Showing papers in "Robotics and Computer-integrated Manufacturing in 2001"

Manufacturing cost modelling for concurrent product development

Abstract: This research work aims to develop an intelligent knowledge-based system that accomplishes an environment to assist inexperienced users to estimate the manufacturing cost modelling of a product at the conceptual design stage of the product life cycle. Therefore, a quicker response to customers’ expectations is generated. This paper discusses the development process of the proposed system for cost modelling of machining processes. It embodies a CAD solid modelling system, user interface, material selection, process/machine selection, and cost estimation techniques. The main function of the system, besides estimating the product cost, is to generate initial process planning includes generation and selection of machining processes, their sequence and their machining parameters. Therefore, the developed system differs from conventional product cost estimating systems, in that it is structured to support concurrent engineering. Manufacturing knowledge is represented by hybrid knowledge representation techniques, such as production rules, frames and object oriented. To handle the uncertainty in cost estimation model that cannot be addressed by traditional analytical methods, a fuzzy logic-based knowledge representation is implemented in the developed system. Based on the analysis of product life cycle, the estimated cost included material, processing, machine set-up and non-productive costs. A case study is discussed and demonstrated to validate the proposed system.

Machining of aerospace titanium alloys

Abstract: The performance of PCBN (AMBORITE*) and PCD (SYNDITE) has been compared with that of coated tungsten carbide tool currently being used to machine titanium aerospace alloy. Tests confirm that SYNDITE gives a better surface finish, longer tool life and more manageable swarf than other tools. In addition, the “quick-stop” technique establishes that, for all three cutting tools, a layer is formed between the rake face and the underside of the emerging chip which has a fundamental effect on cutting and wear mechanisms.

Robot calibration using a 3D vision-based measurement system with a single camera

Abstract: One of the problems that slows the development of off-line programming is the low static and dynamic positioning accuracy of robots. Robot calibration improves the positioning accuracy and can also be used as a diagnostic tool in robot production and maintenance. This work presents techniques for modeling and performing robot calibration processes with off-line programming using a 3D vision-based measurement system. The measurement system is portable, accurate and low cost, consisting of a single CCD camera mounted on the robot tool flange to measure the robot end-effector pose relative to a world coordinate system. Radial lens distortion is included in the photogrammetric model. Scale factors and image centers are obtained with innovative techniques, making use of a multiview approach. Results show that the achieved average accuracy using a common off-the-shelf CCD camera varies from 0.2 to 0.4 mm, at distances from 600 to 1000 mm from the target, respectively, with different camera orientations. Experimentation is performed on two industrial robots to test their position accuracy improvement using the calibration system proposed: an ABB IRB-2400 and a PUMA-500. The robots were calibrated at different regions and volumes within their workspace achieving accuracy from three to six times better when comparing errors before and after calibration, if measured locally. The proposed off-line robot calibration system is fast, accurate and easy to set up.

A preliminary study on the potential use of the analytical hierarchical process (AHP) to predict advanced manufacturing technology (AMT) implementation

Abstract: The implementation of advanced manufacturing technology (AMT) requires not only substantial investment in the technology, but also changes in the culture and organizational structure of the organization. It requires careful planning at all levels of the organization to ensure that the implementation will achieve the intended goals. It is a complex process with many factors to be considered before the full benefits of AMT can be realized. A preliminary study on the potential use of the analytical hierarchical process (AHP) has been proposed to help the organizations in planning the AMT implementation process. The AHP method has the ability to structure complex, multi-person, multi-attribute, and multi-period problem hierarchically. Pairwise comparisons of the element (usually, alternatives and attributes) can be established using a scale indicating the strength with which one element dominates another with respect to a higher-level element. This scaling process can then be translated into priority weights (scores). The AMT implementation process has been divided into stages or modules, and each module is independent of the other. Four main modules have been identified—the institutionalization, acceptance, routinization and infusion modules. The factors/elements in each module were identified from the literature and the relative importance for each element established by priority weights. Once the priority weights of the elements/determinants of the module have been calculated, the presence of the corresponding element in the companies will be evaluated. An evaluation rating of these elements multiplied by the established priority weights will determine the prediction weight for the elements and the module. The application of this procedure is described for the institutionalization module, and can be similarly extended to the other AMT implementation modules. By establishing the prediction weight for each module, the companies will be able to evaluate the strength of the corresponding factors present before embarking on the AMT, identify and create awareness of the essential elements in the AMT implementation process and identify the actions necessary before implementing AMT. The AHP can be a useful guide in the decision making process of AMT implementation, especially for small and medium scale industries.

