Underactuated Part Alignment System for Industrial Assembly Applications

2012 ◽  
Vol 5 (1) ◽  
Author(s):  
Brian J. Slaboch ◽  
Philip A. Voglewede

This paper introduces the underactuated part alignment system (UPAS) as a cost-effective and flexible approach to aligning parts in the vertical plane prior to an industrial robotic assembly task. The advantage of the UPAS is that it utilizes the degrees of freedom (DOFs) of a SCARA (selective compliant assembly robot arm) type robot in conjunction with an external fixed post to achieve the desired part alignment. Additionally, the UPAS is not constrained to work with rigid, polygonal parts. Three path planning techniques are presented that can be used with the UPAS to achieve the proper part rotation. The results from laboratory testing show that the UPAS can be used to consistently achieve the desired part rotation to within 0.5% of the desired value.

Author(s):  
Brian J. Slaboch ◽  
Philip Voglewede

This paper introduces the Underactuated Part Alignment System (UPAS) as a cost-effective and flexible approach to aligning parts in the vertical plane prior to an industrial robotic assembly task. The advantage of the UPAS is that it utilizes the degrees of freedom (DOFs) of a SCARA (Selective Compliant Assembly Robot Arm) type robot in conjunction with an external fixed post to achieve the desired part alignment. Three path planning techniques will be presented that can be used with the UPAS to achieve the proper part rotation.


Author(s):  
Ivan Ćatipović ◽  
Nastia Degiuli ◽  
Andreja Werner ◽  
Većeslav Čorić ◽  
Jadranka Radanović

Towing as a specific type of sea transport is often used for installing objects for drilling and exploitation of underwater gas and oil wells. Also, towing proved to be a cost-effective solution for the installation of the offshore wind turbine electric generators at sea locations. Because of the mass of these objects the need for towing increases progressively. Time domain numerical model for the wave-induced motions of a towed ship and the towline tension in regular head seas is presented in this paper. For the sake of simplicity, one end of the towing line is attached to ship’s bow and another end has prescribed straight line motion. All considerations are done in the vertical plane so the ship is modeled as a rigid body with three degrees of freedom. Hydrodynamic loadings due to waves are taken into account along with added mass and damping. Dynamics of the towing line is described by finite elements. Due to the nonlinear properties of the problem calculations are done in time domain. Comparison of the obtained numerical results is made with previously published results.


Author(s):  
G Castelli ◽  
E Ottaviano ◽  
A González

In this article, a manipulator is presented belonging to the class of cable-suspended robots, for which the cable length variations are related by suitable functions in order to achieve specific kinematic characteristics. In particular, in this article, a Cartesian cable-suspended robot is proposed that has eight cables to have three degrees of freedom (DOF) in Cartesian space. The eight cables of the robot are arranged in parallel by pairs with identical length, with the aim of constraining the moving platform to keep a constant orientation with respect to the fixed frame. The robot can be used for selective compliant assembly robot arm (SCARA) motions (when an additional revolute actuated joint is placed on the moving platform) for a variety of applications in which a large workspace is required. In this article, a geometry analysis of the robot is presented together with a numerical simulation of the kinetostatics and dynamics to investigate the robot's performances in several operative conditions. Furthermore, a characterization of the position workspace regions is reported for this cable-suspended robot.


2014 ◽  
Vol 527 ◽  
pp. 230-236
Author(s):  
Mohamed Laid Hadjili ◽  
Kamel Kara ◽  
Oussama Ait Sahed ◽  
Jamal Bouyanzar

In this work a fuzzy model-based predictive control (FMPC) method that uses modified particle swarm optimization (PSO) is presented. The main objective of this work is the application of this method to the control of a Selective Compliant Assembly Robot Arm (SCARA) with four degrees of freedom (4-DOF).


2021 ◽  
Vol 101 (3) ◽  
Author(s):  
Korbinian Nottensteiner ◽  
Arne Sachtler ◽  
Alin Albu-Schäffer

AbstractRobotic assembly tasks are typically implemented in static settings in which parts are kept at fixed locations by making use of part holders. Very few works deal with the problem of moving parts in industrial assembly applications. However, having autonomous robots that are able to execute assembly tasks in dynamic environments could lead to more flexible facilities with reduced implementation efforts for individual products. In this paper, we present a general approach towards autonomous robotic assembly that combines visual and intrinsic tactile sensing to continuously track parts within a single Bayesian framework. Based on this, it is possible to implement object-centric assembly skills that are guided by the estimated poses of the parts, including cases where occlusions block the vision system. In particular, we investigate the application of this approach for peg-in-hole assembly. A tilt-and-align strategy is implemented using a Cartesian impedance controller, and combined with an adaptive path executor. Experimental results with multiple part combinations are provided and analyzed in detail.


