Showing papers in "Robotics and Computer-integrated Manufacturing in 2005"
TL;DR: In this article, the authors considered the completion time as a constraint and proposed a 2-phase algorithm to minimize the manufacturing cost of the reconfigurable virtual enterprise, where a polynomial bounded algorithm was proposed to find the earliest completion time, and then the solution was improved by exchanging the candidate partners in keeping the solution in the feasible region.
Abstract: Agility is the competitive advantage in the global manufacturing environment. It is believed that the agility can be realized by dynamically reconfigurable virtual enterprise. However, the configuration of virtual enterprises is a challenge to us. In selecting the partners for the reconfiguration of virtual enterprise, many factors should be taken into consideration. However, the manufacturing cost and time to market are the most important factors. In this paper, in considering the completion time as a constraint we model the partner selection problem by an integer programming formulation to minimize the manufacturing cost. The formulation is then transformed into a graph-theoretical formulation and a 2-phase algorithm is developed to solve the problem. In the first phase, a polynomial bounded algorithm is proposed to find the earliest completion time, so we obtained a feasible solution. In phase 2, we improve the solution by exchanging the candidate partners in keeping the solution in the feasible region. Although we may not find the optimal solution for the problem by the improvement algorithm, the objective is reduced iteration by iteration. Thus, the algorithm is efficient and can be applicable to practical problems. An illustrative example is presented to show the application of the proposed algorithm.
132 citations
TL;DR: In this article, an ultrasonically vibrated workpiece holder and a two-stage experimental investigation of ultrasonic assisted drilling of A1100-0 aluminum workpieces are reported and analyzed.
Abstract: Accuracy and surface finish play an important role in modern industry. Undesired projections of materials, known as burrs, reduce the part quality and negatively affect the assembly process. A recent and promising method for reducing burr size in metal cutting is the use of ultrasonic assistance, where high-frequency and low-amplitude vibrations are added in the feed direction during cutting. Note that this cutting process is distinct from ultrasonic machining. This paper presents the design of an ultrasonically vibrated workpiece holder, and a two-stage experimental investigation of ultrasonically assisted drilling of A1100-0 aluminum workpieces. The results of 175 drilling experiments with uncoated and TiN-coated drills are reported and analyzed. The effect of ultrasonic assistance on burr size, chip formation, thrust forces and tool wear is studied. The results demonstrate that under suitable ultrasonic vibration conditions, the burr height and width can be reduced in comparison to conventional drilling.
130 citations
TL;DR: An innovative encoding is introduced to take into account the multiple solutions of the inverse kinematic problem and the results show that the method can determine the optimum sequence of a considerable number of task points for robots up to six-degrees of freedom.
Abstract: Industrial robots should perform complex tasks in the minimum possible cycle time in order to obtain high productivity. The problem of determining the optimum route of a manipulator's end effector visiting a number of task points is similar but not identical to the well-known travelling salesman problem (TSP). Adapting TSP to Robotics, the measure to be optimized is the time instead of the distance. In addition, the travel time between any two points is significantly affected by the choice of the manipulator's configuration. Therefore, the multiple solutions of the inverse kinematics problem should be taken into consideration. In this paper, a method is introduced to determine the optimum sequence of task points visited by the tip of the end effector of an articulated robot and it can be applied to any non-redundant manipulator. This method is based on genetic algorithms and an innovative encoding is introduced to take into account the multiple solutions of the inverse kinematic problem. The results show that the method can determine the optimum sequence of a considerable number of task points for robots up to six-degrees of freedom.
112 citations
TL;DR: An efficient approach to machine condition monitoring and health diagnosis, based on the Discrete Harmonic Wavelet Packet Transform (DHWPT), which enables higher signal-to-noise ratios and consequently, more effective and intelligent use of the available sensor information, leading to more accurate system health evaluation.