Development of a web-based system for engineering change management

Abstract: Engineering changes (ECs) are changes and/or modifications in forms, fits, functions, materials, dimensions, etc., of products and constituent components. ECs usually induce a series of downstream changes. Multiple disciplines and responsibilities are therefore involved in managing ECs. Previous investigations conducted by the authors and other researchers have shown that paper-based and standalone computerised EC management (ECM) systems have limited support for such intensive teamwork and close communication. This paper proposes to establish a web-based framework that supports ECM procedures and activities. A web-based ECM system is able to provide better information sharing, simultaneous data access and processing and more prompt communication and feedback. The amount of paperwork and the throughput time of managing ECs are significantly reduced while the effectiveness and the efficiency are substantially improved. This paper focuses on discussing the issues of design, development, and implementation of this prototype web-based ECM system.

Process modeling and analysis of manufacturing supply chain networks using object-oriented Petri nets

Abstract: This paper presents a systematic methodology for modeling and analysis of manufacturing supply chain business processes. The proposed approach first employs Computer Integrated Manufacturing Open System Architecture (CIMOSA) behavior rules to model the business process routing structures of manufacturing supply chain networks. Object-oriented predicate/transition nets (OPTNs) are then developed for the modular modeling and analysis of process models. Based on the structure of OPTNs, a procedure to obtain the system's P -invariants through objects’ P -invariants is suggested. From the P -invariants obtained, system structural properties such as deadlock and overflow can be analyzed. By using Petri net unfolding techniques and by extracting the process model of each object from the entire process model, the sequencing analysis for operations in supply chain processes becomes possible. Several manufacturing supply chain examples are used to illustrate the effectiveness of the proposed method.

Rapid response manufacturing through a rapidly reconfigurable robotic workcell

Abstract: This article describes the development of a component-based technology robot workcell that can be rapidly configured to perform a specific manufacturing task. The workcell is conceived with standard and inter-operable components including actuator modules, rigid link connectors and tools that can be assembled into robots with arbitrary geometry and degrees of freedom. The reconfigurable “plug-and-play” robot kinematic and dynamic modeling algorithms are developed. These algorithms are the basis for the control and simulation of reconfigurable robots. The concept of robot configuration optimization is introduced for the effective use of the rapidly reconfigurable robots. Control and communications of the workcell components are facilitated by a workcell-wide TCP/IP network and device-level CAN-bus networks. An object-oriented simulation and visualization software for the reconfigurable robot is developed based on Windows NT. Prototypes of the robot workcells configured to perform the light-machining task and the positioning task are constructed and demonstrated.

A PC-based open robot control system: PC-ORC

Abstract: An open architecture manufacturing system pursues to integrate manufacturing components on a single platform. Therefore, a particular component can be easily added and/or replaced. In this paper, a modular and object-oriented approach for the PC-based open robot control (PC-ORC) system is investigated. A standard reference model for controlling robots, which consists of a hardware platform, an operating system module, and various application software modules, is first proposed. Then, PC-ORC system, which can reconfigure the control system in various production environments, is developed. The PC-ORC is constructed based upon the object-oriented method. Hence, it allows an easy implementation and modification of various modules. The PC-ORC consists of basic software, application objects, and additional hardware devices on a PC platform. Finally, by applying the proposed PC-ORC to a SCARA robot, the performance of the PC-ORC is examined.

Nonlinear regenerative chatter in turning

Abstract: Chatter is a topic of immense engineering importance because its occurrence in machining results in poor surface finish, promotes tool wear and hampers productivity. In this paper, a single degree of freedom, delay differential equation model is presented. The central idea of the model is the study of regenerative chatter effect, which qualitatively explains the nonlinear dynamics in machining. Stability charts are derived for the linearized case in a two dimensional phase plane (μ, Ω) with the bifurcation parameter μ representing the dynamic variation of the chip thickness, and the critical rotational speed Ω. The governing nonlinear equations are integrated in time by Adams Predictor corrector Method. Phase portraits are drawn between the instantaneous tool position x1 and the relative tangential velocity x2. It has been shown that in the absence of a cubic nonlinearity, the chatter response appears to be more chaotic.

