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Optimum design is proven significant for improving task performances of robotic manipulators under certain constraints. However, when it is utilized for collaborative robots (Cobots), there are still many challenges such as complex smooth surface links, time-varying kinematic configurations, computational expensiveness, and nonstructural parameter...
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Citations
... Numerous studies have addressed speed control for safety, employing proximity sensing [15] and safety maps in workspace [16]. Researchers have also reduced robot inertia through methods such as link optimization [17], [18] and topology optimization [19]. Redundant kinematic structures have been utilized for tasks not requiring full robot degrees of freedom, optimizing robot configuration to minimize inertia during unexpected collisions [20]. ...
In collaborative robotics, the safety of humans interacting with cobots is crucial. There is a need for collaborative robots that can move quickly while still being safe. This paper introduces the use of a kinematically redundant actuator in impedance control mode to reduce collision forces, aiming to improve both the safety and efficiency of collaborative robots. By distributing power across multiple drive-trains, each with unique properties such as reflected inertia, the actuator's behavior during collisions is optimized, which is key for safe interactions. Using theoretical analysis and practical experiments, we evaluate the response performance of the redundant actuator in various collision situations according to ISO/TS 15066, comparing it with that of a standard single-drive actuator. Our experiments show that the redundant actuator significantly lowers collision forces, with a 44% reduction in peak forces and an 81% decrease in transferred impulses during collisions. The paper concludes by offering a design parameter recommendation for designing actuators with reduced reflected inertia.
... Robots with the optimal configuration of specifications based on multiple performance factors were found by Hu, et al. [33] using a statistical fuzzy cluster analysis-based technique. Piotrowski, et al. proposed a combination of optimal robot selection and workstation assignment for a CIM system that integrated a multi-chromosome genetic method with a first-fit bin packing approach [50]. ...
Modern aircraft industries mostly rely on “Advanced Manufacturing Technologies” (AMTs) to improve the quality of the aircraft product assembly, since it has a huge potential to improve the production efficiency. Robotics-based computer-integrated manufacturing is an example of the AMTs that can meet the required accuracy of the aircraft assembly. Although there is a massive research content in the decision-making approach of aircraft assembly/manufacturing process, one important problem (“industrial robot selection”) has been chosen for current research. Regarding challenges of the decision-making process based on knowledge management in the aircraft assembly and manufacturing processes due to its complexity, this research illustrates the innovative concept of flexible industrial decision-making approaches to evaluate and integrate the design and selection criteria (referred to as a choice, an option, and an alternative). In this research, some sophisticated and beneficial “Multi Attribute Decision Making” (MADM) preference approaches are employed concerning more manageable, accessible, and flexible decision-making for the aircraft assembly and manufacturing process. According to the preferred ranking-based methods, the MADM subset tools are used in the mathematical model for the decision-making challenges of the real-world aircraft manufacturing industry. The eight most prospective preference ranking-based MADM approaches are utilized to resolve challenges of decision-making based on the real-time aircraft manufacturing and assembly environment. Then, sensitivity and performance analysis is employed to examine the performance stability of the eight preference ranking approaches. It is evident that COPRAS, COPRAS-G, ORESTE, OCRA, ARAS and PSI methods are simple to understand and implement. On the other hand, EVAMIX and EXPRO methods are comparatively complex to apply due to their complicated mathematical formulations and involvement of several preference functions and threshold values. The research has practical value in resolving the decision-making challenges in any manufacturing industry concerning different conditions and meeting different manufacturing requirements.
... The successful research and development of UR lightweight robots from Universal Robots A/S in Denmark marks that the cobot has entered the application development stage (Ostergaard 2012). Since then, a lot of cobots have been developed, such as LBR iiwa (Albu-Schaeffer et al. 2007), YuMi (Matthias 2015), Franka, SHIR5 (Hu et al. 2020), etc. The current research on the pHRI of cobots is mainly divided into three aspects: ...
