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 Assembly Automation   [SJR: 0.657]   [H-I: 26]   [1 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 0144-5154    Published by Emerald  [312 journals]
• Glove-based virtual hand grasping for virtual mechanical assembly
• First page: 349
Abstract: Assembly Automation, Volume 36, Issue 4, September 2016.
Purpose Hand gesture-based interaction can provide far more intuitive, natural, and immersive feelings for users to manipulate 3D object for virtual assembly. A mechanical assembly consists of mostly general-purpose machine elements or mechanical parts that can be defined into four types based on their geometric features and functionalities. For different types of machine elements, engineers formulate corresponding grasping gestures based on their domain knowledge or customs for ease of assembly. Therefore, this work tries to support a virtual hand to assemble mechanical parts. Design/methodology/approach It proposes a novel glove-based virtual hand grasping approach for virtual mechanical assembly. The kinematic model of virtual hand is set up firstly by analyzing the hand structure and possible movements, and then four types of grasping gestures are defined with joint angles of fingers for connectors and three types of parts respectively. The recognition of virtual hand grasping is developed based on collision detection and gesture matching. Moreover, stable grasping conditions are discussed. Findings A prototype system is designed and developed to implement the proposed approach. The case study on virtual assembly of a two-stage gear reducer demonstrates the functionality of the system. From the users' feedback, it is found that more natural and stable hand grasping interaction for virtual assembly of mechanical parts can be achieved. Originality/value It proposes a novel glove-based virtual hand grasping approach for virtual mechanical assembly.
Citation: Assembly Automation
PubDate: 2016-07-20T11:44:38Z
DOI: 10.1108/AA-01-2016-002

• Automatic multi-stereo-vision reconstruction method of complicated tubes
for industrial assembly
• First page: 362
Abstract: Assembly Automation, Volume 36, Issue 4, September 2016.
Purpose Complicated tubes extensively exist in the industrial equipment. The manufacturing precision of the tubes is difficult to be ensured with bending machine. Therefore, the tubes’ 3D geometric error should be fixed according to measurement results. However, there are no convenient methods to accomplish the measurement accurately and effectively. Thus, this paper proposed a new tube measurement method to achieve tube’s automatic measurement. The accurate measurement results can be used to fix the geometric error of the tube to achieve stress-free assembly. Design/methodology/approach Tubes’ shape can be determined by control points. First, reconstruct the point clouds of the centre line by multi-stereo-vision technology. Then, thin the point clouds to the spine of the tube by MLS(moving least-squares) and segment the it into lines and arcs. Finally, calculate the control points and reconstruct the model. We can get the tube’s geometric dimensions from the model. Findings The experiment results indicate that the multi-stereo-vision technology can solve the occlusion problem and measure the complicated tubes efficiently and accurately. Originality/value The paper proposed a tube measurement method. The repeatability measuring precision was 0.12 mm and the absolute measuring precision was within 0.78 mm. The tube spectra assessed in this paper are in the range of angles between two adjacent line segments of 3–177° and the shortest length of the line segment is greater than 5 mm, confirming that the proposed algorithm can measure various complicated tubes effectively and accurately.
Citation: Assembly Automation
PubDate: 2016-07-20T11:44:35Z
DOI: 10.1108/AA-10-2015-078

• Evaluation of residual clearance after pre-joining and pre-joining scheme
optimization in aircraft panel assembly
• First page: 376
Abstract: Assembly Automation, Volume 36, Issue 4, September 2016.
Purpose For the automatic drilling and riveting in panel assembly, gaps between the skin and strangers are inevitable and undesirable. At present, the determination of pre-joining schemes relies on workers’ experience, introducing excessive number and inappropriate locations of pre-joining. This paper aims to present a new method for the evaluation of residual clearances after pre-joining and the pre-joining scheme optimization, providing operation guidance for the workers in panel assembly workshop. Design/methodology/approach In this paper, an equivalent gap assembly model for pre-joining is proposed on the basis of the mechanism of variation. This model retains the essential elastic behavior of the key features during the pre-joining operation, and calculates the residual clearances in the view of the potential energy. Subsequently, this method is embedded into a Pareto-optimality-based genetic algorithm, and the optimal pre-joining schemes are achieved with the consideration of the total residual clearances and the permissive tolerances. Findings The equivalent gap assembly model has the capability to predict an acceptable degree of accuracy of the residual clearances, and achieve the optimized pre-joining schemes with less number of pre-joining at the same level of residual clearances. Practical implications The optimized pre-joining schemes are given in the form of Pareto-optimality set, and workers can select suitable results according to their inclination to the quality and efficiency. Originality/value The paper is the first to propose the equivalent gap assembly model for the pre-joining operation, which provides for the simplification of the calculation of residual clearances based on the constrained variation principles.
Citation: Assembly Automation
PubDate: 2016-07-20T11:44:42Z
DOI: 10.1108/AA-12-2015-129