A robust trajectory tracking control of a polishing robot system based on CAM data

Abstract: Polishing a die that has free-form surfaces is a time-consuming and tedious job, and requires a considerable amount of high-precision skill. In order to reduce the polishing time and cope with the shortage of skilled workers, a user-friendly automatic polishing system was developed in this research. The polishing system is composed of two subsystems, a three-axis machining center and a two-axis polishing robot. The developed polishing system with five degrees of freedom is able to keep the polishing tool normal to the die surface during operation. A sliding mode control algorithm with velocity compensation is proposed to reduce tracking errors. Trajectory tracking experiments showed that the effect of reducing the tracking error by the proposed sliding mode control is superior to that by the proportional derivative control. The polishing data is generated from computer-aided design (CAD) data or from teaching data by PolyCAM, a computer-aided manufacturing (CAM) system consisting of 4 modules: a geometric modeller, a CAD data exchange module, a polishing data generation module, and a graphic simulator. To evaluate the performance of the polishing robot system, some polishing experiments on a shadow-mask die were performed.

Micromechanism fabrication using silicon fusion bonding

Abstract: Silicon fusion bonding is studied as an enabling technology for the fabrication of microrobotic mechanisms. The e!ects of both surface activation technique and annealing temperature on bond strength are considered using a crack-opening technique. As part of the study, the relationship between patterned silicon feature size and the resulting bond strength is explored. Based on the experimental results, recommendations for an optimal silicon fusion bonding process for micromechanism fabrication are presented. The experimental results indicate that bulk silicon bonding strength can be achieved independent of feature size at temperatures as low as 3003C, with positive implications for micromechanism fabrication. 2001 Elsevier Science Ltd. All rights reserved.

Intelligent AGV driving toward an autonomous decentralized manufacturing system

Abstract: This paper proposes two methods that give intelligence to automatically guided vehicles (AGVs). In order to drive AGVs autonomously, two types of problems need to be overcome. They are the AGV navigation problem and collision avoidance problem. The first problem has been well known since 1980s. A new method based on the feature scene recognition and acquisition is proposed. The sparse distributed memory neural network (SDM) is employed for the scene recognition and acquisition. The navigation route for the AGV is learnt by use of Q-learning depending on the recognized and acquired scenes. The second problem is described as mutual understanding of behaviors between AGVs. The method of mutual understanding is proposed by the use of Q-learning. Those two methods are combined together for driving plural AGVs autonomously to deliver raw materials between machine tools in a factory. They are incorporated into the AGVs as the machine intelligence. In experimental simulations, it is verified that the first proposed method can guide the AGV to the suitable navigation and that the second method can acquire knowledge of mutual understanding of the AGVs’ behaviors.

The definition of assembly line balancing difficulty and evaluation of balance solution quality

Abstract: Assembly line balancing is a classic ill-structured problem where total enumeration is infeasible and optimal solutions uncertain for industrial problems. A quantitative approach to classifying problem difficulty and solution quality is therefore important. Two existing measures of difficulty, order strength and west ratio are compared to a new compound expression of difficulty, project index. Project index is based on individual assessment of precedence (precedence index) and task time (task time index). The current working definition of project index is given. Early criteria for judging assembly lines use balance delay and smoothness index, both are flawed as criteria. Line and balance efficiency are developed as more appropriate. Project index, line and balance efficiency will be illustrated for a published test-case examined by the “A∼Line” balancing package. The potential for a “learning” approach, selecting models to suit problems using the measures of difficulty, will form part of the conclusions within this paper.

Next generation stamping dies — controllability and flexibility

Abstract: In sheet metal forming, external energy is transferred to sheet metal through a set of tooling to plastically deform a workpiece. The design of the tooling and its associated forming process parameters play important roles in this manufacturing process since they directly affect the quality and cost of the final product. With increasing demands from customers, government regulations, and global competition, the controllability and flexibility of stamping dies have been challenged. In this paper, we will summarize the research activities conducted at the Advanced Materials Processing Laboratory at Northwestern University in the area of sheet metal forming. An overview of our approach towards the system will be given followed by a summary of individual projects in the areas of failure prediction, design and control of a variable binder force, and the segmented die design with local adaptive controllers.

Development of a sensor information integrated expert system for optimizing die polishing

Abstract: This paper presents a polishing expert system integrated with sensor information which can modify the polishing sequence and conditions initially set by the system using the on-site polishing status detected. A practical system using AE sensors is developed for rotational and curved-surface polishing. A database and a knowledge base for polishing processes are established by using the results of experiments and also expert's experience. Evaluations are performed for a die of an automobile headlight lamp by using both the sensor-integrated expert system and the expert system without sensor. The results show that the sensor-integrated expert system provides more optimal polishing conditions since the proposed system takes advantage of the on-line sensor information.

