Novel approach to kinematic analysis and development of a low cost measurement system for a five axis robot

Abstract

Robot manipulators are capable of efficiently executing a variety of tasks with an excellent repeatability but their nominal accuracy is relatively poor due to variation between the nominal robot model and the real robot The absolute accuracy can be improved through robot calibration which is costeffective The measurement system indicates the different types of equipment which is used to collect the series of pose measurements at the tool of the robot Some devices currently used are as follows Laser Tracking system Laser interferometer Co ordinate measuring machines Time of flight devices and camera devices and short range devices like Dial gauge Micrometer and Linear Voltage Differential Transformer In our calibration methodology low cost micro electromechanical systems MEMS based inertial sensors and position sensor can be used for measuring orientation and position of the end effector replacing traditional expensive devices The first step in calibration procedure is to create a kinematic model of the robot links and joints which relates the outputs of the joint displacement to the pose of the end effector The kinematic problem is defined as the transformation from cartesian space to the joint space and vice versa The kinematic model of the Vi Micro system Robot VRT 6 robot is done based on Denavit Hartenberg DH representation The forward kinematics will enable us to determine the position of the end effector if all the joint variables are known The joint variables are the angles between the links in case of revolute joints and link extension in case of prismatic joints The inverse kinematics is also performed to determine joint variables for the given end effector position and orientation The Kinematic model of the VRT6 robot has been validated using Matlab GUI newline