• A study on the control of an Automatic Picking System (APS) in a warehouse
• First page: 388
Abstract: Assembly Automation, Volume 36, Issue 4, September 2016.
Purpose This paper explores methods of defining ejecting zones used in automatic picking systems (APSes), particularly in A-frame APSes. An A-frame APS automatically ejects products onto a conveyor, which then brings the products to their destination. Ejecting zones are moving zones on a conveyor, and each ejecting zone corresponds to one picking order. Products are ejected as a zone passes channels in which the products are stored. Design/methodology/approach First, three ejecting zone types are defined, and their operations are explained. Second, picking orders are analysed and categorized by considering the structure and the picking mechanism of an A-frame APS. In addition, picking-order instances reflecting actual data are randomly generated according to each category. Finally, the performance of the ejecting zones is evaluated using the picking-order instances and computer simulations. Findings The results from the computer simulations suggest the ejecting zone types suitable for use with various picking order types considering order fulfilment speed and energy usage. Research limitations/implications In this paper, we only adopt a triagngular distribution which is considered most practical distribution in the industry. Practical implications It is believed that these results can provide managers and operators with useful guides to facilitate the effective operation of an A-frame APS. The provided ideas have been implemented at the pharmaceutical warehouse of the largest logistics company in Korea. Originality/value It is essential to define the ejecting zones when operating an A-frame APS efficiently, but there is almost no research in this area. This paper focuses on defining ejecting zones as well as methods to utilize these zones.
Citation: Assembly Automation
PubDate: 2016-07-20T11:44:48Z
DOI: 10.1108/AA-02-2016-018

• Design of a novel bionic prosthetic knee joint
• First page: 398
Abstract: Assembly Automation, Volume 36, Issue 4, September 2016.
Purpose This paper is to find a new method that could be applied to the high and mid grade prosthesis knee joint. Design/methodology/approach Based on analysis, calculation, modeling, simulation and experimental study of the motion law of knee joint, this paper not only determines the structure and parameters of the knee joint and calculates the instantaneous center, but also analyzes the stance stability and completes the optimization. With the help of experimental tests (fatigue test and gait curve test), the quality and performance of the designed knee joint is verified. Findings The experimental results shows that the gait curve of the designed knee joint is much closer to health people. The designed prosthesis knee joint, with adjustable swing speed and gait curve which are close to health limb, has a better performance when compared to the ordinary knee joint with four-bar linkage structure. Originality/value This paper developed a prosthesis knee joint based on a novel design method that could be applied to the “high and mid ”grade prosthesis knee joint and verified its function on an amputee performed the lower amputation, which could provide theoretical support for researches and designs related to prosthesis knee joint in future.
Citation: Assembly Automation
PubDate: 2016-07-20T11:44:36Z
DOI: 10.1108/AA-08-2015-066

• Force and position deviations estimation for ultra-thin-tube assembly
• First page: 405
Abstract: Assembly Automation, Volume 36, Issue 4, September 2016.
Purpose Micro ultra-thin tubes have important implications in aerospace, nuclear energy and other fields. In micro-assembly process, these parts are characterised by following reasons: 1) the small size can easily lead to damage when gripping, even for low intensity; 2) mainly affected by the instability of light source, for vision-based systems, the visual information about ultra-thin tubes is difficult to gather, and the contact state is hard to monitor. Design/methodology/approach The paper presents a new method to adjust the position deviations based on contact forces during micro-assembly processes. Specific research is such that: the assembly model was established based both on mechanics calculation and numerical simulation; the assembly task was carried out on an in-house microassembly system with coaxial alignment function (MSCA), the contact statements were controlled based on force sensor feedback signals; and the model of the relationship between contact force and assembly deviations was established. Through a comparative study, the results of experiment and simulation differ by less than 11%, validating the accuracy and feasibility of the method. Findings The model of assembly force and position deviations of micro ultra-thin tubes based on MSCA has been built. Besides, the assembly force threshold, and the assembly process parameters have been obtained. Originality/value The assembly process parameters obtained from experiments can be applied in the precision assembly, and provide theoretical guidance and technical support to the precision assembly of the multi-scale parts.
Citation: Assembly Automation
PubDate: 2016-07-20T11:44:50Z
DOI: 10.1108/AA-11-2015-109

• Layout validation and re-configuration in Plug & Produce Systems
• First page: 412
Abstract: Assembly Automation, Volume 36, Issue 4, September 2016.
Purpose This paper aims to provide a method and decision support tool to enhance swift reconfiguration of Plug&Produce systems in the presence of continuously changing production orders. Design/methodology/approach The paper reviews different production scenarios and system design and configuration methods and more particularly specify the need of decision support tools for Plug&Produce systems that integrate configuration and planning activities. This problem is then addressed by proposing a method that helps reducing the solution space of the reconfiguration problem and allows the timely selection of the most promising reconfiguration alternative. Findings The proposed method was found to be helpful in reducing the reconfiguration alternatives that need to be considered and in selecting the most promising one for different orders. The advantages and limitations of this method are identified, and an illustrative test-case of the approach is presented corroborating the method applicability in the absence of large queues in the system. Originality/value This paper addresses a less explored domain within the Plug&Produce systems research field, which is the system reconfiguration. It is proposed a method to support system validation and reconfiguration jointly with an illustrative test-case. This represents an original contribution to Plug&Produce research field and it can have impact in improving agility and decreasing the complexity of reconfiguration activities to cope with constantly changing production orders.
Citation: Assembly Automation
PubDate: 2016-07-20T11:44:33Z
DOI: 10.1108/AA-12-2015-119

• An automated assembly technology for large mobile radar antenna
• First page: 429
Abstract: Assembly Automation, Volume 36, Issue 4, September 2016.
Purpose Large-scale mobile radars are still erected manually by using lifting equipment, which often fails to meet the requirements on precision, quality and efficiency in the erecting process. The paper introduces techniques for automatic assembly of large mobile radar antenna. Design/methodology/approach A large-scale metrology system for accurate identification of the positions and orientation of the radar antenna components is presented. A novel 3- DOF parallel mechanism is designed to realize orientation adjustment of three axes synchronous, and thus, guarantees the efficiency and accuracy of positioning process. Findings The system described in this paper is practicable in outdoor environment and provides a holistic solution that gives full consideration of the operation conditions and the environmental influences. In performance evaluation tests, the measured absolute accuracy is less than (+/-1mm) and repeatability is less than (+/-0.5mm) in the positioning task for 10m×3m large antenna. Originality/value This paper presents a new conception of an automatic assembly technology for the large radar antenna application.
Citation: Assembly Automation
PubDate: 2016-07-20T11:44:44Z
DOI: 10.1108/AA-12-2015-125