A study of the build-time estimation problem for Stereolithography systems

Abstract: In this paper the problem of build-time estimation for Stereolithography systems is examined. Experimental results from various case studies indicate that the accuracy of estimation greatly depends on the type of part geometry representation processed and the uncontrolled laser power fluctuations. It is shown that estimation based on sliced (CLI) representation can be extremely accurate, assuming that the average laser power during fabrication can be predicted. On the other hand, estimations based on tessellated (STL) representation, although not so accurate, satisfy the accuracy requirements imposed at early stages of the Stereolithography process, where no slice data are available. As part of this study, build-time itself is also analyzed and factors affecting it are identified and investigated experimentally. Results indicate that hatching time depends not only on the hatching distance and speed, as originally assumed, but also on the number of hatching vectors employed.

Optimal shape error analysis of the matching image for a free-form surface

Abstract: When using an optical non-contact scanning system to measure an object that has a large surface, large curvature, or a full 360° profile, one can acquire only one set of sectional measurement points each time. For reconstructing the entire object, every set of sectional measurement points acquired at different positions must match. Therefore, the optimal shape error analysis for the matching image of two or more sets of sectional measurement points is desired. This paper presents a measurement system that combines two CCD cameras, one line laser and a three-axis motion stage. It forms an optical non-contact scanning system in association with the mathematical method of direct shape error analysis for the use in reverse engineering. This analysis and measurement system can be used for the profile measurements of free-form objects. It analyzes the matching image of a free-form surface with high efficiency and accuracy. The validity and applicability of this system are demonstrated by two practical examples.

A generalized Petri net modeling approach for the control of re-entrant flow semiconductor wafer fabrication

Abstract: Re-entrant flow manufacturing lines, such as occur in semiconductor wafer fabrication, are characterized by a product routing that consists of multiple visits to a workstation or group of workstations during the manufacturing process. In this paper, a modeling approach is based on the use of generalized Petri nets for a re-entrant flow manufacturing line is presented. Specifically, three Petri net models representing a re-entrant flow line with three work centers and six machines are modeled. How these models may be used to represent a variety of queuing disciplines and work release policies is discussed.

An integrated approach for the configuration of automated manufacturing systems

Abstract: The paper proposes a new integrated approach for supporting firms in their decisions of dimensioning automated production systems. The problem is closely related to the performance evaluation of the system since discriminating indicators are necessary to rank different alternatives. Traditionally, analytical methods and simulation have been used to evaluate the production system performance, with minor emphasis on the relationships between the tools and their use. Given the complexity of the problem, it is not possible to use only analytical methods that cannot enter deeply in problem details; at the same time the space of potential system configurations is too large to be evaluated by means of detailed tools such as simulation. In the proposed methodology, the problem is decomposed hierarchically into different sub-problems; each one has a different level of detail and a specific performance evaluation tool is used. At each level of the analysis, each system configuration is compared, by means of statistical tests, with the other alternatives with the purpose of discarding unprofitable solutions.

Integrated design-to-control approach for holonic manufacturing systems

Abstract: Next generation manufacturing systems will be integrated networks of distributed resources simultaneously capable of combined knowledge and material processing. These manufacturing systems will be required to be agile, flexible, and fault-tolerant. The objective of this research is to define a generic open architecture for such kind of distributed manufacturing systems, especially for holonic manufacturing systems (HMS). This paper will address issues associated with HMS, and propose a reference architecture based on a design-to-control concept. The primary focus will be given to the collaborative and integrated design-to-control approach based on machining feature, agent technology, and function block standards. Emphasis is also extended and given to metamorphic process planning and control of HMS using multi-agent negotiation and cooperation. The proposed approach, together with the open architecture, shows much promise for improving the entire manufacturing system performance under the ever-changing real-time and distributed shop floor environments.

Automatic verification of a manufacturing system

Abstract: Due to increasing complexity and costs involved, powerful techniques are needed to analyse manufacturing systems. In order to improve these techniques, which are often based on simulation, our research focuses on application of formal methods to manufacturing systems. We translate a simulation model into a format suitable for model checking. The advantage of model checking, as opposed to simulation, is that we can prove liveness, eventually something good will happen, and safety, something bad will never happen, properties of manufacturing systems. We applied our approach to a model of a manufacturing system consisting of a turntable, a drill, and a testing device. The model was written in the χ language, which has been used extensively to simulate large manufacturing systems. We translated the model into promela , the input language of the popular model checker spin . After that, we used spin to verify that the model does not have deadlock and that it makes progress under all circumstances.

