increase.4. PROPOSED TECHNIQUE Leather sheet is passed through IR transceivers; triggering of which are dependent on presence or absenceof the sheet. This is then to be feed to the microcontroller which accumulates the pattern of the sheet. Thepattern is then displayed on the LCD in terms of number of pieces passed through the IR transceivers.4.1. Functionality: The This process will start at the first pulse from any fist sampled piece of width represented by Ywhich will be high if any IR transceivers connected in „OR logic‟ represented by X1, X2, X3…X7 will behigh and will continue until any of Yn drops to low. As shown in figure Yn represents sampled Length pieceunder observation, whereas X1 - X7 represents width of the section under observation detected by IRtransceivers. Triggering of IR transceiver shows the presence or absence of the leather sheet at the desiredlocation . The system "hold and accumulate" feature measure the area of each segment starting from thefirst sensor to be triggered to the last segment and in last it add up all the segment to calculated the total area.
Fig. 2: Leather sheet placed on sensor array. LED will display the presence or absence of sheet for each length patch. When whole piece is passed,LCD will display the total area of leather piece in Sq inches using mathematical formula stored inmicrocontroller. Sampled time is the time after which controller acquires the data from the microcontroller isto be feed into microcontroller. For monitoring purpose complete Pattern of leather sheet is then transferredto CPU using MAX 232 serial interface.4.2. Block Diagram: Fig. 3: Block Diagram of the Process.4.3. Processes Flow: Fig. 4: Processes Flow.4.4. Variables: X = Width of the section under observation in mm Y = Length of the section under observation mm Z = Area of the section under observation mm2 Ts = Sampling time in seconds S = Conveyer belt speed mm/sec Ns = Number of active sensors As = Sensor footprint in mm4.5. Calculations: Revolution Linear Actual S. No. Frequency (HZ) RPM Motion Value revolution/s (Inches/Sec) (Inches/Sec) 1 10 120 160 120 2 20 240 320 240 3 30 360 500 360 4 40 480 640 480 5 50 600 800 600 Table 1: Frequency of Motor to its equivalent Linear Motion.160 (inches / second) = 4.06400 m / sS = 40.64 mm/secIf the sampling rate is a sample after every second.Yn= S * TsXn = N * As
Total Area = Z = = + + +….Footprint of Sensor:- 5mm 4mmFor Z6: -X6 = No. of triggered sensors * As = 4 * 4 mm = 16mmY6 = S * Ts = 40.64 mm/sec * 1sec = 40.64 mmZ6 = 16mm * 40.64 mm = 650.24 mm2Total Area = Z = Z1 + Z2 + ……+Z295. CONCLUSION: Technique % Error Signaling System Calibration Cost Pinwheel 2 N/A External Low Roller Planimeter 0.2 YES External High Vision Based 3 YES External High Photo-electric 0.04 YES Self Low Table 2 : Conclusion.6. RESULT: The proposed system is very fast as it uses transportation mechanism to measure the area. Secondly, due tothe involvement of only a few moving part the system has less vibration. The accuracy of the system dependsupon the footprint and the distance between the sensors. As the calculations are bit simpler so a lessexpensive controller can easily fulfill the task. The error in system can easily be found using any regularobject of known area such as paper or plastic.7. ACKNOWLEDGMENT: This is to acknowledge the indispensible support and contribution of Air Cdre. (R) Engr. M. KhalidHussain, Dr. Syed Irfan Hyder, Mr. Iqbal Khan, and Mr. Taifoor Safdar in this academic article. Without theadvice, recommendations and motivation of these gentlemen, this paper would not have been possible.8. REFERENCES:  Mr. B. Barker, “Photographs by Enid Sheldon from the 1980s,” http://www.otley.co.uk/gallery/sheldon/industries/leather/index.htm, 24 May. 2008. “Code of Practice for the area measurement of leather by the pinwheel measuring machine” International council ofTanners APRIL 1998. Engineer Supply "http://www.engineersupply.com/ About-Planimeters.aspx", Jan 2006  R. Adil, S.J. Khan "Surface area measurement of leather system based image processing techniques applied to theautomation applications", 2010 The 3rd International Conference on Machine Vision pp 590-592 Dec 2010 R. Muhammad, F. Faizan, M. Shoaib, T. Qadri “Irregular surface area measuring instrument” in 2nd InternationalConference on Education Technology and Computer, v 1, p V156-V159, June 22- 24. K. Zojiro; F. Yasuaki; N. Yoshio; T. Yoshinori; T. Mamoru; Y. Shin “A Study on Approach Speeds of the Handsunder Metal Press Machine Operation” in 45th Conference the Human Factors and Ergonomics Society pp, 1119-1122,2001. Penna, M.A. "Camera calibration: a quick and easy way to determine the scale factor" Pattern Analysis and MachineIntelligence, IEEE Transactions, pp.1240 - 1245 Vol 13, Issue:12 Dec 1991. “Specialty Motions, Inc,” http://www.smi4motion.com/ smi2/solutions / linear-actuatorpackages/variable-speed-controlled-linear-actuator-packages.html, Sept 15, 2010. J.L.Jones, J.W. Farmer, "Area measuring machine", U.S. Patent Office 2356761 serial 353786, August 29, 1944. Allos, Janan E.; Saadallah, Suhail; Hasso, Ezzideen A.,"A Digital Planimeter for Industrial Applications" , IEEETransactions on Industrial Electronics, Volume IE-31 Issue 2 pp.152, 23 April 2007.