• An optimization methodology for multi model walking-worker assembly
systems: an application from Busbar energy distribution systems
• First page: 439
Abstract: Assembly Automation, Volume 36, Issue 4, September 2016.
Citation: Assembly Automation
PubDate: 2016-07-20T11:44:46Z
DOI: 10.1108/AA-09-2015-072

• Optimal control method on assembly precision for remanufactured car engine
based on state space model
• First page: 460
Abstract: Assembly Automation, Volume 36, Issue 4, September 2016.
Purpose The optimal control on reassembly (remanufacturing assembly) error is one of the key technologies to guarantee the assembly precision of remanufactured product. However, because of the uncertainty existing in remanufactured parts, it is difficult to control assembly error during reassembly process. Based on the state space model, the optimal control method on reassembly precision is proposed to solve this problem. Design/methodology/approach Initially, to ensure the assembly precision of remanufactured car engine, this paper puts forward an optimal control method on assembly precision for remanufactured car engine based on the state space model. This method takes assembly workstation operation and remanufactured part attribute as the input vector, reassembly status as the state vector, and assembly precision as the output vector. Then, the compensation function of reassembly workstation operation input vector is calculated to direct the optimization of reassembly process. Finally, a case study of a certain remanufactured car engine crankshaft is constructed to verify the feasibility and effectiveness of the method proposed. Findings The optimal control method on reassembly precision is an effective technology in improving the quality of remanufactured crankshaft. The average qualified-rate of remanufactured crankshaft has increased from 83.05% to 90.97% as shown in the case study. Originality/value The optimal control method on reassembly precision based on the state space model is available to control the assembly precision, thus enhancing the core competitiveness of remanufacturing enterprises.
Citation: Assembly Automation
PubDate: 2016-07-20T11:44:40Z
DOI: 10.1108/AA-07-2015-062

• Guaranteed cost design for model-based cyber-physical assembly: a convex
optimization approach
• First page: 217
Abstract: Assembly Automation, Volume 36, Issue 3, August 2016.
Purpose The purpose of this paper is to propose a guaranteed cost control design procedure for model-based cyber-physical assembly systems. In order to reflect the cyber-physical environment, the network-induced delays and disturbances are introduced in the mathematical model. Design/methodology/approach Based on the linear matrix inequality approach, the guaranteed cost controller is designed such that the guaranteed cost can be satisfied and the corresponding convex optimization algorithm is provided. Moreover, H-infinity theory is employed to deal with the disturbance with the given H-infinity attenuation level. Findings By constructing appropriate Lyapunov-Krasovskii functionals, delay-dependent sufficient conditions are established in terms of linear matrix inequalities and the controller design procedure is given. Originality/value A simplified cyber-physical assembly model is given, based on which the designed controller can allow us to control the closed-loop cyber-physical assembly systems with the guaranteed cost.
Citation: Assembly Automation
PubDate: 2016-06-16T11:33:04Z
DOI: 10.1108/AA-11-2015-098

• Tolerance simulation of composite wingbox assembly considering
• First page: 224
Abstract: Assembly Automation, Volume 36, Issue 3, August 2016.
Purpose Tolerance simulation’s reliability depends on the concordance between the input probability distribution and the real variation. The prescribed clamp force introduced changes in parts’ variation, which should be reflected in the input probability distribution for the tolerance simulation. The paper presents a tolerance analysis process of the composite wingbox assembly considering the preloading-modified distribution, especially focuses on the spring-in deviation of the thin-walled C-section composite beam (TC2B). Design/methodology/approach Based on FEA model of TC2B, the preloading-modified Probability Distribution Function (PDF) of the spring-in deviation is obtained. Thickness variations of the TC2B are obtained from the data of the downscaled composite wingbox. These variations are input to the Computer Aided Tolerance (CAT) tools, and the final assembly variations are obtained. The assembly of the downscaled wingbox illustrates the effect of preloading on the probability distribution of the spring-in deviation. Findings The results have shown that the final assembly variations estimated with the modified probability distribution is more reliable than the variation of the initial normal distribution. Originality/value The tolerance simulation work presented in the paper will enhance the understanding of the composite parts assembling with spring-in deviations; improve the chance to choose assembling processes that allow specifications to be met and helps with tolerance allocation in composites assembly.
Citation: Assembly Automation
PubDate: 2016-06-16T11:33:02Z
DOI: 10.1108/AA-08-2015-067

• A new approach for estimating leagile decoupling point using data
envelopment analysis
• First page: 233
Abstract: Assembly Automation, Volume 36, Issue 3, August 2016.
Purpose To propose a new approach for determining decoupling point in leagile chain, based on lean and agile criteria regarding market and customer demands and internal capabilities of the chain with the ultimate goal of fulfilling customer needs and increasing chain profit. Design/methodology/approach In the new approach, lean and agile criteria have been defined for assessing the effectiveness and efficiency of supply chain. The efficiency and effectiveness ratios have been calculated for lean and agile processes using input oriented and output oriented BCC methods, respectively. Based on the results, inefficient and ineffective units have been addressed and the decoupling point has been determined. Findings Findings indicate that decoupling point can be regarded as a border line between two strategies of lean and agile production, and fuzzy decoupling point and also lean-agile distance can provide the basis for distinguishing the two strategies. Practical implications Determining decoupling point has an important role in dynamic performance of a supply chain. By the proposed approach, managers can estimate the most probable area for decoupling point. Moreover, by appropriate determination of decoupling point, an organization can increase its public responsibility by appropriate usage of its resources and faster responding to customers' requirements. Originality/value In this study, in addition to determining a decoupling point in a supply chain with the aim of increasing productivity, the subject of leagile strategy of supply chains has been developed.
Citation: Assembly Automation
PubDate: 2016-06-16T11:33:10Z
DOI: 10.1108/AA-07-2015-063

