Automation of Object Sorting Using an Industrial Roboarm and MATLAB Based Image Processing

Transcription

1 Automation of Object Sorting Using an Industrial Roboarm and MATLAB Based Image Processing Prof. D. B. Rane 1, Gunjal Sagar S. 2, Nikam Devendra V. 3, Shaikh Jameer U. 4 Department of Electronic Engineering, P.R.E.C. Loni, Savitribai Phule Pune University, India Abstract In recent years the importance of process automation has been increased as the growth of any industry is directly depends on it. For precise output and accuracy of industrial process robots with sophisticated sensors are used. In modern era application of image processing in many industrial processes has proven its prevalence and dominance. This paper present color based object sorting system which uses the machine vision and the operations in image processing. The proposed work is to develop compact, easy and accurate objects sorting machine using real time color image processing method to continuously evaluate and inspect the color deformity using camera based machine vision. After the evaluation of quality the object is sorted into predefined quality groups with the help of pick and place roboarm. If the inspected object fails to follow quality norms it is rejected out by the system. The proposed system will have broad areas of applications in many fields where continuously evaluation of the quality is required. Keywords Roboarm, image processing, machine vision, webcam, MATLAB, servo motor. I. INTRODUCTION Colour based sorting is extensively used in many industries for sorting purposes to ensure the quality of the object is up to the mark e.g. Food processing industries, pharmaceutical industries, automotive industries, agriculture industries. Such sorting reduces the human effort, labour cost and also time of operation. Most of errors caused by humans due to their limited potential are eliminated due to use of automated system supported by colour based sorting using image processing. The field of robotics is growing with a faster rate in recent years and many advanced technologies are coming up with their own advancements. Robots due to its ease of operation used in domestic, industrial and military purposes thus the horizons of this field are increasing day by day. The roboarm used in this project work is used to sort the objects moving on conveyor belt depending upon its colour properties into the predetermined categories. This robotic arm is controlled by the controller used i.e. ARM 7 which is a 32 bit microcontroller having RISC architecture. This controller is programmed to move the dc and servo motors used in roboarm. The roboarm is manufactured using aluminium brackets which are durable and lightweight. The gripper is used to hold object which is fitted at the tip of the roboarm. The software development is the vital task in the proposed project development. The software is entirely coded in MATLAB to check the colour of the object used for sorting purpose. The work in the paper is considered to sort objects such as apple depending on its attributes such as colour. Thus by using fully automated system the time required for the sorting process is reduced to the great extent, so proposed system is fast, accurate, economical, robust and cost efficient. Objectives of the project: 1. To sort objects depending upon the colour. 2. To provide automation to the process using robotic arm. 3. To analyse the quality of the object. 4. To design easy and simplified operational system. 5. To count and display count of the object. 187

2 Camera PC with MATLAB RS232 IR sensor Power Supply II. BLOCK DIAGRAM LCD ARM 7 Driver Conveyor Belt Driver Pulley Servo Motor Idler Pulley Rectifier Unit Central Power Supply Unit Two types of power supply are required to drive this system. One is used to drive ARM processor and other is used for driving DC motor. ARM7 processor kit is interfaced with PC using RS232 cable. Two pair of IR sensor are used to detect of object at two different position on the conveyor belt. Roboarm is most and foremost requirement of the system. Here we are using 4 axis roboarm. It moves up-down and right-left. Roboarm is constructed using five servomotors. Out of these five servomotors one is used at base, two at middle and two at the arm of the roboarm. Camera is placed at exactly centre of the conveyor belt. B. Object Placement: III. FLOW CHART AND WORKING It is first part of the system in that all objects which we have to be sort are placed on the conveyor belt. We have taken object as fruit in that an apple. Hence we have to place different size, shape and colour apples on the conveyor belt. Object placement should be done as one apple get sorted after that another apple is placed on the conveyor belt. After placing an apple on the conveyor belt then start conveyor belt for further processing. Block Diagram Description: Fig. Block Diagram at control room. ARM processor is the heart of the entire system and used for data analysis and storage. It will capture the all the answers feed by users and will do the comparison with standard answers enter by system operator. There various modules are connected to the system are camera, two pair of IR sensor, two DC motor, five servomotor, conveyor belt, display module, power supply module. Camera is input sensor which is connected to PC using USB cable. Camera is used to capture real time image of object. There is PC with MATLAB software is connected to ARM processor by using RS232 cable. LCD display is connected to ARM to display object count and message like object is rejected or object is ok. Driver IC is driving servomotor. There are two DC motors which are used to drive conveyor belt. The conveyor motor receives power and signal from the central supply through rectifier and control circuit. The control circuit consisting of a potentiometer will allow the user to manually control the speed of conveyor belt by the regulatory knob. Polyester is used as a belt material. A conveyor belt consists of two or more pulleys, with a continuous loop of material the conveyor belt that rotates about them. Out of these two DC motors one is used as driver pulley and other is used as idler pulley. C. Capture Image: When an apple placed on conveyor belt is cuts first IR sensor pair. Then conveyor belt is stop moving and takes stable position. The camera used in this case will be overhead and it will take the snapshot of the object for Colour sensing purpose. With the help of camera real time image of an apple is taken. This image should be good quality and which is send to PC with MATLAB software. D. Image Processing: Important terms related to image processing Pixel: Pixel is the building blocks of an image. In other words, a pixel is the smallest possible image that can be detected on your screen. Binary Image: An image that consists of mainly black and white pixels. Grey scale Image: It contains intensity values ranging from a minimum (absolute black) to a maximum (absolute white) and in between varying shades of grey. Typically, this range is between 0 and 255. Colour Image: An image is composed of the three primary colours, Red, Green and Blue. Hence is called as RGB image. 188