Abstract: This paper presents an efficient approach to machine condition monitoring and health diagnosis, based on the Discrete Harmonic Wavelet Packet Transform (DHWPT). Specifically, vibration signals measured from a bearing test bed were decomposed into a number of frequency sub-bands, and key features associated with each sub-band were selected, based on the Fisher linear discriminant criterion. The key features were then used as inputs to a neural network classifiers for assessing the system's health status. Comparing to the conventional approach where statistical parameters from raw vibration signals are used, the presented approach enables higher signal-to-noise ratios and consequently, more effective and intelligent use of the available sensor information, leading to more accurate system health evaluation.
109 citations
TL;DR: It is shown that the (square of the) time-optimal feedrate can be determined as a piecewise-rational function of the curve parameter xi, with break-points corresponding to the roots of certain polynomial equations.
Abstract: The problem of specifying the feedrate variation along a curved path, that yields minimum traversal time for a 3-axis CNC machine subject to constraints on the feasible acceleration along each axis, is addressed. In general, this time-optimal feedrate incurs bang-bang control, i.e., maximum acceleration/deceleration is demanded of at least one axis throughout the motion. For a path defined by a polynomial parametric curve r(xi), we show that the (square of the) time-optimal feedrate can be determined as a piecewise-rational function of the curve parameter xi, with break-points corresponding to the roots of certain polynomial equations. Furthermore, this type of feedrate function is amenable to a real-time interpolator algorithm that drives the machine directly from the analytic curve description, eliminating the need for linear/circular G code approximations. The theoretical and computational aspects of such time-optimal feedrate functions are presented, together with experimental results from their implementation on a 3-axis mill driven by an open-architecture software controller. (C) 2004 Elsevier Ltd. All rights reserved.
109 citations
TL;DR: In this article, the concept of product improvement was based on the activation and tracking of (ECs) through the developmental-design phase and the manufacturing phase, and a special method was used to recognize activities within the process and the degree of involvement of individual participants.
Abstract: The ability to manage engineering changes (ECs) efficiently reflects the agility of an enterprise. A large majority of products become gradually improved and perfected through the developmental-design process, during which the set design requirements are met or even upgraded, thus prolonging the product life cycle. The concept of product improvement was based on the activation and tracking of (ECs) through the developmental-design phase and the manufacturing phase. A special method was used to recognize activities within the process and the degree of involvement of individual participants. The individuals involved in the process were provided with appropriate information and the required communication channels with others were ensured. The EC process was generalized and applied to different types of production. A product's complexity and design level were analyzed first, and key factors such as CE methods, process definition, information system, communication and organization were used as a tool for optimizing the EC process. The method was tested and successfully applied into industrial practice.
104 citations
TL;DR: In this paper, a new type of virtual cellular manufacturing (CM) system is considered, and a multi-objective design procedure is developed for designing such cells in real time.
Abstract: In this paper, a new type of virtual cellular manufacturing (CM) system is considered, and a multi-objective design procedure is developed for designing such cells in real time. Retaining the functional layout, virtual cells are addressed as temporary groupings of machines, jobs and workers to realize the benefits of CM. The virtual cells are created periodically, for instance every week or every month, depending on changes in demand volumes and mix, as new jobs accumulate during a planning period. The procedure includes labor grouping considerations in addition to part-machine grouping. The procedure is based on interactive goal programming methods. Factors such as capacity constraints, cell size restrictions, minimization of load imbalances, minimization of inter-cell movements of parts, provision of flexibility, etc. are considered. In labor grouping, the functionally specialized labor pools are partitioned and regrouped into virtual cells. Factors such as ensuring balanced loads for workers, minimization of inter-cell movements of workers, providing adequate levels of labor flexibility, etc. are considered in a pragmatic manner.
103 citations
TL;DR: In this article, a genetic algorithm (GA) was applied to the computer-aided process planning (CAPP) system to find the optimal process plan for a single manufacturing system as well as distributed manufacturing systems.