• An integer-coded differential evolution algorithm for simple assembly line
balancing problem of type 2
• First page: 246
Abstract: Assembly Automation, Volume 36, Issue 3, August 2016.
Purpose In this paper, a new differential evolution algorithm (DEA) is developed for solving the simple assembly line balancing problem of type 2 (SALBP-2). Design/methodology/approach The novel approaches of mutation operator and crossover operator are presented. A self-adaptive double mutation scheme is implemented and an elitist strategy is also employed in the selection operator. Findings Test and comparison results show that the proposed IDEA obtains the better results for SALBP-2. Originality/value The presented DEA is called the integer-coded differential evolution algorithm (IDEA), which can directly deal with integer variables of SALBP-2 on a discrete space without any posterior conversion. The proposed IDEA will be an alternative in evolutionary algorithms, especially for various integer/discrete -valued optimization problems.
Citation: Assembly Automation
PubDate: 2016-06-16T11:32:59Z
DOI: 10.1108/AA-11-2015-089

• Parallel autonomous guided vehicle assembly line for a semi-continuous
manufacturing system
• First page: 262
Abstract: Assembly Automation, Volume 36, Issue 3, August 2016.
Purpose This paper proposed a parallel automated assembly line system to produce multiple products in a semi-continuous system. Design/methodology/approach The control system developed in this research consists of a manufacturing system for the two level hierarchical dynamic decisions of AGV dispatching/next station selection and machining schedules and a station control scheme for operational control of machines and components. In this proposed problem the assignment of multiple AGVs to different assembly lines and the semi-continuous stations is a critical objective. AGVs and station scheduling decisions are made at the assembly line level. On the other hand, component and machining resource scheduling are made at the station level. Findings The proposed scheduler first decomposes the dynamic scheduling problems into static AGV and machine assignment during each short-term rolling window. It optimizes weighted completion time of tasks for each short-term window by formulating the task and resource assignment problem as a minimum-cost network flow (MCF) problem during each short-term scheduling window. A comprehensive decision making process and heuristics are developed for efficient implementation. A simulation study is worked out for validation. Originality/value Several assembly lines are configured to produce multiple products in which the technologies of machines are shared among the assembly lines when required. The sequence of stations is pre-specified in each assembly line and the components of a product are kept in machine magazine. The transportation between the stations in an assembly line (intra assembly line) and among stations in different assembly lines (inter assembly line) are performed using autonomous guided vehicles (AGVs).
Citation: Assembly Automation
PubDate: 2016-06-16T11:33:03Z
DOI: 10.1108/AA-08-2015-065

• A Method for Common Design Structure Discovery in Assembly Models Using
Information from Multiple Sources
• First page: 274
Abstract: Assembly Automation, Volume 36, Issue 3, August 2016.
Purpose Design is a time-consuming stage for mechanical production. Some design structures frequently occur in different products and can be shared by multiple assembly models. Thus, identifying these structures and adding them to a design knowledge library significantly speeds up the design process. Most studies addressing this issue have traditionally focused on part models and have not extended to assembly models. This paper seeks to find a method for common design structure discovery in assembly models. Design/methodology/approach CAD models have a great deal of valuable information defined by different designers in the design stages, especially the assembly models, which are actually carriers of information from multiple sources. In this paper, we propose an approach for discovering common design structure in assembly models by comparing information from multiple sources. Assembly models are first represented as attribute connection graphs (ACGs), in which we mainly consider topological information and various attributes of parts and connections. Then, we apply a K-means clustering method based on a similarity analysis of different attributes to classify the parts and connections and transform ACGs of assemblies into type code graphs (TCGs). After this, a discovery algorithm that improves upon fast frequent subgraph mining (FFSM) is used to identify common design structures in assemblies. Findings We have developed a new method for discovering common design structures in assembly models, which considers the similarity of information from multiple sources and allows some differences in the details to keep both commonalities and individualities of common design structures. Practical implications Experiments show that the proposed method is efficient and can produce a reasonable result. Originality/value This discovery method helps designers to find common design structures from different assembly models and shorten the design cycle. It is an effective approach to build a knowledge library for product design that can shorten the design cycle.
Citation: Assembly Automation
PubDate: 2016-06-16T11:33:00Z
DOI: 10.1108/AA-07-2015-058

• Modeling and predicting of aeronautical thin-walled sheet metal parts
riveting deformation
• First page: 295
Abstract: Assembly Automation, Volume 36, Issue 3, August 2016.
Purpose Riveting deformation is inevitable due to local relatively large material flows and typical compliant parts assembly, which affects the final product dimensional quality and fatigue durability. However, traditional approaches are concentrated on elastic assembly variation simulation and do not consider the impact of local plastic deformation. This paper presents a successive calculation model to study the riveting deformation where local deformation is taken into consideration. Design/methodology/approach Based on the material constitutive model and friction coefficient obtained by experiments, an accurate three-dimension finite element (FE) model was built primarily using ABAQUS and verified by experiments. A successive calculation model of predicting riveting deformation was implemented by the Python and Matlab and solved by the ABAQUS. Finally, three configuration experiments were conducted to evaluate the effectiveness of the model. Findings The model predicting results, obtained from two simple coupons and a wing panel, showed that it was a good compliant with the experimental results and the riveting sequences had a significant effect on the distribution and magnitude of deformation. Practical implications The proposed model of predicting the deformation from riveting process was available in the early design stages and some efficient suggestions for controlling deformation could be obtained. Originality/value A new predicting model of thin-walled sheet metal parts riveting deformation was presented to help the engineers to predict and control the assembly deformation more exactly.
Citation: Assembly Automation
PubDate: 2016-06-16T11:33:01Z
DOI: 10.1108/AA-10-2015-077

