Multi-robot cells for spot welding use coordinated robots to assemble metal panels via spot welding by coordinated robots, for instance in the construction of car doors. The design of multi-robot ...cells for spot welding required both cell design and off-line motion planning. Cell design involves resource selection (such as robots and welding guns) and resource configuration, while considering cell productivity, costs, flexibility and reconfigurability. Motion planning involves allocating welding points to each resource and calculating collision-free motion plan for each robot. Currently, cell design and motion planning are sequential and manual activities, managed by different and separate industrial functional units. This results in several cycles before the design converges to a feasible final solution. The proposed approach introduces a unified methodology, aiming at optimizing the holistic cell design and motion planning, that reduces design time and errors. The feasibility of the proposed approach has been demonstrated in several ad-hoc basic replicable cases and in one industrial case. The outcome of this research improves state of the art, reducing design and motion planning time over current technology. Moreover, the method has been integrated into a computerized approach which has the potential to accelerate the whole cell design and motion planning processes and to reduce human efforts.
•Design and motion planning of multi-robot cells for body-in-white assembly.•Method to reduce human effort in the computation of alternative solutions.•Simultaneous resolution and optimization of the design and the motion planning.•Testing of the approach on several replicable cases and one industrial case.
Intelligent automation, including robotics, is one of the current trends in the manufacturing industry in the context of “Industry 4.0”, where cyber-physical systems control the production at ...automated or semi-automated factories. Robots are perfect substitutes for a skilled workforce for some repeatable, general, and strategically-important tasks. However, this transformation is not always feasible and immediate, since certain technologies do not provide the required degree of flexibility. The introduction of collaborative robots in the industry permits the combination of the advantages of manual and automated production. In some processes, it is necessary to incorporate robots from different manufacturers, thus the design of these multi-robot systems is crucial to guarantee the maximum quality and efficiency. In this context, this paper presents a novel methodology for process automation design, enhanced implementation, and real-time monitoring in operation based on creating a digital twin of the manufacturing process with an immersive virtual reality interface to be used as a virtual testbed before the physical implementation. Moreover, it can be efficiently used for operator training, real-time monitoring, and feasibility studies of future optimizations. It has been validated in a use case which provides a solution for an assembly manufacturing process.
•Benefits of robot cell calibration and effect of robot system error on different programing methods are discussed.•An easy-to-use robot cell calibration solution with touch panel is proposed.•Error ...effect of the proposed cell calibration is analyzed via simulation.•Experiments on a commercial mobile device show that the proposed solution can reach calibration accuracy to sub-mm level with high consistent repeatability.
Robot cell calibration is the basic commissioning task in robot applications. Traditional way is either tedious manual calibration or complex machine calibration with expensive sensors. This paper presents a novel solution to complete the robot cell calibration with touch panel, which is an easily accessible and low-cost device in daily use on tablets or smart phones. In this paper, we discuss the robot cell calibration problem and propose the touch panel based calibration system approach. In particular, the error effect of touch panel on calibration has been analyzed. The practical calibration performance has been validated via experiments.
Robot manipulators are widely used in various areas of industrial factory automation. However, their base positioning is still achieved through trial-and-error methods based on the intuition and ...expertise of the engineer, even with the use of off-line programming software. Most previous studies do not provide on-line or on-site solutions suitable for practical applications because the nonlinearity and derivative complexity of the robot kinematics result in heavy computational burden and lengthy processing times. In this paper, we suggest a convex programming approach that uses time-efficient and reliable methods to solve the optimization problem in order to determine the base position of a six-degrees-of-freedom articulated robot with a spherical wrist. The proposed method uses convex optimization to accurately check the reachability of the given task without solving the inverse kinematics and to determine the feasible base position to satisfy singularity avoidance and spatial limitations. The feasibility of the proposed method is evaluated through various simulations, and the results show that not only the feasible base position but also the range of allowable base locations as an ellipsoidal volume can be provided within a few minutes without high computing performance or large resources.
In the production of electrical machines based on the pull-in technology, the stator, with a share of 35% of the total costs, is the most expensive component in the electric motor and offers a ...variety of automation possibilities of the process. The insertion of the phase insulation paper into the stator winding head is mostly done within manual assembly stations. This process step offers automation potential for the production of a process-safe phase insulation. The aim is to develop and qualify an automated application method. Therefore, the process is redesigned by the idea of a robot-supported application of the phase insulation with a spray system. For feasibility studies, a robot-supported spray insulation system is designed, built and subsequently integrated into a robot cell. Using several test setups, different process tests are carried out to check the application possibilities of sprayable insulation materials as phase insulation in the stator winding head. In particular, the effects of the various process parameters on the indentation strength of the new insulation materials are being investigated using laboratory tests.
The paper addresses the problem of 2-machine robotic cell scheduling of one-unit cycle with sequence-dependent setup times and different loading/unloading times of the parts. As an alternative ...metaheuristic algorithm, the cuckoo search algorithm has recently attracted growing interests of researchers. It has the capability to search globally as well as locally to converge to the global optimality by exploring the search space more efficiently due to its global random walk governed by Levy flights, rather than standard isotropic random walk. In this study, a discrete cuckoo search algorithm is proposed to determine the sequence of robot moves along with the sequence of parts so that the cycle time is minimized. In the proposed algorithm, the fractional scaling factor based procedure is presented to determine the step length of Levy flights distribution in discrete from and then, using this step length, two neighborhood search techniques, interchange and cyclical shift methods are applied to the current solution to obtain improved solution. A response surface methodology based on desirability function is used to enhance the convergence speed of the proposed algorithm. Also, a design of experiment is employed to tune the operating parameters of the algorithm. Finally, empirical results with a large number of randomly generated problem instances involving large part sizes varying from 200 to 500 under different operating conditions are compared with two well-known algorithms in the literature and demonstrate the effectiveness of the proposed algorithm.
This book is a printed edition of the Special Issue entitled “Multi-Robot Systems: Challenges, Trends, and Applications” that was published in Applied Sciences. This Special Issue collected seventeen ...high-quality papers that discuss the main challenges of multi-robot systems, present the trends to address these issues, and report various relevant applications. Some of the topics addressed by these papers are robot swarms, mission planning, robot teaming, machine learning, immersive technologies, search and rescue, and social robotics.
► Layout method for robotic cellular manufacturing systems (RCMSs) is proposed. ► Design requirements for RCMS layouts are clarified. ► A sequence-pair scheme is introduced for the RCMS layout ...representation. ► A genetic algorithm is used to solve the multiobjective optimization problems.
This paper proposes a multiobjective layout optimization method for the conceptual design of robot cellular manufacturing systems. Robot cellular manufacturing systems utilize one or more flexible robots which can carry out a large number of operations, and can conduct flexible assemble processes. The layout design stage of such manufacturing systems is especially important since fundamental performances of the manufacturing system under consideration are determined at this stage. In this paper, the design criteria for robot cellular manufacturing system layout designs are clarified, and objective functions are formulated. Next, layout design candidates are represented using a sequence-pair scheme to avoid interference between assembly system components, and the use of dummy components is proposed to represent layout areas where components are sparse. A multiobjective genetic algorithm is then used to obtain Pareto optimal solutions for the layout optimization problems. Finally, several numerical examples are provided to illustrate the effectiveness and usefulness of the proposed method.
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