Abstract: In a distributed manufacturing environment, factories possessing various machines and tools at different geographical locations are often combined to achieve the highest production efficiency. When jobs requiring several operations are received, feasible process plans are produced by those factories available. These process plans may vary due to different resource constraints. Therefore, obtaining an optimal or near-optimal process plan becomes important. This paper presents a genetic algorithm (GA), which, according to prescribed criteria such as minimizing processing time, could swiftly search for the optimal process plan for a single manufacturing system as well as distributed manufacturing systems. By applying the GA, the computer-aided process planning (CAPP) system can generate optimal or near-optimal process plans based on the criterion chosen. Case studies are included to demonstrate the feasibility and robustness of the approach. The main contribution of this work lies with the application of GA to CAPP in both a single and distributed manufacturing system. It is shown from the case study that the approach is comparative or better than the conventional single-factory CAPP.
93 citations
TL;DR: A new multi-agent system (MAS) architecture to support the inter-enterprise functions/resources integration and collaboration over the networked environment, including the hybrid agent architecture and hybrid network architecture is proposed.
Abstract: The manufacturing industries are now experiencing fierce pressure of competition from every corner on this planet. In addition, the advancement in computer networks and information technologies has been gradually reshaping the manufacturing companies by shifting from the industrial age to the information era. Due to these elevated competitiveness and advanced computer technology, a number of new manufacturing and management strategies (e.g., CE or CIM) have emerged for the innovation of manufacturing enterprises. Although they have different definitions and scopes, there are several common issues: inter-enterprise functions integration; inter-enterprise resources integration; and collaboration. This paper proposes a new multi-agent system (MAS) architecture to support the inter-enterprise functions/resources integration and collaboration over the networked environment, including the hybrid agent architecture and hybrid network architecture. In contrast to the existing agent architectures, the proposed agent architecture enables agents to exhibit the hybrid (continuous and discrete) behavior and interactions. In addition, our network architecture is more suitable for building the large-scale distributed manufacturing systems that are prone to dynamic random changes of their environment. Based on the proposed MAS architecture, a collaborative product development environment is implemented as a starting point, and a multidisciplinary team-oriented design problem is illustrated to provide the vision of the proposed MAS architecture.
77 citations
TL;DR: A scheduling model for optimal production sequencing in a flexible assembly system that is modeled using timed Petri nets and task scheduling is solved with a dynamic programming algorithm to minimize the completion time for a single product or a batch of products.
Abstract: This paper investigates a scheduling model for optimal production sequencing in a flexible assembly system. The system features a set of machines working together in the same workspace, with each machine performing a subset of operations. Three constraints are considered: (1) the precedence relation among the operations specified by the assembly tree; (2) working space that limits concurrent operations; and (3) the variation of process time. The objective is to find both a feasible assignment of operations to machines and schedule tasks in order to minimize the completion time for a single product or a batch of products. The assembly process is modeled using timed Petri nets and task scheduling is solved with a dynamic programming algorithm. The method calculates the time required precisely. A detailed case study is discussed to show the effectiveness of the model and algorithm.
76 citations
TL;DR: In this paper, profile verification techniques for free-form surface inspection with and without datum information are discussed, and the inspection of free-from surfaces includes two major processes: (1) the localization of measurement data to design coordinate system based on the datum reference information or a number of extracted surface features; and (2) the further localization based on surface characteristics so that the deviation of the measured surface from the design model is minimized.
Abstract: Free-form surface inspection requires the measurement surface and the corresponding design model in a common coordinate system so that comparison between the two surfaces can be made. In practical engineering applications, the free-form shaped parts are sometimes assigned profile tolerance with or without the reference of design datum(s) based on consideration of assembly, functionality and other manufacturing requirements. This paper discusses the profile verification techniques for free-form surface inspection with and without datums. The inspection of free-from surfaces includes two major processes: (1) the localization of measurement data to design coordinate system based on the datum reference information or a number of extracted surface features; and (2) the further localization based on the surface characteristics so that the deviation of the measured surface from the design model is minimized. Implementation and tests of inspection samples have been carried out to verify the developed inspection techniques.