• Dimensional variation propagation modeling and analysis for single-
station assembly based on multiple constraints graph
• First page: 308
Abstract: Assembly Automation, Volume 36, Issue 3, August 2016.
Purpose Modeling and analysis of dimensional variation propagation is a crucial support technology for variation reduction, product/process design evaluation and recognition of variation source. However, owing to the multi-deviation (i.e. part deviations and fixture deviations) and multi-interaction (i.e. part-to-part interaction, part-to-fixture interaction and station-to-station interaction) in assembly processes, it is difficult for designers to describe or understand the variation propagation (or accumulation) mechanism clearly. In this paper, a variation propagation modeling and analysis method based on multiple constraints is proposed by aiming at single station. Design/methodology/approach Initially, Part-to-Part Constraints (PPCs) and Part-to-Fixture Constraints (PFCs) are applied for the multi-interaction of assembly, and Multiple Constraints Graph (MCG) model is proposed for expressing PPCs, PFCs, parts, as well as the variation propagation relation among them. Then, Locating Points (LPs) are adopted for representing the deviations in constraints, and formulas for calculating the deviations of LPs are derived. On that basis, a linearized relation between LPs’ deviations and part’s locating deviations is derived. Finally, a wing box is presented to validate the proposed method, and the results indicate the methodology’s feasibility. Findings Multiple constraints graph is an effective tool for dimensional variation propagation modeling and analysis, which is shown as an example of this paper. Originality/value Functions of geometric constraints in dimensional variation propagation are revealed, and multiple constraints graph is proposed to formulize dimensional variation propagation.
Citation: Assembly Automation
PubDate: 2016-06-16T11:33:12Z
DOI: 10.1108/AA-11-2015-090

• Collision avoidance for mobile robots based on artificial potential field
and obstacle envelope modelling
• First page: 318
Abstract: Assembly Automation, Volume 36, Issue 3, August 2016.
Purpose In this paper, the collision avoidance problem for a mobile robot is investigated by constructing an artificial potential field (APF) based on geometrically modelling the obstacles with a new method named the obstacle envelope modelling (OEM). Design/methodology/approach The obstacles of arbitrary shapes are enveloped in OEM using the primitive which is an ellipse in a two-dimensional plane or an ellipsoid in a three-dimensional space. Since the surface details of obstacles are neglected elegantly in OEM, the workspace of a mobile robot is made simpler so as to increase the capability of APF in a clustered environment. Findings Further, a dipole is applied to the construction of APF produced by each obstacle, among which the positive pole pushes the robot away and the negative pole pull the robot close. Originality/value As a whole, the dipole leads the robot to make a derivation around the obstacle smoothly, which greatly reduces the local minima and trajectory oscillations. Computer simulations are conducted to demonstrate the effectiveness of the proposed approach.
Citation: Assembly Automation
PubDate: 2016-06-16T11:33:12Z
DOI: 10.1108/AA-01-2016-008

• Logic workflow structure modeling of product variant design and activity
path generating
• First page: 333
Abstract: Assembly Automation, Volume 36, Issue 3, August 2016.
Purpose Product variant design process consists of a series of asynchronous activities. These activities and the logic relations among them are important in constructing general logic workflow structure which is the foundation of deriving activity path for variant design business. Traditional process modeling approaches have not defined activities for product variant design and cannot describe the complex relations among these activities due to lack of logic express elements. Thus, logic workflow structure modeling method is anticipated to meet the requirements of logic description and path generation in product variant design application. This paper aims to address these issues. Design/methodology/approach The paper identifies the variant design modes of different types of parts, and defines their variant design activities. The procedure of constructing general logic workflow structure of product variant design is proposed. Simultaneously, the principles of inferring logic relations among activities are put forward based on their adjacency information and connectivity probability. A general logic workflow structure of product variant design is constructed. Based on this, activity path corresponding to a variant design business can be generated. And the algorithm of generating activity path is designed as well. In addition, Boolean vectors of activity path, based on the functional contour matrix of polychromatic set theory, can be inferred which denotes the functional character of activity path. Findings A general logic workflow structure for product variant design has been established, which comprises variant design activities and basic process logic nodes. The logic relations among activities can be inferred based on their in-degree / out-degree and connectivity probability. The function character of activity path can also be expressed based on Polychromatic Set theory. Originality/value The combination of variant design activity and basic process logic node makes diverse variant design business descriptions possible in a general workflow structure. The proposed approach provides evidences for designer to plan and develop product variant design system effectively.
Citation: Assembly Automation
PubDate: 2016-06-16T11:32:44Z
DOI: 10.1108/AA-02-2015-007

• Guest Editorial
• Authors: Bo Shen
First page: 109
Abstract: Assembly Automation, Volume 36, Issue 2, April 2016.