Author(s):  
Michael John Chua ◽  
Yen-Chen Liu

Abstract This paper presents cooperation and null-space control for networked mobile manipulators with high degrees of freedom (DOFs). First, kinematic model and Euler-Lagrange dynamic model of the mobile manipulator, which has an articulated robot arm mounted on a mobile base with omni-directional wheels, have been presented. Then, the dynamic decoupling has been considered so that the task-space and the null-space can be controlled separately to accomplish different missions. The motion of the end-effector is controlled in the task-space, and the force control is implemented to make sure the cooperation of the mobile manipulators, as well as the transportation tasks. Also, the null-space control for the manipulator has been combined into the decoupling control. For the mobile base, it is controlled in the null-space to track the velocity of the end-effector, avoid other agents, avoid the obstacles, and move in a defined range based on the length of the manipulator without affecting the main task. Numerical simulations have been addressed to demonstrate the proposed methods.


1981 ◽  
Vol 69 (2) ◽  
pp. 191-202 ◽  
Author(s):  
M. Desmond Burke

Author(s):  
Bronius Baksys ◽  
Jolanta Baskutiene ◽  
Saulius Baskutis

Purpose This paper aims to consider the experimental and theoretical investigation of the vibratory alignment of the peg-hole, when the peg is fixed in the remote centre compliance (RCC) device, and the vibrations are provided either to the hole or to the peg. Design/methodology/approach The experimental analysis of the circular and rectangular peg-hole vibratory alignment using the attached to the robot arm RCC device, under vibratory excitation of the hole, has been performed. The parameters of the vibratory excitation and the part-to-part pressing force influence on the alignment process have been analysed. The mathematical approach of the vibratory alignment using the passive compliance device with the vibrations provided to the peg has been proposed, and the simulation has been carried out. Findings The research has approved the applicability of the RCC device for both of the vibratory alignments of the non-chamfered peg-hole parts either circular or rectangular ones. The compensation of the axial misalignments has been resulted by the directional displacement of the peg supported compliantly. To perform the successful alignment of the parts, it has been necessary to adjust the frequency and the amplitude of the vibrations, the pressing force, the lateral, as well as the angular stiffness of the device. Research limitations/implications The experiments on the vibratory alignment of the rectangular peg-hole parts have been carried out considering only the translational misalignment moved into one direction. The non-impact regime of the vibratory alignment has been analysed. Practical implications The obtained results can be applied in designing the reliable and efficient devices of the vibratory assembly for the alignment of the non-chamfered peg-hole parts, as well as for chamfered ones, if the axial misalignment exceeds the width of the chamfer. The vibratory technique and passive compliance provide possibility to accomplish the assembly operations using the non-expensive low accuracy robots. Originality/value The new method and the mathematical approach of the vibratory assembly using the RCC device can ensure the reliable alignment of the non-chamfered parts, chamfered circular and the rectangular ones, in case the axial misalignment exceeds the assembly clearance, and prevent jamming and wedging.


2021 ◽  
Vol 8 ◽  
Author(s):  
Zubair Iqbal ◽  
Maria Pozzi ◽  
Domenico Prattichizzo ◽  
Gionata Salvietti

Collaborative robots promise to add flexibility to production cells thanks to the fact that they can work not only close to humans but also with humans. The possibility of a direct physical interaction between humans and robots allows to perform operations that were inconceivable with industrial robots. Collaborative soft grippers have been recently introduced to extend this possibility beyond the robot end-effector, making humans able to directly act on robotic hands. In this work, we propose to exploit collaborative grippers in a novel paradigm in which these devices can be easily attached and detached from the robot arm and used also independently from it. This is possible only with self-powered hands, that are still quite uncommon in the market. In the presented paradigm not only hands can be attached/detached to/from the robot end-effector as if they were simple tools, but they can also remain active and fully functional after detachment. This ensures all the advantages brought in by tool changers, that allow for quick and possibly automatic tool exchange at the robot end-effector, but also gives the possibility of using the hand capabilities and degrees of freedom without the need of an arm or of external power supplies. In this paper, the concept of detachable robotic grippers is introduced and demonstrated through two illustrative tasks conducted with a new tool changer designed for collaborative grippers. The novel tool changer embeds electromagnets that are used to add safety during attach/detach operations. The activation of the electromagnets is controlled through a wearable interface capable of providing tactile feedback. The usability of the system is confirmed by the evaluations of 12 users.


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