TL;DR: Based on differential geometry theory, applying the dynamic extension approach of relative degree, the exact feedback linearization on the kinematic error model of mobile robot is realized in this paper, where trajectory-tracking controllers are designed by pole-assignment approach.
Abstract: Based on differential geometry theory, applying the dynamic extension approach of relative degree, the exact feedback linearization on the kinematic error model of mobile robot is realized. The trajectory-tracking controllers are designed by pole-assignment approach. When angle speed of mobile robot is permanently nonzero, the local asymptotically stable controller is designed. When angle speed of mobile robot is not permanently nonzero, the trajectory-tracking control strategy with globally tracking bound is given. The algorithm is simple and applied easily. Simulation results show their effectiveness.
TL;DR: The kinematic modeling and error modeling are established with all errors considered using Jacobian matrix method for the robot and a very effective Jacobian approximation method is introduced to calculate the forward kinematics problem instead of Newton–Raphson method.
Abstract: The TAU robot presents a new configuration of parallel robots with three degrees of freedom. This robotic configuration is well adapted to perform with a high precision and high stiffness within a large working range compared with a serial robot. It has the advantages of both parallel robots and serial robots. In this paper, the kinematic modeling and error modeling are established with all errors considered using Jacobian matrix method for the robot. Meanwhile, a very effective Jacobian approximation method is introduced to calculate the forward kinematic problem instead of Newton–Raphson method. It denotes that a closed form solution can be obtained instead of a numerical solution. A full size Jacobian matrix is used in carrying out error analysis, error budget, and model parameter estimation and identification. Simulation results indicate that both Jacobian matrix and Jacobian approximation method are correct and with a level of accuracy of micron meters. ADAMS's simulation results are used in verifying the established models.
TL;DR: In this article, an active controller designed from wave point of view is used to absorb chatter vibration energy in a broad frequency band to improve machining performance of a non-rotating boring bar.
Abstract: Machining performance such as that of the boring process is often limited by chatter vibration at the tool–workpiece interface. Among various sources of chatter, regenerative chatter in cutting systems is found to be the most detrimental. It limits cutting depth (as a result, productivity), adversely affects surface finish and causes premature tool failure. Though the machining system is a distributed system, all current active controllers have been designed based upon a simplified lumped single degree of freedom cutting process model. This is because it was found that in the majority of cutting processes, there exists only one dominating mode. However, such simplification does have some potential problems. First, since the system itself is a distributed system, theoretically it consists of infinite number of vibration modes. When the controller is designed to control the dominating mode(s) only, the energy designed to suppress the particular mode(s) may excite the rest of the structural modes, which unavoidably causes the so-called spillover problem. Second, the success of the control design of such simplified single degree of freedom system relies on the availability of accurate model parameters (such as the effective mass, stiffness and damping), which is unfortunately very hard to acquire. This is because the global properties are varying with the metal removal process and the movable components of machine tool. In this paper, an active controller designed from wave point of view is used to absorb chatter vibration energy in a broad frequency band to improve machining performance of a non-rotating boring bar. In contrast to most of the current active chatter control design, the wave controller is designed based on the real distributed cutting system model. The main advantage of such a control scheme to chatter suppression is its robustness to model uncertainties. The control scheme also eliminates the control spillover problem.
TL;DR: In this paper, an expert system (DieEX) is developed for planning the machining operations of a die and a mold, where the geometry and the material of the workpiece, tool material, tool condition and operation type are considered as input values.
