Elasto-geometrical error and gravity model calibration of an industrial robot using the same optimized configuration set

Deng, Kenan; Gao, Dong; Ma, Shoudong; Zhao, Chang; Lu, Yue

doi:10.1016/j.rcim.2023.102558

Cited by 21 publications

(6 citation statements)

References 52 publications

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“…Figure 11 a shows a scatter plot of position errors before and after calibration at different points, with a noticeable reduction in error after calibration, signifying an improvement in accuracy post calibration. Figure 11 b illustrates a histogram of the frequency of position errors, comparing our method with three others: MDH [ 31 ], NTM [ 27 ], and RFCM [ 17 ]. Our method demonstrates fewer occurrences of higher errors, with the majority of errors congregating towards the lower end of the scale.…”

Section: Calibration Experiments Of Kinematic and Joint Compliance Modelmentioning

confidence: 99%

“…The robot compliance model focuses on the elasticity of the materials constituting the robot, addressing deformation errors under applied forces [15,16]. Due to its own weight and external loads, the robot experiences structural deformation in its links and joints [17]. Current research on the joint stiffness modeling of six-degree-of-freedom robots mainly analyzes deformations in joints 2 and 3, establishing simplified linear torsion spring models [18].…”

Section: Introductionmentioning

confidence: 99%

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Kinematic and Joint Compliance Modeling Method to Improve Position Accuracy of a Robotic Vision System

Ye,

Jia,

Wang

et al. 2024

Sensors

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In the field of robotic automation, achieving high position accuracy in robotic vision systems (RVSs) is a pivotal challenge that directly impacts the efficiency and effectiveness of industrial applications. This study introduces a comprehensive modeling approach that integrates kinematic and joint compliance factors to significantly enhance the position accuracy of a system. In the first place, we develop a unified kinematic model that effectively reduces the complexity and error accumulation associated with the calibration of robotic systems. At the heart of our approach is the formulation of a joint compliance model that meticulously accounts for the intricacies of the joint connector, the external load, and the self-weight of robotic links. By employing a novel 3D rotary laser sensor for precise error measurement and model calibration, our method offers a streamlined and efficient solution for the accurate integration of vision systems into robotic operations. The efficacy of our proposed models is validated through experiments conducted on a FANUC LR Mate 200iD robot, showcasing notable improvements in the position accuracy of robotic vision system. Our findings contribute a framework for the calibration and error compensation of RVS, holding significant potential for advancements in automated tasks requiring high precision.

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Section: Calibration Experiments Of Kinematic and Joint Compliance Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Kinematic and Joint Compliance Modeling Method to Improve Position Accuracy of a Robotic Vision System

Ye,

Jia,

Wang

et al. 2024

Sensors

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“…They used measurements within the entire joint space to identify the model parameters and validated the robot model in a cube with a side length of 0.7m. A similar approach was proposed by Deng et al [22], which combined a kinematic and joint compliance model. They used a two-step method based on sequential floating forward selection to find the optimal set of robot configurations for parameter identification.…”

Section: ) Kinematic Calibration and Joint Error Compensationmentioning

confidence: 99%

Compensation of Geometric, Backlash, and Thermal Drift Errors Using a Universal Industrial Robot Model

Sigron,

Aschwanden,

Bambach

2024

IEEE Trans. Automat. Sci. Eng.

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In order to facilitate the use of articulated robots for complex industrial applications, methods to improve the absolute positioning accuracy are needed. This work introduces a robot-independent calibration procedure that allows to compensate for geometric and backlash errors as well as for thermal drift. To this end, a unifying robot model is introduced based on the product of exponentials formula that complies with the requirements of the calibration process. The model is able to represent any kind of serial kinematic chain, which guarantees universal applicability. The full parameter identification is performed simultaneously based on a single data set containing all modeled effects. The individual modeling approaches have been verified experimentally using two different industrial robots. The positioning accuracy could be improved to industrial standards within the selected workspace. More precisely, the average position error was reduced from 3.39mm to 0.13mm for a KUKA KR-16 robot and from 0.36mm to 0.12mm for a KUKA KR-30 within all operating conditions. The generalizing property of the thermal expansion model was assessed by compensating the thermal drift for an unseen and fundamentally different thermal excitation of the robot structure, limiting the thermally induced positioning error to 0.1mm.Note to Practitioners-This paper was motivated by the fact that modern industrial robots are known to be able to execute the same movement repeatedly with high precision but are unable to visit an arbitrary sequence of commanded positions with high accuracy. In practice, this means that each pose of a given process must be taught to the robot by moving it to the target position and storing the robot's posture. To overcome this limitation, this work introduces a robot model that is able to express the geometric properties of the robot, as well as the joint backlash and the thermal expansion of the robot links. The model parameters must be evaluated based on a measurement sequence of 300-400 robot poses during the heating up of the robot structure. Therefore, depending on the size of the robot, the calibration procedure takes one to four hours. To use the thermal expansion correction, realtime measurements based on four low-cost temperature sensors are used. Since the modeled robot characteristics only change due to long-term wear, there is no need to repeat the calibration procedure frequently. The introduced calibration method allows to move the robot to arbitrary positions or along arbitrary trajectories within the employed workspace, with a positioning error of less than 0.2mm. This facilitates non-repetitive pick and place, assembly, or additive manufacturing tasks.

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“…However, the absolute positioning accuracy of the robots itself is relatively low, making it challenging to meet the machining precision requirements. In addition, due to its low stiffness, it is easy to produce machining deformation, resulting in low dimensional accuracy of the machined surface, affecting the use of the workpiece performance [5][6][7]. Error compensation is one of the most effective means to enhance machining accuracy.…”

Section: Introductionmentioning

confidence: 99%

Integrated robotic machining error compensation for intersecting hole of large spherical shells

ma,

Lu,

Deng

et al. 2024

Preprint

Self Cite

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Industrial robots are emerging for applications in machining critical components such as flange holes for spherical, cylindrical, and other types of vacuum vessel components. However, the main factor limiting their machining applications is the relatively low stiffness of industrial robots, leading to tool path errors during machining. Hence, this paper proposed an integrated error compensation method considering intersecting hole position and axial tolerance constraints. Firstly, a robot machining trajectory is generated, and the cutting allowance and sampling strategy are determined by running the machining trajectory empty run before machining. Then, integrated constraints are introduced, and a new target hole surface is constructed as a mirror surface under the integrated constraints of error compensation. The tool path is adjusted according to the mirror compensation principle to ensure consistency between the machined and nominal holes. The integrated constraints enable a quick and effective assessment of the suitability of the workpiece for precision machining before actual machining, thereby eliminating unnecessary machining of unqualified workpieces and improving productivity. The reconstructed target hole surface satisfies the integrated constraint criterion and achieves a balanced combination of positional and axial tolerances, making full use of both types of tolerances. Finally, the effectiveness of the method is verified on a large workpiece. The experimental results show that the positional error is reduced from uncompensated (1.03, -0.51) mm to compensated (0.25, -0.005) mm, and the axial error of the intersecting hole surface is reduced from uncompensated 22.32 mm to compensated 1.39 mm.

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Elasto-geometrical error and gravity model calibration of an industrial robot using the same optimized configuration set

Cited by 21 publications

References 52 publications

Kinematic and Joint Compliance Modeling Method to Improve Position Accuracy of a Robotic Vision System

Kinematic and Joint Compliance Modeling Method to Improve Position Accuracy of a Robotic Vision System

Compensation of Geometric, Backlash, and Thermal Drift Errors Using a Universal Industrial Robot Model

Integrated robotic machining error compensation for intersecting hole of large spherical shells

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