A New Fixed Axis-Invariant Based Calibration Approach to Improve Absolute Positioning Accuracy of Manipulators

Abstract

This paper studies the calibration of industrial robots. Aiming at the problems of cumbersome industrial robot modeling and poor calibration effects, this paper proposes a new calibration method for determining the DH frame and DH parameters of industrial robots by measuring first and modeling afterwards. Firstly, the theory of Fixed Axis-Invariant is proposed, the Axis-Invariant is determined based on dual-vectors, and the origin of Fixed Axis-Invariant is determined by intersection obtained through the projection from one measuring point to the Axis-Invariant. Secondly, a method for solving the D-H frame and D-H parameters of industrial robots based on Fixed Axis-Invariant is proposed. Then, combined with laser tracker and industrial robot control software for secondary development, the developed software can be used to automatically measure and obtain the D-H frame and D-H parameters of industrial robot. Finally, compared with other calibration methods, it can be seen that the calibration method based on Fixed Axis-Invariant proposed in this paper can obtain better results. It can improve the absolute positioning accuracy of industrial robots to less than 0.28 mm, which can solve the problems of cumbersome industrial robot modeling and poor calibration effects.

A Novel Explicit Canonical Dynamic Modeling Method for Multi-Rigid-Body Mechanisms Considering Joint Friction

“…All the vectors and matrices used in the formulae in this paper are shown in bold italics. To improve the calibration accuracy of the structural parameters of multi-body mechanisms and better control multi-body mechanisms, we propose a natural reference system establishment method based on the axis-invariant [51]. A schematic and the natural reference system of the 6-DOF manipulator built in our laboratory are shown in Figure 2.…”

“…In this paper, a novel modeling approach based on explicit dynamic modeling theory (created and developed in [22,23,[49][50][51][52]) for multi-rigid-body mechanisms with joint friction is presented. Based on the explicit dynamic modeling theory we have proposed, the constraint force equations required for joint friction modeling are established and improved, and two joint friction models are developed.…”

Online Measuring of Robot Positions Using Inertial Measurement Units, Sensor Fusion and Artificial Intelligence

“…Next, the error is calculated from measured points and the desired nominal coordinates. In this case, the classic calibration method involves the development of a kinematic model with error parameters that is supposed to accurately describe the real robot position [18], [19]. In the online calibration process, the kinematic model in the controller is adjusted while the robot operates, without the need to suspend its operation to perform the calibration due to natural wear and maintenance stops or tool changes.…”

Kinematic calibration and feedforward control of a heavy-load manipulator using parameters optimization by an ant colony algorithm

“…They then designed a multichannel feedforward controller to compensate for the trajectory tracking errors from different sources [29]. Other scholars have proposed other solutions [30][31][32]. However, few studies have paid attention to the rounding error of the robot servo control process.…”