Abstract: In the modern manufacturing of sophisticated parts with 3D sculptured surfaces, die and mold making operations are the most widely used machining processes to remove unwanted material. To manufacture a die or a mold, many different cutting tools are involved, from deep hole drills to the smallest ball nose end mills. Since the specification of each tool is very different from each other, each mold or die is specific with their complicated shapes and many machining rules exist to consider, a great deal of expertise is needed in planning the machining operations. An expert system (DieEX) developed for this purpose is described in the present work. The geometry and the material of the workpiece, tool material, tool condition and operation type are considered as input values and various recommendations about the tool type, tool specifications, work holding method, type of milling operation, direction of feed and offset values are provided.
TL;DR: This paper provides a simple example of a control application that is distributed across two devices and investigates how this distributed implementation can be exploited to enhance the system's fault tolerance using a contingencies-based approach to reconfiguration.
Abstract: In this paper, we describe our experience using a Java-based platform to implement an emerging real-time distributed control model (IEC 61499). We provide a simple example of a control application that is distributed across two devices (Dallas Semiconductor TINI boards) and also investigate how this distributed implementation can be exploited to enhance the system's fault tolerance using a contingencies-based approach to reconfiguration.
TL;DR: In this article, an integrated approach to selective disassembly sequence planning is presented, which can efficiently generate a feasible and near-optimal sequence plan for selective-disassembly, with ensuring both batch disassembly of components and tool accessibility to fasteners.
Abstract: De-manufacturing (DM) is defined as a process to disassemble certain parts or components from a product. The parts or components are selected for recycling, reuse, maintenance or disposal. Selective-disassembly as the disassembly of the selected parts is a key process in DM. Allowing a partial and non-procedural disassembly sequence in DM, selective-disassembly aims to minimize the number of removals regardless of assembly indenture levels. It is necessary for selective-disassembly to have an effective and optimal sequence planning in order to reduce tremendous time and cost involved in product DM. The Wave propagation (WP) method, a dominant approach to selective-disassembly sequence planning, focuses on topological disassemblability of parts. It is inefficient to achieve the aim because of two missed considerations: tool accessibility to a fastener in non-procedural and partial disassembly, and batch removability to directly access a part for separation or replacement. This paper presents an integrated approach to selective-disassembly sequence planning. The two examples presented here demonstrate that the approach is efficient and practical for DM. The implemented approach can efficiently generate a feasible and near-optimal sequence plan for selective-disassembly, with ensuring both batch disassembly of components and tool accessibility to fasteners.
TL;DR: In this paper, the authors present a solution for scheduling material handling devices in the cellular manufacturing environment using the holonic control approach, which is capable of accommodating new arriving jobs and delivering good solutions in real time.
Abstract: In a real-world manufacturing environment, finding the right sequences and associated schedules with resource, precedence, and timing constraints is a difficult task. Moreover, a decision time period of hours or even minutes is simply too long. Good solutions are often needed in real time. One approach to overcome the limitations of classical scheduling is the use of distributed schemes such as agent or holonic-based control architectures. This paper presents a solution for scheduling material handling devices in the cellular manufacturing environment using the holonic control approach. In holonic systems, under real-time constraints, a feasible schedule for the material handling devices emerges from the combination of individual material handling holons’ schedules. Internal evaluation and allocation algorithms and specific cooperation mechanisms between the holons in the architecture are the basis for the resultant emergent schedules. These evaluation algorithms are developed using several scenarios that take into account uncertainties that usually exist in a dynamic manufacturing environment, such as new orders entering into the system. The study results obtained show that the holonic system is capable of accommodating new arriving jobs and delivers good solutions in real time.
TL;DR: The multi-agent system is designed to provide manufacturing control with three important characteristics: high robustness, quick response and good expandability.
Abstract: This paper presents a multi-agent system for the control of manufacturing systems. The multi-agent system is designed to provide manufacturing control with three important characteristics: high robustness, quick response and good expandability. A prototype multi-agent-based control system has been developed for a flexible assembly cell as an example. The prototype multi-agent system contains several reactive agents. Each agent acts according to its built-in behaviours, and the behaviours are able to respond to stimuli from the manufacturing environment. A system architecture to implement the multi-agent-based control system is proposed and the coordination model of the reactive agents is developed. The generic agent structure is established for individual reactive agents, and the behaviours and the subsumption architecture of each agent are designed.
