Calibration of robot tool centre point using camera-based system

Abstract

Robot Tool Centre Point (TCP) calibration problem is of great importance for a number of industrial applications, and it is well known both in theory and in practice. Although various techniques have been proposed for solving this problem, they mostly require tool jogging or long processing time, both of which affect process performance by extending cycle time. This paper presents an innovative way of TCP calibration using a set of two cameras. The robot tool is placed in an area where images in two orthogonal planes are acquired using cameras. Using robust pattern recognition, even deformed tool can be identified on images, and information about its current position and orientation forwarded to control unit for calibration. Compared to other techniques, test results show significant reduction in procedure complexity and calibration time. These improvements enable more frequent TCP checking and recalibration during production, thus improving the product quality.

A Framework for Inclusion of Unmodelled Contact Tasks Dynamics in Industrial Robotics

“…Another aspect required for the completion of the kinematic model is the identification of DH parameters of the end effector, i.e., tool. For the purpose of automatic parameter identification, the TCP parameters can be determined using a procedure based on the analysis of images of the tool from two orthogonal planes [ 32 , 33 ], since the solution can deliver parameters directly in the form of a homogenous transformation matrix, making it easier to include in the overall model. However, any other procedure can be used as well.…”

“…The approach proposed in this paper relies on recently developed modifications of the Dynamic Time Warping algorithm [ 13 ] together with algorithms for automatic identification of kinematic parameters of an industrial robot [ 32 , 33 , 34 , 35 , 36 ] to enable a reliable and applicable solution for inclusion of intentional dynamics of a robot’s end effector. Using the robot’s kinematic model, it is possible to determine projection of intentional contact forces onto individual axes of the robot and comparing them with expected values enables distinction between phases of normal operation and erroneous states, including collisions, load manipulation anomalies, and improper alignment.…”

Automatic Calibration of the Adaptive 3D Scanner-Based Robot Welding System

“…The method is based on detecting the contact between a robot tool and a flat, electrically conductive plate. Alternatively, an optical approach using external sensors ( Gordić and Ongaro, 2016 ; Luo and Wang, 2018 ), or a profilometer itself, can be used ( Li et al, 2011 ; Liska et al, 2018 ). However, these methods require special algorithms for recognizing the reference shape and simultaneous movement of the robot around this object.…”

Robust auto tool change for industrial robots using visual servoing

“…However, some solutions based on computer vision can be found in literature to improve the process of automatic robot tool change. For instance, a calibration method is presented in (Gordic & Ongaro, 2016) to correct image distortion in order to obtain an accurate location of the tool center point. Similarly, other works (Motta, de Carvalho, & McMaster, 2001) (Du & Zhang, 2013) (Yin, Ren, Zhu, Yang, & Ye, 2013) proposed techniques for modeling and performing robot calibration processes using a vision-based measurement system.…”