A novel TCF calibration method for robotic visual measurement system

Yin, Shi; Guo, Yin; Ren, Yongjie; Zhu, Jigui; Yang, Shu; Ye, Shenghua

doi:10.1016/j.ijleo.2014.08.049

Cited by 20 publications

(5 citation statements)

References 12 publications

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“…The self-calibration is achieved by means of the definite geometric characteristics of the external reference block (Filion, 2018). For robots that have different types of sensors, reference identifications can also be measured by force sensors or cameras Yin, 2014). The above advanced calibration method uses different high-precision calibration devices with which the robot can realize self-calibration through teaching.…”

Section: Introductionmentioning

confidence: 99%

On-line self-calibration method for unattended manipulators based on Gaussian motion model and visual system

Tang

Zhang

2021

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Purpose For some special manipulators such as the ones work at the space station, nuclear or some other unmanned environments, the overload, collision, vibration, temperature change or release of the internal stress would affect the structural parameters. And thus the operation precision might constantly decrease in long-term use. In these unmanned environments, the unattended manipulators should calibrate itself when they execute high precision operations or proceed self-maintenances. The purpose of this paper is to propose an automatic visual assistant on-line calibration (AVOC) method based on multi-markers. Design/methodology/approach A camera fixed on the end of the manipulator is used to measure one to three identification points, which forms an unstable multi-sensor eye-in-hand system. A Gaussian motion method which combines the linear quadratic regulator control and extended Kalman filter together is proposed to make the manipulator track the planned trajectories when its inaccurate structural parameters form uncertain motion errors. And a Monte-Carlo method is proposed to form a high precision and stable signal acquisition when the visual system has measurement errors and intermittent signal feedback. An automatic sampling process is adopted to select the optimal measurement points basing on their variances. Findings Data analysis and experiment results prove the efficiency and feasibility of the method proposed in this paper. With this method, the positioning accuracy is largely promoted from about 2 mm to 0.04–0.05 mm. Originality/value Experiments were carried out successfully on a manipulator in a life sciences glove box that will work at the Chinese space station. It is a low cost and efficient manipulator calibration method. The whole autonomic calibration process takes less than 10 min and requires no human intervention. In addition, this method not only can be used in the calibration of other unmanned articulated manipulator that works in deep ocean, nuclear industry or space but also be useful for the maintenance work in modern factories owing a lot of industrial robots.

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Section: Introductionmentioning

confidence: 99%

On-line self-calibration method for unattended manipulators based on Gaussian motion model and visual system

Tang

Zhang

2021

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“…This requires skilled manual interactions from the user, although the calibration object is still relatively simple. On the other hand, there are many examples of more complicated artefacts being used, such as a ball shaped object [14][15][16][17][20][21][22], disk shaped objects [23], objects with multiple stepped surfaces [24] or pin shaped objects [25]. The advantage of the more complex artefacts is that mostly the calibration is performed automatically, meaning the user interaction requirements are greatly simplified; however, the increased complexity of the artefact means it is harder to manufacture and more expensive.…”

Section: Introductionmentioning

confidence: 99%

Robust hand-eye calibration of 2D laser sensors using a single-plane calibration artefact

Sharifzadeh

Bíró

Kinnell

2020

Robotics and Computer-Integrated Manufacturing

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When a vision sensor is used in conjunction with a robot, hand-eye calibration is necessary to determine the accurate position of the sensor relative to the robot. This is necessary to allow data from the vision sensor to be defined in the robot's global coordinate system. For 2D laser line sensors hand-eye calibration is a challenging process because they only collect data in two dimensions. This leads to the use of complex calibration artefacts and requires multiple measurements be collected, using a range of robot positions. This paper presents a simple and robust hand-eye calibration strategy that requires minimal user interaction and makes use of a single planar calibration artefact. A significant benefit of the strategy is that it uses a low-cost, simple and easily manufactured artefact; however, the lower complexity can lead to lower variation in calibration data. In order to achieve a robust hand-eye calibration using this artefact the impact of robot positioning strategies is considered to maintain variation. A theoretical basis for the necessary sources of input variation is defined by a mathematical analysis of the system of equations for the calibration process. From this a novel strategy is specified to maximize data variation by using a circular array of target scan lines to define a full set of required robot positions. A simulation approach is used to further investigate and optimise the impact of robot position on the calibration process, and the resulting optimal robot positions are then experimentally validated for a real robot mounted laser line sensor. Using the proposed optimum method, a semi-automatic calibration process, which requires only four manually scanned lines, is defined and experimentally demonstrated.

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“…This can be done only after stopping the production, and the result is dependent on operator skill. In Yin, et al (2014), this method is partially subjected. As mentioned above, they evaluated the visual sensor as a robot end function and performed TCP calibration.…”

Section: Introductionmentioning

confidence: 99%

High precise and zero-cost solution for fully automatic industrial robot TCP calibration

Çakır

Deniz

2019

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Purpose The purpose of this study is to present a novel method for industrial robot TCP (tool center point) calibration. The proposed method offers fully automated robot TCP calibration within a defined cycle time. The method is applicable for large-scale installations due to its zero cost for each robot. Design/methodology/approach Precise and expensive measuring equipment or specially designed reference devices are required for robot calibration. The calibration can be performed by using only one plane plate in this method, and the calibration procedure is defined step by step: the robot moves to the target plane position. Then, the TCP touches the plane and the actual robot configuration is recorded. Then robot moves back into position and the same step is repeated for a new sample. Alternatively, the robot can be stationary and the plane can be moved towards the robot TCP. TCP is calculated by processing the difference of the contact points recorded at different positions. The process is fully automated. No special equipment is used. The calculations are very simple, and the robot controller can easily be realized. Findings The conventional manual robot TCP calibration process takes about 15 min and takes more time in case of the high accuracy. The proposed method reduces this time to less than 3 min without operator support. Practical tests have shown that TCP calibration can be performed with 0.1-0.6 mm of accuracy. This solution is an automated process and does not require special installation and it also has approximately zero cost. For this reason, this study recommends using the proposed solution widely in areas where even one or hundreds of robots are located. Research limitations/implications In this study, the data were directly taken from the robot controller without using any special measuring equipment. The industrial robot used in the tests has no absolute calibration. The classical “four-point method” was used for reference TCP data. It is the initial acceptance that this process conducted with extreme care and by using a needle-tipped tool will not produce exact values. It was observed that deviation of the TCP from a fixed point in reorient motions was not more than 0.5 mm. This method has been validated for different bits. The pilot works for different robot applications in Ford Otosan Gölcük Plant have been completed and dissemination has started. Originality/value Although the approach uses is clear and simple, it is surprising that the calculation of TCP using plane equations has so far not been mentioned in the literature. The disadvantage of using either fixed point or sphere as a reference is that the TCP cannot automatically guide to the target. This problem was overcome with the use of a larger target plane plate and the process was fully automated. The proposed method can be widely used in practical applications.

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A novel TCF calibration method for robotic visual measurement system

Cited by 20 publications

References 12 publications

On-line self-calibration method for unattended manipulators based on Gaussian motion model and visual system

On-line self-calibration method for unattended manipulators based on Gaussian motion model and visual system

Robust hand-eye calibration of 2D laser sensors using a single-plane calibration artefact

High precise and zero-cost solution for fully automatic industrial robot TCP calibration

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