Citation: Assembly Automation
PubDate: 2016-02-24T10:04:13Z
DOI: 10.1108/AA-02-2016-014

• Takagi-Sugeno System for supervisory formation control of seeker mounted
unmanned aerial vehicles
First page: 111
Abstract: Assembly Automation, Volume 36, Issue 2, April 2016.
Purpose The main purpose of this paper is achieving a leader-follower formation of UAVs which is a cooperative scenario inspired by formation flying of living organisms such as geese. Designing a control strategy based on only vision measurement (without radio communication), and keeping connectivity in vision are important challenges in the formation flying problem which is the base of formation flying in living organisms. Design/methodology/approach To achieve the mentioned purposes, a feedback linearization technique is employed. Moreover, a Takagi-Sugeno based supervisory control strategy for visibility maintenance combined with an acceleration estimator in order to compensate the leader maneuvers is proposed. Findings We conclude that by employing practical seeker sensors, all the mentioned objectives (under the proposed strategy) can be satisfied. Originality/value Keeping formation and visibility maintenance in the presence of the leader maneuver are the main contributions of the paper.
Citation: Assembly Automation
PubDate: 2016-02-24T10:03:31Z
DOI: 10.1108/AA-09-2015-074

• Path planning for intelligent robot based on switching local evolutionary
PSO algorithm
• Authors: Nianyin Zeng, Hong Zhang, Yanping Chen, Binqiang Chen, Yurong Liu
First page: 120
Abstract: Assembly Automation, Volume 36, Issue 2, April 2016.
Purpose This paper presents a novel particle swarm optimization (PSO) based on a non-homogeneous Markov chain and differential evolution (DE) for path planning of intelligent robot when having obstacles in the environment. Design/methodology/approach The three-dimensional path surface of the intelligent robot is decomposed into a two-dimensional plane and the height information in z axis. Then, the grid method is exploited for the environment modeling problem. After that, a recently proposed switching local evolutionary PSO (SLEPSO) based on non-homogeneous Markov chain and differential evolution is analyzed for the path planning problem. The velocity updating equation of the presented SLEPSO algorithm jumps from one mode to another based on the non-homogeneous Markov chain, which can overcome the contradiction between local and global search. In addition, DE mutation and crossover operations can enhance the capability of finding a better global best particle in the PSO method. Findings Finally, the SLEPSO algorithm is successfully applied to the path planning in two different environments. Comparing with some well-known PSO algorithms, the experiment results show the feasibility and effectiveness of the presented method. Originality/value Therefore, this can provide a new method for the area of path planning of intelligent robot.
Citation: Assembly Automation
PubDate: 2016-02-24T10:03:52Z
DOI: 10.1108/AA-10-2015-079

• An advanced immune based strategy to obtain an optimal feasible assembly
sequence
• Authors: M V A Raju Bahubalendruni, Deepak B B V L, Bibhuti Bhusan Biswal
First page: 127
Abstract: Assembly Automation, Volume 36, Issue 2, April 2016.
Purpose A suitable assembly sequence consequences low cost manufacturing process with in minimal lead time. Optimal feasible Assembly sequence generation subjected to several assembly predicates influences search space of the problem and thereby computational time. The purpose of this investigation is to develop an intelligent methodology to find out an optimal feasible assembly sequence while considering the assembly predicates. Design/methodology/approach The proposed research work is carried by using two artificial immune system based models namely Bone Marrow Model and Negative Selection Algorithms in order to achieve the below objectives. • To obtain the possible number of assembly sequences. • To obtain the feasible assembly sequences while considering different assembly predicates. • To obtain an optimal feasible assembly sequence. Findings Proposed bone-marrow model determines the possible assembly sequences to ease the intricacy of the problem formulation. Further evaluation has been carried out through negative-selection censoring & monitoring models. These developed models reduce the overall computational time in order to determine the optimal feasible assembly sequence. Originality/value In this paper, the novel and efficient strategies based on artificial immune system have been developed and proposed to obtain all valid assembly sequences and optimized assembly sequence for a given assembled product using assembly attributes. The introduced methodology is proven its effectiveness in achieving optimal assembly sequence with less computational time.
Citation: Assembly Automation
PubDate: 2016-02-24T10:03:37Z
DOI: 10.1108/AA-10-2015-086

• A new genetic algorithm approach to smooth path planning for mobile robots
• Authors: Baoye Song, Zidong Wang, Li Sheng
First page: 138
Abstract: Assembly Automation, Volume 36, Issue 2, April 2016.
Purpose In this paper, the smooth path planning problem is considered for a mobile robot based on the genetic algorithm and the Bezier curve. Design/methodology/approach The workspace of a mobile robot is described by a new grid-based representation that facilitates the operations of the adopted genetic algorithm. The chromosome of the genetic algorithm is composed of a sequence of binary numbered grids (i.e., control points of the Bezier curve). Ordinary genetic operators including crossover and mutation are used to search the optimum chromosome where the optimization criterion is the length of a piecewise collision-free Bezier curve path determined by the control points. Findings This paper has proposed a new smooth path planning for a mobile robot by resorting to the genetic algorithm and the Bezier curve. A new grid-based representation of the workspace has been presented, which makes it convenient to perform operations in the genetic algorithm. The genetic algorithm has been used to search the optimum control points that determine the Bezier curve based smooth path. The effectiveness of the proposed approach has been verified by a numerical experiment, and some performances of the obtained method have also been analyzed. Research limitations/implications There still remain many interesting topics, for example, how to solve the specific smooth path planning problem by using the genetic algorithm? how to promote the computational efficiency in the more grids case? These issues deserve further research. Originality/value The purpose of this paper is to improve the existing results by making the following three distinctive contributions: 1) a rigorous mathematical formulation of the path planning optimization problem is formulated; 2) a general grid-based representation ($2^{n} \times 2^{n}$ grids) is proposed to describe the workspace of the mobile robots in order to facilitate the implementation of the GA where $n$ is chosen according to the trade-off between the accuracy and the computational burden; and 3) the control points of the Bezier curve are directly linked to the optimization criteria so that the generated paths are guaranteed to be optimal without any need for smoothing afterwards.
Citation: Assembly Automation
PubDate: 2016-02-24T10:03:48Z
DOI: 10.1108/AA-11-2015-094