Low-cost implementation of distance maps for path planning using matrix quadtrees and octrees

Abstract: Hierarchical tree representations are used for computing and representing distance maps in homogeneous or weighted 2D and 3D environments. It is shown that the matrix forms of quadtree and octree descriptions are proper for storing not only image or spatial data but also distance data. Distance maps are used in collision-free path planning in environments with static obstacles. The resulting sequences of free-region quadrants and octants enable to compute distance-optimized paths to the chosen resolution level. More illustrative examples are included and analyzed for 2D and 3D workspaces.

A genetic-based approach to simulation of self-organizing assembly

Abstract: The paper proposes a new and innovative biologically oriented idea in conceiving intelligent systems in modern factories of the future. The intelligent system is treated as an autonomous organization structure efficiently adapting itself to the dynamic changes in the production environment and the environment in a wider sense. Simulation of self-organizing assembly of mechanical parts (basic components) into the product is presented as an example of the intelligent system. The genetic programming method is used. The genetic-based assembly takes place on the basis of the genetic content in the basic components and the influence of the environment. The evolution of solutions happens in a distributed way, nondeterministically, bottom-up, and in a self-organizing manner. The paper is also a contribution to the international research and development program intelligent manufacturing systems, which is one of the biggest projects ever introduced.

Contoured edge slice generation in rapid prototyping via 5-axis machining

Abstract: Rapid prototyping, though a relatively new discipline, has proven to be a valuable tool in the reduction of the time and cost associated with developing new products. The value of rapid prototyping shows the promise of increasing even further as it matures and offers higher quality parts, in less time, and for lower costs. Improvements in these areas are all addressed in current rapid prototyping research in various ways. This paper presents a method for greatly improving the geometric accuracy, and thus the overall quality, of rapid prototype parts by making use of 5-axis machining. An algorithm is presented to generate the contoured edge slices for the rapid prototype parts in several levels of complexity. A simple algorithm is presented to generate a single edge contour for each section of the slice, and a more complex algorithm is also presented to allow for the 5-axis machining of “sub-layers” within a slice. It will be shown that sub-layer 5-axis machining provides the possibility to produce the most accurate rapid prototype parts on the market today. The benefits and limitations of the process will be enumerated and summarized. An inexpensive design for the implementation of a 5-axis machine configuration for a proposed sheet-based rapid prototyping process will be presented. A novel characteristic of the proposed process is that it does not require that the sheets be produced independently and post-assembled via a registration system. The process allows for the parts to be built up on a platen as the layers are cut, thus removing the need for a registration system and eliminating post-assembly errors. Sample parts and algorithm verification will also be presented.

Scheduling manufacturing systems in an agile environment

Abstract: Producing customized products to respond to changing markets in a short time and at a low cost is one of the goals in agile manufacturing. To achieve this goal customized products can be produced using an assembly-driven product differentiation strategy. The successful implementation of this strategy lies in efficient scheduling of the system. However, little research has been done in addressing the scheduling issues related to assembly-driven product differentiation strategies in agile manufacturing. In this paper, scheduling problems associated with the assembly-driven product differentiation strategy in a general flexible manufacturing system are defined, formulated, and solved. The manufacturing system consists of two stages: machining and assembly. At the machining stage, multiple identical machines produce parts. These parts are then assembled at the assembly stage to form customized products. The products to be produced in the system are characterized by their assembly sequences that are represented by different digraphs. The scheduling problem is to determine the sequence of products to be produced in the system so that the maximum completion time (makespan) is minimized for any given number of machines at the machining stage. The scheduling problems discussed in this paper have not been solved in the literature. The originality of the paper lies in defining and formulating the problems in the context of agile manufacturing and developing optimal and near-optimal for solving them. The heuristic algorithm solves the scheduling problem in two steps. First, an optimal aggregate schedule is determined by solving a two-machine flowshop problem. Next, the optimal aggregate schedule is decomposed by solving a simple integer programming formulation model. The computational experiment shows that the heuristics provide optimal and near-optimal solutions to the scheduling problems.

