1. Task-oriented evaluation of the feasible kinematic directional capabilities for robot machiningSaša Stradovnik, Aleš Hace, 2022, izvirni znanstveni članek Opis: Performing the machining of complex surfaces can be a challenging task for a robot, especially in terms of collaborative robotics, where the available motion capabilities are greatly reduced
in comparison with conventional industrial robot arms. It is necessary to evaluate these capabilities
prior to task execution, for which we need efficient algorithms, especially in the case of flexible
robot applications. To provide accurate and physically consistent information about the maximum
kinematic capabilities while considering the requirements of the task, an approach called the Decomposed Twist Feasibility (DTF) method is proposed in this study. The evaluation of the maximum
feasible end-effector velocity is based on the idea of decomposition into the linear and angular motion
capabilities, considering a typical robot machining task with synchronous linear and angular motion.
The proposed DTF method is presented by the well-known manipulability polytope concept. Unlike
the existing methods that estimate the kinematic performance capabilities in arbitrarily weighted
twist space, or separately in the translation and the rotation subspace, our approach offers an accurate
and simple solution for the determination of the total kinematic performance capabilities, which is
often highly required, especially in the case of robot machining tasks. The numerical results obtained
in this study show the effectiveness of the proposed approach. Moreover, the proposed DTF method
could represent suitable kinematic performance criteria for the optimal placement of predefined tasks
within the robot workspace Ključne besede: robot surface machining, task feasibility, task-dependent kinematic capability, kinematic performance evaluation, manipulability index, manipulability polytope, motion decomposition, Decomposed Twist Feasibility method, DTF method Objavljeno v DKUM: 01.04.2025; Ogledov: 0; Prenosov: 2
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2. Toward optimal robot machining considering the workpiece surface geometry in a task-oriented approachAleš Hace, 2024, izvirni znanstveni članek Opis: Robot workpiece machining is interesting in industry as it offers some advantages, such as higher flexibility in comparison with the conventional approach based on CNC technology. However, in recent years, we have been facing a strong progressive shift to custom-based manufacturing and low-volume/high-mix production, which require a novel approach to automation via the employment of collaborative robotics. However, collaborative robots feature only limited motion capability to provide safety in cooperation with human workers. Thus, it is highly necessary to perform more detailed robot task planning to ensure its feasibility and optimal performance. In this paper, we deal with the problem of studying kinematic robot performance in the case of such manufacturing tasks, where the robot tool is constrained to follow the machining path embedded on the workpiece surface at a prescribed orientation. The presented approach is based on the well-known concept of manipulability, although the latter suffers from physical inconsistency due to mixing different units of linear and angular velocity in a general 6 DOF task case. Therefore, we introduce the workpiece surface constraint in the robot kinematic analysis, which enables an evaluation of its available velocity capability in a reduced dimension space. Such constrained robot kinematics transform the robot’s task space to a two-dimensional surface tangent plane, and the manipulability analysis may be limited to the space of linear velocity only. Thus, the problem of physical inconsistency is avoided effectively. We show the theoretical derivation of the proposed method, which was verified by numerical experiments.periments. Ključne besede: robotics, automation, robot machining, workpiece surface polishing, collaborative robot, manipulability, complex surface geometry, motion planning Objavljeno v DKUM: 25.11.2024; Ogledov: 0; Prenosov: 0 |
3. Workpiece placement optimization for robot machining based on the evaluation of feasible kinematic directional capabilitiesSaša Stradovnik, Aleš Hace, 2024, izvirni znanstveni članek Opis: Workpiece placement plays a crucial role when performing complex surface machining task robotically. If the feasibility of a robotic task needs to be guaranteed, the maximum available capabilities should be higher than the joint capabilities required for task execution. This can be challenging, especially when performing a complex surface machining task with a collaborative robot, which tend to have lower motion capabilities than conventional industrial robots. Therefore, the kinematic and dynamic capabilities within the robot workspace should be evaluated prior to task execution and optimized considering specific task requirements. In order to estimate maximum directional kinematic capabilities considering the requirements of the surface machining task in a physically consistent and accurate way, the Decomposed Twist Feasibility (DTF) method will be used in this paper. Estimation of the total kinematic performance capabilities can be determined accurately and simply using this method, adjusted specifically for robotic surface machining purposes. In this study, we present the numerical results that prove the effectiveness of the DTF method in identifying the optimal placement of predetermined machining tasks within the robot’s workspace that requires lowest possible joint velocities for task execution. These findings highlight the practicality of the DTF method in enhancing the feasibility of complex robotic surface machining operations. Ključne besede: workpiece placement optimization, robotic surface machining, feasible kinematic directional capabilities, decomposed twist feasibility (DTF) method, manipulability, non-linear optimization Objavljeno v DKUM: 12.08.2024; Ogledov: 64; Prenosov: 25
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4. Manipulability of a haptic mechanism within the cylindrical space of an MR scannerMatej Rajh, Srečko Glodež, Jože Flašker, Karl Gotlih, 2012, izvirni znanstveni članek Opis: The aim of this paper is to present developed 3 DOF haptic mechanism and 3D visualization method for analysis of mechanism manipulability problems within limited space. Improvement in mechanism manipulability within cylindrical space is crucial for devices, which operate in MR tunnel. This solution enables the plotting of quantitative 3D representation for each point in the mechanism's workspace, using selected resolution which can be determined in advance. The cross-section between the limited space and the whole arbitrary workspace shows the ability for movement execution. Ključne besede: gibljivost, Jacobijeva matrika, delovni prostor, haptični mehanizem, MR-združljivost, omejen prostor, manipulability, Jacobian matrix, workspace, haptic mechanism, MR compatibility, limited workspace Objavljeno v DKUM: 10.07.2015; Ogledov: 1410; Prenosov: 98
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