• On the small fiber-coupled laser controller for animal robot
• Authors: Haixia Wang, Yuliang Wang, Yaozong Sun, Qiong Pu, Xiao Lu
First page: 146
Abstract: Assembly Automation, Volume 36, Issue 2, April 2016.
Purpose Because of the inconvenience and inflexibility of the laser controller, the applied range of the Optogenetics is limited. A portable remote-controlled laser controller system including the remote-controlled system and the laser stimulator is designed in the paper. Design/methodology/approach The remote-controlled system is handheld, which can wirelessly adjust the power and the emitting frequency of the laser by utilizing the ZigBee module. Findings The laser stimulator can be mounted on the animal due to only small weight of 35g and small volume of 40*40*20mm, which accomplishes validly the adjustable power and frequency by changing the current amplitude and duty radio. In the end, the experiments verify the reliability and effectiveness of the laser controller. Originality/value In virtue of the modular design of the driven circuit and the reasonable layout, the whole system has the advantages of small volume, convenient control and high stability, which provide the convenience for the development of portable optogenetics animal robot experiment and has broad market prospects.
Citation: Assembly Automation
PubDate: 2016-02-24T10:03:51Z
DOI: 10.1108/AA-11-2015-097

• Bio-inspired approach to invariant recognition and classification of
fabric weave patterns and yarn color
• Authors: Babar Khan, Fang Han, Zhijie Wang, Rana J Masood
First page: 152
Abstract: Assembly Automation, Volume 36, Issue 2, April 2016.
Purpose We proposed a biologically inspired processing architecture to recognize and classify fabrics with respect to the weave pattern (fabric texture) and yarn color (fabric color) Design/methodology/approach By using the fabric weave patterns image identification system, this study analyzed the fabric image based on the HMAX model of computer vision, to extract feature valuesrelated to texture of fabric. RGB color descriptor based on opponent color channels simulating the single opponent and double opponent neuronal function of the brain is incorporated in to the texture descriptor to extract yarn color feature values. Finally, Support Vector Machine (SVM) Classifier is used to train and test the algorithm. Findings This two-stage processing architecture can be used to construct a system based on computer vision to recognize fabric texture, and to increase the system reliability and accuracy. Using this method, the stability and fault-tolerance (invariance) was improved. Originality/value Traditionally, fabric texture recognition is performed manually by visual inspection. Recent studies have proposed automatic fabric texture identification based on computer vision. In the identification process, the fabric weave patterns are recognized by the warp and weft floats. However, due to the optical environments and the appearance differences of fabric and yarn, the stability and fault-tolerance (invariance) of the computer vision method are yet to be improved. By using our method, the stability and fault-tolerance (invariance) was improved.
Citation: Assembly Automation
PubDate: 2016-02-24T10:04:04Z
DOI: 10.1108/AA-11-2015-100

• A bio-inspired scan matching algorithm for mobile robots in outdoor
environments
• Authors: Fei Yan, Ke Wang, Jizhong Xiao, Ruifeng Li
First page: 159
Abstract: Assembly Automation, Volume 36, Issue 2, April 2016.
Purpose The most prominent example of scan matching algorithm is the Iterative Closest Point (ICP) algorithm. But the ICP algorithm and its variants excessively depend on the initial pose estimate between two scans. The paper proposes a scan matching algorithm, which is adaptable to big initial pose errors. Design/methodology/approach The environments are represented by flat units and upright units. The upright units are clustered to represent objects that the robot cannot cross over. The object cluster is further discretized to generate layered model consisting of cross-section ellipses. The layered model provides simplified features that facilitate an object recognition algorithm to discriminate among common objects in outdoor environments. A layered model graph is constructed with the recognized objects as nodes. Based on the similarity of sub-graphs in each scans, the layered model graph-based matching algorithm generates initial pose estimates and use ICP to refine the scan matching results. Findings Experimental results indicate that the proposed algorithm can deal with bad initial pose estimates and increase the processing speed. Its computation time is short enough for real-time implementation in robotic applications in outdoor environments. Originality/value This paper proposes a bio-Inspired scan matching algorithm for mobile robots based on layered model graph in outdoor environments.
Citation: Assembly Automation
PubDate: 2016-02-24T10:04:14Z
DOI: 10.1108/AA-11-2015-103

• Bio-inspired neural network with application to license plate recognition:
hysteretic ELM approach
• Authors: Liang Chen, Leitao Cui, Rong Huang, Zhengyun Ren
First page: 172
Abstract: Assembly Automation, Volume 36, Issue 2, April 2016.
Purpose The paper presents a bio-inspired neural network for improvement of information processing capability of the existing artificial neural networks. Design/methodology/approach In the network, we introduce a property often found in biological neural system – hysteresis – as the neuron activation function; and a bionic algorithm – extreme learning machine (ELM) – as the learning scheme. We give the gradient descent procedure to optimize parameters of the hysteretic function and develop an algorithm to online select ELM parameters, including number of the hidden-layer nodes and hidden-layer parameters. The algorithm combines the idea of the cross validation and random assignment in original ELM. Finally, we demonstrate the advantages of the hysteretic ELM neural network by applying it to automatic license plate recognition. Findings Experiments on automatic license plate recognition show that the bio-inspired learning system has better classification accuracy and generalization capability with consideration to efficiency. Originality/value Comparing with the conventional sigmoid function, hysteresis as the activation function enables has two advantages: 1) the neuron’s output not only depends on its input, but also on derivative information, that provides the neuron with memory; 2) the hysteretic function can switch between the two segments, thus avoiding the neuron falling into local minima and having a quicker learning rate. The improved ELM algorithm in some extent makes up for declining performance because of original ELM’s complete randomness with the cost of a litter slower than before.
Citation: Assembly Automation
PubDate: 2016-02-24T10:04:18Z
DOI: 10.1108/AA-11-2015-105

