Accuracy assessment of the modern industrial robot

Abstract

The main drawback to programming robots offline lies in the poor accuracy of the robot. Robots are mainly programmed using the traditional teach and repeat method of programming which requires only good repeatability. As a result robots are manufactured with this in mind. Little is done to improve or even quote figures for the accuracy, which is generally regarded as being poor. A trial has been conducted on three modern serial linkage robots to assess and compare robot accuracy. Using a laser interferometry measurement system each robot has been measured in a similar area of its working envelope. The results and conclusions from this trial show that compared to older robots the accuracy can be remarkably good though it is dependent on a calibration process which is far from robust.

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

“…In the article [26], the authors emphasize that the main disadvantage of programming robots in offline mode is their low accuracy. They indicate that industrial robots are mainly programmed using methods that only require good repeatability.…”

“…The factors of accuracy of positioning are influenced by factors described more widely, among others, at work [21], such as positioning errors and trajectory rendering (for example due to deformations caused by the temperature, inaccuracies of control system signals or inertial forces). According to the PN-ISO 9283 standard, the accuracy of unidirectional positioning (AP) describes the deviation between the set position and the average value of the actual positions when reaching the set position from the same direction [26]. Repeatability of the manipulator is the ability to move the effector tip to the same, set point in space.…”

“…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].…”

Uncertainty measurement with the kinematic telescopic bar during industrial robot inaccuracy tests

“…The QC20-W Ballbar diagnostic system, dedicated to CNC machines, is used in this study. Although the use of the QC20-W Ballbar system for CNC machine tools is very wide [1,4,[8][9][10], in robots it is applied on a much lower scale [2,[11][12][13][14]. Some authors [11,12] compare the accuracy of selected industrial robots with the use of a ball-shaped, telescopic kinematic bar.…”

Industrial Robot Repeatability Testing With High Speed Camera Phantom V2511

“…Although interferometers are characterised by much higher precision of measurement, their application in multi-axis articulated industrial robots is limited. This is predominantly on account of their limitations concerning linear measurements in one specified direction [5,7,17,20]. Similarly, in the case of ballbar instrumentation, the measurement can be taken only in a defined plane.…”