3 RGB value: All colours which we see around us can be made by adding red, blue and green components in varying proportions. Hence, any colour of the world can uniquely be described by its RGB value. A. Flowchart: START Initialize DC motors, Servo motors, IR sensor, Camera, LCD. Start conveyer belt Is IR cut? Stop conveyer belt Capture real time image of object Verify object using Image processing Is object OK? Yes Yes No No Which stands for Red, Blue and Green values. This triple colour has each value ranging from 0 to 255, with 0 obviously meaning no component of that particular colour and 255 meaning full component. For example, pure red colour has RGB value [ ], pure white has [ ], pure black has [0 0 0] and has RGB value [ ]. Representation of an Image in MATLAB: An image in MATLAB is stored as a 2D matrix (of size m x n). Where each element of the matrix represents the intensity of light/colour of that particular pixel. Hence, for a binary image, the value of each element of the matrix is either 0 or 1 and for a grey scale image each value lies between 0 and 255. A colour image is stored as an m x n x 3 matrix where each element is the RGB value of that particular pixel. You can consider it as three 2D matrices for red, green and blue intensities. In this total processing we are finding the fruit is good quality or not. E. Roboarm: It is basically 4 axis roboarm. This is used to send an apple to different position. If apple is good quality then fruits are get down at trolley at the end of the conveyor belt. If apple is bad quality then second IR sensor pair is get activated. When an apple cuts second IR pair then conveyor belt gets stop and roboarm is get activated. Then it keeps an apple at its desired location which we have set. It is a type of mechanical arm, usually programmable, with similar function to a human arm. The arm may be the sum total of the mechanism or may be part of a more complex robot. The links of such a manipulator are connected by joints allowing either rotational motion or translational displacement. There are five servomotors are used for roboarm. Active second IR pair Run conveyer belt When second IR cut then stop conveyer Activate ROBOARM pick rejected object by ROBOARM And placed at desired location Run conveyer belt Put OK object at trolley Fig. A four axis roboarm. STOP 189

4 F. Servomotors: Servomotors are nothing but DC motors. Servomotors have built in gearing system and feedback loop control circuitry. These motors do not require any type of driver circuitry. When the shaft of the motor is at the desired position, power supplied to the motor is stopped. If not, the motor is turned in the appropriate direction. The desired position is sent via electrical pulses through the signal wire. The motor's speed is proportional to the difference between its actual position and desired position. So if the motor is near the desired position, it will turn slowly, otherwise it will turn fast. This is called proportional control. This means motor will only run as hard as necessary to accomplish the task at hand Servomotors have rotary actuators that allow precise angular position. There are five servomotors used for roboarm. 1. Industry: Object sorting roboarm can be used in food processing industries to sort the fruits depending upon their colour, dimensions and weight. 2. Medical: Robotic arms are used in telesurgery and also helpful in precision surgeries. 3. Hazardous environments: roboarm can be used in environments such as coal mines, radiation places which is either hazardous or dangerous to access. 4. Defence: Roboarm can be used to defuse the bombs. 5. Roboarm can be used in space exploration programs. VI. FUTURE SCOPE The proposed system will be a demo version, so for a large scale production the number of robotic arms, cameras and length of conveyor system can be modified. Advance design of robotic arm can be further used to pick large and heavy objects and sort them effectively. Generally image capture is a big challenge as there is a chance of high uncertainty due to the external lighting conditions. Same way while collecting object from conveyor system by a roboarm there is variation in the weight and size of a object so further design can be modified so fruits can be collected stably. Speed and efficiency of a system can be further improved by using ARM9 or ARM11 processor for the same purpose. Automatic Trolley system can be designed to guide the sorted objects to their desired locations. Fig. Servomotor IV. ADVANTAGES 1. High efficiency 2. High speed of operation. 3. High precision: margin of error can be reduced to great extent. 4. High degree of intelligence. 5. Low failure rate with long life. 6. Reliable operation and maintenance. 7. Fully automatic operation. V. APPLICATIONS The robots find numerous applications in industrial, domestic, medical, pharmaceutical, and hazardous environment where there are threats to human life. Some major applications given as follow: VII. CONCLUSION The sorting machine sorts the objects depending upon the colours of the objects successfully with the help of the roboarm and MATLAB program in image processing. The USB webcam serves as an eye of the system which captures the real time image of the objects. The roboarm picks the faulty quality object and places it at predefined place, while good quality object continues its motion on conveyor belt and finally drops into object carrier system. The LCD displays the object count with the status about the quality of the object. The servomotors used in the roboarm plays the vital role as control movement of the roboarm wholly depends control signal given to servo motor. Hence to operate the system accurately the synchronization between IR sensors, dc motors of the conveyor belt and roboarm is very essential. 190

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