TL;DR: An internet-based product customization system for CIM is proposed that enables enterprises to meet with customers’ individual requirements more effectively by providing more customization approaches and eases enterprises to optimize their product development processes and supply chains according to customers' requirements in a systematic way.
Abstract: Product customization systems are important for enterprises to bring out innovative and profitable products to the market quickly. The current systems for product customization allow customers to specify their requirements by selecting and configuring products. Customers’ individual requirements beyond product configuration cannot be fulfilled in these systems. The integration among the product customization system and other application systems of the enterprise is seldom considered. This paper proposes an internet-based product customization system for CIM. The system enables enterprises to meet with customers’ individual requirements more effectively by providing more customization approaches. Through system integration for CIM, the system eases enterprises to optimize their product development processes and supply chains according to customers’ requirements in a systematic way. System structure and function model are presented in this paper. Working mechanism for the system is proposed. Key technologies for system implementation including customer requirements description and system integration are also discussed in detail in the paper. Finally, an internet-based customization system for ceramics products is developed as a case study.
TL;DR: Petri Net augmentations pertaining to various issues include the implication of generated error recovery trajectories in the production activities, linking of production activity Net and the error recovery subnet, potential deadlocks, the role of resources, and part handling.
Abstract: The construction of error recovery Petri subnets and similar representations have received considerable attention in the literature. Previous work has presented a multi-agent system representing various levels of control in a reconfigurable architecture. Agents pertaining to production, mediation, and error recovery within such an architecture were considered. Our focus here is on the workstation level of a hierarchy where the workstation has the capability for recovery from physical errors. The implications of error recovery tasks from the perspective of control are also discussed. The approach is based on integrating Petri subnet models within a general Petri Net model for a manufacturing system environment. In essence, the error recovery plan consists of a trajectory (Petri subnet) having the detailed recovery steps that are then incorporated into the workstation control logic. The logic is based on a Timed Petri Net model of the total production system. The Petri subset models consist of a sequence of steps required to reinstate the system back to a normal state. Once generated, the recovery subnet is incorporated into the Petri Net model of the original expected (error-free) model. Petri Net augmentations pertaining to various issues are discussed in detail throughout the paper. Issues include the implication of generated error recovery trajectories in the production activities, linking of production activity Net and the error recovery subnet, potential deadlocks, the role of resources, and part handling.
TL;DR: In this paper, a novel approach is proposed to solve the quality assurance problem in predicting the acceptance of computer numerical control machined parts, rather than focusing on the prediction of precise surface roughness values.
Abstract: There have been many studies, mainly by the use of statistical modeling techniques, as to predicting quality characteristics in machining operations where a large number of process variables need to be considered. In conventional metal removal processes, however, an exact prediction of surface roughness is not possible or very difficult to achieve, due to the stochastic nature of machining processes. In this paper, a novel approach is proposed to solve the quality assurance problem in predicting the acceptance of computer numerical control (CNC) machined parts, rather than focusing on the prediction of precise surface roughness values. One of the data mining techniques, called rough set theory, is applied to derive rules for the process variables that contribute to the surface roughness. The proposed rule-composing algorithm and rule-validation procedure have been tested with the historical data the company has collected over the years. The results indicate a higher accuracy over the statistical approaches in terms of predicting acceptance level of surface roughness.
TL;DR: Beside the introduction of a set of necessary components to develop such a framework, the paper offers new modelling concepts, a modelling approach and a reference architecture for organization networks.
