Model-based Planning of Machining Operations for Industrial Robots

Schnoes, Florian; Zaeh, Michael F.

doi:10.1016/j.procir.2019.04.331

Cited by 26 publications

(20 citation statements)

References 13 publications

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“…Zudem ist durch die hohe Flexibilität der Roboterkinematik eine spanende 5-Achs-Bearbeitung möglich, wodurch die Bearbeitung großer, komplexer Werkstücke ermöglicht wird [3,4]. Allerdings wirkt sich der serielle Aufbau der Roboterkinematik nachteilig auf die Bearbeitungsqualität und Maßhaltigkeit am Werkstück aus [7,8]. Dies ist neben einer verminderten Bahngenauigkeit [1,8,9,10] auf die geringere und stark posenabhängige Steifigkeit der Roboterstruktur im Vergleich zu einem Bearbeitungszentrum (BAZ) zurückzuführen [8,9,11].…”

Section: Motivation Und Problemstellungunclassified

“…Allerdings wirkt sich der serielle Aufbau der Roboterkinematik nachteilig auf die Bearbeitungsqualität und Maßhaltigkeit am Werkstück aus [7,8]. Dies ist neben einer verminderten Bahngenauigkeit [1,8,9,10] auf die geringere und stark posenabhängige Steifigkeit der Roboterstruktur im Vergleich zu einem Bearbeitungszentrum (BAZ) zurückzuführen [8,9,11]. Die Bearbeitungskräfte führen zu einer statischen Abdrängung der Werkzeugspitze (Tool Center Point -TCP) von der Soll-Bahn [2,5,7,9,12].…”

Section: Motivation Und Problemstellungunclassified

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Einsatz von Industrierobotern in der Zerspanung/Use of industrial robots in machining - metrological investigation on how the radial depth of cut influences the machining accuracy in robot-guided machining

Götz¹,

Gebhardt²,

Kleinhenz³

et al. 2020

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Der zunehmende Einsatz von Industrierobotern in der Zerspanung setzt eine deutliche Erhöhung der Bearbeitungsgenauigkeit voraus. Dies bedingt aufgrund der Steifigkeitseigenschaften von Robotern eine Optimierung der Bearbeitungsstrategien und Zerspanparameter. Der Beitrag beschreibt die experimentelle Untersuchung des radialen Arbeitseingriffs bei der Kunststoffzerspanung, um über die Wahl geeigneter Eingriffsgrößen das Schwingungs- und Abdrängungsverhalten des Roboters und damit die Bearbeitungsqualität zu verbessern.   The prerequisite for an extended use of industrial robots in machining is a significant increase in machining accuracy. This requires an optimization of machining strategies and cutting parameters due to the stiffness of the robot. This paper presents an experimental investigation of the radial depth of cut in plastics machining to improve both the vibration and displacement behavior of the robot and the machining quality by selecting suitable intervention variables.

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Section: Motivation Und Problemstellungunclassified

Einsatz von Industrierobotern in der Zerspanung/Use of industrial robots in machining - metrological investigation on how the radial depth of cut influences the machining accuracy in robot-guided machining

Götz¹,

Gebhardt²,

Kleinhenz³

et al. 2020

View full text Add to dashboard Cite

show abstract

“…In each case, an equivalent stiffness value is computed (with for example the Conservative Congruence Transformation [8]) and used to calculate the corresponding static deflection of the tool center point [1]. This deflection is used to shift the initial trajectory, also called the mirroring method [9].…”

Section: Introductionmentioning

confidence: 99%

Coupled Multibody Model Of Industrial Robot With Milling Simulator For Trajectory Compensation

Dambly¹,

Huynh²,

Verlinden³

et al. 2021

Proceedings of the 10th ECCOMAS Thematic Conference on MULTIBODY DYNAMICS

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Robotic machining is a fast-growing technology in the field of mechanical manufacturing. Indeed, it is generally accepted that for the same working space, a fully equipped robotic machining cell can cost 30 to 50 % less than a conventional machine tool. However, inaccuracies resulting either from vibrations or deflections occur while the robot is subjected to cutting forces, inherent to its flexible structure. As an order of magnitude, the stiffness at the tool-tip is about 1N/µm for industrial robots against more than 50N/µm for CNC machine tools. The flexibility source has been investigated and appears to be caused by the robot articulations in a proportion of 80% while the remaining flexibility issues from the structural elasticity. In order to improve the accuracy of robotic machining operations, several approaches have been carried out such as the study of stable cutting conditions and the online/offline compensation of the tool trajectory.Two aspects of the operation must be modeled, on the one hand the model of the cutting machine, being an industrial robot in robotic machining, and on the other hand, the machining model including the resulting geometry of the workpiece. A coupled model is then proposed with the multi-body model of the robot subjected to machining forces. The multi-body model includes the flexibility induced by the structure and the articulations. In order to compensate the deviations, a solution is proposed where the trajectory is discretized in nodes with a compensation taking the system dynamics into account by successive simulations of the operation. The algorithm involves two steps, firstly it aims to detect critical locations of the path and add or reposition nodes to reduce the deviation and secondly an optimization layer modifies nodes positions and velocities for a finer reduction. The method is deployed for three systems of increasing complexity for a face milling operation, showing a machining error reduction.

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“…Process force models are coupled with multi-body-models of robots to predict compliance [3,14,16] or backlash [5] caused path deviations and compensate or reduce them. They can be combined with model-based workpiece placing and process parameter optimization [18]. Therefore, the use of offline compensation methods is very cost-effective, except for the costs incurred for the development or procurement of the software.…”

Section: Introduction and State Of The Artmentioning

confidence: 99%

Hybrid compliance compensation for path accuracy enhancement in robot machining

Hähn

Weigold

2020

Prod. Eng. Res. Devel.

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Robot machining processes with high material removal rates lack of high path accuracy mainly due to the low stiffness of industrial robots. The low stiffness leads to process forces caused deviations of the tool center point (TCP) from the planned position of more than 1 mm in industrial applications. To enhance the path accuracy a novel hybrid compliance compensation is developed. It combines a force sensor and model based online compensation with forces of an offline simulation to instantly react to predictable high force changes e.g. at a milling cutter exit from the work piece. The method is applied to a KUKA KR 300 robot. A compliance model based on a forward kinematic with virtual joints is implemented on an external controller. Cartesian or axis specific compensation values are calculated and transferred to the robot via a control circuit. A compliance measurement method is developed and a force torque sensor is mounted to the flange of the robot. The system is validated in with Cartesian and axis specific compensation values as well as with and without pilot control.

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Model-based Planning of Machining Operations for Industrial Robots

Cited by 26 publications

References 13 publications

Einsatz von Industrierobotern in der Zerspanung/Use of industrial robots in machining - metrological investigation on how the radial depth of cut influences the machining accuracy in robot-guided machining

Einsatz von Industrierobotern in der Zerspanung/Use of industrial robots in machining - metrological investigation on how the radial depth of cut influences the machining accuracy in robot-guided machining

Coupled Multibody Model Of Industrial Robot With Milling Simulator For Trajectory Compensation

Hybrid compliance compensation for path accuracy enhancement in robot machining

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