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Francisco Yumbla,Meseret Abayebas,June-Sup Yi,Jeongmin Jeon,Hyungpil Moon 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.4
In this study, we propose the use of a distribute manipulator for repositioning and alignment process of cable connectors to obtain the accurate pose of the connector. The accurate pose is critical for a successful mating process in wiring harness assembly tasks. Conventional actuators such as robotics grippers rely on active manipulations; for example, they uses belts and, rollers for the repositioning of the cables, and others such as parallel grippers used directly to grasping the connector. However, all these systems need a lot of many pieces and mechanisms to manipulate the cables or high accuracy control process for grasping the connector in a certain position, thus increasing the difficulty when the cables and connectors are smaller. Therefore, we present a vibrating plate to perform in-hand manipulation to reposition the cable and align the connector. We modeled and analyzed the relationship between the vibration frequency and the velocity of the cable. Furthermore, we experimentally show that the moving velocity of the cable is proportional to the vibration system frequency, and the proposed vibrating plate can reliably move the connector to the desired pose.
Analysis of the mating process of plug-in cable connectors for the cable harness assembly task
Francisco Yumbla,June-Sup Yi,Meseret Abayebas,Hyungpil Moon 제어로봇시스템학회 2019 제어로봇시스템학회 국제학술대회 논문집 Vol.2019 No.10
In this paper, we analyze the mating process of plug-in cable connectors for wiring harness assembly tasks by showing the challenging difficulties around this task including the possible solutions: a new gripper design concept and analyzing the permissible error range (tolerance) between the connectors. For wiring harness assembly tasks, knowing the accurate pose of the grasped cable connector in the gripper is very critical for the successful mating process, and conventional mating processes rely on force control or mechanical passive compliance. Nowadays, we notice that collaboration robotic manipulators or small size industrial robotic manipulators attain high accuracy and repeatability levels (sub-millimeter) thus demonstrate very precise position control capacities. Using those capacities of the robotic manipulator, we analyze the permissible error range of connector for the mating process. For that reason, we propose a new design of a gripper for an accurate alignment and holding of the position between the cable and the gripper. Therefore, if we know the exact position of the connector in reference to the gripper, and the tolerance between the connectors is larger than error position of the robot arm, the mating process can be achieved by just using position control of conventional industrial robots.
Preliminary Connector Recognition System Based on Image Processing for Wire Harness Assembly Tasks
Francisco Yumbla,Meseret Abeyabas,Tuan Luong,June-Sup Yi,Hyungpil Moon 제어로봇시스템학회 2020 제어로봇시스템학회 국제학술대회 논문집 Vol.2020 No.10
In this paper, we analyze and propose a recognition process of plug-in cable connectors for wiring harness assembly tasks using image processing. For manipulation and routing of wire harness, knowing the accurate pose of the cable connector is very critical in the grasping moment. The recognition process is crucial to minimize the error in the manipulation of the connectors. Nowadays, we notice that collaborative robot manipulators or small size industrial robot manipulators attain high accuracy and repeatability levels (sub-millimeter); thus, demonstrate very precise position control capabilities. Using those capacities and with the correct recognition system, we can apply to the automation of the wire harness assembly process. For that reason, we propose a connector recognition system to obtain the precise position of the connectors on a work table; which is necessary to obtain a successful grasping and manipulation of the connectors in a wire harness. The system and the recognition process are explained in detail, and validated experimentally.
Francisco Yumbla,Seungjun Woo,Emiliano Quinones Yumbla,Tuan Luong,Hyungpil Moon 제어로봇시스템학회 2020 제어로봇시스템학회 국제학술대회 논문집 Vol.2020 No.10
This paper aims to analyze the range of motions and characteristics of a quadruped robot for stair climbing and crossing over an obstacle. Humans have a higher range than quadruped animals due to longer legs. We can make fewer steps and reach the same distance, can climb stairs by two or three steps and not only one, and cross over high obstacles thanks to our leg range. However, stability is different because quadruped has four contact points, whereas humans have only. Quadrupeds maintain walking stability because their gravity center falls within the triangle of support from the three legs when one is up, but in the same condition, humans encounter a complex challenge to maintain equilibrium. We propose using these inherent characteristics of a quadruped robot for motion analysis of stair climbing by two or three steps and cross over a big obstacle while maintaining high stability in a quadruped robot. We aboard in the discussion significant aspects of leg dimensions and joint ranges with geometrical analysis to find the optimal position of the feet. The motion effectiveness was verified experimentally by implementing the motions from the preliminary tests to a quadruped robot.
Meseret A. Tadese,Francisco Yumbla,Nabih Pico,Hyungpil Moon 제어로봇시스템학회 2022 제어로봇시스템학회 국제학술대회 논문집 Vol.2022 No.11
A precise dynamic model is critical for collaborative robots to achieve satisfactory performance in modelbased control or other applications such as dynamic simulation and external torque estimation. However, due to nonlinear friction behavior in robot actuation, it is difficult to identify precise dynamic parameters. In this paper, a reliable dynamic friction model, which incorporates the influence of temperature fluctuation on joint friction, is utilized to increase the accuracy of identified dynamic parameters. First, the friction of the joint module is investigated. Extensive test series are performed in the full velocity operating range at temperatures ranging from 23 ℃ to 51 ℃ to investigate friction dependency on joint module temperature. Then, dynamic parameter identification is performed using the inverse dynamics identification model and weighted least squares method. Based on the friction model identified in the first step, friction toque is computed, and the effect is eliminated by subtracting it from experimental data for dynamic parameter identification. Finally, the proposed notion is verified experimentally, and the results demonstrate that using a precise dynamic friction model improves the accuracy of dynamic parameters identification.