Abstract: Nowadays, virtual enterprises, extended enterprises, wide supply chains and enterprise networks are organizational structures recognized by the scientific and professional communities. The challenges in engineering these systems consist in providing solutions that take into account both the social and the technical aspects simultaneously. This paper presents an engineering framework for organization networks. Beside the introduction of a set of necessary components to develop such a framework, the paper offers new modelling concepts, a modelling approach and a reference architecture for organization networks.
TL;DR: In this article, a spatial three degrees of freedom parallel mechanism enhanced by a passive leg is proposed, which can be used in several applications, e.g. motion simulator, micromanipulator and machine tools.
Abstract: In this paper, a spatial three degrees of freedom parallel mechanism enhanced by a passive leg is proposed. The proposed parallel mechanism can be used in several applications, e.g. motion simulator, micromanipulator and machine tools. First, the geometric model of the three degrees of freedom parallel mechanism is addressed, in which a fourth kinematic link—a passive link connecting the base center to the platform center—is introduced. This last link is used to constrain the motion of the platform to only three degrees of freedom, i.e. the degree of freedom of the mechanism depends on the passive leg. The passive leg also enhances the global stiffness of the structure and distributes the torque from machining. Second, the kinematic analysis with the consideration of link flexibility is conducted. A kinetostatic model of the three degrees of freedom parallel mechanism with a passive link is then established and analyzed using lumped-parameter model. With the proposed method, a significant effect of the link flexibility on the mechanism's precision has been demonstrated. The influence of the change of structure parameters, including material properties, on the system behavior is discussed. Compliance mapping is also illustrated. The kinetostatic model proposed in the paper can be extended for optimal design and control of parallel kinematic machines. Finally, design optimization is conducted using genetic algorithms and some design guideline is given.
TL;DR: In this paper, a methodology to characterize fixturing system's geometry constraint status with focus on under-constraint is proposed, which assists the designer to improve deficit locating scheme and provides guidelines for revision to eventually achieve deterministic locating.
Abstract: Geometry constraint is one of the most important considerations in fixture design. Analytical formulation of deterministic location has been well developed. However, how to analyze and revise a non-deterministic locating scheme during the process of actual fixture design practice has not been thoroughly studied. In this paper, a methodology to characterize fixturing system's geometry constraint status with focus on under-constraint is proposed. An under-constraint status, if it exists, can be recognized with given locating scheme. All un-constrained motions of a workpiece in an under-constraint status can be automatically identified. This assists the designer to improve deficit locating scheme and provides guidelines for revision to eventually achieve deterministic locating.
TL;DR: In this paper, the implementation of an advanced master-slave teleoperator system using cable-driven WAM and PHANToM devices is presented, where the pragmatic issues on the implementation based on two different designs of the teleoperator control schemes and the performance of the system under these two tele operator control schemes are discussed.
Abstract: Bilateral teleoperation involves the motion control of a slave mechanism with a master mechanism that is capable of reflecting the sensory information such as force and torque signals captured from the master mechanism. Normally, the master and slave mechanisms in a teleoperator system are physically separated and are connected via some communication interface. As technology in robotic mechanism design continuously develops, advanced teleoperator systems are emerging. From the handling of hazardous and delicate materials in nuclear decommissioning to medical applications such as orthopedic and laparoscopic surgery, the demand for high bandwidth and fine-force reflecting bilateral teleoperator systems has become more and more important. This paper focuses on the implementation of an advanced master–slave teleoperator system using cable-driven WAM and PHANToM devices. Special emphasis is placed on the pragmatic issues on the implementation based two different designs of the teleoperator control schemes and the performance of the system under these two teleoperator control schemes.
TL;DR: In this article, a heuristic approach is presented to solve two core problems of a good facilities design, namely facility location and facility layout, which can be formulated as p -median clustering problems.