• Neural-network-based containment control of nonlinear multi-agent systems
under communication constraints
• Authors: Chao Ma
First page: 179
Abstract: Assembly Automation, Volume 36, Issue 2, April 2016.
Purpose The purpose of this paper is to investigate the neural-network-based containment control of multi-agent systems with unknown nonlinear dynamics. Moreover, communication constraints are taken into account to reflect more realistic communication network. Design/methodology/approach Based on the approximation property of the radial basis function neural networks, the control protocol for each agent is designed, where all the information is exchanged in the form of sampled data instead of ideal continuous-time communications. Findings By utilizing Lyapunov stability theory and Lyapunov-Krasovskii functional approach, sufficient conditions are developed to guarantee that all the followers can converge to the convex hull spanned by the stationary leaders. Originality/value Since ideal continuous-time communications of the multi-agent systems are very difficult or even unavailable to achieve, the neural-network-based containment control of nonlinear multi-agent systems is solved under communication constraints. More precisely, sampled-data information is exchanged, which is more applicable and practical in the real world applications.
Citation: Assembly Automation
PubDate: 2016-02-24T10:04:21Z
DOI: 10.1108/AA-11-2015-107

• A novel path planning method for biomimetic robot based on deep learning
• Authors: Yang Lu, Shujuan Yi, Yurong Liu, Yuling Ji
First page: 186
Abstract: Assembly Automation, Volume 36, Issue 2, April 2016.
Purpose We designed a multi-layer convolutional neural network to solve biomimetic robot path planning problem. Design/methodology/approach At first, the convolution kernel with different scales can be got by using the sparse auto encoder training algorithm, the parameter of the hidden layer is a series of convolutional kernel, and we use these kernels to extract first-layer features. Then we get the second-layer features through the max-pooling operators, which improves the invariance of the features. At last, we use fully connected layers of neural networks to accomplish the path planning task. Findings The NAO biomimetic robot respond quickly and correctly to the dynamic environment. The simulation experiments show that the deep neural network outperforms in dynamic and static environment than the conventional method. Originality/value A new method of deep learning based biomimetic robot path planning is proposed. We designed a multi-layer convolutional neural network which includes max-pooling layer and convolutional kernel. Then the first and second layers features can be extracted by these kernels. Finally, we use the sparse auto encoder training algorithm to train the convolutional neural network so as to accomplish the path planning task of NAO robot.
Citation: Assembly Automation
PubDate: 2016-02-24T10:04:21Z
DOI: 10.1108/AA-11-2015-108

• Improved GA and pareto optimization-based facial expression recognition
• Authors: Fowei Wang, Bo Shen, Shaoyuan Sun, Zidong Wang
First page: 192
Abstract: Assembly Automation, Volume 36, Issue 2, April 2016.
Purpose The purpose of this paper is to improve the accuracy of the facial expression recognition by using genetic algorithm (GA) with an appropriate fitness evaluation function and Pareto optimization model with two new objective functions Design/methodology/approach In order to achieve facial expression recognition with high accuracy, the Haar-like features representation approach and the Bilateral filter are firstly used to preprocess the facial image. Secondly, the uniform LGBP is employed to extract the facial feature so as to reduce the feature dimension. Thirdly, an improved GA and Pareto optimization approach are employed to select the optimal significant features. Fourthly, the random forest classifier is chosen to achieve the feature classification. Subsequently, some comparative experiments are implemented. Finally, the conclusion is drawn and some future research topics are pointed out. Findings The experiment results show that the proposed facial expression recognition algorithm outperforms ones in the existing literature in terms of both the actuary and computational time. Originality/value The GA and Pareto optimization algorithm are combined to select the optimal significant feature. In order to improve the accuracy of the facial expression recognition, the GA is improved by adjusting an appropriate fitness evaluation function and a new Pareto optimization model is proposed that contains two objective functions indicating the achievements in minimizing within-class variations and in maximizing between-class variations.
Citation: Assembly Automation
PubDate: 2016-02-24T10:04:28Z
DOI: 10.1108/AA-11-2015-110

• Bio-inspired kinematical control of redundant robotic manipulators
• Authors: Ali Leylavi Shoushtari, Stefano Mazzoleni, Paolo Dario
First page: 200
Abstract: Assembly Automation, Volume 36, Issue 2, April 2016.
Purpose In this paper an innovative kinematic control algorithm is proposed for redundant robotic manipulators. The algorithm takes advantage of a bio-inspired approach. Design/methodology/approach A simplified 2 DOFs model is presented to handle kinematic redundancy in the x-y plane; an extension to three-dimensional tracking tasks is presented as well. A set of sample trajectories were used to evaluate the performances of the proposed algorithm. Findings The results from the simulations confirm the continuity and accuracy of generated joint profiles for given end-effector trajectories as well as algorithm robustness, singularity and self-collision avoidance. Originality/value This paper shows how to control a redundant robotic arm by applying human upper arm-inspired concept of inter-joint dependency.
Citation: Assembly Automation
PubDate: 2016-02-24T10:03:30Z
DOI: 10.1108/AA-11-2015-116

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