... The realization of above performance indices are closely related to the design of smooth surface links and integrated joints. The structural parts of the robot are made of lowdensity and high-strength materials (such as 7075 aluminum alloy, magnesium alloy, etc.), and the mass of the structural parts is reduced through hollow design and structural optimization (Hu et al. 2020). At the same time, high energy density components (such as torque motors, hollow harmonic reducers, split encoders, etc.) are selected to further increase the power density of joints and reduce the mass of joints (Albu-Schaeffer et al. 2007). ...
Aiming at maximizing working performance of collaborative robots (cobots) under the constraint of safe physical human–robot interaction (pHRI), a safety design and optimization method for cobots is proposed to fullfill working performance requirements with sufficiently eliminating hazards and reducing risks of cobots. This safety design and optimization method can optimize and synthesize the correlated performance indices such as effective mass, terminal velocity and terminal stiffness property of cobots by drawing the human–robot interaction(HRI) safety diagram based on the human biomechanical limits (HBL), so as to simultaneously optimize working performance and sufficiently reduce risks of cobots. Through the correlation analysis of the safety requirement and the working performance, the coupling matrix diagram is constructed to obtain the correlated performance indices of cobots. And the mathematical model of correlated performance indices and HRI safety evaluation indices (SEIs) is derived by establishing the safety design analysis model of cobots. Then the HRI safety diagram is drawn with the restriction of HBL, and the reasonable correlated performance indices of cobots are selected to optimize working performance and sufficiently reduce risks of it simultaneously. According to the proposed method, the safety design and optimization of a seven degrees of freedom (DOFs) cobot is carried out, and the correlated performance indices that optimize working performance and sufficiently reduce risks of the cobot at the same time are determined.
... Using the applied simulation modeling methods, the authors were already able to transfer the results to a real-world environment, where they can predict the impact of collaborative workplaces on the manufacturing system efficiency [10]. At the same time, they proved that the optimal design of collaborative workplaces is important to improve the performance of robotic manipulators and workers in particular [11]. With the proper implementation of collaborative workplaces, we can reduce the risks of worker health problems as collaborative robots perform tasks that are difficult and repetitive for workers [12]. ...
This paper presents the use of Siemens’ Tecnomatix simulation modelling tool to evaluate the importance of the sustainable manufacturing perspective for human-robot collaboration. The research focuses on evaluating key parameters (utilization, scrap rate, cost, time, and quantities) of sustainable manufacturing from social, environmental, and economic perspectives. The simulation model was used to obtain time and quantity-based parameters of the collaborative workplace that can be directly applied to the real-world environment. The results show high suitability of simulation modelling methods to evaluate the collaborative workplace from the perspective of sustainable manufacturing. The obtained results provide answers to the original question of how multidisciplinary research can evaluate the impact of collaborative robots on humans and the sustainability of the manufacturing system. Results presents that human-robot collaboration, when studied at an advanced stage, can deal with different labor shortages in developed countries and ensure the global competitiveness of companies through a highly efficient and sustainable manufacturing system.KeywordsSustainable ManufacturingHuman-robot collaborationWorkplaceSimulation
... Rout, B.K. et al. [21] utilized evolutionary optimization methods for structural optimization while concurrently designing the optimal parameters and tolerances for the robot arm. Hu, M. et al. [22] conducted multi-objective optimization of Cobots by selecting structural dimensions and parameterizing joint components as optimization variables. Liu et al. [23] designed the joint structure and linkages of the robot, identifying the parameters that influence its performance. ...
In the structural design of serial robots, topology and dimensional parameters design are independent, making it challenging to achieve synchronous optimization design between the two. To address this issue, a topology-and-dimension-parameter integrated optimization method (TPOM) is proposed by setting critical variables to connect topology layout and dimensional features. Firstly, the topology layout is extracted by the edge detection technique. Structural manufacturability reconstruction is conducted by measuring the dimensions of the layout through a program. Additionally, for the reconstructed structural layout, critical variables are set using three-dimensional software (SOLIDWORKS2021). The experiments primarily involve critical variables, quality, and deformation as variables. Then, the response surface methodology is selected to construct the stiffness–mass metamodel, and based on this, the structural deformation is analyzed. Lastly, the multi-objective genetic algorithm (MOGA) is employed to optimize the critical variables, and an optimized structure is established for validation. The results indicate that the proposed method (TPOM) reduces the mass of the structure by 15% while maintaining its stiffness. In addition, the deformation of the whole structure is less than 0.352 mm, which meets the requirements of industrial applications. Through quantitative analysis of the experimental results, the feasibility and superiority of the proposed method have been demonstrated.