Knowledge intensive Petri net framework for concurrent intelligent design of automatic assembly systems

Abstract: The integration of design and planning of flexible assembly system has been recognized as a tool for achieving efficient assembly in a production environment that demands assembly with a high degree of flexibility. This paper proposes a concurrent intelligent approach and framework for the design of robotic flexible assembly systems. The principle of the proposed approach is based on the knowledge Petri net formalisms, incorporating Petri nets with more general problem-solving strategies in AI using knowledge-based system techniques. The complex assembly systems are modeled and analyzed by adopting a formal representation of the system dynamic behaviors through knowledge Petri net modeling from the specifications and the analysis of those models. A template is first defined for a knowledge Petri net model, and then the models for assembly system individuals are established in the form of instances of the template. The design of assembly systems is implemented through a knowledge Petri net-based function–behavior–structure model. The research results show that the proposed knowledge Petri net approach is applicable for design, simulation, analysis and evaluation, and even layout optimization of the flexible assembly system in an integrated intelligent environment. The integration of assembly design and planning process can help reduce the development time of assembly systems.

Human-like behavior of robot arms: general considerations and the handwriting task—Part I: mathematical description of human-like motion: distributed positioning and virtual fatigue

Abstract: This two-part paper is concerned with the analysis and achievement of human-like behavior by robot arms (manipulators). The analysis involves three issues: (i) the resolution of the inverse kinematics problem of redundant robots, (ii) the separation of the end-effector's motion into two components, i.e. the smooth (low accelerated) component and the fast (accelerated) component, and (iii) the fatigue of the motors (actuators) of the robot joints. In the absence of the fatigue, the human-like performance is achieved by using the partitioning of the robot joints into “smooth” and “accelerated” ones (called distributed positioning—DP). The actuator fatigue is represented by the so-called “virtual fatigue” (VF) concept. When fatigue starts, the human-like performance is achieved by engaging more the joints (motors) that are less fatigued, as does the human arm. Part I of the paper provides the theoretical issues of the above approach, while Part II applies it to the handwriting task and provides extensive simulation results that support the theoretical expectations.

Machine grouping using sequence-based similarity coefficients and neural networks

Abstract: Most neural network approaches to the cell formation problem do not use information on the sequence of operations on part types. They only use as input the binary part-machine incidence matrix. In this paper we investigate two sequence-based neural network approaches for cell formation. The objective function considered is the minimization of transportation costs (including both intracellular and intercellular movements). Constraints on the minimum and maximum number of machines per cell can be imposed. The problem is formulated mathematically and shown to be equivalent to a quadratic programming integer program that uses symmetric, sequence-based similarity coefficients between each pair of machines. Of the two energy-based neural network approaches investigated, namely Hopfield model and Potts Mean Field Annealing, the latter seems to give better and faster solutions, although not as good as a Tabu Search algorithm used for benchmarking.

Automated design of sheet metal punches for bending multiple parts in a single setup

Abstract: Sheet metal bending is a process in which bends are formed using a combination of a punch and a die. A very large number of mechanical products such as furniture panels, shelves, cabinets, housing for electro-mechanical devices, etc. are created by using the sheet metal bending process. Bending tools need to satisfy the following two criteria: (1) tools should be able to withstand bending forces, and (2) tool shapes should be such that there is no tool-part interference. In this paper, we describe a methodology for automatically designing shapes of bending punches for bending multiple parts in a single setup. We create parametric geometric models of punches. These parametric models describe the family of possible punch shapes. Using the part geometry and parametric punch shape models, we automatically generated constraints on tool parameters that eliminate the possibility of part-tool interference. We use mixed-integer techniques to identify parameters of punch shapes that result in the maximum punch strength. Finally, we perform strength analysis of the designed punch shape using "nite element analysis methods, to verify that the designed punch shape is capable of withstanding the bending forces. 2001 Elsevier Science Ltd. All rights reserved.

Human-like behavior of robot arms: general considerations and the handwriting task—Part II: the robot arm in handwriting

Abstract: This paper (Part II) investigates the motion of a redundant anthropomorphic arm during the writing task. Two approaches are applied. The first is based on the concept of distributed positioning which is suitable to model the “writing” task before the occurrence of fatigue symptoms. The second approach uses the concept of “virtual fatigue” (VF) which is a variable that dynamically behaves in a way analogous to the biological fatigue. VF enables the arm to reconfigure itself and take postures appropriate for the current level of fatigue. The study includes the analysis of legibility and inclination of handwriting, and a set of simulation results that show most practical aspects of robot human-like performance.