Estimation of Error in Determining the Centers of Rotation of Links in a Kinematic Chain for Industrial Robot Calibration Techniques

Abstract

621.865.8.001.5 and E. V. RomashWe have analyzed the Kasa and Levenberg algorithms for estimating the error in determining the center of rotation of links in a kinematic chain of an industrial robot. We develop recommendations for the initialization of calibration techniques for commercially produced industrial robots using a laser coordinate-measuring system. Keywords: industrial robot calibration, laser tracker, centers of degrees of freedom, nonlinear least squares method.Currently, in mechanical engineering there is an increasing demand for quality products having a complex geometric shape. In a number of machining operations, such as shaped processing, drilling and deburring, the manufacture of these products requires orienting tools in a special way. To do this, it is advisable to use robotic technological complexes (RTC), which, being fl exible manufacturing systems in comparison with multi-axis machining centers, have a signifi cantly lower cost [1,2]. However, RTC industrial robots provide lower precision. Improving precision is a real challenge, according to [3].Correct calibration is the primary basis for accurate RTC performance characteristics. Any calibration of an industrial robot includes a procedure for determining the actual values of control parameters and their communication to the control system (control model). Analysis of the research over the last 5 years shows that the problem of developing the methodology for this operation has received insuffi cient study [4][5][6][7][8][9][10][11][12][13][14][15][16]. This article discusses the fi rst stage of calibration, namely, the method of determining the actual values of the coordinates of the centers of rotation of the links in the kinematic chain of an industrial robot -centers of the degrees of freedom (DF). Since DF is a connection of two links enabling transfer to one of them of the control coordinate and including the drive, a motion-transmitting link, then the center of the DF is a point belonging to the axes of rotation of the links [17].

The comparison of the process of manual and robotic positioning of the electrode performing radiofrequency ablation under the control of a surgical navigation system

“…For convenience, the results were tabulated ( Table 1). The successful application of robots in such operations is linked to the quality of their preliminary calibration [26][27][28][29] .…”

Comparative experimental assessment of the accuracy of nanosecond laser surgery of the oral cavity when the instrument is moved by a robotic complex and a surgeon

“…The Leica Laser Tracker LTD8 coordinate measuring machine from Leica (Germany) was used to measure coordinate points during functional movements and typical motion paths (4).…”

“…The results of the development of industrial robotics are reflected in mechanical design, kinematics, control algorithms and programming. Researchers in [4] actively improve the approaches associated with improving the accuracy of positioning of the robots. Currently, these developers are also working on such parameters of robots as adaptability, in which the use of sensory information makes it possible to respond to changing conditions, and autonomy -the ability to perform tasks without human observation.…”

Geometrical Approach for Industrial Robot Axis Calibration Using Laser Tracker

“…During identification of the industrial robot Gelios 20 geometrical parameters [10], after calibration of joint coordinate zero offsets the non-perpendicularity of the 5 th and 6 th axes was found. The angle between those axes is 89,912˚.…”

“…The method of CPA-analysis is used for parameters identification [8,9], that allows to determinate the industrial robot joint axes position. Error evaluation of joint axes centers determination was investigated in [10].…”