... Therefore, it is challenging to model the dynamics of spatially flexible robotic arms. Hu et al. presented an optimal configuration selection method for calibration of robots which is researched by the influencing factor separation method [7,8]. When performing the grasping task, the space robot arm will inevitably generate vibrations owing to its flexibility, which will affect the accuracy of the operation. ...
Aiming at the problem that the vibration of space robot will reduce the dynamic accuracy of robot, a method of vibration suppression of space robot through trajectory planning is proposed. First, the joint was simplified to a linear torsion spring, and the flexible rod was modelled using the finite element method, resulting in a flexible motion model of the robot. Then, a rigid-soft coupled dynamic model that combined the flexible motion model with the Lagrange method was established. Using the dynamic model, the factors influencing the vibration behaviour of space robots were analysed. Finally, the space robot was subjected to vibration suppression through trajectory planning. As verified by experimental analysis, different trajectories and loads affect the excitation force and inherent characteristics of the robot. In the design process, it is necessary to consider the relationship between the excitation force and natural frequency. The trajectory planning method has apparent effects on vibration suppression. The vibration amplitude was significantly reduced, which can improve the positioning accuracy and work efficiency of the robot.
... In this section, a 7-Dofs series collaborative robot (cobot) SHIR5-II is taken as an illustration to carry out the elastic deformation modeling and experimental validating, as shown in Fig. 4. The SHIR5-II cobot has a 7-Dofs anthropomorphic configuration with the mass about 25 kg, and the rated load is 5 kg [23]. It consists of lightweight links and highenergy-density modular joints connected in series. ...
In this paper, an elastic deformation modeling method of series robots with consideration of gravity that combines the finite element structure method (FESM) with the virtual joint method (VJM) is proposed to improve the positioning accuracy of robots. This method has characteristics of low computational complexity, high precision, as well as high real time. Compared with the previous research, the influence of joint and link mass on the elastic deformation of robots can be considered. Firstly, the entire robot model is split into several independent components and these components are expressed as a combination of a rigid body and a 6-Dofs virtual joint. Through the VJM, an extended kinematic model of series robots is built with these 6-Dofs virtual joints. Secondly, the stiffness parameters of robot components or virtual joints are extracted and considered comprehensively by the FESM. Thirdly, according to the extended kinematic model, the elastic deformation model is established to obtain the positioning error caused by external wrenches and gravity of robots. Lastly, a series robot SHIR5-II is taken as an illustration to perform elastic deformation modeling by the proposed method. Based on laser tracker and finite element software, the static compliance test, the static compliance simulation and the 7-Dofs VJM-based elastic deformation modeling of SHIR5-II robot are performed to verify the effectiveness of this modeling method.
... Additionally, the Human Robot Collaboration (HRC) shows potential on addressing the requirement for modular product development with the use of smaller lot sizes. Collaborative robots deliver significant benefits, with respect to the implementation of production cells, which can easily change their operation for different product families (Michalos et al. 2018;Mingwei, Wang, and Pan 2020). These are great capabilities for the implementation of HRC into the replacing battery stations, by providing increased flexibility and high reconfiguration in the production of modular batteries, while enabling complex operations in smaller lot size. ...
