Varol, A., Carabott, V., Vivet, M., Delannoy, P.: Sorting Coins with Different Diameters Through the Use of a Robot, Matik'97, Makine Tasarım Teorisi

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2 2.5. SORTING COINS WITH DIFFERENT DIAMETERS THROUGH THE USE OF A ROBOT ABSTRACT Control Technology is an exiting dynamic interdisciplinary field of study. In recent years, interest in this field and their application in industry has grown day to day. Robots are a part of Control Technology and major parts of a robot are the power supply, the manipulator and the controller. A robot can be controlled using different programming languages. In this study, a fixed robot has been programmed to sort the coins of different allowed diameters. Therefore, a fixed position is defined to feed the machine and the coins are collected according to their sizes. To control of the robot LOGO programming language is used. 1. THE GOAL OF THIS STUDY The aim of this study is to sort 4 kinds of coins according to their diameters namely 20, 25, 30 and 40 mm using Fischertechnik construction boxes [1, 2]. In order to sort coins with different diameters through the use of a robot following parts are necessary: - Motors, switches and Fischertechnik boxes. - A plug light with lens and with stray light cap. - A photoresistor (LDR) with stray light cap. - A potentiometer (LIN) 2. FUNCTIONS AND CONTROL A fixed position is defined to feed the machine with coins of different allowed diameters randomly. Four positions are defined in advanced to collect the coins according to their sizes. The global process for a coin is as follows [3, 4]. 1st stage : Determination of the diameter of the coin 244

3 2nd stage diameter determined during stage 1. : Drop of the coin in the position corresponding to A plug light is mounted in front of a photoresistor making a photocell. The plug light has connection with M4 (light on) while the photoresistor has the connection with switch 8 (E8) on the plugging box. If the light waves a free route between the light and photoresistor then the switch E8 has logical value 1 otherwise 0. There are 3 additional motors lines in use. One of them is used to drive the magnet M1 and the second one is used for the up and down movements of M2 while the third one is used for rotating left and right directions of M3. 8 switches are used to help in controlling the robot. The function of the switches are as follows: E1 E2 E3 E4 E5 E6 E7 E8 Controls the up movement of the magnet in vertical direction. Controls the down movement of the magnet in vertical direction. Controls the position where the metallic coins with 40 mm diameters are collected (P1). Controls the position where the metallic coins with 25 mm diameters are collected (P2). Controls the start position of robot. Controls the position where the metallic coins with 30 mm diameters are collected (P3). Controls the position where the metallic coins with 20 mm diameters are collected (P4). Controls the switch (0-1) corresponding to the photocell. 0 if the ray of light is interrupted. 245

4 1 if no light of the lamp go freely on the LDR A potentiometer is used to determine sizes of coins. After being caught by the magnet the coin is moved between the light and the photoresistor. The needed rotation to have the ray of light disappearing the reappearing is transmitted mechanically to the potentiometer, so the potentiometer gives values which are used to distinguish the diameters of the coins. The value of the potentiometer is defined with a variable named LARGE, and a procedure program with the name ASAF is written. Only one captor is used by the system : EX which measures the value of the potentiometer. 3. PHYSICAL DESCRIPTION The robot has vertical arm on which a horizontal one is mounted to hold the magnet. All movements of the robot are controlled by LOGO program. LOGO is a general purpose artificial language. It is also based on a simple natural syntax, without parenthesis, commas and special characters except the quotation mark ( ) and colon ( : ) [1]. An interface links the computer to the robot and the robot is wired by using a plugging box (Figure 1). 246

5 Figure 1: The picture of a mounted robot for sorting coins 4. THE SCHEMATIC DESCRIPTION OF THE ROBOT Pluging E3 E4 P1 P2 box E2 M2 E1 M3 SP M4 E8 P3 E7 E6 E5 P4 Figure 2. The schematic description of the robot Symbols M1 M2 M3 M4 Remarks Motor 1, left and right turning Motor 2, up and down movement Magnet, take the coins Light on ACTION MOTOR SWITCHE S Left rotating M1 Right rotating M1 Up Movement M2 E1 Down Movement M2 E2 Magnet M3 Light on M4 Position P1 E3 247

