Analysis of the behavior of a linear axis with an industrial robot

Industrial robots offer a variety of advantages for large-part manufacturing, e.g. the machining of vertical tail planes or wing spars, over conventional machine tools. Their compact footprint and modular design enable broad industrial applicability. However, the spherical workspace of a single articulated industrial robot may be insufficient for large parts. To overcome this limitation, industrial robots are combined with workspace extensions like linear axes. When the linear axis is interpolated with the robot joints, it enables continuous process movement, increasing production speed and flexibility. Mounting the robot on the linear axis introduces the carriage, a dynamic body with distinct properties, into the kinematic chain; consequently, as the first dynamic element, the carriage significantly influences the articulated robot and the combined system’s dynamics. Experiments on a linear axis designed for path-accurate robot processes including two rack-and-pinion drives demonstrate that the coupling effects of the linear axis and the articulated robot, as well as the dynamic properties of the combined system, are pose-dependent. The optimal integration of the external axis into the control system requires a thorough characterization of these dynamic properties. This work presents a rigid multibody model inspired by an inverse pendulum that couples the linear axis translatory with the mounted robots’ rotary axes movements at acceleration level and by trigonometric terms. The model reveals how dynamic properties of the linear axis change according to the robots pose and its multi-DOF stiffness and damping properties. This enables the optimization of control system parameters and the narrowing of filter bandwidths. An approach for industrial controller tuning based on the introduced model is presented. Implementation focuses on the linear axis within the industrial controller, with improvements validated through path measurement of the tool center point of the robot.

Subjects

Industrial Robot

Linear Axis

Multibody Dynamic

Control

DDC Class

629.1: Aviation

Lizenz

https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication version

publishedVersion

Name

ssrn-6287478.pdf

Type

Main Article

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978.44 KB

Format

Adobe PDF

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Analysis of the behavior of a linear axis with an industrial robot