Energy and environmental impacts are at the top of the list of major global challenges to be addressed within the next few years. With transportation being one of the most pollutant sectors, focus has been directed towards Electric Vehicles, due to their significantly less dependency on fossil fuels. Nevertheless, electric mobility is currently characterized by a limited driving range, leading manufacturers to investigating new methods that could increase range and charging efficiency. Current research is mainly focused on increasing battery performance and reducing charging time. This study concentrates on presenting a novel approach, based on replacing battery stations, where the vehicle’s batteries are replaced with a fully charged one (available at the station), while new modular batteries could be made on the spot. The existing gas station networks could be used for the replacement of electric car batteries. This will be addressing the issue of time-consuming charging of batteries. Through the assimilation of Industry 4.0 Key Enabling Technologies, the respective challenges can be addressed. This is illustrated through a holistic framework, whereby the requirements for the context-aware design of the car itself are also given and a specific solution, based on the mechanical mounting of batteries is discussed..
... First, the kinematic model of robots, considering the small deformation of modules, should be built. Most cobots, such as the UR5 (Ostergaard, 2012), IIWA (Albu-Schaeffer et al., 2007) and SHIR5-II (Hu et al., 2020), have a typical series configuration that consists of lightweight links and integrated joints connected in series, as shown in Figure 1. Therefore, for kinematic and stiffness modeling of cobots, the robot model can be divided into several joint and link modules. ...
... The collaborative robot SHIR5-II is taken as an example to perform stiffness modeling, identification and updating in this paper, as shown in Figure 1. The anthropomorphic cobot SHIR5-II with 7-DOF consists of smooth surface links and integrated joints connected in series (Hu et al., 2020). The integrated joints include motors, harmonic reducers, encoders, torque sensors, etc. ...
Purpose
The purpose of this paper is to introduce a method for stiffness modeling, identification and updating of collaborative robots (cobots). This method operates in real-time and with high precision and can eliminate the modeling error between the actual stiffness model and the theoretical stiffness model.
Design/methodology/approach
To simultaneously ensure the computational efficiency and modeling accuracy of the stiffness model, this method introduces the finite element substructure method (FESM) into the virtual joint method (VJM). The stiffness model of the cobots is built by integrating several 6-degree of freedom virtual joints that represent the elastic deformation of the cobot modules, and the stiffness matrices of these modules can be identified and obtained by the FESM. A model-updating method is proposed to identify stiffness influence coefficients, which can eliminate the modeling error between the actual prototype model and the theoretical finite element model.
Findings
The average relative error and the cycle time of the proposed method are approximately 6.14% and 1.31 ms, respectively. Compared with other stiffness modeling methods, this method not only has high modeling accuracy in high dexterity poses but also in low dexterity poses.
Originality/value
A hybrid stiffness modeling method is introduced to integrate the modeling accuracy of the FESM into the VJM. Stiffness influence coefficients are proposed to eliminate the modeling error between the theoretical and actual stiffness models.
... The application of cobot is becoming increasingly extensive in areas from 3 C electronics, automobile, home appliances to new energy, hardware bathroom, metal machinery, and other industries (Hu et al., 2020;Muijs & Snijders, 2017). The application in the manufacturing industry will gradually become the stock market, and the competition between manufacturers is increasingly fierce and cruel. ...
The rapid development of robot technology has introduced a substantial impact on manufacturing. Numerous studies have been carried out to apply collaborative robots (cobots) to address manufacturing productivity and ergonomics issues, which has brought extensive opportunities. In this context, a systematic literature search in the Web of Science, Scopus, and Google Scholar databases was carried out by electronic and manual search. Thus, 59 relevant contributions out of 4488 studies were analyzed by using preferred reporting items for systematic reviews and meta-analysis (PRISMA). To provide an overview of the different results, studies are summarized according to the following criteria: country, author, year, study design, robot category, results, and future opportunities. The effects of cobots on safety, system design, workplace design, task scheduling, productivity, and ergonomics are discussed to provide a better understanding of the application of cobots in manufacturing. To incentive future research, this paper reviews the development of cobots in manufacturing and discusses future opportunities and directions from cobots and manufacturing system perspectives. This paper provides novel and valuable insights into cobots application and illustrates potential developments of future human-cobot interaction.