6 Position P2 Start position Position P3 Position P4 Photocell E4 E5 E6 E7 E8 5. THE FLOW CHART OF WORK A flowchart of this work is necessary to be successful and to do not waste the time. This flowchart is given in Figure 3. Planning the work Defining the necessary parts Defining of movements of motors, switches, lamps and technical decisions as described in 4 Selection of bricks from Fischertechnik boxes and numbering all of parts Mounting Check the status of the motors and switches, step by step Writing the part software and checking for each step separately Figure 3. The flowchart of the work 6. THE FULL PROGRAM AND THEIR MEANING First two procedures written for intermediate tests : Calibration of the values : TO TES1 MAKE "X 0 REPEAT 10 [MAKE "Y SS DROP MAKE "X SUM :X :Y PR :Y] PR :X / 10 Test of the photocell on E8 : 248

7 TO TES MCW "M4 PR STATUS "E8 TES Last procedure written : continuous work! must be broken by CTRL+PAUSE TO VAROL ASAF DOWN DROP VAROL Procedure that makes the decision ; we must have only 3 separate stacks of coins! TO ASAF MAKE "LARGE 2 * SS IF :LARGE < 210 [P2 STOP] IF :LARGE < 260 [P3 STOP] IF :LARGE < 316 [P1 STOP] MSTOP "M1 Procedure that takes a coin then measures it and gives the result TO SS UP SP DOWN TAKE UP STMEAS OP MEASURE 249

8 Reaching the first edge : start the measuring process TO STMEAS MAKE "AS "RG MCW "M4 REACHVAL 0 MAKE "TT1 EX? After the first edge is reached, reaching the second and give the value of the difference: TO MEASURE REACHVAL 1 MAKE "TT2 EX? OP :TT2 - :TT1 Reaching an edge : from free light to occulted or reverse, with a step by step run on M1 for more precision. TO REACHVAL :N MCW "M1 MSTOP "M1 IF NOT EQUALP STATUS "E8 :N [REACHVAL :N] Basic procedures for the moves : The global variable AS keeps the value of the last move of the robot,then the following to go back to SP (start position) is the inverse... TO P1 MAKE "AS "LF 250

9 MCCW "M1 WATCH "E3 MSTOP "M1 TO P2 MAKE "AS "LF MCCW "M1 WATCH "E4 MSTOP "M1 TO P3 MAKE "AS "RG MCW "M1 WATCH "E6 MSTOP "M1 TO P4 MAKE "AS "RG MCW "M1 WATCH "E7 MSTOP "M1 TO SP IF EQUALP STATUS "E5 1 [STOP] IF EQUALP :AS "RG [MCCW "M1] [MCW "M1] WATCH "E5 MSTOP "M1 TO DROP MCW "M3 MSTOP "M3 251

10 TO TAKE MCCW "M3 TO DOWN IF EQUALP STATUS "E2 1 [STOP] MCW "M2 WATCH "E2 MSTOP "M2 TO UP IF EQUALP STATUS "E1 1 [STOP] MCCW "M2 WATCH "E1 MSTOP "M2 7. CONCLUSION Robots are an important parts of industry in our world today. They play important roles for a rapidly development of a country. Choosing the type of a robot which will be used by teaching and learning as a cognitive tools at a university is also important. Robot should be flexible for basic concept acquisition, to keep contact between reality and the approach of basic modeling and to train students in inductive approaches to make them imaginative. 252

11 REFERENSES [1] Delannoy, P.: Technical Guidelines For Activities Based On LOGO, Med-Campus Program, Cog-tech. 94 [2] Manipulator Assembling Handbook, LIUM, Loboatoire d Informatique, Université du Maine, B.P LE MANs [3] Delenoy P., Martial V.; Specifications for Cubsort, A Sorting Machine For Cubes, Cognitive TECHnologies for Education, Med Campus, 1994 [4] Vivet, M.; WHICH Goals and WHICH Pedagogical Attitudes Should one use with Micro-Robots in a Classroom, Med-Campus Program; 1-13 August 1994, Side 253

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