On the Accuracy, Repeatability, and Degree of Influence of Kinematics Parameters for Industrial Robots

Abstract

In this article, we discuss industrial robot characteristics of accuracy and repeatability. The factors that affect these characteristics are identified, and an error tree is developed. Subsequently, the accuracy and repeatability are investigated utilizing the Denavit-Hartenberg kinematics parameters, the homogeneous transformation matrix, and the differential transformation matrix theory, and corresponding measures are developed. The formulation indicates that the influence matrices associated with joint variables are constant. A new measure called degree of influence is established that qualitatively assesses the relative contribution of each kinematic parameter variation to the accuracy and repeatability of rigid manipulators. The developed formulation provides for easy evaluation of the degree of influence measures for rigid manipulators in either numerical or symbolic form. A numerical example is included in which the degree of influence of the kinematics parameters for an articulated manipulator, PUMA 560, are evaluated and analysed.

Testing of an industrial robot’s accuracy and repeatability in off and online environment

“…In order to achieve the maximum efficiency and reliability of automated and robotic production lines, numerous scientific studies are carried out aimed at both the development of technical means themselves, as well as methods for their programming and exploitation [1,2,4,5,8,10,11,13,18]. In the case of industrial robots, the accuracy and repeatability of positioning are extremely important features affecting their operation [3,6,7,12,19,21,22,26]. Therefore, research is conducted to improve the existing state of operation of this type of technical means, as well as to improve the measurement methods of their parameters [7, 9, 14-17, 20, 23, 24].…”

A Novel Optimal Design of Measurement Configurations in Robot Calibration

“…Sufficiently high end-effector repeatability is a necessary condition for robot calibration, and in general, the precision of the absolute positioning is lower; for example, for a robot with a repeatable positioning accuracy of ±0.05 mm, the absolute positioning accuracy can only reach 2∼3 mm [15]. The factors influencing the end-effector repeatability include sensor noise of joint angles measurement, backlash caused by gear gaps, change of temperature, and other random factors.…”

Influence of the Localization Strategy on the Accuracy of a Neurosurgical Robot System

“…Although repeatability, defined as the ability of the robot to return to the same position and orientation, is an important feature in medical robotics, absolute accuracy is more significant since the robot is sent to arbitrary target positions and orientations. Absolute accuracy of a robot is defined as its ability to move to a desired position in the threedimensional (3D) space with respect to a reference frame [2] [3]. Accuracy of a robot can also be defined as a measure of difference between the calculated position and the real position of the robot.…”