INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 5, ISSUE 06, JUNE 2016 ISSN 2277-8616 57 IJSTR©2016 www.ijstr.org Position Control Method For Pick And Place Robot Arm For Object Sorting System Khin Moe Myint, Zaw Min Min Htun, Hla Myo Tun Abstract: The more increase the number of industries in developing countries, the more require labourers or workers in that. To reduce the cost of labour force and to increase the manufacturing capacity of industries, the advanced robot arms are more needed. The aim of this journal is to eliminate the manual control for object sorting system.Robot arm design in this research uses two joints, three links and servo motors to drive. Microcontroller is used to generate required PWM signal for servo motors. In this research the position control of robot arm was designed by using kinematic control methods. There are two types of kinematic control methods which are forward and reverse kinematic methods. In forward kinematic method, the input parameters are the joint angles and link length of robot arm and then the output is the position at X,Y,Z coordinate of tool or gripper. In inverse kinematic, the input parameters are position at X,Y,Z coordinate of gripper and the link length of robot arm and then the output parameters are the joint angles. So, kinematic methods can explain the analytical description of the geometry motion of the manipulator with reference to a robot coordinate system fixed to a frame, without consideration of the forces or the moments causing the movements. For sorting system, Metal detector is used to detect the metal or non-metal. This position control of pick and place robot arm is fully tested and the result is obtained more precisely. Keywords: kinematic analysis, Microcontroller, servo motors, Robot arm, sorting system. ———————————————————— I. INTRODUCTION A robot is an electromechanical device connected with joints and links, driven by motors or actuators, guided by sensors and controlled through a software program, to manipulate and handle parts, tools for preformation various operations in many different kinds of work environment. Following the Karel Capek’s drama, R.U.R. (Rossum’s Universal Robots), in which automatons in human form carried out arduous tasks, robots made their industrial debut in 1960s. Since this advent of robots in the industry, numerous and multifaceted research and development strides in robotics have been witnessed. Also, as the world continues to engage in intense and sophisticated technological operations and activities, and in many specific applications, robot arm has increased significantly.[1] And then, robot arm is very useful in many different application areas such as industry; some dangerous works including radioactive effects. There are four mainly robot configurations such as 1.Cartesian robot, 2. Cylindrical robot, 3.Polar robot or Spherical robot and 4.Joint arm robot or articulated robot. And several types of robot manipulators have been developed in times past; examples of these are the Tomorrow Tool (T3), introduced by Cincinnati Milacron, Inc. in 1974, the Programmable Universal Manipulator for Assembly (PUMA) developed by Victor Scheinman at the pioneering robot company Unimation, the Selective Compliant Articulated Robot for Assembly (SCARA), the AdeptOne robot by Adept Technology, Inc., the Shuttle Remote Manipulator System (SRMS), etc. One of the vitally important functions of a robot manipulator in the industry is a pick-and-place operation, such as, lifting a payload from within its work space, carrying it to a predetermined position and then releasing it. For instance, Sanjay Lakshmi Narayan who worked on[2] ―Position Control of Pick and Place Robotic Arm, which is a 5-DOF articulated robot arm for real-time molding machine operation; Karl Berntorp proposed the application of a mobile robot with kinematic redundancy for future pick-and-place operation in the grocery stores; [3] Binbin Lian showed how the dimensional parameters of a 2-DOF parallel manipulator could be optimized to realize high-performance pick-and-place operation; in order to obtain effective pick-and-place operation, Altuzarra O proposed two design methods for a mechanical drive which would yield an increased end-effector angular range; and Bin Liao et al. carried out an optimal design of a three-degree-of-freedom planar revolute-chain parallel manipulator with a view to improving its operational velocity and accuracy for pick-and-place tasks.[5] The configuration of robot arm in this journal is similar to articulated robot arm which has three revolute joints and irregular workspace .The advantages of articulated robot arm are higher reach from base, useful in continuous path generation, applied to welding operation and reaching the congested small openings without interference. The rest of journal is presented as Section (II) explains Methods using in research and Section (III) show Analytical calculation. After that Section (IV) build system block diagram and next Sections are testing experimental results and observation. Finally, Section (VIII) presents the conclusion of this journal. II. METHOD USING IN RESEARCH Robot kinematics method is the study of the motion (kinematics) of robots. In a kinematic analysis, the positions of all the links are calculated without considering the forces that cause this motion. In the kinematic analysis of manipulator position, there are two separate problems to solve: direct kinematics and inverse kinematics. Robot kinematics is the study of the motion of robotic mechanisms. Since the performance of specific manipulator tasks is achieved through the movement of the manipulator linkages, kinematics is the fundamental importance in robot design and control. A kinematic equation provides the relationship between the joint displacement and the resulting of end effector position and orientation. The problem of finding the end-effector position and orientation for a given set of joint displacements is referred to as the forward kinematics problem. That is, the forward kinematics problem allows one to specify in a unique manner the relationship between the (n x 1) joint vector θ. Normally; the forward Kinematic equation can be obtained from the spatial geometry of the manipulator or by solving certain matrix algebraic equations. [4] The more increase the number of degrees of freedom (n), the more complex kinematic equation becomes. Hence, the required amount of computation to compute the position of end-effectors can become quite large. Direct kinematics is for solving the forward transformation equations to find the location of the gripper in terms of the angles and displacements between the links. Inverse kinematics means for solving the inverse