Abstract: Facilities design is closely related to efficient use of available resources. This paper presents a heuristic approach to solve two core problems of a good facilities design: facility location and facility layout. The latter group of problems will be solved for warehouse and production systems in particular. All these problems can be formulated as p -median clustering problems. Teitz and Bart (Oper. Res. 16 (1968) 955–961) developed the vertex substitution method to solve those problems. This paper introduces effective improvements on this heuristic. The approach is tested on a large number of randomly generated cases and on problems taken from the literature. The results demonstrate the effectiveness and superiority of our method.
TL;DR: In this paper, the design of a micro-assembly cell is discussed along with the development of a virtual assembly environment to study microassembly problems and issues, and a genetic algorithm-based assembly sequence generator is discussed which works in coordination with a 3D path planning approach.
Abstract: The term ‘micro-assembly’ is used to describe the assembly of micron-sized parts that are extremely small (in the order of 10 −6 m). As manual assembly of micro-devices is extremely difficult and tedious, there is a need to design computer-controlled approaches to facilitate rapid assembly. In this context, the design of automated or semi-automated environments for micro-assembly applications becomes important. In this paper, the design of a micro-assembly cell is discussed along with the development of a virtual assembly environment to study micro-assembly problems and issues. A genetic algorithm-based assembly sequence generator is discussed which works in coordination with a 3D path planning approach. A physical micro-assembly cell has been created to aid in the assembly of such micro-devices. This physical cell is interfaced with a virtual reality (VR)-based assembly environment to assist in the micro-assembly activities and comprises of micro-positioners, a micro-gripper (for pick-and-place operations to complete specific micro-assembly tasks), and a camera (to provide guidance and feedback during and after assembly).
TL;DR: The concept of the PLF is introduced, including descriptions of GDEs and engineering symbols, as well as the method of how to define them, and the solution to the problems of PLF modeling is provided.
Abstract: This paper introduces the concept of the PLF (Product Layout Feature), including descriptions of GDEs (Geometric Datum Elements) and engineering symbols, as well as the method of how to define them, and provides a solution to the problems of PLF modeling. As a result of the solution, collaborative design activities among multi-teams from different disciplines can be consistently carried out on PLF models in the PDM environment. It resolves the tough problem of consistently maintaining a product scheme to prevent defects arising from inconsistent general design data or incorrect versions of the layout scheme existing within the schemes of downstream design. By using the principles of the given method and utilizing previous research projects, a prototype system is developed to support collaborative design based on the PLF model in complicated product design.
TL;DR: The development of a distributed chromosome GA to reduce the execution time of GARP, a genetic algorithm for packing three-dimensional non-convex objects having cavities and holes, which allows the Sinterstation 2000 to be used more productively by designing a packing method for multiple parts.
Abstract: Genetic algorithms (GAs) are excellent approaches to solving complex problems in optimization with difficult constraints. The classic bin-packing optimization problem has been shown to be a NP-complete problem. The loading multiple parts into the build cylinder of a rapid prototyping machine is a type of a bin-packing optimization problem. There are GA applications that work with variations of the bin-packing problem, such as stock cutting, vehicle loading, air container loading, scheduling, and knapsack problems. These applications are mostly based on one-dimensional or two-dimensional considerations, using very specific assumptions. Ikonen et al. (A genetic algorithm for packing three-dimensional non-convex objects having cavities and holes. In: Proceedings of the Seventh International Conference on Genetic Algorithms. Michigan State University, July 19–23, 1997.) have developed a GA for rapid prototyping called GARP, which utilizes a three-dimensional chromosome structure for the bin-packing of a Sinterstation 2000s build cylinder. GARP allows the Sinterstation 2000 to be used more productively by designing a packing method for multiple parts. GARP was developed using a sequential GA, so execution time is influenced by the number of parts to be packed. Anticipating greater use of time compression technologies, GARP's execution time needs to be reduced. This paper will detail the development of a distributed chromosome GA to reduce the execution time of GARP. The implementation of this distributed GA will improve the efficiency of GARP, by using multiple CPUs to help solve the problem of bin-packing the build cylinder for the rapid prototyping machine.